previously Actinomyces naeslundii genospecies 2

Taxonomy
Family: Actinomycetaceae,

Natural habitats
They are commonly isolated in the human oral cavity and play a major role in the formation of oral biofilm or dental plaque.

Clinical significance
A. oris, A. odontolyticus, and A. viscosus are the primary Actinomyces species in infants' mouths as well as in early dental plaque.

A. oris it has also been linked to root caries, periodontal disease and even opportunistic infections such as actinomycosis.

Taxonomy:
Family: Bifidobacteriaceae

Natural habitat
Alloscardovia omnicolens, are inhabitants of the gastrointestinal tract and oral cavity of humans and animals and have been considered nonpathogenic for humans.

Clinical significance
However, the actual site of isolation and the clinical significance of A. omnicolens is unclear. This may be due in part to the difficulties in distinguishing this organism from other genera such as Actinomyces.

They appears to have a predilection for the urinary tract and they has also been isolated from blood, saliva, lung, and aortic valves abscesses.

Taxonomy
Family: Actinomycetaceae,
Genus: Schaalia turicensis
Formely: Actinomyces turicensis

Natural habitats
Is part of the indigenous microflora of human mucous membranes, may be isolated from human clinical sources without evidence of its pathogenicity.

Schaalia turicensis (A. turicensis ) is normally present in the vagina, gut, and skin on the lower part of the body

Clinical significance
It has also been isolated frequently from pilonidal sinuses, perianal an decubital abscesses, ear, nose and throat infections, post-operative wounds and IUCDs.

A. turicensis (Schaalia turicensis) has been described as a potential pathogen mostly in genital infections, followed by urinary tract infections and skin related infections

Actinomycosis, caused by Actinomyces israelii, less frequent by Actinomyces odontolyticus. (Schaalia odontolytica)

Taxonomy
Family: Actinomycetaceae,
Genus: Schaalia odontolytica
Formely: Actinomyces odontolyticus

Natural habitats
As with all other actinomycotic diseases, Schaalia odontolytica is an endogenous infection arising from the mucous membranes

Clinical significance
Clinical disease in patients with Schaalia odontolytica closely resembles disease caused by A. israelii and other actinomyces species.

Infections by Schaalia odontolytica primarily involve the cervicofacial regions, the chest, abdomen, and pelvis with rare involvement of the central nervous system, bones, and joints

Be aware of infections due to A. schaalii, it is a uropathogen with potential invasiveness leading to severe infections. Taxonomy
Family: Actinomycetaceae,
Genus: Actinotignum schaalii
Formerly: Actinobaculum schaalii

Genus: Actinotignum
A. schaalii
A. urinale

Natural habitats
The natural habitat of A. schaalii remains unknown, but it is probably part of the commensal flora of the human genital or urinary tract.

Clinical significance
They are associated with genital and urinary tract infections, mainly in elderly and patients with underlying urological conditions.

Some evidence suggests that this bacterium may also cause urinary tract infections among pediatric patients.

Investigation must be performed for patients for whom urine culture remains ‘sterile’ under aerobic conditions whereas many Gram-positive rods and leukocytes appear on smear microscopy and of patients who do not respond to treatments for UTIs.

Severe infections have also been described, such as urosepsis, bacteremia, cellulitis and endocarditis.

Bacteremia with A. schaalii is associated with a mortality rate of 16%, with over 50% of patients experiencing severe sepsis.

The pathogenic potential of coryneform bacteria has been underestimated

Taxonomy
Family: Corynebacteriaceae

Natural habitats
Part of the normal flora of skin, their potential pathogenicity still remains to be assessed.

They has been mainly isolated from skin, blood and from normally sterile body fluids

Clinical significance
C. mucifaciens should be considered as important human pathogen in patients with severe illness and compatible history of exposure even in individuals with no clearly identified immunosuppression.

C. mucifaciens has mainly been isolated from blood cultures and other sterile body fluids, but it has also been recovered from abscesses, soft tissue, dialysates, and cavitary pneumonia, as welkl as ear and nasaopharynx.

Corynebacterium species are becoming recognized as an increasing cause of opportunistic infections.

Paenibacillus is a genus originallt included within the genus Bacillus and than reclassified as a seperate genus in 1993.
The name reflects: Latin paene means almost, so paenibacilli are literally "almost bacilli".

Taxonomy
Family: Bacillaceae

Natural habitats
Ubiquitous in nature

Clinical significance
P. chibensis is rarely associated with human infections but has been reported as an opportunistic pathogen in immunocompromised individuals.
It can cause infections such as
- bacteremia
- wound infections
although such cases are uncommon.
The clinical significance of P. chibensis remains limited, but it should be considered in atypical infections in vulnerable patients.
They could cause allergies as a result of its histamine producing properties

Paenibacillus is a genus original included within the genus Bacillus and than reclassified as a seperate genus in 1993.
The name reflects: Latin paene means almost, so paenibacilli are literally "almost bacilli".

Taxonomy
Family: Bacillaceae

Natural habitats
Ubiquitous in nature

Clinical significance
P. amylolyticus is is generally considered non-pathogenic but has been associated with rare cases of opportunistic infections, particularly in immunocompromised individuals. It can cause wound infections, bacteremia, and other soft tissue infections.
Its clinical significance is limited, but it can be an emerging pathogen in certain high-risk settings.

Lactobacillus species produce lactic acid as their single or major metabolic end product from glucose fermentation

Taxonomy
Family: Lactobacillaceae
Genus: Ligilactobacillus murinus
Formely: Lactobacillus murinus

Natural habitats
They are widely distributed in the environment
They belong to the normal flora of the intestine, urogenital tract and mouth.

Clinical significance
Despite the reputation of lactobacilli as beneficial organisms, they can be involved in serious infections, especially in immunocompromised individuals.

Lactobacilli are particularly associated with advanced dental caries, where they are considered a secondary colonizer because of their preference for low-pH habitats, but probaply play a role in exacerbating existing lesions.

The clinical infections most commonly caused by lactobacilli are bacteremia and endocarditis, with an associated relatively high mortality rate, with the mouth, the primary route of entry to the bloodstream.

The pathogenic potential of coryneform bacteria has been underestimated

Taxonomy
Family: Corynebacteriaceae

Natural habitats
They are part of the normal oropharyngeal flora.

Clinical significance
This organism has not yet been fully recognized as a respiratory infection caused by C. propinquum.
Gram staining of the purulent sputum is an essential tool to evaluate wheter C. propinquum is a respiratory pathogen or not, because this organism is a commensal bacteria.

