β-Lactam Resistance Genes: Characterization, Epidemiology, and First Detection of blaCTX-M-1 and blaCTX-M-14 in Salmonella spp. Isolated from Poultry in Brazil-Brazil Ministry of Agriculture's Pathogen Reduction Program

Salmonella spp. are widespread in nature; however, human infections occur mainly through ingestion of contaminated food, specially poultry and eggs. In Brazil, the Ministry of Agriculture (MAPA) oversees food production in general, with the goal of preventing transmission of pathogens through the food chain. In 2004, MAPA initiated a program to monitor and control levels of Salmonella in poultry during slaughter. This study analyzes isolates from MAPA's program for beta-lactam resistance and the resistance genes involved, as well as the geographic distributions of potentially clonal populations of resistant isolates within Brazil. Initially, 1,939 Salmonella spp. isolated between 2004 and 2011 were examined. These isolates were tested for antimicrobial susceptibility, and 100 isolates resistant or intermediate to ampicillin and ceftriaxone were screened initially for the presence of bla(SHV), bla(TEM), bla(OXA), bla(PSA), bla(CMY-1), and bla(CMY-2) genes. There were 55 isolates whose resistance genes were not identified by this panel and these isolates are the subject of this report. These 55 isolates were differentiated into 31 distinct ribogroups, with multiple beta-lactam resistance genes, including AmpC bla(CMY), bla(TEM), bla(CTX-M-1), bla(CTX-M-2), bla(CTX-M-8), and bla(CTX-M-14). Isolates carrying variants of bla(CTX-M) were identified in three geographic regions. Salmonella carrying particular genetic variants of bla(CTX-M) and belonging to the same ribogroup were identified from multiple poultry slaughtering facilities. In some instances, these presumptive clonal-related isolates were from facilities over 300 miles apart, indicating potential clonal spread between two geographic regions. This is the first report of bla(CTX-M-1) and bla(CTX-M-14) in Salmonella in Brazil.