Bacterial Isolates and Antibiotic Resistance of Escherichia coli Isolated from Fresh Poultry Excreta Used for Vegetable Farming in Freetown, Sierra Leone

Abstract

The transfer of antibiotic resistance from animals to humans is of concern in recent times. One potential source of such transfer is the untreated poultry excreta used as manure in farming. We aim to identify bacterial isolates and antibiotic susceptibility patterns of Escherichia coli in poultry excreta in Sierra Leone. This was a cross-sectional study of fresh poultry excreta samples collected from four commercial poultry sites in Freetown, Sierra Leone, from June–September 2021. Bacterial isolates were tested against eight antibiotics using established standards. Of 100 samples, 93 showed Escherichia coli (93%): of those, eight isolates also had Salmonella (8%). E. coli was 100% resistant to all three ‘Watch’ drugs (erythromycin, cefoxitin and streptomycin) and tetracycline. E. coli was least resistant to ampicillin (12%), followed by chloramphenicol (35%). The prevalence of multidrug resistance was 95.6%. Multiple antibiotic resistance index ranged from 0.5–0.7 (optimal < 0.2), indicating high prior exposure to antibiotics in these poultries. Such high levels of resistance in E. coli isolated from poultry excreta could pose a serious threat to humans. We recommend (i) routine surveillance to monitor antibiotic resistance in poultry excreta, (ii) using poultry excreta as manure only after treatment and (iii) restricting the use of antibiotics as prophylactics and growth promoters in poultry feeds.