Identification and antimicrobial resistance of Salmonella enterica isolated from live birds at commercial resellers

Abstract

The objective of this study was to investigate the sanitary and management characteristics of live-bird resellers as well as identify and undertake an antigenic characterization of Salmonella enterica and its sensitivity to antimicrobials. Structured questionnaires were applied and 627 samples were collected from the cages, consisting 209 samples of excreta, 209 of feed and 209 drinker swabs. These were processed by conventional bacteriology. The obtained isolates were subjected to the susceptibility test and to 12 antimicrobial tests by the disk diffusion method. Of the studied resellers, 91.7% house Gallus gallus domesticus, together with other animal species; sell birds with little zoosanitary documentation; have unsatisfactory active surveillance; and use and sell antimicrobials indiscriminately. The presence of Salmonella enterica was detected in 1.4% (9/627) of the samples analyzed in the cages, with 1.9% (4/209) found in excreta, 0.95% (2/209) in feed and in 1.4% (3/209) in drinker swabs. These were characterized antigenically as Salmonella Heidelberg, Gallinarum, Risen, Ndolo, Saint Paul, Mbandaka and subsp enterica O:6,7. When susceptibility to antimicrobials was determined, 44.4% resistance (4/9) was detected for trimethoprim-sulfamethoxazole, 33.3% (3/9) for enrofloxacin, 22.2% (2/9) for ciprofloxacin, ceftiofur and amoxicillin and 11.1% (1/9) for tetracycline and fosfomycin. Salmonella Heidelberg, as well as serovars Gallinarum, Risen, Saint Paul and Mbandaka, showed resistance to at least one of the tested antimicrobials. Trimethoprim-sulfamethoxazole and enrofloxacin were the antimicrobials that showed the least efficacy. Serovars such as Heidelberg, Gallinarum and Mbandaka have multiresistance to antimicrobials commonly used in human and veterinary medicine, implying potential risks to One Health.

Keywords: Chickens; Excreta; Feed; Salmonellosis; Water