Klebsiella pneumoniae carbapenemase production among K. pneumoniae isolates and its concern on antibiotic susceptibility

The emergence of Klebsiella pneumoniae carbapenemase (KPC) resistance has led to the countdown of activity of carbapenems, which were considered as drugs of last resort for infections caused by Enterobacteriaceae. The aims of the present study were the detection of KPC-production among K. pneumoniae isolates, select the appropriate method for its detection and assess the consequence of KPC production on the antibiotics susceptibility. One hundred and four non-duplicated K. pneumoniae isolates were collected from University teaching hospitals of Tabriz, Iran. The disk diffusion, E-test, and Modified Hodge test were performed for the determination of antibiotic susceptibility pattern, Minimum Inhibitory Concentrations (MICs) determination and the production of carbapenemase, respectively. BlaKPC-2 gene was detected by using PCR. High levels of resistance were observed towards co-trimoxazole (69.2%), followed by cefazolin (66.3%), ceftriaxone (65.4%), ofloxacin and ciprofloxacin (54.8%), gentamicin (50%), and amikacin (39.4%). According to the disk diffusion method, the frequency of imipenem and meropenem resistance was 31.7% and 32.7%, respectively. Colistin was the most effective antibiotic among panels of antibiotics tested. Imipenem MICs range, MIC50 and MIC90 were 0.19–32 μg/mL, 4 μg/mL, and 16 μg/mL, respectively. Modified Hodge test was positive in 24 (63.2%) isolate however, blaKPC-2 gene was detected in 8 (21.1%) carbapenem- resistant isolates. Results of the present study revealed a high rate of carbapenem- resistance in K. pneumoniae by phenotypic method, however the presence of one of the molecular, namely blaKPC-2 was not found as predominant cause. Therefore, their reliable detection should be the first priority to combat the infections. Being a simple test, the imipenem disk diffusion could be considered as an appropriate method for the detection of carbapenem-resistant isolates in the routine diagnosis.