Risk factors and Alleles of extended spectrum Beta-Lactamase(ESBL) producing Escherichia coli at the University Teaching Hospital, Zambia

The limitation of antibacterial treatment options imposed by the emergence of bacterial resistant organisms calls for the correct identification of the genes involved in mediating resistance. In this study, antimicrobial resistance was determined in terms of the presence of extended-spectrum beta-lactamases (ESBL) among Escherichia coli isolates obtained from patients admitted at the University Teaching Hospital (UTH) in Zambia. A total of 400 rectal swabs were obtained and subjected to initial screening using MacConkey agar supplemented with cefotaxime. blaTEM, blaSHV and bla CTX-M genes in ESBL producing E. coli were detected using Polymerase Chain Reaction (PCR). All CTX-M positive isolates were subjected to sensitivity patterns using 11 different antibiotics: ampicillin (AMP), trimethoprim-sulphamethoxazole (SXT), streptomycin (STR), tetracycline (TET), gentamycin (GEN), nalidixic acid (NAL), ceftazidime (CAZ), chloramphenicol (CHL), norfloxacin (NOR), ciprofloxacin (CIP) and cefotaxime (CTX).
The prevalence of ESBL producing E. coli was 19% (76/400). Among the ESBL producing E. coli, 25 out of 76 (32.9%) were positive for CTX-M genes. Of the 25 CTX-M positive isolates, 9 (36%) isolates were positive for SHV genes and 9 (36%) were positive for TEM genes. The highest resistance was found to be to nalidixic acid (96%), followed by sulfamethoxazole-trimethoprim, tetracycline and ceftazidime (92% each). The least resistance was to ampicillin (60%). Male gender (p=0.014, 95% CI=1.198-4.813) and history of surgery (p=0.01, 95% CI=1.196-3.740) were found to be significant risk factors for ESBL presence. The findings emphasize that ESBL-producing bacteria are present among patients at the UTH, and that these organisms exhibit co-resistance to several classes of antibiotics.