Klebsiella pneumoniae

A Microbial Biorealm page on the genus Klebsiella pneumoniae

Classification

Higher order taxa

Domain: Bacteria;

Phylum: Proteobacteria;

Class: Gammaproteobacteria;

Order: Enterobacteriales;

Family: Enterobacteriaceae;

Genus: Klebsiella;

Species: K. pneumoniae

NCBI

Species

Klebsiella pneumoniae

NCBI: Taxonomy

Description and significance

Describe the appearance, habitat, etc. of the organism, and why it is important enough to have its genome sequenced. Describe how and where it was isolated. Include a picture or two (with sources) if you can find them.

K. pneumoniae is a gram negative bacterium. (5) K. pneumoniae is pathogenic and is commonly found in the gastrointestinal tract and hands of hospital personnel. (3) The reason for its pathogenicity is the thick capsule layer surrounding the bacterium. It is 160 nm thick of fine fibers that protrudes out from the outer membrane at right angles. (6) Another site on the human body that this bacteria can be found is the nasopharynx. Its habitat is not limited to humans but is ubiquitous to the ecological environment. This includes surface water, sewage, and soil. (4)

Genome structure

Describe the size and content of the genome. How many chromosomes? Circular or linear? Other interesting features? What is known about its sequence? Does it have any plasmids? Are they important to the organism's lifestyle?

The complete genome was determined in 2006 at the Genome Sequencing Center at Washington University in St. Louis. The genome was named Klebsiella pneumoniae subsp. pneumoniae MGH 78578. It includes one chromosome of 5.3 Mbp. There are five plasmids, pKPN3, pKPN4, pKPN5, pKPN6, and pKPN7. Respectively, each plasmid length is 0.18 Mbp, 0.11 Mbp, 0.089 Mbp, 0.0043 Mbp, and 0.0035 Mbp. The DNA is circular. The sequence of K. pneumoniae genome was found to be closely related that of Escherichia coli K-12. (1)

Cell structure and metabolism

Describe any interesting features and/or cell structures; how it gains energy; what important molecules it produces.

In 1992, K. pneumoniae could be determined apart from other species of Klebsiella. Two oligonucleotide probes and the hydroxylated fatty acid C14:0-2OH were distinctive of K. pneumoniae. (2)

Ecology

Describe any interactions with other organisms (included eukaryotes), contributions to the environment, effect on environment, etc.

Pathology

How does this organism cause disease? Human, animal, plant hosts? Virulence factors, as well as patient symptoms.

K. pneumoniae is an important cause of human infections. (See Description and significance) Infections or diseases are usually nosocomial or hospital-acquired. In 1998, K. pneumoniae and K. oxytoca accounted for 8% of nosocomial bacterial infections in the United States and in Europe. Diseases include urinary tract infections, pneumonia, septicemias, and soft tissue infections. (3) CPS and LPS O side chain are two of the most important virulence factors of K. pneumoniae (7) They serve to protect the bacterium from phagocytosis by the host.