Background:The emergence of carbapenem-resistant and hypervirulent hypermucoviscous Klebsiella pneumoniae strains poses a significant public health challenge. We determined the MDR profiles, antibiotic resistance factors, virulence gene complement, and hypermucoviscous features of 200 clinical K. pneumoniae isolates from two major tertiary care hospitals 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. Combined 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. Significant differences in resistance to gentamicin and levofloxacin were observed between the 200 isolates. Many of the isolates harbored genes specifying extended-spectrum and/or carbapenem-resistant β-lactamases: bla CTX-M-15 (46%), bla NDM-1 (39%), and bla OXA-48 (24%). The prevalence of the hypermucoviscous phenotype was 22% and 13% of the MDR isolates carried the rmpA gene (regulator for mucoid phenotype). Key virulence factor genes detected include those encoding: porins (ompK35 and ompK36; at 56 and 55% prevalence, respectively); adhesins (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.

Miniaturised antibiotic susceptibility testing: 100 times smaller microcapillary broth microdilution gives equivalent result to standard microplate broth microdilution.

Antibiotic resistance in urinary tract infections is a major global challenge and improved cost-effective and high throughput antibiotic susceptibility tests (AST) are urgently needed to inform correct antibiotic selection. We evaluated a high throughput microfluidic test strip for AST and minimum inhibitory concentration (MIC) determination in 20 urinary pathogenic E. coli (UPEC) isolates using six commonly prescribed or therapeutically beneficial antibiotics. The microfluidic MIC performs broth microdilution in 1 microliter volume capillaries, 100 X smaller than standard broth microdilution. Each test strip contains 10 parallel capillaries which are dipped into a single well of a 96 well plate, significantly increasing throughput over a microtitre plate. When tested with clinical UPEC isolates at standardised inoculum density, these devices gave 100% essential agreement (+/- 1 doubling dilution of antibiotic) to the gold standard microplate broth microdilution method described by CLSI. Although for some antibiotic/isolate combinations an earlier endpoint readout reduced accuracy, MIC test strips read at a 6h endpoint still gave 69 to 100 % essential agreement depending on the antibiotic. Growth could be detected significantly earlier than 6h, but with a trade-off between speed vs accuracy. These high-throughput, multiplexed test strips could be used to increase throughput and give faster results than microplates while retaining the core broth microdilution methodology of gold standard techniques for AST and MIC determination.

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