Beta-Lactamase-Producing Escherichia coli Isolates Recovered from Pig Handlers in Retail Shops and Abattoirs in Selected Localities in Southern Nigeria: Implications for Public Health

Abstract

Antibiotic resistance evolution among pathogenic microorganisms has become a huge burden globally as it has increased the burden of diseases amongst humans and animals. The prevalence of extended-spectrum beta-lactamase-producing Escherichia coli (ESBL-Ec) and metallo beta-lactamase-producing Escherichia coli (MBL-Ec) isolated from pig abattoir and handlers in retail shops was studied. In addition, the relationship between the isolates’ prevalence and the background characteristics of the butchers/retailers was also investigated. Samples from 32 hand swabs of pork sellers at retail shops and 8 butchers at abattoirs, as well as 272 swabs taken from knives, tables, floors, water troughs, and carcasses from both retail shops and abattoirs, were collected. Escherichia coli (E. coli) was isolated from hand swabs, fomites, and carcasses and were identified by standard microbiological procedures. The isolates susceptibility to nitrofurantoin (300 µg), ciprofloxacin (5 µg), ceftazidime (30 µg), cefuroxime (30 µg), gentamicin (10 µg), cefixime (5 µg), ofloxacin (5 µg), amoxicillin/clavulanic acid (30 µg), imipenem (10 µg), and meropenem (10 µg) and their ability to produce ESBL and MBL was determined by phenotypic methods. Demographic information of the handlers was retrieved by means of a structured questionnaire and, in some cases, via face to face interviews. Out of 104 E. coli isolates from both sources, 52 (50.0%) and 8 (7.7%) were ESBL and MBL producers, respectively. ESBL was more prevalent on the hands of the retailers (40.6%) and butchers (75.0%). The isolates were 100% resistant to ceftazidime, cefotaxime, and amoxicillin–clavulanic acid and 4.8% resistant to nitrofurantoin. Diverse resistance patterns were observed among ESBL-Ec and MBL-Ec. It was found that 90% of ESBL-Ec and 100% of MBL-Ec were multidrug-resistant. A possible epidemiological link between the two sources was observed. The prevalence of E. coli ESBL- and MBL-producing isolates was associated with the duty performed by handlers (p = 0.012) and gender (p = 0.012). Our results provide evidence that the handlers’ hands and abattoir environment had a great role to play in the high prevalence and resistance profiles of the microorganisms.