Corynebacterium species are becoming recognized as an increasing cause of opportunistic infections.

Most of the respiratory disease occurred in immunosuppressed hosts.

Taxynomy
Family: Cellulomonadaceae

Natural habitat
T. whipplei is all over in the environment, in sewage, plants and in human stools and saliva.

Clinical significance
1) classical Whipplei Disease (WD), which present with weight loss, diarrhea, and arthropathy in 75% of patients by the time of diagnosis.

2) isolated infection of cardiac valves without classical WD

3) asymptomatic carriers of T. whipplei. In these cases it is still unclear whether the asymptomatic carriers are only passing the agent through their stool.

T. whipplei infection also results quite often in cardiac, lung, and central nervous systen (CNS) signs and symptoms, which can occur even in the absence of gastrointestinal manifestations.

PAY ATTENTION
culture-negative endocarditis

Taxonomy
Family: Corynebacteriaceae
Genus: Turicella otitidis
Formely: Corynebacterium otitidis

Natural habitats
The habitat of T. otitidis seems to be confined almost exclusively to the ear or adjoining areas, and T otitidis does not appear to form part of the commensal flora at any other anatomical site.

Clinical significance
Its significans in acute or chronic otitis media is controversial.

The true pathogenic status of T. otitidis remains unclear, primely due to underreporting of the coryneform bacteria from many clinical specimens.
These organisms are often dismissed as contaminants by laboratorians and clinicians alike.

Therefore only in the presence of consistent reporting in association with clinical findings can the true pathogenicity of this organism be determined.

M. abscessus belongs to the family of nontuberculous mycobacteria (NTM) classified in the rapidly growing mycobacteria (RGM)

Taxonomy
Family: Mycobacteriaceae
Genus: Mycobacteroides abscessus
Formely: Mycobacterium abscessus

M. abscessus ssp abscessus
M. abscessus ssp massiliense
M. abscessus ssp bolletii

Natural habitats / RGM
They are ubiquitous in soil, water and dust.
It has been known to contaminate medications and products, including medical devices.

General information
Infections caused by M. absessus complex, are more difficult to treat because of antimicrobial drug resistance.

M. abscessus can cause a variety of infections such as post traumatic wound infection and disseminated cutaneous diseases and chronic otitis media, bacteremia and ocular and other infections..

It is also cause of serious lung infections in persons with various chronic lung diseases, such as cystic fibrosis.

Symptoms
Skin is usually red, warm, tender to the touch, swollen and painful.
Other signs of infection are fever, chills, muscle aches, and a general feeling of illnes.

Taxonomy
Family: Bifidobacteriaceae

Natural habitats
They can be found in the anorectal biota of healthy adults of both sexes as well as in that for children. It is also part of the endogenous vaginal biota of in women of reproductive age.
The optimal pH for the growth of G. vaginalis is between 6 and 7, at elevated pH in the vagina.
The organism can also be recovered from the urethras of the male partners of women with bacterial vaginosis.

Clinical significance
The "gold standard" for the diagnosis of BV (bacterial vaginosis) is direct examination of vaginal secretions and not the culture of G. vaginalis, since G. vaginalis can also be recovered from healthy women.
BV is examination of the vaginal discharge to detect thr typical "fishy" trimethylamine odor, wich is enhanced after alkalinization with 10% KOH.

The typical smear of vaginal discharge from BV patients shows "Clue cells" (bacteria covering epithelial cell margins) together with a mixed biota consisting of large numbers of gram-negative (predominantly Prevotella and Porphyromonas spp) and gram-variable (G. vaginalis) rods and coccobacilly, wheras lactobacilli are almost always absent.

The isolation of G. vaginalis can support the diagnosis of BV.

The pathogenic potential of coryneform bacteria has been underestimated

Taxonomy
Family: Corynebacteriaceae

Natural habitats
They are part of the oropharynx and the most frequent Corynebacterium isolated from throat swabs of healthy persons.
Its pathogenic potential remains unclear.

Clinical significance
Was originally described as being exclusively isolated from respiratory tract specimens,
They have now also been discovered from the gingiva, blood cultures, and abscesses.

C. durum was the Corynebacterium sp most frequently isolated from throat swabs, but it was not recovered from nasopharyngeal samples of healthy adults.
Therefore, its pathogenic potential remains unclear.

Paenibacillus is a genus originallt included within the genus Bacillus and than reclassified as a seperate genus in 1993.
The name reflects: Latin paene means almost, so paenibacilli are literally "almost bacilli".

Taxonomy
Family: Bacillaceae

Natural habitats
Soil and feed, for cattle and other livestock

Clinical significance
Paenibacillus pabuli clinical relevance in humans is limited, and there are few documented cases of infection or disease caused by this bacterium.
In summary, while P. pabuli may have therapeutic potential, it is not widely considered a major clinical pathogen in humans.

Paenibacillus is a genus originallt included within the genus Bacillus and than reclassified as a seperate genus in 1993.
The name reflects: Latin paene means almost, so paenibacilli are literally "almost bacilli".

Taxonomy
Family: Bacillaceae

Natural habitats
Ubiquitous in nature

Clinical significance:
Paenibacillus macerans is a bacterium that can also be associated with human infections, though these are rare.
Clinically, it has been isolated from wound infections, respiratory tract infections, and other medical conditions, particularly in immunocompromised individuals.
The clinical significance of Paenibacillus macerans mainly lies in its potential to cause opportunistic infections, but it is not typically considered a major pathogen. It may also be involved in nosocomial (hospital-acquired) infections, particularly in patients with underlying conditions or those with prolonged hospital stays.

Its antibiotic resistance profile and ability to survive in various environments make it noteworthy in clinical microbiology, especially in cases where conventional treatments fail.

Leprosy is also known as Hansen’s disease, after the scientist who discovered M. leprae in 1873.

Taxonomy
Family: Mycobacteriaceae

History
Leprosy has been around since ancient times, often surrounded by terrifying, negative stigmas and tales of leprosy patients being shunned as outcasts.

Outbreaks of leprosy have affected, and panicked, people on every continent.

The oldest civilizations of China and Egypt, and India feared leprosy was an incurable, mutilating, and contagious disease.

Natural habitats
This bacteria is believed to live in the soil.

Scientists think that the reservoir for this bacteria is the new world armadillos and African primates.

At the beginning the idea that the habitat of this bacteria was in soil was just an hypothesis but some research were done and DNA of the M. leprae was found in soil close to where people were infected with leprosy.

Its ideal temperature is about 30-33oC

Clinical significance
Leprosy
Is an infectious disease that causes severe, disfiguring skin sores and nerve damage in the arms and legs.

