Carriage and antimicrobial susceptibility patterns of rectal ESBL E. coli in surgical patients at the University Teaching Hospitals in Lusaka, Zambia.

Background: Surgical site infections (SSIs) are on the rise and are a global concern as they complicate the recovery of patients postoperatively. Bacterial colonization of the patient's skin and alimentary tract are known to be major contributing sources to SSIs. However, Zambia lacks data relating to carriage rates of antibiotic-resistant rectal Escherichia coli among surgical patients.

Methods: This was a cross-sectional study aimed at determining the preoperative (preop) and postoperative (postop) carriage and antimicrobial susceptibility patterns of rectal ESBL-producing E. coli (ESBL-Ec) in elective surgery patients at the highest tertiary hospital in Lusaka, Zambia. Phenotypic methods were used in the identification of E. coli. Antibiotic susceptibility patterns and identification of ESBL-Ec was determined by Kirby-Bauer disc diffusion.

Results: A total of 120 study participants were recruited, of which 75 were followed up at least 72 h after surgery. From 195 rectal swabs cultured, 177 (90.8%) were positive for E. coli, of which 53 (29.9%) were ESBL-Ec, with a significantly (P < 0.0001) higher proportion in postop (47.9%) than preop (17.3%) participants. Overall, ESBL-Ec isolates showed higher resistance in postop than preop to cefotaxime (100% versus 88.9%, respectively), ampicillin (100% versus 94.4%), ciprofloxacin (88.3% versus 83.3%), amoxicillin/clavulanic acid (80% versus 66.7%) and cefepime (80% versus 77.8%). MDR ESBL-Ec strains were more frequent in postop than in preop participants (91.4% versus 88.9%).

Conclusions: The study showed a significantly higher rate of antimicrobial-resistant rectal E. coli in postop than preop participants. There is a need to ascertain the source of the resistance and to institute robust infection control measures, preop screening of surgical patients for ESBL-Ec, and to raise awareness on prudent use of antibiotics.