Klebsiella pneumoniae (K. pneumoniae), a Gram-negative bacterium that is facultative anaerobic, belongs to the Enterobacteriaceae family and the Klebsiella genus. It possesses a thick capsule, lacks spores and flagella, and typically colonizes the mucosal surfaces of the human body, particularly the oral and nasal mucosa as well as the gastrointestinal mucosa[1]. K. pneumoniae can survive in a multitude of ecological niches, including soil, water, a range of plant species, insects, birds, reptiles, and many different mammals, where it can exist as a commensal organism or act as a potential pathogen[2].
The majority of K. pneumoniae infections globally are opportunistic health-care-associated infections (HAIs). The most common manifestations are pneumonia, urinary tract and wound infections, any of which can progress to bacteraemia. Outside the hospital setting, K. pneumoniae can act as a “true” pathogen — that is, it can cause severe community-acquired infections (CAIs). Common CAIs include endophthalmitis, pneumonia, necrotizing fasciitis, non-hepatic abscess, meningitis and pyogenic liver abscess in the absence of biliary tract disease. The ability to cause infections in unusual and/or multiple sites is considered characteristic of hypervirulent K. pneumoniae infections, which are often accompanied by bacteraemia and/or metastatic spread[3]. The World Health Organization recognizes extended-spectrum β-lactam (ESBL)-producing and carbapenem-resistant K. pneumoniae (CRKp) as a critical public health threat[4] . In Europe alone, such strains reportedly account for >90,000 infections, >7,000 deaths annually[5].
The most highly resistant lineages of K. pneumoniae (for example, those resistant to third-generation cephalosporins and/or carbapenems) have become global problems. These include CG258, CG15, CG20 (CG17), CG29, CG37, CG147, CG101 (CG43) and CG307, which are not related to one another but are each widely geographically distributed and common causes of MDR HAIs and/or outbreaks[6]. K. pneumoniae is intrinsically resistant to ampicillin (that is, the aminopenicillin used to treat Gram-negative infections) through production of the class A β-lactamase enzyme SHV, encoded in the K. pneumoniae chromosome by the core gene blaSHV. Changes in expression and/or activity of the efflux pumps OqxAB and AcrAB have been associated with resistance to multiple antibiotics, such as fluoroquinolones, nitrofurantoin, tigecycline, chloramphenicol and carbapenems[7].
Hypervirulent K. pneumoniae infections are the most common in CG23, CG65 (including ST65 and ST375) and CG86. Hypervirulent K. pneumoniae clones typically carry a combination of virulence-associated variants of core pathogenicity factors (K1 or K2 capsules; O1 or O2 LPS) as well as accessory virulence factors (rmpA and/or rmpA2, and acquired siderophores ybt, iuc and iro). In rarer instances, strains with non-K1 or non-K2 capsules (for example, K5, K20, K54 and K57) and/or without the accessory virulence factors have also been reported to cause hypervirulent infections[8].
Samples collection date:
Samples host information:
O type information:
K type information:
Samples MLST information:
Samples phylogroup information:
Samples Virulence information:
Samples Resistance information:
[1] Bengoechea J A, Sa Pessoa J. Klebsiella pneumoniae infection biology: living to counteract host defences[J]. FEMS Microbiol Rev, 2019, 43(2): 123-144.
[2] Wyres K L, Holt K E. Klebsiella pneumoniae as a key trafficker of drug resistance genes from environmental to clinically important bacteria[J]. Curr Opin Microbiol, 2018, 45: 131-139.
[3] Russo T A, Marr C M. Hypervirulent Klebsiella pneumoniae[J]. Clin Microbiol Rev, 2019, 32(3): e00001–e00019.
[4] Shrivastava S R L, Shrivastava P S, Ramasamy J. World health organization releases global priority list of antibiotic-resistant bacteria to guide research, discovery, and development of new antibiotics[J]. Journal of Medical Society, 2018, 32(1): 76-77.
[5] Cassini A, Högberg L D, Plachouras D, et al. Attributable deaths and disability-adjusted life-years caused by infections with antibiotic-resistant bacteria in the EU and the European Economic Area in 2015: a population-level modelling analysis[J]. The Lancet Infectious Diseases, 2019, 19(1): 56-66.
[6] Wyres K L, Hawkey J, Hetland M A K, et al. Emergence and rapid global dissemination of CTX-M-15-associated Klebsiella pneumoniae strain ST307[J]. J Antimicrob Chemother, 2019, 74(3): 577-581.
[7] Liu B, Wu H, Zhai Y, et al. Prevalence and molecular characterization of oqxAB in clinical Escherichia coli isolates from companion animals and humans in Henan Province, China[J]. Antimicrob Resist Infect Control, 2018, 7: 18.
[8] Lee I R, Molton J S, Wyres K L, et al. Differential host susceptibility and bacterial virulence factors driving Klebsiella liver abscess in an ethnically diverse population[J]. Sci Rep, 2016, 6: 29316.