Klebsiella pneumoniae on Endo agar. Large, mucous colonies after 24 hours of cultivation in aerobic
As a general rule, Klebsiella infections tend to occur in people with a weakened immune system. Many of these infections are obtained when a person is in the hospital for some other reason (a nosocomial infection). The most common infection caused by Klebsiella bacteria outside the hospital is pneumonia.
Klebsiella ranks second to E. coli for urinary tract infections in older persons. It is also an opportunistic pathogen for patients with chronic pulmonary disease, enteric pathogenicity, nasal mucosa atrophy, and rhinoscleroma. Feces are the most significant source of patient infection, followed by contact with contaminated instruments.