Leprosy is actually not that contagious.

You can catch it only if you come into close and repeated contact with nose and mouth droplets from someone with untreated leprosy.

Children are more likely to get leprosy than adults.

Symptoms
Leprosy primarily affects the skin and the nerves outside the brain and spinal cord, called the peripheral nerves.

It may also strike the eyes and the thin tissue lining the inside of the nose.

The main symptom of leprosy is disfiguring skin sores, lumps, or bumps that do not go away after several weeks or months.
The skin sores are pale-colored.

It usually takes about 3 to 5 years for symptoms to appear after coming into contact with the leprosy-causing bacteria. Some people do not develop symptoms until 20 years later.

There are three forms of the disease, with lepromatous being the most severe, tuberculoid, and borderline leprosy.
The precise mode of transmission is not fully understood.

The bacteria are likely spread by direct contact and through air dispersement, from coughing or sneezing.

Manifestations
Infected individuals will notice skin lesions in early stages, leader to paralysis or loss of sensation in those areas, and eventually loss of extremities.
Blindness can occur as the disease advances.

M. fortuitum belongs to the family of nontuberculous mycobacteria (NTM) classified in the rapidly growing mycobacteria (RGM)

Taxonomy
Family: Mycobacteriaceae
Genus: Mycobacteroides fortuitum
Formely: Mycobacterium fortuitum

M. fortuitum group
M. fortuitum
M. bonickei, M. houstonense, M. mageritense, M. mucogenicum, M. peregrinum, M. senegalense, M. septicum

Natural habitats / RGM
They are generally considered to be environmental saprophytes which are widely distributed in nature; they have been isolated from soil, dust, natural surface and municipal water, wild and domestic animals, and fish

Contaminated ice machines are a relatively important hospital reservoir for the RGM, especially M. fortuitum

Clinical significance
The most frequently recognized clinical diseases.
Localized post-traumatic wound infections. Surgical wound infections, especially following augmentation mammoplasty, cardiac surgery and catheter infections.

Localized infection in sporadic community-acquired disease usually occurs after a traumatic injury followed by potential soil or water contamination. Such injuries as stepping on a nail, motor vehicle accidents, compound fractures, etc., are typical of the clinical histories seen in patients with RGM disease.

Disseminated infections with M. fortuitum are rare.

The first case report appeared in 1990, when Sack described a patient with a history of intravenous IV drug abuse and AIDS, who had cutaneous lesions from which M. fortuitum was isolated. Cultures of specimens from lymph nodes, urine, pleural effusions, and feces all yielded M. fortuitum.

M. chelonae belongs to the family of nontuberculous mycobacteria (NTM) classified in the rapidly growing mycobacteria (RGM)

Taxonomy
Family: Mycobacteriaceae
Genus: Mycobacteroides chelonae
Formely: Mycobacterium chelonae

M. chelonae is further grouped in the M. chelonae-abscessus group
M. chelonae
M. abscessus
M. immunogenum

Natural habitats / RGM
They are generally considered to be environmental saprophytes which are widely distributed in nature; they have been isolated from soil, dust, natural surface and municipal water, wild and domestic animals, and fish.

They resist the activity of disinfectants and biocides such as organomercurials, chlorine, and alkaline glutaraldehyde

Clinical significance
The most frequently recognized clinical diseases.
M. chelonae in normal hosts, localized post-traumatic wound infections and post-traumatic or post-surgical corneal infections and catheter infections
M. chelonae in immunosuppressed persons.

Disseminated skin infections in patients receiving corticosteroids and in organ transplant recipients and catheter infections.

M. abscessus in normal hosts, chronic lung infections, localized post-traumatic wound infections and surgical wound infections and chronic otitis media.

M. abscessus in immunosuppressed persons.
Disseminated skin infections in patients receiving corticosteroids and in organ transplant recipients

Localized infection in sporadic community-acquired disease usually occurs after a traumatic injury followed by potential soil or water contamination.
Such injuries as stepping on a nail, motor vehicle accidents, compound fractures, etc., are typical of the clinical histories seen in patients with RGM disease.

Pulmonary disease with M .chelonae is uncommon, and other atypical mycobacteria such as M. avium complex, M. kansasii, and M. abscessus are the more likely lung pathogens.
Confirmation of the presence or absence of mycobacteria in clinical specimens has traditionally required culture, because of the relative insensitivity of direct microscopy.

In general, clinical specimens that are normally sterile, such as blood, cerebrospinal fluid, or serous fluids, can be inoculated directly onto media.

In comparison, nonsterile specimens, such as sputum or pus, must be chemically decontaminated first in order to eliminate common bacteria and fungi that would overwhelm the culture.

However, decontamination procedures may inhibit the growth of mycobacteria, especially NTM, as well.

R. equi ia a facultative intracellular micro-organism, who can survive an multiply in the macrophages.

Taxonomy
Family: Nocardiaceae
Genus: Prescotella equi
Formerly Corynebacterium equi / Rhodococcus equi

Natural habitats
In the environment, commonly found in dry and dusty soil, domesticated animals, (horses and goats), wild animals, bloodsucking arthropods, plants and in fresh and salt water.

Infection is primarily by inhalation of the bacteria, and also inoculation into a wound or mucous membrane and exposure to domestic animals.

Clinical significance
Are rarely found in humans.

At risk groups are immunocompromised people, such as HIV-AIDS patients or transplant recipients.

R. equi (P. equi) is still the most commonly found of this genus.
They are found in immune compromised patients, such as HIV, in these patients, the infection can be life threatening.

Possible infections, pneumonia, bacteremia, skin infections, endopthalmitis, peritonitis, catheter-related sepsis and abscess of the prostate.

Tsukamurella species are frequently misidentified as Rhodococcus or Corynebacterium species.

Taxonomy
Family: Tsukamurellaceae

Natural habitats
They have been found in soil, sludge, and arthropods.

Clinical significance
Are rarely found in humans.

Can cause opportunistic infections in humans.

Known infections are from the skin, peritonitis and catheter-related sepsis.

The Streptomyces group contains approximately 597 validly named species or subspecies and remains problematic. Many of these species have been patented because of the commercially useful products they synthesize.

Taxonomy Family: Streptomycetaceae

Natural habitats
In the environment, soil, sand and rotten plant material. Especially from North- and South America, Africa and Arabia.

Clinical significance
The most common type of infection is mycetoma, they penetrate in wounds in the skin.

Taxonomy
Family: Gordoniaceae

Natural habitats
In the environment, soil, marine sediments and wastewater systems.

Infection is primarily by inhalation of the bacteria.

