Phenotypic and molecular identification of antimicrobial resistance in Escherichia coli and Salmonella species isolated from apparently healthy broilers and zoo birds in Cameroon Identification phénotypique et moléculaire de la résistance aux antimicrobiens chez les espèces d’Escherichia coli et de Salmonella isolées en portage chez des poulets de chair et d’oiseaux de zoo au Cameroun

Abstract

Background: Knowledge of antimicrobial resistance patterns of bacteria in food and pet birds in our environment is a prerequisite to effective control of bacterial diseases in humans and other food animals. Particularly, there is a dearth of information on the prevalence of resistant bacteria in pet and zoo birds in Cameroon. This study was carried out to determine the antibiotic resistance profiles of Escherichia coli and Salmonella spp isolates in apparently healthy poultry and zoo birds in Cameroon and to phenotypically and genotypically identify extended spectrum β-lactamases (ESBLs) isolates in the poultry and aviary birds.
Methodology: This was a cross-sectional study of 320 randomly selected birds, which included 172 poultry and 148 zoo birds over a period of nine months, from which a total of 320 different non-repetitive samples were collected. The specimens were processed by standard microbiological culture methods at the National Veterinary Laboratory (LANAVET), Yaoundé annex, Cameroon. All isolated bacteria from cultures were identified as E. coli and Salmonella spp by conventional biochemical test scheme and confirmed with API®20E gallery. Antibiotic susceptibility test (AST) of confirmed isolates was done using the Kirby–Bauer disc diffusion technique, with AST results interpreted according to CLSI guidelines. Isolates with phenotypic characteristics of extended-spectrum beta-lactamase were subjected to molecular identification for bla_CTX-M, bla_TEM and bla_SHV genes. Data obtained were analyzed using descriptive statistics.
Results: Out of the 320 samples, a total of 88 E. coli and 17 Salmonella species were isolated from both broilers and zoo birds with an overall isolation prevalence of 27.5% and 5.3% respectively. High resistance of E. coli was observed among isolates from broiler, especially to trimethoprim-sulfamethoxazole (96.7%), ampicillin and ticarcillin (88.3%), norfloxacin (81.7%), piperacillin (78.3%) and ceftriaxone (63.3%). However, the resistance pattern among isolates from aviary birds was low with the highest resistance observed for imipenem (39.28%). The isolates had multiple antibiotic resistance (MAR) indices between 0.18-0.94 with an average of 0.3. A striking MAR index of 0.94 was observed in an ESBL isolate. Detection of β-lactamase genes in 16 phenotypic ESBL-producing E. coli and Salmonella isolates showed the presence of 75.0%, 6.3% and 12.5% for bla_CTX-M, bla_TEM, and bla_SHV genes respectively.
Conclusion: ESBL isolates were widespread among apparently healthy broilers in live-bird markets in Cameroon with ESBL-producing E. coli and Salmonella species showing high resistance to penicillin, quinolones and sulphonamides. In addition, there is evidence of antibiotic-resistant bacteria in wild birds which can be transmitted to humans through fecal droppings or by being in close contact with them.