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From Wikipedia, the free encyclopedia

Klebsiella pneumoniae
K. pneumoniae on a MacConkey agar plate.
Scientific classification
Kingdom: Bacteria
Phylum: Proteobacteria
Class: Gamma Proteobacteria
Order: Enterobacteriales
Family: Enterobacteriaceae
Genus: Klebsiella
Species: K. pneumoniae
Binomial name
Klebsiella pneumoniae
(Schroeter 1886)
Trevisan 1887

Klebsiella pneumoniae is a Gram-negative, non-motile, encapsulated, lactose fermenting, facultative anaerobic, rod shaped bacterium found in the normal flora of the mouth, skin, and intestines.[1] It is clinically the most important member of the Klebsiella genus of Enterobacteriaceae; it is closely related to K. oxytoca from which it is distinguished by being indole-negative and by its ability to grow on both melezitose and 3-hydroxybutyrate. It naturally occurs in the soil and about 30% of strains can fix nitrogen in anaerobic condition.[2] As a free-living diazotroph, its nitrogen fixation system has been much studied.

Members of the Klebsiella genus typically express 2 types of antigens on their cell surface. The first, O antigen, is a lipopolysaccharide of which 9 varieties exist. The second is K antigen, a capsular polysaccharide with more than 80 varieties.[3] Both contribute to pathogenicity and form the basis for subtyping.



The Danish scientist Hans Christian Gram (1853–1938), developed the technique now known as Gram staining in 1884 to discriminate between K. pneumoniae and Streptococcus pneumoniae.

Klebsiella was named after the German bacteriologist Edwin Klebs (1834–1913).

Multiply-resistant Klebsiella pneumoniae have been killed in vivo via intraperitoneal, intravenous or intranasal administration of phages in laboratory tests.[4]

Clinical significance

It can cause Klebsiella pneumonia.

Research conducted at King's College, London has implicated molecular mimicry between HLA-B27 and two molecules in Klebsiella microbes as the cause of ankylosing spondylitis.[5] As a general rule, Klebsiella infections tend to occur in people with a weakened immune system from improper diet (alcoholics and diabetics). 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.

New antibiotic resistant strains of K. pneumoniae are appearing, and it is increasingly found as a nosocomial infection.[6]

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.

See also


  1. ^ Ryan KJ; Ray CG (editors) (2004). Sherris Medical Microbiology (4th ed. ed.). McGraw Hill. ISBN 0838585299.  
  2. ^ Postgate J (1998). Nitrogen fixation, 3rd ed.. Cambridge University Press.  
  3. ^ Podschun R, Ullman U (1998). "Klebsiella spp. as Nosocomial Pathogens: Epidemiology, Taxonomy, Typing Methods, and Pathogenicity Factors". Clinical Microbiology Reviews 11 (4): 589–603.  
  4. ^ [1]
  5. ^ Rashid T, Ebringer A (2006). "Ankylosing spondylitis is linked to Klebsiella-the evidence (Epub ahead of print)". Clin Rheumatol. PMID 17186116.  
  6. ^ [2]

External links



Up to date as of January 23, 2010

From Wikispecies


Main Page
Superregnum: Bacteria
Regnum: Bacteria
Phylum: Proteobacteria
Classis: Gamma Proteobacteria
Ordo: Enterobacteriales
Familia: Enterobacteriaceae
Genus: Klebsiella
Species: Klebsiella pneumoniae


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