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The objective of this study was to evaluate the phenotypic and genotypic profile of antimicrobial susceptibility and the possible involvement of extended spectrum beta-lactamases (ESBLs) in the resistance profile of Salmonella Heidelberg (SH) isolated from chicken meat. We used 18 SH isolates from chicken meat produced in 2013 in the state of Paraná, Southern Brazil. The isolates were submitted to disk-diffusion tests and from these results it was possible to determine the number of isolates considered multiresistant and the index of multiple antimicrobial resistance (IRMA) against ten antimicrobials routinely used in human and veterinary medicine. It was considered multidrug resistant the isolate that showed resistance to three or more classes of antibiotics. Another test performed was the disc-approximation in order to investigate interposed zones of inhibition, indicative of ESBLs production. In the isolates that presented multidrug resistance (18/18), a search of resistance genes involved in the production of ESBLs was performed using PCR: blaCMY-2, blaSHV-1, blaTEM-1, blaCTX-M2, blaOXA-1, blaPSE-1 and AmpC. The overall antimicrobial resistance was 80.55%. The highest levels of resistance were observed for nalidixic acid and ceftiofur (100%). The most commonly resistance pattern found (42.1%) was A (penicillin-cephalosporin-quinolone-tetracycline). The results were negative for ghost zone formation, indicative of ESBLs. However, PCR technique was able to detect resistance genes via ESBLs where the blaTEM-1 gene showed the highest amplification (83.33%), and the second most prevalent genes were blaCMY-2 (38.88%) and AmpC gene (38.88%). The blaOXA-1 and blaPSE-1 genes were not detected. These results are certainly of concern since SH is becoming more prevalent in the South of Brazil and able to cause severe disease in immune compromised individuals, showing high antimicrobial resistance to those drugs routinely used in the treatment and control of human and animal salmonellosis.

Salmonellosis is a disease caused by a bacterium Salmonella, a gram negative bacilli found in many environments, responsible for signifi cant economic losses in poultry, and of great impact on public health. Among more than 2500 serovars, S. Heidelberg seems to be more invasive causing disease of greater severity than other serovars. The objective of this study was to investigate, through real-time PCR (qPCR), differences in the expression of a virulent gene (invA) and an antibiotic resistance gene (blaCTXM-2) of S. Heidelberg isolated from poultry meat (slaughterhouses) and drag swabs (fi eld). Even though all isolates showed the presence of the invA gene, there were differences in the expression among the isolates, where isolates from the fi eld showed greater expression of invA compared to samples isolated from meat products. On the other hand, isolates from the slaughterhouses showed greater expression of the blaCTX-M2 than those isolated from fi eld samples.