Prevalence, Antimicrobial Resistance, and Diversity of Salmonella along the Pig Production Chain in Southern Brazil.

Luciano Dos Santos Bersot,Cibeli Viana,Valéria Quintana Cavicchioli,Anderson Carlos Camargo,José Paes De Almeida Nogueira Pinto,Maria Teresa Destro,Luís Augusto Nero,Raquel Cristina Konrad Burin

doi:10.3390/pathogens8040204

Abstract

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.

Highlights

Pork is the second most widely animal protein consumed worldwide, and Brazil is the fourth world producer and exporter [1]
Pig production is one of the most important husbandry activities in Brazil, studies focusing on the detection of pathogens are important to ensure sanitary control during the production and safety of the meat distributed for sale
The results showed that in the nursery, only 4.8% (32/662) of samples were positive for Salmonella, while in the pig finishing farms, the prevalence increased to 13.9%

Summary

Introduction

Pork is the second most widely animal protein consumed worldwide, and Brazil is the fourth world producer and exporter [1]. Salmonella spp. can be considered as a component of pig intestinal microbiota [5]. They are usually asymptomatic carriers, excreting the pathogen intermittently or when stressed [8]. Pig farms usually breed animals in high density barns, facilitating the spread and persistence of Salmonella spp. in the environment [6,9]. Many countries are concerned with regard to the spread and persistence of multidrug-resistant (MDR) Salmonella, and these strains have been reported in pigs, slaughterhouses, and the final products as well as in clinical samples [10,11,12,13,14]. Genes related to resistance against antimicrobials are often transferred through mobile elements ( plasmids) amongst bacteria including Salmonella, which makes the fight against antimicrobial resistance a challenge [15,16]

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Conclusion