Taxonomy
Family: Fusobacteriaceae

Natural habitats
Normal commensals of the human oropharynx, gastrointestinale tract, and female genital tract.

Clinical significance
Infection caused by Fusobacterium varium is vary rare.
The organism has been isolated mostly from intra abdominal infections

Taxonomy
Family: Prevotellaceae

Natural habitats
Belong to the normal flora of the oropharynx, gastrointestinal tract, the genitals and urinary tract.

Clinical significance
Prevotella species are among the dominating microorganisms of the oral cavity, where they, despite their commensalism, can be involved in nearly all types of oral infections.

They are found in the mouth, pleural-, lung- and other infections and they are typical polymicrobial infections

History
Leptotrichia was among the first microorganisms described and probably recognized by van Leeuwenhoek already in 1683.

Taxonomy
Family: Leptotrichiaceae

Natural habitats
Leptotrichia colonize the oral cavity and genitourinary tract.
These anaerobic bacteria belong to the normal flora of humans and are seldom found in the clinically significant specimens.

Clinical significance
On rare occasions, Leptotrichia has been isolated from blood cultures of patients with lesions in the oral mucosa, in particular from patients with neutropenia.

These organisms should be considered potential pathogens in neutropenic patients, especially when breaks in the mucosal barriers are present through which they frequently spread to the bloodstream.

Taxonomy
Family: Fusobacteriaceae

Natural habitats
This bacterium is part of the normal flora of the mouth and pharynx, upper respiratory tract, sexual organs and gastrointestinal tract

Clinical significance
It is a key organism in maturation of pathogenic biofilms in periodontal pockets and considered an important pathogen in peri-implantitis, root and canal infection, dentoalveolar abscesses, and spreading odontogenic infections.

They have a wide range of infections, like blood, brain, chest, heart, lung, liver, appendix, joint, abdomen, genitourinary tract as well as infected human bite lesions.

Taxonomy
Family: Fusobacteriaceae

2 subspecies:
F. necrophorum subsp fundiliforme (biovar B) dominant isolate in humans
F. necrophorum subsp necrophorum is a commonly pathogen in animals

Natural habitats
Mainly isolated from the oral cavity

Clinical significance
This bacterium is extremely virulent and caused very severe infections, mostly in children or young adults, coming through a pharynges tonsillitis.

It was formerly the most anaerobic bacteria found in tonsillar abscesses of young adults.

They also occur in abscesses in the lungs, pleura and liver.

F. necrophorum is now less found than in the era before the use of antibiotics, so this bacterium is very treacherous, because doctors are not familiar with F. necrophorum.

A Gram-stained smear with highly pleomorphic Gram-negative rods in a positive blood culture bottle from a septic patient following a sore throat may indicate invasive Fusobacterium necrophorum infection.

Lemierre syndrome
Develops most often after a strep sore throat has created a peritonsillar abscess, anaerobic bacteria like Fusobacterium necrophorum can flourish.

The bacteria penetrate from the abscess into the neighboring jugular vein in the neck and there they cause an infected clot (thrombosis) to form, from which bacteria are seeded throughout the body by the bloodstream (bacteremia).

Pieces of the infected clot break off and travel through the lungs as emboli blocking branches of the pulmonary artery bringing the heart’s blood to the lungs.

This causes shortness of breath, chest pain and severe pneumonia.

Taxonomy
Family: Prevotellaceae
Genus: Seggatella oris
Formely: Prevotella oris

Natural habitats
Belong to the normal flora of the oropharynx, gastrointestinal tract, the genitals and urinary tract.

Clinical significance
Prevotella species are among the dominating microorganisms of the oral cavity, where they, despite their commensalism, can be involved in nearly all types of oral infections.

They are found in the mouth, pleural-, lung- and other infections and they are typical polymicrobial infections

Taxonomy
Family: Prevotellaceae

Natural habitats
Belong to the normal flora of the oropharynx, gastrointestinal tract, the genitals and urinary tract.

Clinical significance
Prevotella species are among the dominating microorganisms of the oral cavity, where they, despite their commensalism, can be involved in nearly all types of oral infections.

