The use of antimicrobials in food producing animals can lead to increased bacterial resistance. Important information to address this problem can be provided by monitoring antimicrobial resistance (AMR) in foodborne pathogens. As part of preliminary activities for the implementation of AMR surveillance in Brazil, a nationwide survey on AMR in Salmonella enterica isolates from poultry meat was conducted. The survey evaluated 146 Salmonella isolates from poultry meat in 2014, and 163 isolates obtained in 2017. Minimal inhibitory concentrations of 13 antimicrobials were determined by broth microdilution, and isolates were assigned to serotypes by automated ribotyping. High resistance rates were found in 2014 and 2017, in particular to nalidixic
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 β-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 blaSHV, blaTEM, blaOXA, blaPSA, blaCMY-1, and blaCMY-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 β-lactam resistance genes, including AmpC blaCMY, blaTEM, blaCTX-M-1, blaCTX-M-2, blaCTX-M-8, and blaCTX-M-14. Isolates carrying variants of blaCTX-M were identified in three geographic regions. Salmonella carrying particular genetic variants of blaCTX-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 blaCTX-M-1 and blaCTX-M-14 in Salmonella in Brazil.
A two-stage study compared the BAX system PCR method with the reference culture method used by the Brazilian Ministry of Agriculture and Food Supply for the detection of Salmonella in food, water, and environmental samples. In stage 1, fish matrix samples (n = 258) were spiked at several levels with Salmonella and a combination of Salmonella and non-Salmonella competitive organisms. Replicates were analyzed by the BAX system PCR method and the reference method with comparable results (sensitivity > or = 97.5%, specificity > or = 83.3%) from both methods at the limit of detection. In stage 2, a total of 1,988 samples with 70 product types were analyzed with both methods. Five laboratories were involved in this study, and the samples used were from routine analyses. The BAX system PCR method was shown to be comparable to the reference method, with a limit of detection of 1.0 to 2.0 CFU/25 g of sample. Analysis of the results obtained in stage 2 and in the combination of stages 1 and 2 for the BAX system showed the following performance: sensitivity > or = 99.0%, specificity > or = 97.2%, false-negative rate < or = 1.1%, and false-positive rate < or = 2.8%. Therefore, the BAX system appears to be equivalent to the reference method, with > or = 97.3% agreement.
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