Clinical significance
Are rarely found in humans. Pathogenicity is unknown.

This organism is known to cause infections in immunocompromised and immunocompetent hosts.
It can cause, skin infections, chronic pulmonary disease, catheter-related sepsis, wound infections and septicemia.

Taxonomy
Family: Gordoniaceae
Formerly called Rhodococcus bronchialis

Natural habitats
In the environment, soil, marine sediments and wastewater systems.

Infection is primarily by inhalation of the bacteria.

G. polyisoprenivorans is able to corrode rubber.

Clinical significance
Are rarely found in humans. Pathogenicity is unknown.

This organism is known to cause infections in immunocompromised and immunocompetent hosts.

It can cause, skin infections, chronic pulmonary disease, catheter-related sepsis, wound infections and b septicemia.

Formerly called Rhodococcus bronchialis

Taxonomy
Family: Gordoniaceae

Natural habitats
In the environment, soil, marine sediments and wastewater systems.
Infection is primarily by inhalation of the bacteria.

Clinical significance
Are rarely found in humans. Pathogenicity is unknown.

This organism is known to cause infections in immunocompromised and immunocompetent hosts.

It can cause, skin infections, chronic pulmonary disease, catheter-related sepsis, wound infections and b septicemia.

Formerly known as Oerskovia xanthineolytica

Taxonomy
Family: Promicromonosporaceae
Former name: Oerskovia xanthineolytica

Natural habitats
The environment like the soil, water, decaying plant material.

Clinical significance
Rarely cause human infections.

Infections mainly occur in immunocompromised patients and very often associated with a foreign body.

Taxonomy
Family: Nocardiaceae

Natural habitats
While the aerobic Actinomycetes are widely distributed in the environment, the extent to which particular species geographically restricted is not well known.

Their primary ecological niche is probably the decomposition of plants material.

Clinical significance
Nocardia infections generally result either from trauma related introduction of the organism or, particularly in immunocompromised patients, from inhalation and the resulting formation of a pulmonary focus.

The most common form of human nocardiosis disease is a slowly progressive pneumonia, the common symptoms of which include cough, dyspnea, and fever.

It is not uncommon for this infection to spread to the pleura or chest wall.

Every organ can be affected if a systemic spread takes place.
They are involved in the process of endocarditis and the infection can take the form of encephalitis and/or brain abscesses.

Taxonomy
Family: Nocardiaceae

Natural habitats
While the aerobic Actinomycetes are widely distributed in the environment, the extent to which particular species geographically restricted is not well known.

Their primary ecological niche is probably the decomposition of plants material.

Clinical significance
Nocardia infections generally result either from trauma related introduction of the organism or, particularly in immunocompromised patients, from inhalation and the resulting formation of a pulmonary focus.

The most common form of human nocardiosis disease is a slowly progressive pneumonia, the common symptoms of which include cough, dyspnea, and fever.

It is not uncommon for this infection to spread to the pleura or chest wall.

Every organ can be affected if a systemic spread takes place.
They are involved in the process of endocarditis and the infection can take the form of encephalitis and/or brain abscesses.

Taxonomy
Family: Nocardiaceae

Natural habitats
While the aerobic Actinomycetes are widely distributed in the environment, the extent to which particular species geographically restricted is not well known.
Their primary ecological niche is probably the decomposition of plants material.

Clinical significance
Nocardia infections generally result either from trauma related introduction of the organism or, particularly in immunocompromised patients, from inhalation and the resulting formation of a pulmonary focus.

The most common form of human nocardiosis disease is a slowly progressive pneumonia, the common symptoms of which include cough, dyspnea, and fever.

It is not uncommon for this infection to spread to the pleura or chest wall.

Every organ can be affected if a systemic spread takes place.
They are involved in the process of endocarditis and the infection can take the form of encephalitis and/or brain abscesses.

Taxonomy
Family: Nocardiaceae

Natural habitats
While the aerobic Actinomycetes are widely distributed in the environment, the extent to which particular species geographically restricted is not well known.

Their primary ecological niche is probably the decomposition of plants material.

Clinical significance
They produces an actinomycotic mycetoma in humans.
The pus can have sulfur granule or grain, a clumping of filamentous bacteria seen in infected living tissue, this is considered characteristic of the infection, but is not always present and is also not specific.

Isolates of this species are perhaps the most resistant of all Nocardia isolates

Taxonomy
Family: Nocardiaceae

Natural habitats
While the aerobic Actinomycetes are widely distributed in the environment, the extent to which particular species geographically restricted is not well known.

Their primary ecological niche is probably the decomposition of plants material.

Clinical significance
Nocardia infections generally result either from trauma related introduction of the organism or, particularly in immunocompromised patients, from inhalation and the resulting formation of a pulmonary focus.

The most common form of human nocardiosis disease is a slowly progressive pneumonia, the common symptoms of which include cough, dyspnea, and fever.

It is not uncommon for this infection to spread to the pleura or chest wall.

Every organ can be affected if a systemic spread takes place.

They are involved in the process of endocarditis and the infection can take the form of encephalitis and/or brain abscesses.

Taxonomy
Family: Nocardiaceae

Natural habitats
While the aerobic Actinomycetes are widely distributed in the environment, the extent to which particular species geographically restricted is not well known.

Their primary ecological niche is probably the decomposition of plants material.

Clinical significance
Nocardia infections generally result either from trauma related introduction of the organism or, particularly in immunocompromised patients, from inhalation and the resulting formation of a pulmonary focus.

The most common form of human nocardiosis disease is a slowly progressive pneumonia, the common symptoms of which include cough, dyspnea, and fever.

It is not uncommon for this infection to spread to the pleura or chest wall.

Every organ can be affected if a systemic spread takes place.

They are involved in the process of endocarditis and the infection can take the form of encephalitis and/or brain abscesses.

Lactobacillus species produce lactic acid as their single or major metabolic end product from glucose fermentation

Taxonomy
Family: Lactobacillaceae
Genus: Ligilactobacillus salivarius
Formely: Lactobacillus salivarius

Natural habitats
They are widely distributed in the environment
They belong to the normal flora of the intestine, urogenital tract and mouth.

Clinical significance
Despite the reputation of lactobacilli as beneficial organisms, they can be involved in serious infections, especially in immunocompromised individuals.

Lactobacilli are particularly associated with advanced dental caries, where they are considered a secondary colonizer because of their preference for low-pH habitats, but probaply play a role in exacerbating existing lesions.

The clinical infections most commonly caused by lactobacilli are bacteremia and endocarditis, with an associated relatively high mortality rate, with the mouth, the primary route of entry to the bloodstream.

