Antibiotic Use and Antibiotic Resistance of Salmonella Species in Different Poultry Farms in Selected Districts of East Shewa Zone, Oromia Regional State, Central Ethiopia
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Date
2021-06
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Abstract
Antibiotics are limited resources. The more antibiotics are used today, the lesser it is likely they will still be effective in the future. Antibiotic resistance is considered one of the major threats to the world’s health as antibiotic resistant infections are increasing in humans, animals and the environment from time to time. Misuse and overuse of antibiotics is a primary contributor for the development of antibiotic resistance. The World Health Organization estimates that in the past decade the number of deaths attributed to antibiotic resistant bacteria exceeded the combined number of deaths due to influenza, human immunodeficiency virus and traffic accidents. Salmonella is the major cause of foodborne zoonotic bacterial infections worldwide and poultry is a major source of this zoonotic infection. Drug resistant Salmonella, such as quinolone and the higher generation cephalosporin resistant strains are regarded by World Health Organization as a critically important highest priority pathogen. Hence, a cross sectional study was conducted from September, 2017 to January, 2021 to determine the prevalence and antibiotic resistance of Salmonella species isolated from poultry and to evaluate a prudent use of antibiotics in intensive and semi-intensive commercial and backyard poultry farms in a selected districts (Ada’a, Lome, Akaki and Adama) of East Shewa zone of Oromia regional state, central Ethiopia. A multi-stage sampling technique was used to select districts, peasant association and poultry farms. A total of 780 samples (500 chicken fecal, 153 egg, 100 chicken meat and 27 hand swab from poultry farm workers) were collected for Salmonella isolation and identification. Three hundred eighty eight individuals (n=388) were included in the study for the assessment of prudent use of antibiotics using structured questionnaire surveys. Based on microbial isolation and identification, the prevalence of Salmonella was 18.4% (95% CI=14.6-21.3) in the fecal samples, 14.8% (95% CI=1.5-28.5) in the hand swabs of poultry farm workers, 4.5% (95% CI=1.2-7.7) of eggs and 6% (95% CI=1.3-10.7) of meat samples with the overall prevalence of 13.97% (95% CI=11.6-16.4).
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The highest prevalence of salmonella infection was observed in intensive production system (16.9%) and the lowest was found in backyard scavenging system (7.4%). One of the serious zoonotic strains (S. typhmurium) was recorded as a dominant serovar (69.7%) followed by S. Saintpaul (18.2%), S. Kentucky (6%), S. Newport (3%) and S. Anatum (3%) during this study. Risk factors such as poultry production system (P=0.006), production type (P=0.001), breed of chicken (P=0.005) and sample type (P=0.001) were significantly associated with Salmonella prevalence. A total of 37 Salmonella isolates were tested for their resistance against 15 antibiotics using disc diffusion method. Majority of the isolates (64.86%) were resistant or intermediately resistant to at least one antibiotic. The prevalence of resistance was high to chloramphenicol (62.2%), tetracycline (59.5%), ampicillin (54.1%) and streptomycin (51.4%). More than half of the isolates (56.8%) were multidrug resistant. The widespread occurrence of drug resistant Salmonella in poultry farms clearly demonstrated that, there is lack of awareness about prudent use of antibiotics, which highly contributed to the development of antibiotic resistant bacteria. All farms used one or more antibiotics and administered them mainly through feed/water. Tetracycline (100%) and sulfadiazine + trimethoprim (94.1%), fluroquinolones (41.5%) and cloxacillin + ampicillin (29.1%) were the most frequently used antibiotics. Antibiotics were used for disease treatment (100%), for disease prevention (56%) and /or for growth promotion (32.2%). Veterinary pharmacies (100%), veterinary clinic (51.0%), human pharmacies (26.8%) and illegal open market (16.2%) were the sources of antibiotics for the poultry producers. Sixty two percent of the farms obtained antibiotics through prescription from veterinarian and the rest were as self-prescription (32.2%) or as recommended by friends with prior experience (11.9%). Only 37.9% of the prescribed antibiotics administered by veterinary professional while majority of the farms administered antibiotics by themselves, based on the drug labels or as directed by a prescriber or pharmacist. Antibiotic stewardship programs such as removing the use of antibiotics for growth promotion, controlling illegal open market access as well as increasing veterinary and diagnostic services will help to mitigate antibiotic resistance. Measures to control of Salmonella infections in poultry are needed to reduce foodborne infections in humans.
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PhD Thesis
Keywords
Antibiotic use, antibiotic resistance, poultry, Salmonella