Antimicrobial multiresistance and biofilm formation in Salmonella enterica isolated from broiler production chain

Abstract

Poultry and poultry products are considered the predominant sources of Salmonella enterica contamination and are important reservoirs of bacteria with antimicrobial resistance. The objective of this study was to identify Salmonella with multidrug resistance (MDR) phenotype, with the ability to form biofilms and elucidate the presence of genes that encode antimicrobial resistance in isolates from the broiler production chain in the state of Maranhão, Brazil. A total of 121 strains of S. enterica of different serovars were evaluated for antimicrobial susceptibility, and of these, 26 strains were used to detect the ability to form biofilms and identify resistance genes using PCR. Antimicrobial resistance was observed in 95 (78.5%) Salmonella isolates, and 57 (47.1%) showed MDR phenotype. The isolates showed greater resistance to the sulfonamide principles (58.7%), trimethoprim (48.8%), tetracycline (45.4%), nalidixic acid (44.6%), amoxicillin and ampicillin (26.4%), and cefazolin (22.3%). Salmonella Schwarzengrund (n=21/61.7%), Albany (n=15/62.5%), and Enteritidis (n=4/44.5%) showed the highest indices of MDR phenotype. The ability to form biofilms at 37°C was found in 13 of the 26 strains evaluated, which were considered poor producers. The resistance genes blaCTX-M, blaCTX-M2, blaSHV, sul1, sul2, tetA, tetB, tetC, tetE, dfrA12, and dfrA1 were observed in the serovars Schwarzengrund, Albany, Enteritidis, Heidelberg, and Typhimurium. The results showed a high occurrence of S. enterica, with multiple resistance to conventional antimicrobials and the ability to form biofilms in the poultry production chain.