Lactobacillus species produce lactic acid as their single or major metabolic end product from glucose fermentation

Taxonomy
Family: Lactobacillaceae
Genus: Lactocaseibacillus rhamnosum
Formely: Lactobacillus rhamnosum

Natural habitats
They are widely distributed in the environment
They belong to the normal flora of the intestine, urogenital tract and mouth.

Clinical significance
Despite the reputation of lactobacilli as beneficial organisms, they can be involved in serious infections, especially in immunocompromised individuals.

Lactobacilli are particularly associated with advanced dental caries, where they are considered a secondary colonizer because of their preference for low-pH habitats, but probaply play a role in exacerbating existing lesions.

The clinical infections most commonly caused by lactobacilli are bacteremia and endocarditis, with an associated relatively high mortality rate, with the mouth, the primary route of entry to the bloodstream.

Lactobacillus species produce lactic acid as their single or major metabolic end product from glucose fermentation

Taxonomy
Family: Lactobacillaceae

Natural habitats
They are widely distributed in the environment
They belong to the normal flora of the intestine, urogenital tract and mouth.

Clinical significance
Despite the reputation of lactobacilli as beneficial organisms, they can be involved in serious infections, especially in immunocompromised individuals.

Lactobacilli are particularly associated with advanced dental caries, where they are considered a secondary colonizer because of their preference for low-pH habitats, but probaply play a role in exacerbating existing lesions.

The clinical infections most commonly caused by lactobacilli are bacteremia and endocarditis, with an associated relatively high mortality rate, with the mouth, the primary route of entry to the bloodstream.

Lactobacillus species produce lactic acid as their single or major metabolic end product from glucose fermentation

Taxonomy
Family: Lactobacillaceae

Natural habitats
They are widely distributed in the environment
They belong to the normal flora of the intestine, urogenital tract and mouth.

Clinical significance
Despite the reputation of lactobacilli as beneficial organisms, they can be involved in serious infections, especially in immunocompromised individuals.

Lactobacilli are particularly associated with advanced dental caries, where they are considered a secondary colonizer because of their preference for low-pH habitats, but probaply play a role in exacerbating existing lesions.

The clinical infections most commonly caused by lactobacilli are bacteremia and endocarditis, with an associated relatively high mortality rate, with the mouth, the primary route of entry to the bloodstream.

Taxonomy
Family: Listeriaceae

Of the seven species within the genus Listeria, only L. monocytogenes and L. ivanovii are pathogenic.

Natural habitats
They are widely distributed in the environment

Clinical significance
Listeria ivanovii is primarily a pathogen of ruminants.

Systemic infections in immunodeficiency virus-infected and non-immunosuppressed patients have, however been described.

Is the bacterium that causes the infection listeriosis

It can grow and reproduce in the host’s cells and is one of the most virulent food-borne pathogens.

Taxonomy
Family: Listeriaceae

Of the seven species within the genus Listeria, only L. monocytogenes and L. ivanovii are pathogenic.

Natural habitats
They are widely distributed in the environment
They have been isolated from soil, decaying vegetables, sewage, water, animal feed, fresh and frozen poultry, raw milk, cheese and slaughter house waste.

Because of its widespread occurrence, L. monocytogenes has many opportunities to enter food productions and processing environments and, because of its ability to grow at 4oC, to cause human disease in persons ingesting colonized food.

Clinical significance
They cause the disease listeriosis, a serious infection caused by eating food contaminated with the bacteria.

The disease affects primarily pregnant women, the bacteria is able to cross the placenta, and infect the fetus, which may result in spontaneous abortion or stillbirth, newborns, and adults with weakened immune systems

Listeriosis is a serious disease for humans.
The two main clinical manifestations are sepsis and meningitis.

Meningitis is often complicated by encephalitis, a pathology that is unusual for bacterial infections

Microbacteria account for the majority of yellow-pigmented coryneform bacteria isolated from clinical samples

Taxonomy
Family:Microbacteriaceae

Natural habitats
Occur in the environment and in dairy products.

Clinical significance
Rarely causes an infection, but the infection can be serious.

Have been isolated from blood cultures, foreign-body infections, wound infections.

Diphtheriae is an acute, toxin-mediated disease caused by the bacterium C. diphtheria.

The name of the disease is derived from the Greek diphtheria, meaning ”leather hide”, because of the leathery layer that grows on the tonsils, throat, and nasal passage.

Taxonomy
Family: Corynebacteriaceae
- C. diphtheria biotype gravis
- C. diphtheria biotype mitis
- C. diphtheria biotype belfanti
- C. diphtheria biotype intermedius (lipophyl)

Natural habitats
Human carriers are the reservoir for C. diphteriae and are usually asymptomatic.

C. diphtheria can be isolated from the nasopharynx as well as from skin lesions, which actually represent a reservoir for the spread of diphtheria.

Transmission
Transmission is most often person-to-person contact or contact with items that have the bacteria on them, such as an infected person’s cup or used tissue.

Rarely, transmission may occur from skin lesions.

Clinical significance
C. diphtheria infects the nasopharynx or skin.

Toxigenic strains secrete a potent exotoxin which cause diphtheria.

Toxin production (toxigenicity) occurs only when the bacteria itself infected (lysogenized) by a specific virus (bacteriophage) carrying the genetic information for the toxin (tox gene). Only toxigenic strains can cause severe disease.

The symptoms of diphtheria include pharyngitis, fever, swelling of the neck or area surrounding the skin lesion.

Diphtheritic lesions are covered by an adherent pseudomembrane. (characteristic)

The toxin is distributed to distant organs by the circulatory system and may paralysis and congestive heart failure.

C. diphtheria may also cause cutaneous diphtheria.

Some people with poor hygienic standards (e.g., drugs or alcohol abusers) are prone to colonization on the skin, (more often than in the pharynx ) by C. diphtheria strains, which are often nontoxigenic.

Diphtheria spread easily, but can be prevented through the use of vaccines.

If left untreated, diphtheria can cause severe damage to kidneys, nervous system, heart and can be fatal.

The pathogenic potential of coryneform bacteria has been underestimated

C. ulcerans is , together with C. peudotuberculosis, the closest relative of C. diphteriae.

Taxonomy
Family: Corynebacteriaceae

Natural habitats
Part of the normal flora of humans and livestock.
Is a veterinary pathogen that causes mastitis in cattle.

Clinical significance
Disease associated with C. ulcerans is rare, but if they are recovered from pseudomembranous material, the disease must be treated like a case of diphtheria.
They can be transmitted from companion pets to humansa and cause significant infection.

