The prevalence of TEM and SHV genes among Extended-Spectrum Beta-Lactamase-producing Klebsiella pneumoniae and Escherichia coli

Abstract

Background: Antimicrobial resistance to cephalosporin, penicillin and aztreonam is mediated by Extended-Spectrum Beta-Lactamases (ESBL) via hydrolysis of antibiotics. The most common bacteria associated with ESBL among the Enterobacteriaceae are Escherichia coli and Klebsiella pneumonia. Pathogenic Escherichia coli is associated with diarrhoea affecting mostly elderly, children under five years and the immunocompromised. There are a number of antibiotic regimens for treatment among them cephalosporins. There is reported increase in microbial resistance to cephalosporin use and the resistance is mediated by either TEM or SHV genes.

Objective: To investigate the prevalence of ESBL-producing E. coli and Klebsiella pneumonia from patients presenting with diarrhea in Machakos District Hospital, Kenya.

Methods: Bacterial isolates were identified to species level by biochemical methods and tested for sensitivity to twelve different antibiotics including cephalosporins, aminoglycosides and quinolones. Those resistant to cephalosporins with a zone diameter of ≤20 mm were tested phenotypically for Extended Spectrum Beta Lactamase (ESBL) phantom development and confirmed by MicroScan. Resistant strains to cephalosporin were further tested for presence and frequency of TEM and SHV genes.

Results: Out of the 200 K. pneumonia and 100 E.coli tested, 18 (6%) were positive for ESBL production phenotypically. These 18 (100 %) isolates demonstrated phantom phenomena phenotypically. Eight (4%) and 2 (1%) of the 200 K. pneumonia isolates had TEM and SHV resistant genes, respectively. There were 5 (5%) TEM and 3 (3%) SHV detected from 100 E. coli isolates. The 18 phenotypically detected and E-test-positive strains (10 Klebsiella spp. and 8 E. coli) were retested with VITEK (GNS-532 card), and 17 of these strains (94.4%) were subsequently found to be ESBL positive. One strain (5.6%) tested ESBL negative by VITEK. The cefotaxime ESBL strip detected the presence of ESBL activity in these 18 phenotypically-positive strains.

Discussion: The detection of ESBL-producing E. coli and Klebsiella isolates from Machakos District Hospital was 6%. The findings point out the need for continuous surveillance to determine prevalence of ESBL-producing Enterobacteria strains for better management of diarrheal illness.

Key words: Extended spectrum Beta Lactamases; Cephalosporin resistance genes; Enterobacteriaceae