Staphylococci in poultry intestines: a comparison between farmed and household chickens

Authors: SYED, MUHAMMAD - University Of Haripur; ULLAH, HAKIM - Hazara University; TABASSUM, SADIA - Hazara University; FATIMA, BUSHRA - University Of Haripur; Woodley, Tiffanie; RAMADAN, HAZEM - Mansoura University; Jackson, Charlene

Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/3/2020
Publication Date: 6/26/2020
Citation: Syed, M., Ullah, H., Tabassum, S., Fatima, B., Woodley, T.A., Ramadan, H., Jackson, C.R. 2020. Staphylococci in poultry intestines: a comparison between farmed and household chickens. Poultry Science. 99(9):4549-4557. https://doi.org/10.1016/j.psj.2020.05.051.
DOI: https://doi.org/10.1016/j.psj.2020.05.051

Interpretive Summary: Presence of staphylococci in poultry has been reported previously, but no comparative study covering both farmed and household chickens has been done. In the present study, staphylococci from farmed and household chicken intestines from Pakistan were isolated and tested for resistance to antimicrobials, presence of resistance genes, and inhibitory activity against other bacteria; correlation of resistance phenotype and genotype was also evaluated. At least 12 staphylococcal species were identified; S. carnosus subspecies carnosus was the predominant species from both sources. The majority of farmed chicken staphylococci were resistant to tigecycline, while the highest level of resistance among the household chicken staphylococci was to clindamycin. Isolates from both types of birds were multidrug resistant ranging from two to eight antimicrobial classes and up to ten antimicrobials. Isolates also produced inhibitory activity against seven clinical bacterial strains. This study demonstrated that the staphylococcal population among farmed and household chickens varies by species and resistance to antimicrobials which may reflect the influence of the environment or habitat of each bird type on the intestinal microflora. As resistance in the staphylococci to antimicrobials used to treat human infections was detected, further study is warranted to determine strategies to prevent transfer of these resistant populations to humans via contamination of the poultry meat. This information is useful for scientists as they develop prevention and control strategies of antimicrobial resistant bacteria in poultry production.

Technical Abstract: Both pathogenic as well as non-pathogenic species of staphylococci have been reported in poultry, but these studies have not compared staphylococcal flora of both farmed and household broiler chickens. Staphylococci from farmed (n=51) and household chicken intestines (n=43) were isolated and tested for resistance to antimicrobials, presence of resistance genes, and inhibitory activity against other bacteria; correlation of resistance phenotype and genotype was also evaluated. At least 12 staphylococcal species were identified; S. carnosus subspecies carnosus was the predominant species from both sources. The majority of farmed chicken staphylococci were resistant to tigecycline (38/51; 74.8%) while the highest level of resistance among the household chicken staphylococci was to clindamycin (31/43; 72.1%). The mecA gene was only detected in staphylococci from household chickens whereas ermC and tetK or tetM were found in staphylococci from both groups of birds. Multidrug resistance (MDR; resistance = 2 antimicrobial classes) was observed for 88% of resistant staphylococci ranging from two to eight classes and up to ten antimicrobials. Isolates produced inhibitory activity against seven clinical bacterial strains primarily Enterococcus faecalis (25/88; 28.4%) and Escherichia coli (22/88; 25%). This study demonstrated that the staphylococcal population among farmed and household chickens varies by species and resistance to antimicrobials. These results may reflect the influence of the environment or habitat of each bird type on the intestinal microflora. As resistance in the staphylococci to antimicrobials used to treat human infections was detected, further study is warranted to determine strategies to prevent transfer of these resistant populations to humans via contamination of the poultry meat.