The pathogenic potential of coryneform bacteria has been underestimated

Taxonomy
Family: Corynebacteriaceae

Natural habitats
They are part of the normal oropharyngeal flora.

Clinical significance
C. pseudodiphteriticum is part of the oropharyngeal microbiome.
This species has been documented to cause pneumonia in various patient populations, including causing a outbreak among cystic fibrosis patients.
Other infections attributed to this agent include UTIs, wounds, endocarditis, and skin ulcers.

Most of the respiratory disease occurred in immunosuppressed hosts.

The pathogenic potential of coryneform bacteria has been underestimated

Taxonomy
Family: Corynebacteriaceae

Natural habitats
They are part of the normal biota of the skin, particularly of inpatients.

Clinical significance
C. jeikeium is a frequently encountered Corynebacterium in clinical specimens, being associated with endocarditis, sepsis, prosthetic device, heart valve, bone marrow, bile, wounds UTIs and other infections.

Nosocomial transmission has been described.

It resistant to multiple antibiotics.

The pathogenic potential of coryneform bacteria has been underestimated

Taxonomy
Family: Corynebacteriaceae

Natural habitats
They are part of the normal biota of the skin.

Clinical significance
C. urealyticum is one of the relatively frequently isolated clinically significant corynebacteria in clinical specimens.

They are strongly associated with urinary tract infections. Recovery of this bacterium is often associated with urine with an alkaline pH, resulting in struvite crystals.

C. urealyticum bacteriuria occurs mainly in patients hospitalized for a long period, who are severely immunocompromised, urological manipulated, and elderly.

Recovery of the organism from urine does not always signify UTI, however, they are frequent colonizer of the skin of hospitalized patients with or without UTIs.

They have been considered an infrequent cause of infections other than UTI, including endocarditis, bacteremia, osteomyelitis, soft tissue infection, and wound infections.

The pathogenic potential of coryneform bacteria has been underestimated

Taxonomy
Family: Corynebacteriaceae

Natural habitats
They occur in the normal flora on both skin and oropharynx.

Clinical significance
Has rarely been reported as a pathogen, but they should be recognized as a potential pathogen in immunocompromised patients.
They are found to be clinically relevant when recovered from any sterile site excluding the eye.

The pathogenic potential of coryneform bacteria has been underestimated

Taxonomy
Family: Corynebacteriaceae

Natural habitats
They are part of the normal skin biota.

Clinical significance
C. amycolatum is the most frequently encountered nonlipophilic Corynebacterium species in human clinical material.

Urinary tract infections, bacteremia, respiratory tract and line infections

The pathogenic potential of coryneform bacteria has been underestimated

Taxonomy
Family: Corynebacteriaceae

Natural habitats
They are part of the normal biota of the skin and mucous membranes in humans and other mammals.

Clinical significance
C. accolens is found in specimens from the eyes, ears, nose, and oropharynx.
Evidence confirming the Corynebacterium isolates as the causative agents of these infection is not provided

Endocarditis of native aortic and mitral valves due to this agent has been described.

B.licheniformis, B.subtilis, B. amyloliquefaciens and B.pumilus comprise the subtilis group, which has been associated with food borne gastro-enteritis

Taxonomy
Family: Bacillaceae

Natural habitats
Spores occur in soil, on bird feathers, may survive severe heat treatment

Clinical significance:
Bacillus pumilus is generally considered non-pathogenic but can occasionally cause opportunistic infections, especially in immunocompromised individuals.
Clinical significance includes:
- Wound infections: Rare cases have been reported, particularly in individuals with weakened immune systems.
- Bacteremia: It has been linked to bloodstream infections in some cases, primarily in hospitalized patients.
- Contamination: B. pumilus can also be a contaminant in clinical samples and laboratory settings.
Although rarely pathogenic, B. pumilus is of interest for its potential in industrial applications, such as in the production of enzymes.

Taxonomy
Family:Micrococcaceae

Natural habitats
Is a normal in habitant of the mouth and upper respiratory tract.

Clinical significance
Isolated from dental carries and very rarely cause disease.

The most common infection is endocarditis, in people with underlying heart valve disorder.

Taxonomy
Family: Erysipelotrichaceae

Non pathogenic: E. tonsillarum and E. inopinata

Natural habitats
Is distributed worldwide in nature, and is carried by a variety of animals, mammals, birds and fish but is most frequently associated with pigs.

Contamination of water and soil from the feces and urine of sick and asymptomatic animals often occurs.

Clinical significance
They causes mostly erysipeloid, a localized cellulitis within 2-7 days around the inoculation side.

The disease is contacted through the skin abrasion, injury, or a bite on the hands or arms of individuals handling animals or animal products.

They include peritonitis, endophtalmitis, osteomyelitis, intracranial and spinal abscesses, prosthetic joint arthritis, pneumonia, and meningitis.

Erysipeloid
is an occupationaldisease, occurring most frequently among veterinarians, butchers, and particularly fish handlers.
The lesions usually violaceous and painful, indurated with edema inflammation but without suppuration, and clearly delineated at the border.

Dissemination and endocarditis can occur, especially in immunocompromised patients; their prognosis is generally poor.

Healing of erysipeloid usually takes 2-4 weeks, sometimes months, and relapses are common.

Lesions should be taken for Gram-staining and culture.

SWABS from the surface of the skin are not useful.

Taxonomy
Family: Dermabacteriacea

Natural habitats
They are part of the normal human skin biota

Clinical significance
Its role in clinic has not yet defined.

Various strains isolated in blood, abscesses or wounds

More than 90% of all clinical Brevibacterium are B. casei.

Taxonomy
Family: Brevibacteriaceae

Natural habitats
They are inhabitants of the human skin and can be found in dairy products, fresh and salt water, soil, sewage, fruits, vegetables and rice paddies.

Clinical significance
Rarely causes infection and then only in immunocompromised patients such as, osteomyelitis, peritonitis, bacteremia and malodorous feet

Malodorous feet
Sweat and bacteria is the cause of foot odor.
The most common bacteria Brevibacterium causes smelly feet.
Food odor usually appears to smell cheesy, similar to the smell of ammonia.

They are active on the soles of feet and between the toes.
The bacteria convert methionine to methanethiol, which smells like sulphur, that gives out the foul smell.

History
M. tuberculosis (MTB) was the cause of the "White Plague" of the 17th and 18th centuries in Europe. During this period nearly 100 percent of the European population was infected with MTB, and 25 percent of all adult deaths were caused by MTB

M. tuberculosis, then known as the "tubercle bacillus", was first described on 24 March 1882 by Robert Koch who subsequently received the Nobel Prize in physiology or medicine for this discovery in 1905; the bacterium is also known as "Koch's bacillus".

