Hygiene Compliance in Nigerian Urban-based Abattoirs as Monitored by the Occurrence of Enteric Bacteria on Slabs, Boards, Wastewater and Air

Abstract

Poor sanitation and inadequate hygiene in abattoirs may contribute to zoonoses and foodborne infections. This study monitored the compliance of selected Nigerian urban-based abattoirs with standard sanitation and hygiene requirements, using the occurrence of enteric bacteria as a yardstick. Samples from slaughter slabs, cutting boards and dumpsite bones were collected using the swab-rinse method, while wastewater and airborne bacteria were sampled with sterile flasks and exposed agar plates, respectively. Samples were obtained monthly for six months from 16 randomly selected abattoirs located in four towns. Enteric bacteria were enumerated on selective and differential media, and presumptive isolates were confirmed using the Analytical Profile Index system. A total of 1,966 enteric bacterial isolates were recovered, with no marked monthly variation at each sampling point. Counts were 140-146 CFU/mL in wastewater and 68-72, 59-65 and 52-58 CFU/cm² on slaughter slabs, cutting boards and dumpsite bones, respectively. All contact-surface counts were above the FAO satisfactory limit. Airborne enteric bacterial populations in more than 50% of the abattoirs were classified as fair based on the index of microbial air contamination. Comparison of bacterial populations among isolation points showed significant differences (F = 4.40-86.88; P = 0.000-0.026), with isolates from wastewater discharge points having the highest counts. The identified bacteria were Escherichia coli, Salmonella enterica, Shigella flexneri and Klebsiella aerogenes. Escherichia coli was more prevalent than the other isolates (6.6-16.7% versus 2.2-11.7%). Differences in prevalence by abattoir location were generally not significant, except for Escherichia coli on slabs and cutting boards and Salmonella enterica on slabs. These findings indicate consistently suboptimal adherence to sanitary and hygienic practices in the abattoirs studied.