Klebsiella oxytoca

Classification

Higher order taxa

Bacteria; Proteobacteria; Gammaproteobacteria; Enterobacteriales; Enterobacteriaceae

Species

NCBI: Taxonomy

Klebsiella oxytoca

Description and Significance

Klebsiella oxytoca is a gram-negative bacterium with a cylindrical rod shape measuring 2 µm by 5µm (7). In the 1950’s the strain M5aI was isolated with a notable characteristic of lacking a polysaccharide capsule. It was first named Aerobacter aerogenes and was later identified as K. pneumoniae, a strong pathogen that causes a form of Pneumoniae. It has recently been classified as K. oxytoca because it differs from K. pneumoniae in that it is indole-positive and able to grow on melezitose, but not 3-hydroxybutyrate.

Genome Structure

The genome for K. oxytoca has been sequenced in several strains. Virginia Bioinformatics Institute sequenced the genome for Klebsiella oxytoca KOX105 and determined the plasma length to be 0.0546Mbp with 0 chromosomes (10). The Genome Sequencing Center at Washington University in St. Louis sample sequenced Klebsiella oxytoca M5aI strain VJSK009 to -5.5X WGS coverage in plasmids and determined total genome length to be 5.28Mbp with 56% total GC content (11). The strain Klebsiella oxytoca KCTC1686 has been sequenced showing genome length of 5.97Mbp. Currently, 10 strains of Klebsiella oxytoca are being sequenced as part of the Human Microbiome Project.

Cell Structure and Metabolism

K. oxytoca have a gram-negative capsule composed of thick polysaccharide (K antigen) and lipopolysaccharide layer (O antigen) that protects them from phagocytosis and dessication, components of there cellular structure responsible for there pathogenicity (3). K. oxytoca is an anerobe (8) and can fix nitrogen (777) and can hydrolyze cellubiose (4). It is both catalase positive and indol positive (7). K. oxytoca produce Beta-lactamase, and so are highly resistant to penicillin and ampicillin (8).

Ecology

K. oxytoca like other Klebsiella spp. can be found in a range of environments, and are commonly referred to as ubiquitous and opportunistic in nature (7). K. oxytoca has been found in mammals and insects, where in humans, these microbes colonize along the mucosa membranes of the colon and nasopharynx, and sometimes skin, however they can be found colonizing on all parts of the body (5). Most infections of K. oxytoca are nosocomial, spreading via the hands of medical staff and outbreaks occuring in patients with immunodeficiency or medicated with antibiotics and have been reported to be found in both prenatal and neonatal infants (6).

Pathology

Species from the genus Klebsiella are frequently accountable for nosocomial infections in humans (7). They have the ability to colonize many different areas of the human body such as the skin, GI tract, sterile wounds, urine, and skin (9). While Klebsiella oxytoca does not cause as many of these infections as the more commonly known Klebsiella pneumonia, the genus Klebsiella was deemed responsible for 8% of all nonsocomial bacterial infections in the United States and Europe. Due to this incidence rate, Klebsiella spp. are considered one of the most significant infectious pathogens in the United States. The most common infections caused by Klebsiella spp. found in hospitals are as follows: urinary tract infections, pneumonia, wound infections, septicemia, neonatal septicemia, and nosocomial infections in ICU patients (7). Klebsiella oxytoca has increasingly been present in the blood samples of infants suffering from neonatal septicemia (10). Symptoms of neonatal septicemia include seizures, slow heart rate, temperature changes, jaundice, vomiting, diarrhea, low blood sugar, breaking difficulties, reduction in movements and sucking, and swollen abdomen (11).

Current Research

Klebsiella oxytoca was determined to be the cause of spontaneous arthritis in the knee of a 30-month old child with no prior history of any bacterial infections (12). The child had not been hospitalized recently, was up to date on all vaccinations, and did not present with a urinary tract infection. Normally, cases of spontaneous arthritis in children are associated with Staphylococcus aureus, Kingella kingae, and Streptococcus pneumonia (12). The patient was treated with antibiotics specific to each of those bacteria, respectively, which ultimately proved to be ineffective. During this time no changes occurred in the patient’s symptoms. The bacteria present in the synovial fluid of the knee was finally identified as K. oxytaca, and the antibiotic regimen was adjusted accordingly. The antibiotics, ceftriaxone and amikacin, were used for two days, then switched solely to ceftriaxone due to the results from antimicrobial susceptibility testing (12). X-rays taken post-antibiotic treatment showed a complete recovery in the child's knee.

References

(1) Podschun R., and Ullmann, U. "Klebsiella spp. as a nonsocomial pathogens: epidemiology, taxonomy, typing methods, and pathogenicity factors”. Clinical Microbial Revue. 1998. Volume 11. p. 489-603.

(2) Virginia Bioinformatics Institute (2012). Pathosystems Resource Integration Center: Klebsiella oxytoca KOX105; [accessed 2012 Feb 1. Available from: http://patricbrc.vbi.vt.edu/portal/portal/patric/Genome?cType=genome&cId=163830]

(3) Washington University in St. Louis. (2011). The Genome Institute at Washington University: Klebsiella oxytoca M5aI; [modified 2005 Dec 6; accessed 2012 Feb 1. Available from: http://genome.wustl.edu/genomes/view/klebsiella_oxytoca_m5al]

(4) Doran, J.B., and Ingram, L.O. (1993). Fermentation of Crystalline Cellulose to Ethanol by Klebsiella oxytoca containing Chromosomally Integrated Zymomonas mobilis Genes. Department of Microbiology and cell Science at the Univeristy of Florida, Gainsville, Florida. pp. 533-538.

(5) Charles River International Inc. Klebsiella species (K. oxytoca, K. pneumoniae). 2009.

(6) Berkowitz, L.B., and Umeh, O. (2011). Klebsiella Infections. Medscape Reference.

(7) Morozkina, E.V., and Zvyagilskaya, R.A. (2007). Nitrate Reductases: Structure, Functions, and Effect of Stress Factors.

(8) [http://www.bode-science-center.com/center/relevant-pathogens-from-a-z/klebsiella-oxytoca.html Haartmann. Klebsiella oxytoca (bacterium incl. ESBL).]

(9) Medscape Reference (2011). Drugs, Diseases & Procedures: Klebsiella Infections; [accessed 2012 Feb 15. Available from: http://emedicine.medscape.com/article/219907-overview#a0104]

(10) Sahly, H., and Podschun, R. “Clinical, bacteriological, and serological aspects of Klebsiella infections and their spondylarthropathic sequelae”. Clinical and Diagnostic Laboratory Immunology. 1997. Volume 4. p. 393-399.

(11) U.S. National Library of Medicine (2011). Medline Plus: Neonatal sepsis; [accessed 2012 Feb 15. Available from: http://www.nlm.nih.gov/medlineplus/ency/article/007303.htm]

(12) Mendard, A., et al. “First report of septic arthritis caused by Klebsiella oxytoca”. Journal of Clinical Microbiology. 2010. Volume 48. p. 3012-3023.