Abstract
Klebsiella pneumoniae is an important nosocomial pathogen with an extraordinary resistant phenotype due to a combination of acquired resistant-elements and efflux mechanisms. In this study a detailed molecular characterization of 11 K. pneumoniae isolates of clinical origin was carried out. Eleven clinical isolates were tested for their susceptibilities, by disk diffusion and broth microdilution and interpreted according to CLSI guidelines. Efflux activity was determined by measuring the extrusion of ethidium bromide and biofilm formation was assessed following static growth in Müeller-Hinton and minimal media M9 broths at two temperatures and time points. Template DNA from all 11 isolates was extracted and sequenced. The study collection was found to be resistant to several (extended-spectrum beta-lactam) ESBL-type compounds along with several (fluoro)quinolones (FQ). Resistance to tetracycline accounted for 55% of the study collection (n = 6) and three of the 11 isolates were resistance to carbapenems. Genotyping identified blaCTX-M-15 (82%), blaSHV-12 (55%), and blaTEM-1B (45%) ESBL encoding genes and FQ resistance was associated the presence of the oqxAB operon, identified in 10 of the 11 isolates and qnrB gene in one isolate. The polymorphisms detected in the quinolone resistance-determining regions (QRDRs) were associated with isolates of the clonal group CG15. Sequence types (ST) identified were representative of previously described clonal groups including CG258 (n = 7), CG15 (n = 3), and CG147 (n = 1). Plasmid replicon type databases were queried indicating the presence of IncFII and IncFIB replicon types in the majority of the isolates (91%), followed by IncFIA (45%), and IncR (45%). Two of the 11 isolates were found positive for yersiniabactin siderophore-encoding genes. No differences in the ability to efflux ethidium bromide were identified. Biofilm formation was stronger when the isolates were grown under stressed conditions at 37°C for a period up to 96 h. These data confirm the fact that well-recognized clonal groups of K. pneumoniae of importance to human health carries a diverse repertoire of antimicrobial resistance determinants, particularly related to critically important drugs in the ESBL and FQ classes. The capacity of most isolates to form strong biofilms, when stressed under laboratory-simulated conditions, supports the risk to human health associated with nosocomial infections deriving from indwelling medical devices.
Highlights
Klebsiella pneumoniae is a non-motile, lactose-fermenting, capsulated bacillus belonging to the Enterobacteriaceae family
Results (Table 2) show that the Minimum Inhibitory Concentration (MIC) varied from 8 to 32 μg/mL in accordance with previous reports (Abuzaid et al, 2012; Guo et al, 2015). Results obtained using both of these Antibiotic Susceptibility Test (AST)-based protocols, indicate that all eleven bacterial isolates can be defined as multidrug resistant (MDR), since they were simultaneously resistant to three or more classes of antimicrobial compound
K. pneumoniae has been described over the past decades as an opportunistic pathogen associated with the healthcare setting wherein it is capable of causing severe illnesses
Summary
Klebsiella pneumoniae is a non-motile, lactose-fermenting, capsulated bacillus belonging to the Enterobacteriaceae family. Community-acquired (CA) infections are recognized by the expression of a hypermuicoid phenotype associated with the capsule producing serotypes K1 and K2 together with various siderophores (Shon et al, 2013). The latter can infect healthy individuals and this can lead to pyogenic liver abscesses (PLA), Lemierre’s syndrome, antibiotic-associated haemorrhagic colitis with the potential to disseminate to other parts of the body resulting in endophtalmitis and meningitis with mortality rates ranging from 5 up to 30% being reported (Janda, 2015)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