Tuberculosis has existed throughout history, but the name has changed frequently over time, consumption, phtisis, white plague

General information
MTB is an obligate aerobe.

For this reason, in the classic case of tuberculosis, are always found in the well-aerated upper lobes of the lungs.

The bacterium is a facultative intracellular parasite, usually of macrophages, and has a slow generation time, 15-20 hours, (a physiological characteristic that may contribute to its virulence), compared to other bacteria, which tend to have division times measured in minutes (Escherichia coli can divide roughly every 20 minutes).

It is a small bacillus that can withstand weak desinfectants and can survive in a dry state for weeks.

Its unusual cell wall, rich in lipids (e.g. mycolic acid), is likely responsible for this resistance and is a key virulence factor

Taxonomy
Family: Mycobacteriaceae

Natural habitats
MTB is the etiologic agent of tuberculosis in humans.

Humans are the only reservoir for the bacterium.

Clinical significance
Tuberculosis (TB) is the leading cause of death in the world from a bacterial infectious disease.

The disease affects 1.8 billion people/year which is equal to one-third of the entire world population.

Tuberculosis (TB)
Tuberculosis is caused by a bacterium called Mycobacterium tuberculosis. The bacteria usually attack the lungs, but TB bacteria can attack any part of the body such as the kidney, spine, and brain.

If not treated properly, TB can be fatal.

TB is spread through the air from one person to another.

The TB bacteria are put into the air when a person with TB of the lungs or throat coughs, sneezes, speaks, or sings. People nearby may breathe in these bacteria and become infected.

TB is NOT spread by
- shaking someone’s hand
- sharing food or drink
- touching bed linens or toilet seats
- sharing toothbrushes
- kissing

Not everyone infected with TB becomes sick.

As a result, two TB-related conditions exist: latent Tuberculosis and Tuberculosis

Latent Tuberculosis Infection
TB bacteria can live in the body without making you sick.
This is called latent TB infection.
In most people who breathe in TB bacteria and become infected, the body is able to fight the bacteria to stop them from growing.
People with latent TB infection do not feel sick and do not have any symptoms.
People with latent TB infection are not infectious and cannot spread TB bacteria to others.
However, if TB bacteria become active in the body and multiply, the person will go from having latent TB infection to being sick with TB disease. source: CDC

Tuberculosis
TB bacteria become active if the immune system can't stop them from growing.

When TB bacteria are active (multiplying in your body), this is called tuberculosis.

People with tuberculosis are sick. They may also be able to spread the bacteria to people they spend time with every day.

Many people who have latent TB infection never develop TB.
Some people develop TB soon after becoming infected (within weeks) before their immune system can fight the TB bacteria.

Other people may get sick years later when their immune system becomes weak for another reason. For people whose immune systems are weak, especially those with HIV infection, the risk of developing TB is much higher than for people with normal immune systems M. tuberculosis contain complex waxes & cord factor they prevent destruction by lysosomes and macrophages source: CDC

B.licheniformis, B. amyloliquefaciens, B.subtilis and B.pumilus comprise the subtilis group, which has been associated with food borne gastro-enteritis

Taxonomy
Family: Bacillaceae

Natural habitats
Spores are widely distributed in nature.

Clinical significance:
Bacillus subtilis is generally non-pathogenic, it can occasionally be associated with opportunistic infections, particularly in immunocompromised individuals.
It is also used in biotechnology for the production of enzymes and antibiotics.
However, in rare cases, it can cause wound infections, bacteremia, or respiratory infections in vulnerable patients.

Bacillus thuringiensis is distinguished by its characteristic parasporal crystals

Taxonomy
Family: Bacillaceae
Bacillus cereus group: B. anthracis, B. cereus, B. mycoides, B. thuringiensis

Natural habitats
Endospores are widespread in soil and many other environments.
The organism had been isolated from all continents, including Antartica.

Used as bio pesticide

Clinical significance
Bacillus thuringiensis is primarily known for its use as a biopesticide due to its production of insecticidal proteins (Cry toxins).
While it is not typically pathogenic to humans, it can cause rare infections in immunocompromised individuals, such as:
- Wound infections: In individuals with weakened immune systems.
- Bacteremia: Very rarely reported in clinical settings.
B. thuringiensis is more clinically significant as a biocontrol agent in agriculture rather than as a human pathogen. Its antibiotic susceptibility and potential for causing infections are minimal in healthy individuals.

Bacillus mycoides is distinguished by its characteristic rhizoid colonies and absence of motility.

Taxonomy
Family: Bacillaceae
Bacillus cereus group: B.anthracis, B.cereus, B.mycoides, B.thuringiensis

Natural habitats
Spores are widespread, soil, water, air foods etc

Clinical significance
Bacillus mycoides is generally considered non-pathogenic but has been occasionally linked to opportunistic infections in immunocompromised individuals, including:
- Wound infections: Rare cases have been reported, often in patients with pre-existing health conditions.
- Contamination: Due to its environmental prevalence, B. mycoides can also be a contaminant in clinical specimens.

Its clinical significance is limited, and infections are relatively uncommon.
The bacterium is often susceptible to a variety of antibiotics.

Taxonomy
Family: Bacillaceae
Genus: Priestia megaterium
Formely: Bacillus megaterium

Natural habitats
Spores occur in soil, dust, water and plants.

Clinical significance
Bacillus megaterium generally non-pathogenic, it can occasionally be associated with opportunistic infections, particularly in immunocompromised individuals.
Clinical significance includes:
Infections:
- Rarely, B. megaterium can cause infections such as wound infections, bacteremia, and endocarditis.
- Contamination: It is also a potential contaminant in clinical specimens due to its environmental presence.
Infections are typically treated with antibiotics, but the organism is often susceptible to a wide range of antimicrobial agents.

B.licheniformis, B.subtilis, B. amyloliquefaciens and B.pumilus comprise the subtilis group, which has been associated with food borne gastro-enteritis

Taxonomy
Family: Bacillaceae

Natural habitats
Spores occur in soil, dust, water, may survive severe heat treatment

Clinical significance B. licheniformis is generally non-pathogenic but can be an opportunistic pathogen in immunocompromised individuals.
Clinical significance includes:
- Wound infections: Rarely, B. licheniformis can cause infections in patients with compromised immune systems.
- Bacteremia: In rare cases, it has been linked to blood infections, particularly in hospitalized patients.
- Contamination: It can also contaminate clinical samples, laboratory cultures, or medical devices due to its environmental presence.
Overall, B. licheniformis is more recognized for its industrial applications, like enzyme production, than for its role in human disease.

