Overview of antimicrobial resistance and virulence factors in Salmonella spp. isolated in the last two decades from chicken in Brazil

Foodborne infections caused by Salmonella have been linked to a variety of poultry products. The aim of this study was to compare the molecular profile of virulence genes considering different serotypes of Salmonella, isolates were from chicken breast sampled during the last two decades (1999 to 2010 and 2011 to 2018). The resistance to antimicrobials was also evaluated, establishing a comparative epidemiological parameter on the pathogenic potential on this bacterium over time. We tested 238 Salmonella isolates, and 18 different serotypes were observed. These being S. Enteritidis (42.3%, 58/137) and S. Ohio (28.3%, 36/137), the most frequent in the first decade; and S. Heidelberg (25.7%, 26/101) and S. Typhimurium (21.8%, 22/101), in the second. We found four (1.68%) multidrug resistant isolates from the first decade and 28 (11.76%) in the second. All extended spectrum beta-lactamase (ESBL) positive isolates belonged to the S. Heidelberg serotype, and were also detected in the second decade. Considering the nine different antimicrobial classes tested, an increase in the number of resistant isolates was observed over time: from five classes with resistant isolates in the first decade to eight classes in the second, with cefotaxime being the antimicrobial with the highest number of resistant isolates in both decades. All isolates (100%) presented the invA, sitC and tolC genes. In sequence, the most frequent genes were flgL (99.6%), sopB (98.3%), flgK (97.9%), fljB (96.6%), sipA (94.9%), sipB (88.6%), sifA (86.4%), sipD (66.1%), ssaR (51.3%), sopD (37.3%) and spvB (34.3%) was the least frequent; and 13 isolates showing all 14 virulence genes investigated. The ability of these isolates to resist certain antimicrobials, and to express genes encoding virulence factors, reinforce their marked pathogenic potential; while the possibility to trigger diseases in humans through the food chain is a serious public health threat through.