Control of Salmonella spp. in food production chains is very important to ensure safe foods and minimize the risks of foodborne disease occurrence. This study aimed to identify the prevalence and main contamination sources of Salmonella spp. in a pig production chain in southern Brazil. Six lots of piglets produced at different farms were tracked until their slaughter, and samples were subjected to Salmonella spp. detection. The obtained isolates were serotyped, subjected to antimicrobial resistance testing, and pulsed field gel electrophoresis (PFGE). Salmonella spp. was detected in 160 (10.2%) samples, and not detected in pig carcasses after final washing or chilling. Among the 210 Salmonella spp. isolates, S. Typhimurium was the most prevalent (n = 101) and resistant to at least one antimicrobial. High resistance rates were detected against tetracycline (83.8%), chloramphenicol (54.3%), and trimethoprim-sulfamethoxazole (33.3%). The isolates that were non-susceptible to three or more classes of antimicrobials (n = 60) were considered multidrug-resistant (MDR), and isolates resistant to up to six of the tested antimicrobials were found. PFGE allowed the identification of genetic diversity and demonstrated that farm environment and feed supply may be sources for the dissemination of Salmonella spp. along the production chain. The results revealed the sources of Salmonella contamination in the pig production chain and highlighted the risks of antimicrobial resistance spread.

This study aimed to characterize the Salmonella spp. distribution in a poultry processing facility, and to identify their antibiotic resistance profiles. S. enterica was detected in 146 samples (66.7%), and 125 isolates were identified as S. Heidelberg (n = 123), S. Abony (n = 1) and S. O:4,5 (n = 1). S. Heidelberg isolates were subjected to XbaI macrorestriction and PFGE, resulting in 66 pulsotypes grouped in 4 major clusters and demonstrating the cross contamination and persistence of this serotype in the processing facility. Also, S. enterica selected isolates were subjected to antibiotic resistance characterization, with most being categorized as multidrug resistant (n = 122, 97.6%). The resistance to third generation cephalosporins was particularly high: ceftazidime (n = 84, 67.2%) and cefotaxime and ceftriaxone (n = 91, 72.8%). Production of extended-spectrum beta-lactamases (ESBL) was identified in 24 isolates (19.2%) and ESBL-producing isolates were resistant to at least eight different antibiotics. The study highlighted the occurrence and the distribution of S. Heidelberg in the poultry chain, allowing proper understanding of the ecology of this pathogen in the studied facility. Also, the presence of multidrug resistant S. enterica at high frequencies is a concern due to the potential consequences for public health.

Autochthonous microbiota from artisanal cheeses is predominantly composed of lactic acid bacteria (LAB), which are able to produce antimicrobial compounds, such as bacteriocins, suggesting their application in food biopreservation. Knowledge about LAB growth and bacteriocin production during food production and conservation is essential to determine their use. In this way, the study aimed at isolating bacteriocinogenic LAB from twenty-one artisanal cheeses from the western region of Parana state, Brazil, determining the best conditions for growth and bacteriocin production (25°C, 30°C, and 37°C/24h); bacteriocin stability under different ranges of pH (2, 4, 6, 8, and 10 for 2h) and temperature (60oC/2h; 80oC/2h; 121oC/15min). Their activity against different target microorganisms was also evaluated. A total of 34 LAB strains presented characteristics compatible with bacteriocin production. Most of them presented better results for bacteriocin production when cultured at 25ºC and 30ºC. Bacteriocins remained active against L. monocytogenes when exposed from pH 4 to 8 and a wide temperature range; some bacteriocins were even resistant to sterilization temperatures. Bacteriocins produced were able to inhibit spoilage and pathogenic microorganisms, such as L. monocytogenes, B. cereus, and P. fluorescens. These results indicated that isolated bacteriocinogenic LAB present potential to be used as food biopreservatives.