Genetic diversity study of various β-lactamase-producing multidrug-resistant isolates from a tertiary care hospital using ERIC-PCR.

BACKGROUND & OBJECTIVES: The prevalence of multidrug-resistant (MDR) Escherichia coli isolates producing β-lactamase enzyme is a growing problem across the globe. Strain typing is an epidemiologically important tool not only for detecting the cross transmission of nosocomial pathogens but also for determining the source of infection. The present study was conducted to understand the clonal relationship among various β-lactamase-producing MDR E. coli isolates using enterobacterial repetitive intergenic consensus (ERIC) polymerase chain reaction (PCR).

METHODS

A total of 41 MDR E. coli isolates were randomly collected from various clinical samples and processed. Isolated organisms were tested for antibiotics resistance pattern. Phenotypic detection of metallo β-lactamases (MBL) was carried out by the imipenem-ethylenediaminetetraacetic acid disc diffusion/double-disc synergy test. AmpC enzyme production was tested by a modified three-dimensional extract test.

RESULTS

Almost all isolates were found sensitive to colistin. A high percentage of drug resistance was observed in these isolates against ceftazidime (100%), cefotaxime (100%), cefepime (100%), ofloxacin (97.56%), amoxicillin/clavulanic acid (97.56%) and norfloxacin (85.36%). Of the 41 isolates, ESBL producers were found to be predominant, i.e., 22 (53.65%), followed by AmpC (6, 14.63%) and MBL (5, 12.19%).

INTERPRETATION & CONCLUSIONS: At 60 per cent similarity cut-off value, the dendrogram analysis showed that there were a total of 14 unique clusters of ERIC (CL-1 - CL-14) within the 41 E. coli isolates, which revealed the genetic diversity existing between them.