Taxonomy
Family: Morganellaceae

P. alcalifaciens
- P. rustigianii (P. alcalifaciens biogroep 3)
P. rettgeri
P. stuartii

apathogeen P. heimbachae, P. vermicola

Natural habitats
They are ubiquitous in the environment, especially water and clinical samples, such as; urine, feces, blood, wounds and throat. Also occur in animals, mammals, birds, reptiles and insects.

Clinical significance
Patients with burns are at a higher risk of Providencia wound infection, like P. stuartii and P. rettgeri
Patients who develop Providencia urinary tract infections often have long-standing dependence on an indwelling urinary catheter.

Both species (P. rettgeri more commonly than P. stuartii) have recently been implicated as etiologic agents in traveler's diarrhea, making travel history important in patients with acute-onset diarrhea.

Vomiting is common in P. rettgeri gastrointestinal infection.