Distribution, diversity, virulence genotypes and antibiotic resistance for Salmonella isolated from a Brazilian pork production chain

• Published in: International journal of food microbiology Vol. 310; p. 108310
• Main Authors: Viana, Cibeli, Sereno, Mallu Jagnow, Pegoraro, Kadigia, Yamatogi, Ricardo Seiti, Call, Douglas Ruben, dos Santos Bersot, Luciano, Nero, Luís Augusto
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 16-11-2019; Elsevier BV
• Subjects: Abattoirs; Ampicillin; Antibiotic resistance; Antibiotics; Antiinfectives and antibacterials; Antimicrobial agents; Antimicrobial resistance; Bleeding; Carcasses; Chains; Chloramphenicol; Chloromycetin; Ciprofloxacin; Contamination; Distribution; Electrophoresis; Epidemiology; Ertapenem; Farms; Flooring; Floors; Gel electrophoresis; Genotypes; Hogs; Kanamycin; Livestock; Lymph nodes; Lymphatic system; Meat; Meropenem; Multidrug resistance; Nodes; Phenotypes; Phenotyping; Pork; Pulsed-field gel electrophoresis; Salmonella; Streptomycin; Swine; Swine production; Utensils; Virulence; Salmonella; Ciprofloxacin; Pork; Distribution; Antibiotic resistance
• ISSN: 0168-1605; 1879-3460
• DOI: 10.1016/j.ijfoodmicro.2019.108310

Pigs infected with Salmonella are an important source of contamination at slaughterhouses. We characterized the distribution, virulence genotypes and antimicrobial-resistance phenotypes for Salmonella isolates that were collected from different stages of a pork production chain. Each of ten pig lots were sampled for feed (n = 10), water (n = 10), barn floor (n = 10), lairage floor (n = 10), mesenteric lymph nodes (n = 100), tonsils (n = 100), processing environment (n = 120), pork cuts (n = 40) and carcasses after bleeding (n = 100), after singeing (n = 100), after evisceration (n = 100), and after final rinsing (n = 100). Salmonella was isolated according to ISO 6579, and after confirmation the isolates were subjected to serogrouping, macro-restriction digests and pulsed-field gel electrophoresis (PFGE), detection of virulence-related genes and antimicrobial-resistance phenotyping. Salmonella was recovered from barn floors from 3 pig farms (3/10), lairage floors (7/10), carcasses after bleeding (2/100) and final washing (1/100), palatine tonsils (45/100), mesenteric lymph nodes (43/100), utensils (3/120) and cuts (4/40). The most prevalent serogroup was O: 4 (82%) followed by O:3 (7.7%); O:9 (5.1%); O:8 (2.6%) and O:7 (2.6%). Recovered strains (n = 109) were classified into 24 different pulsotypes (XbaI restriction digest), which were arranged into five different clusters. Fourteen different virulence genotypes were observed based on 15 loci, and all isolates were positive for invA, sitC, pagC and tolC. There was a high prevalence of antimicrobial resistance against streptomycin (90.5%), tetracycline (88.1%), ampicillin (81.0%), chloramphenicol (71.4%), and ciprofloxacin (50.0%). No strain was resistant to ertapenem, meropenem or kanamycin. A majority (80.9%) of isolates were considered multidrug resistant (resistant to ≥3 antibiotic classes). This study provides valuable insight about the epidemiology of Salmonella in swine production, and despite the low presence of this pathogen in carcasses and meat cuts, the majority of isolates was multidrug resistant.
•Salmonella was found in 43% of mesenteric lymph nodes and 45% of palatine tonsils.•Strains were classified into 24 distinct pulsotypes and arranged into five clusters.•Virulence related genes were detected in all 112 tested isolates.•Approximately 81% of isolates were considered multidrug resistant.•Resistance against ciprofloxacin was observed in 50% of strains.