Rectal Colonization with Extended Spectrum β-Lactamase producing Enterobacteriacieae in Surgical Patients in a Tertiary Hospital in Calabar, Nigeria

Aim: Extended spectrum β-lactamases are transferable plasmid mediated resistance mechanisms found mainly among Enterobacteriaceae which confer resistance to numerous β-lactam antibiotics. The aim of the study was to determine the rate of rectal colonization of surgical patients with Escherichia coli carrying extended spectrum β-lactamases. Subjects and methods: We collected and cultured rectal swabs from 192 surgical patients in the University of Calabar Teaching Hospital, Calabar, Nigeria. Escherichia coli isolates were identified and antibiotics susceptibility performed using Modified Kirby-Bauer disc diffusion technique. Isolates showing zones of inhibition to third generation cephalosporins below Clinical and Laboratory Standard Institute recommended break-points were screened for ESBL-production by the double-disk synergy method. Results: A total of 67.7%(130) of the patients received prophylactic antibiotics which was continued empirically for ≥5days after surgery. Ceftriaxone was the most empirically prescribed antibiotic used with metronidazole in 63.1%(82/130) and alone in 7.7%(10/130) of patients. Ceftriaxone resistance was observed in 39.6%(76/192) of the rectal E. coli isolates with 3.1%(6/192) showing intermediate susceptibility. Ceftazidime resistance was observed in 40.6%(78/192) with 4.2%(8/192) showing intermediate susceptibility. ESBL mediated resistance was observed in 27.1%(52/192) of isolates. ESBL positive isolates were more likely to be resistant to Gentamicin, Ciprofloxacin and Co-trimoxazole than negative isolates (P<0.001). All isolates were susceptible to Meropenem. Younger patients were more colonized with a preponderance in patients less than 9 years of age (Pearson’s correlation = -0.196;P=0.006). Conclusion: Infection may occur in colonized surgical patients leading to increased morbidity. Pre-surgical screening to identify colonized patients will be beneficial in the early selection of appropriate therapy and management of outbreaks while functional hospital antibiotic stewardship programmes and strict enforcement of national antibiotic regulations will curtail their spread.