Abstract/Summary

Background The emergence of carbapenem resistant and hypervirulent hypermucoviscous Klebsiella pneumoniae strains poses a significant public health challenge. In this study, we elucidated the MDR profiles, antibiotic resistance factors, the virulence gene complement, and hypermucoviscous phenotypes and genotypes of a set of 200 clinical K. pneumoniae isolates from two major tertiary care hospitals located in Islamabad and Rawalpindi, Pakistan. Methods Susceptibility profiling and phenotypic analysis were performed according to the CLSI guidelines. Genetic determinants of antibiotic resistance and virulence were detected by PCR. Biofilm formation analysis was performed by microtiter plate assay. Results The isolates displayed a high degree of antibiotic resistance: 36% MDR-CRKP; 38% carbapenem resistance; 55% gentamicin resistance; 53% ciprofloxacin resistance; and 59% aztreonam resistance. In particular, the level of resistance against fosfomycin (22%) and colistin (15%) is consistent with previous reports of increased resistance levels. Simultaneous resistance to carbapenem and colistin was 7%. Genetic factors associated with colistin resistance (mcr-1 and mcr-2 genes) were detected in 12 and 9% of the isolates, respectively. For both carbapenemase producers and non-producers, significant differences (p <0.01) in levels of resistance to gentamicin and levofloxacin were observed. A high percentage of the isolates harbored genes specifying extended spectrum and/or carbapenem-resistant β-lactamases: blaCTX-M-15 (46%), blaNDM-1 (39%) and blaOXA-48 (24%). Overall, the prevalence of the hypermucoviscous phenotype was 22% and significant numbers (13%; p <0.00001) of the MDR isolates carried the rmpA gene (regulator for mucoid phenotype). Key virulence factor genes detected were those encoding: porins (ompK35 and ompK36; at 56 and 55% prevalence, respectively); fimbrial and non-fimbrial adhesions (fimH, mrkD and ycfM; at 19, 18 and 22% prevalence, respectively); and the polysaccharide regulator, bss, at 16% prevalence. Conclusion This report highlights carbapenem resistant K. pneumoniae (CRKP) prevalence, emerging resistance to fosfomycin and the presence of mcr-1 and mcr-2 in colistin-resistant isolates. Further, the detection of rmpA signifies the prevalence of the hypermucoviscous trait in CRKP clinical isolates from Pakistan.