Klebsiella species
MICROBIOLOGY
- Gram-negative, lactose-fermenting aerobic bacilli [Fig 1] of Enterobacterales order, Enterobacteriaceae family.
- K. pneumoniae, K. oxytoca and K. granulomatis.
- K. ozaenae and K. rhinoscleromatis are non-fermenting subspecies.[10]
- Forms highly mucoid colonies with polysaccharide capsule [Fig 2], a virulence factor that inhibits phagocytosis.
- Colonizes mammalian intestinal and respiratory tracts.[9]
- Easily cultured on non-selective media for sterile specimens or MacConkey agar for contaminated specimens.
- Contaminates sinks[7] and causes nosocomial outbreaks, esp. K. pneumoniae, K. oxytoca.[11]
- K. pneumoniae, K. oxytoca and K. granulomatis.
- Resistance issues[14]
- Beta-lactamases are constitutive, usually produced at low levels, and confer resistance against ampicillin, amoxicillin and ticarcillin.
- Few klebsiellae lack these beta-lactamases.
- Extended-spectrum beta-lactamases (ESBLs) may be plasmid-mediated or chromosomal, confer multidrug resistance (TEM or SHV types), and are detected by in vitro resistance to ceftazidime and aztreonam.
- Carbapenemases:
- Klebsiella pneumoniae carbapenemase, KPC (Ambler Class A): confers broad resistance and is associated with mortality rate >50%.[13]
- Many isolates in the U.S. are sequence type, ST258, a biologically fit lineage that is able to cause outbreaks.[8]
- The phenotype includes strong potentiation of meropenem by vaborbactam.[8]
- Metallo-beta-lactamases (Ambler Class B): types include IMP (imipenemase), VIM (Verona integron-encoded MBL), and NDM-1 (New Delhi metallo-beta-lactamase).
- Require zinc ions in the active site for activity.
- IMP and VIM are not resistant to aztreonam.
- NDM-1 presence is strongly suggested by combined resistance to meropenem, ceftazidime, and cefepime together with clear susceptibility to aztreonam.[17]
- OXA-type carbapenemases (Ambler Class D): include OXA-48, weakly hydrolyze carbapenems, broad-spectrum cephalosporins, and aztreonam; express resistance or decreased susceptibility to carbapenems.
- Often associated with Acinetobacter baumannii.
- Klebsiella pneumoniae carbapenemase, KPC (Ambler Class A): confers broad resistance and is associated with mortality rate >50%.[13]
- Beta-lactamases are constitutive, usually produced at low levels, and confer resistance against ampicillin, amoxicillin and ticarcillin.
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Last updated: November 5, 2021
Citation
Spacek, Lisa A. "Klebsiella Species." Johns Hopkins ABX Guide, The Johns Hopkins University, 2021. Pediatrics Central, peds.unboundmedicine.com/pedscentral/view/Johns_Hopkins_ABX_Guide/540302/3.1/Klebsiella_species.
Spacek LA. Klebsiella species. Johns Hopkins ABX Guide. The Johns Hopkins University; 2021. https://peds.unboundmedicine.com/pedscentral/view/Johns_Hopkins_ABX_Guide/540302/3.1/Klebsiella_species. Accessed December 10, 2024.
Spacek, L. A. (2021). Klebsiella species. In Johns Hopkins ABX Guide. The Johns Hopkins University. https://peds.unboundmedicine.com/pedscentral/view/Johns_Hopkins_ABX_Guide/540302/3.1/Klebsiella_species
Spacek LA. Klebsiella Species [Internet]. In: Johns Hopkins ABX Guide. The Johns Hopkins University; 2021. [cited 2024 December 10]. Available from: https://peds.unboundmedicine.com/pedscentral/view/Johns_Hopkins_ABX_Guide/540302/3.1/Klebsiella_species.
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TY - ELEC
T1 - Klebsiella species
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A1 - Spacek,Lisa,M.D., Ph.D.
Y1 - 2021/11/05/
BT - Johns Hopkins ABX Guide
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PB - The Johns Hopkins University
DB - Pediatrics Central
DP - Unbound Medicine
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