Occurrence and Antibiogram of Extended-Spectrum Cephalosporin- and Cephamycin-Resistant Escherichia coli in Asymptomatic University Students

Background: Apparently healthy individuals could serve as reservoirs and disseminators of extendedspectrum cephalosporin (ESC)- and cephamycin (cefoxitin, FOX)-resistant, and extended-spectrum β-lactamase-producing (ESBL-P) Escherichia coli which jeopardizes antibacterial therapy thereby posing a threat to the health of infected individuals/carriers. Objectives: This study aimed to screen healthy asymptomatic students in the University of Nigeria, Nsukka (UNN) as potential reservoirs of ESC- and FOX-resistant and ESBL-P E. coli and to determine the antibacterial resistance profile. Materials and Methods: Anal swabs were collected from 190 randomly selected healthy asymptomatic students of both genders in UNN between March and July 2018. ESC-resistant E. coli was isolated using MacConkey agar with 2 µg/mL ceftazidime. ESBL production was assessed by combination disc method while cephamycin resistance was determined using cefoxitin disc screening. Phenotypic resistance of the isolates was determined using disc diffusion method. Results: Out of 190 samples, 20 (10.2%) demonstrated growth. Of these, 6 (30%) were FOX resistant (putative AmpC-producers) but none produced ESBL. The resistance of the isolates was 100% to ampicillin (AMP), 95% to ceftazidime (CAZ), tetracycline (TET) and sulfamethoxazole-trimethoprim (SXT), 30% to FOX and chloramphenicol (CHL), 85% to ciprofloxacin (CIP), enrofloxacin (ENR) and streptomycin (STR), and 65% to kanamycin (KAN). All the isolates were susceptible to meropenem (MEM). Among the 20 isolates, 1 (5%) was resistant to 2 classes of antibacterial agents while 19 (95%), including all the FOX-resistant strains, were resistant to ≥ 3 classes of antibacterial agents. The isolates exhibited 11 multiple antibacterial resistance patterns with AMP, CAZ, FOX, TET, CIP, ENR, STR, KAN, SXT being predominant. Conclusion: Healthy asymptomatic students in UNN are potential reservoirs and disseminators of ESC- and cephamycin (FOX)-resistant E. coli.