Some are important pathogens in bite wounds and infections of the head, mouth, neck and lungs and they are typical polymicrobial infections.

C. ureolyticus is phenotypically close to C. gracilis

They are actually microaerophilic rather than obligates anaerobes.

Taxonomy
Family: Bacteroidaceae
Formerly: Bacteroides ureolyticus

Natural habitats
They are part of the flora of the mouth.

Clinical significance
Isolated from patients with infections of the lung, neck, abdomen, oral cavity, urogenital, bone and tissue.

Bacteroides fragilis group, are the most frequently encountered anaerobes in clinical specimens.

They tend to be more virulent and drug resistant than most other anaerobes.

Therefore it is important to identify members of the B. fragilis group
Of these especially B. fragilis, B. thetaiotaomicron, and B. ovatus are highly relevant in human infections.

Taxonomy
Family: Bacteroidaceae
Genus: Phocaeicola vulgatus
Formely: Bacteroides vulgatus

Natural habitats
They inhabit the mucosal surfaces of the oral cavity, gastrointestinal tract and the gut of animals and human.

Clinical significance
They are involved in a variety of infections associated with considerable morbidity and mortality.

Anaerobic bacteria can occasionally spread to the adjacent tissues and the bloodstream with serious consequences.

In cases when gram negatives anaerobes gain entrance to the bloodstream and trigger a systemic inflammatory response, this may result in a sepsis or infective endocarditis with a fatal outcome.

Bacteroides fragilis group, are the most frequently encountered anaerobes in clinical specimens.

They tend to be more virulent and drug resistant than most other anaerobes.

Therefore it is important to identify members of the B. fragilis group
Of these especially B. fragilis, B. thetaiotaomicron, and B. ovatus are highly relevant in human infections.

Taxonomy
Family: Bacteroidaceae

Natural habitats
They inhabit the mucosal surfaces of the oral cavity, gastrointestinal tract and the gut of animals and human.

Clinical significance
They are involved in a variety of infections associated with considerable morbidity and mortality.

Anaerobic bacteria can occasionally spread to the adjacent tissues and the bloodstream with serious consequences.

In cases when gram negatives anaerobes gain entrance to the bloodstream and trigger a systemic inflammatory response, this may result in a sepsis or infective endocarditis with a fatal outcome.

Bacteroides fragilis group, are the most frequently encountered anaerobes in clinical specimens.

They tend to be more virulent and drug resistant than most other anaerobes.

Therefore it is important to identify members of the B. fragilis group
Of these especially B. fragilis, B. thetaiotaomicron, and B. ovatus are highly relevant in human infections.

Taxonomy
Family: Bacteroidaceae

Natural habitats
They inhabit the mucosal surfaces of the oral cavity, gastrointestinal tract and the gut of animals and human.

Clinical significance
They are involved in a variety of infections associated with considerable morbidity and mortality.

Anaerobic bacteria can occasionally spread to the adjacent tissues and the bloodstream with serious consequences.

In cases when gram negatives anaerobes gain entrance to the bloodstream and trigger a systemic inflammatory response, this may result in a sepsis or infective endocarditis with a fatal outcome.

Bacteroides fragilis group, are the most frequently encountered anaerobes in clinical specimens.

They tend to be more virulent and drug resistant than most other anaerobes.

Therefore it is important to identify members of the B. fragilis group
Of these especially B. fragilis, B. thetaiotaomicron, and B. ovatus are highly relevant in human infections.

Taxonomy
Family: Bacteroidaceae

Natural habitats
They inhabit the mucosal surfaces of the oral cavity, gastrointestinal tract and the gut of animals and human.

Clinical significance
They are involved in a variety of infections associated with considerable morbidity and mortality.

Anaerobic bacteria can occasionally spread to the adjacent tissues and the bloodstream with serious consequences.
In cases when gram negatives anaerobes gain entrance to the bloodstream and trigger a systemic inflammatory response, this may result in a sepsis or infective endocarditis with a fatal outcome.