use may also increase the density of resistant organisms within a host that already
harbor such organisms at a lower density resulting in enhanced shedding of these
organisms and increased risk to other hosts.(7)
There is emerging evidence that anti-microbial use in humans may be the major
selective force for multi-drug resistant clones in enterobacteriaceae in many
developing countries that has resulted in an increasingly high prevalence of multi-
drug resistance in these countries.(8-11) This is contrary to the information from the
developed countries where overwhelming evidence seems to suggest that anti-
microbial use in agriculture is the major driving force in the selection and
dissemination of bacterial resistance.(12-17) There is however the need to
investigate this further in order to generate sufficient data that could advice on
proper use of anti-microbial agents in agriculture in the developing countries.
The present study determines the anti-microbial resistance profile of commensal E.
coli isolated from free range chickens in Imo state, Nigeria.
Materials And Methods
Study Area:
The study was carried out in Imo State, Nigeria. Imo State is situated in the central
part of the southeastern region of Nigeria. The State is divided into 27 Local
Government Areas (LGA) for administrative purposes. These LGAs are further
grouped into 3 senatorial zones namely, Owerri, Orlu and Okigwe. The agro-
ecological characteristics and poultry production systems in the area have been
reported.(18)
Identification and selection of sampling sites: The study was conducted in September
2003 at 3 purposively selected peri-urban sites spread across the 3 senatorial zones
of the state. The sites included Nekede (Owerri senatorial zone), Amaraku (Okigwe
senatorial zone) and Umuaka (Orlu senatorial zone). A preliminary field investigation
was made by the researchers to identify the study sites and to make themselves
known to the selected farm operators, and discuss the detailed nature of the work
with them.
At each site, the families that own the chicken and the number of chicken to be
sampled were determined according to the method previously described by
Okoli.(19) Each sampling site was visited twice over a period of three weeks. It was
determined that the birds have not received any antibiotic medication in the previous
two months, since antibiotic treatment has been shown to compromise resistance
results.(20) Altogether, samples were collected from local chicken, free-range exotic
cockerels, old layers, turkeys and broiler roosters.
Collection of samples, cultivation and isolation of organisms: Cloacae swabs were
collected from at least 5 birds randomly selected from the free-range flock at each
study site, using sterile swab sticks (AntecR). MacConkey agar (MCA) (Fluka
BioChemicaR) was used for selective growth and elucidation of colony characteristics
of E. coli.(21) The agar was prepared according to manufacturer's instruction and
each cloacae swab sample streaked directly on MCA and incubated overnight at
37°C. In all cases, the streaking technique described by Cruickshank et al. (22) was
adopted.
OJHAS Vol 4 Issue 3, 2005-3-3: Original Article. Antimicrobial resistance profile of E.coli isolates from tropical free range chickens. www.ojhas.org/issue15/2005-3-3.htm