DISTRIBUTION OF COLISTIN RESISTANCE AMONG FAECAL Escherichia coli ISOLATES

ABSTRACT

Colistin resistant Escherichia coli in poultry is one of the major public health concerns. Escherichia coli is one of the predominant bacteria isolated from poultry and have been recognized as the major reservoir for colistin resistance. The aim of this study was to determine the distribution of colistin resistance among faecal E. coli isolates from poultry birds in Benin City, Edo State. A total of 400 cloacal swab samples were collected from chickens consisting of broilers 240 (60%) and layers 160 (40%) housed in five different poultry farms in Benin City. The specimens were processed bacteriologically and isolates were identified using standard techniques. All the bacterial isolates were examined for their susceptibility to antibiotics using the agar disc diffusion method according to Clinical Laboratory Standard Institute (CLSI). Minimum inhibitory concentration of colistin was done on the isolated E. coli using the macrobroth dilution method. A total of 380 (95%) out of the 400 cloacal swab samples collected yielded growth of E .coli. The prevalence of E .coli growth was not significantly affected by age ,type of poultry birds and farm type (p > 0.05).The susceptibility profile of the E .coli showed varying degrees of sensitivity and resistance with imipenem (83%) being the most active antibacterial agent against E. coli isolates while the least active was amoxicillin (1.1%).The prevalence of colistin resistance against E .coli isolates was 31.8%, with significant difference (p<0.05) in the prevalence of colistin resistance between Broilers(73.6%) and layers (26.4%) and this was affected by the type of farm(p<0.0001). This study showed a high prevalence of E. coli and their resistance rate against colistin. Therefore, adequate measures should be put in place to control and prevent the spread of colistin resistant E. coli among poultry birds and to humans.