ISOLATION OF COLISTIN-RESISTANT Escherichia coli FROM ABBATOIR EFFLUENTS IN BENIN CITY

ABSTRACT
Antimicrobial resistance is one of the greatest challenges for human health worldwide,
which is associated with elevated morbidity and increased economic burdens. Colistin is
one of the last resorts in treating serious, difficult to treat infections caused by multidrugresistant
Gram-negative bacteria, including Escherichia coli. The study was carried out to
investigate the prevalence of colistin-resistant E. coli in abbatoir effluent sources and
their associated risk factors. Eight abbatoir effluent samples were collected from four
different slaughter houses in Benin City. The samples were screened using standard
cultural and biochemical techniques. The antibiotic susceptibility profile was determined
using the Kirby-Bauer disc diffusion method and the phenotypic virulence factors were
determined using standard culture protocols. The results revealed that the occurrence of
colistin-resistant Escherichia coli in abattoir effluents [4/8(50%)]. The percentage
distribution of colistin-resistant Escherichia coli positive samples based on sample
sources or slaughter houses [2/4] was (50%). In overall, the total colistin-resistant
Escherichia coli positive samples were [4/8] (50%). E. coli demonstrated the highest
resistance towards ampicillin and trimethoprim/sulfamethoxazole with a resistance rate of
100%. No resistance observed towards ciprofloxacin (0%). The multiple antibiotics
resistance profile of the E. coli in this study ranged from 0.46 - 0.83. The phenotypic
virulence distribution of E. coli observed were lipase activity [2/8(25%)], β-hemolytic
activity [0/8(0%)] and gelatinase activity [2/8(252%)]. The detection of colistin-resistant
E. coli in both community and hospital environment allays a notable threat to human and
animal health. Therefore, routine antibiotic resistance monitoring is recommended. Public
enlightenment campaign and proper education against indiscriminate antibiotics usage as
animal feed and growth promoters should be curbed in order to curtail the spread of
antimicrobial resistance.