Klebsiella pneumoniae

The genus Klebsiella are Gram-negative, anaerobic, rod-shaped bacteria with a prominent polysaccharide capsule. The organisms were discovered and named after Edwin Klebs, a 19th century German microbiologist. Members of the Klebsiella genus usually express two different types of antigens on their cell surface. The first is a lipopolysaccharide (O antigen); the other is a capsular polysaccharide (K antigen). Both of these antigens contribute to the pathogenicity of the organism. In addition, the Klebsiella genus are often resistant to many types of common antibiotics, including aminoglycosides, fluoroquinolones, tetracyclines, chloramphenicol, and trimethoprim/sulfamethoxazole.

Klebsiella infections most frequently occur in chickens with weakened immune systems. The most frequently reported Klebsiella species affecting poultry is K. pneumoniae.

Where it is found
K. pneumoniae is naturally fond throughout the environment (especially soil) and normal human and animal flora in the oral cavity, skin, and intestines. K. pneumoniae has been reported to be a common contaminate of wood products, which were a source of infection in dairy cattle farms.

K. pneumoniae is a common cause of mastitis in dairy cattle. Affected cows will shed K. pneumoniae in their feces, contaminating the surrounding environment with the organism.


  • Dairy cows
  • chickens