Taxonomy
Family: Bacillaceae
Genus: Lederbergia lentus
Formely: Bacillus lentus

Natural habitats
Is found in soil

Clinical significance
Unknown, considered nonpathogenic.

Taxonomy
Family: Bacillaceae
Genus: Niallia circulans
Formely: Bacillus circulans

Natural habitats
Spores are numerous in soil.

Clinical significance
Bacillus circulans is rarely pathogenic but can cause opportunistic infections in immunocompromised individuals, such as:

- Wound infections: Particularly in patients with compromised immune systems or underlying health conditions.
- Bacteremia: Rare cases have been reported, especially in hospitalized patients.

B. circulans is more often associated with environmental contamination in clinical samples rather than being a primary cause of infection.
It is generally susceptible to a range of antibiotics.

General information
The genus name Trueperella has been proposed in honor of the German microbiologist Hans Georg Trüper.

Taxonomy
Family: Actinomycetaceae
Genus: Treuperella pyogenes
Formely: Actinomyces pyogenes, Arcanobacterium pyogenes

Natural habitats
They are not part of the normal flora of humans, but they are part of the normal flora of animals and also cause infections there

Clinical significance
T. pyogenes may cause pyogenische infections in animals.

Flies for the transmission are suspected to be vectors.

Infections in humans occurs mainly in rural areas; wounds

Cause of; acute pharyngitis, urethritis, cutane- or subcutaneous abscesses or septic arthritis in a diabetic.

Taxonomy
Family: Actinomycetaceae,
Genus: Schaalia turicensis
Formerly: Actinomyces turicensis

Natural habitats
Is part of the indigenous microflora of human mucous membranes, may be isolated from human clinical sources without evidence of its pathogenicity.

A. turicensis (Schaalia turicensis) is normally present in the vagina, gut, and skin on the lower part of the body

Clinical significance
It has also been isolated frequently from pilonidal sinuses, perianal an decubital abscesses, ear, nose and throat infections, post-operative wounds and IUCDs.

A. turicensis (Schaalia turicensis) has been described as a potential pathogen mostly in genital infections, followed by urinary tract infections and skin related infections

Actinomycosis, caused by Actinomyces israelii, less frequent by Actinomyces odontolyticus (Schaalia odontolytica)

Taxonomy
Family: Actinomycetaceae,
Genus: Schaalia odontolytica
Formerly: Actinomyces odontolyticus

Natural habitats
As with all other actinomycotic diseases, A. odontolyticus (Schaalia odontolytica) is an endogenous infection arising from the mucous membranes

Clinical significance
Clinical disease in patients with A. odontolyticus (Schaalia odontolytica) closely resembles disease caused by A. israelii and other actinomyces species.

Infections by A. odontolyticus (Schaalia odontolytica) primarily involve the cervicofacial regions, the chest, abdomen, and pelvis with rare involvement of the central nervous system, bones, and joints

Is proven to be an exception in this genus on account of its aerobic growth, microscopic morphology (no branching), and the types and locations of infections.

Taxonomy
Family: Actinomycetaceae,
Genus: Winkia neuii
Formerly: Actinomyces neuii

Natural habitats
They are most likely of endogenous origin.

Clinical significance
Winkia neuii rarely causes disease in humans
They are isolated from soft tissue abscesses, infected skin, endophthalmitis, bacteremias, and endocarditis

Actinomyces graevenitzii is a newly recognized Actinomyces species that is seldom isolated from clinical specimens.

This organism is an opportunistic human pathogen.

Taxonomy
Family: Actinomycetaceae

Natural habitats
It is possible a component of the oral pharyngeal flora.
Very little is known about the clinical features and pathogenesis

Clinical significance
A. graevenitzii is believed to be associated with classic actinomycosis.

Isolated from human clinical specimens, mainly respiratory tract secretions.

Taxonomy
Family: Bacillaceae

Bacillus cereus group: B. anthracis, B. cereus, B. mycoides, B. thuringiensis

Natural habitats
Soil inhabitant in sporulated form. Anthrax spores in soil can remain infectious for decades.

They are obligate pathogens.

Isolated from blood of animals and human with anthrax, animal carcasses and products and soil contaminated with spores

Clinical significance / ANTHRAX

- cutaneous anthrax
Infection occurs through a break in the skin. Following the incubation period of usually 2 to 3 days, a small papule appears, progressing over the next 24h to a ring of vesicles, with subsequent ulceration and formation of a characteristic blackened eschar.
Subsequent eschar formation may become thick and surrounded by extensive edema.
Fever and pus and pain at the side are normally absent; their presence probably indicate a secondary bacterial infection.

- gastrointestinal anthrax
The symptoms are the result of ulcerations developing primarily in the cecal and terminal ileal mucosae: vomiting, nausea and abdominal pain, accompanied by fever.

This can rapidly progress to bloody diarrhea and systemic infection

- inhalation anthrax / bioterrorism
The inhaled spores are ingested by macrophages and carried from the lungs to the lymphatic system, where the infection progresses.
During transit to lymph nodes, spores germinate into vegetative cells, begin to replicate and produce the capsule and toxins that lead to bacteremia and associated hemorrhage and necrosis.

Anthrax is high on the list of agents that could be used in biological warfare or bioterrorism.

Bacillus cereus group: B.anthracis, B.cereus, B.mycoides, B.thuringiensis

Taxonomy
Family: Bacillaceae

Natural habitats
Spores are widespread in the environment, e.g. soil, water, air or foods

Clinical significance
B. cereus is pathogenic of human and mammals, causing foodborne illness and opportunistic infections (e.g. endophtalmie, keratitis, septicemia, meningitis, endocarditis, pneumonia, osteomyelitis, urinary infections, cutaneous infections).

It is a destructive ocular pathogen.

Taxonomy
Family: Actinomycetaceae
Formally: Corynebacterium

Natural habitats
The natural habitat is not fully understood, but they are recovered from throat as well as from wound swabs.

Clinical significance
They have been isolated from the throat and wounds and are responsible for 0.5-2.5 % of bacterial pharyngitis, especially among adolescents (15-20 years).

Symptoms may resamble a β-hemolytic streptococci, viral infection or penicilline allergy.

A rash of the chest and of the abdomen, neck or extremities.

They often occurs in polymicrobial infections together with typical respiratory pathogens such as streptococci.

The isolation of classical pathogens from specimens that also contain A. haemolyticum might be in part responsible for the tendency to miss the organism.