Search

The pork production chain is an important reservoir of antimicrobial resistant bacteria. This study identified and characterized integrons in Salmonella isolates from a Brazilian pork production chain and associate them with their antibiotic resistance pattern. A total of 41 whole-genome sequencing data of nontyphoidal Salmonella were analyzed using PlasmidSPAdes and IntegronFinder software. Nine isolates (21.9%) had some integrons identified (complete and/or incomplete). Six complete class 1 integrons were found, with streptomycin resistance genes ( aadA1 , aadA2 ) alone or downstream of a trimethoprim resistance gene ( dfrA1 , dfrA12) , and some also containing resistance genes for sulfonamides ( sul1 , sul3 ) and chloramphenicol ( cmlA1 ). Class 2 integron was detected in only one isolate, containing dfrA1 - sat2 - aadA1 gene cassettes. Five isolates harbored CALINs-clusters attC but lacking integrases-with antimicrobial resistance genes typically found in integron structures. In all, integrons were observed among four serotypes: Derby, Bredeney, Panama, and monophasic var. Typhimurium I 4,[5],12:i:-. The association of integrons with antibiotic resistance phenotype showed that these elements were predominantly identified in multidrug resistance isolates, and six of the seven gentamicin-resistant isolates had integrons. So, surveillance of integrons in Salmonella should be performed to identify the potential for the spread of antimicrobial resistance genes among bacteria.

Salmonella spp. is a foodborne pathogen present in the pork production chain, leading to potential contamination of end products and causing salmonellosis cases and outbreaks worldwide. The emergence of multidrug-resistant (MDR) Salmonella spp., especially isolates obtained from animal origin food, is a global concern. This study aimed to isolate Salmonella from swine mesenteric lymph nodes (MLN) and to characterize the virulence and antibiotic resistance profiles. MLN samples were obtained from a swine slaughterhouse and subjected to Salmonella spp. isolation. Ten MLN samples were positive and 29 isolates were identified based on PCR ( invA and ompC ) and serotyping: Derby, Cerro, and Give. Pulsed-field gel electrophoresis allowed to group the isolates based on their serotypes, resulting in three major clusters. All isolates presented the virulence-related genes pefA , sipA , sopB , spaN , and pagC . Relatively high numbers of Salmonella spp. were resistant to neomycin, polymyxin B, ciprofloxacin, tetracycline, and nalidixic acid. Furthermore, 25 isolates presented simultaneous resistance to three or more antibiotic classes, being characterized as MDR. The obtained results confirmed the relevance of swine as reservoirs of Salmonella spp. in the pork production chain and demonstrated the MDR profiles of isolates. Proper control and surveillance are required to avoid the contamination of end products.

This study evaluated 250 animals from 25 different processing lots, processed in four slaughterhouses in São Paulo state, Brazil for the presence of Salmonella in the mesenteric lymph nodes (10 g sample of each animal) and characterized the antibiotics resistance profile, the Pulsed Field Gel Electrophoresis - PFGE and Multi Locus Sequence Typing - MLST profiles of selected strains. The pathogen was present in 36.4% (n = 91, CL 95% 30.4-43.4) of samples and 72% (n = 18, CL 95% 50.6-87.9%) of the analyzed lots. The main serovars were S. Typhimurium (n = 23), Salmonella enterica subsp. enterica 1.4,5,12:i:- (n = 17), followed by S. Infantis (n = 12) and S. Havana (n = 11). Twenty-eight strains (30%) were classified as other serovars. Sixty-eight percent of the strains were resistant to Streptomycin and tetracycline, followed by ampicillin and sulphonamides (62.6%), chloramphenicol (56.0%), trimethoprim-sulfamethoxazole (41.8%) and nalidixic acid (40.7%). The antibiotics with lower resistance rates were cephalothin and aztreonam (both with 3.3% resistant), and ceftriaxone and cefepime (both with 7.7%). Multidrug-resistant strains (MDR) accounted for 70.3% of the isolates. Eight strains were submitted to MLST: four S. Typhimurium and one S.1.4,5,12:i:-, all belonging to the ST 19, two Salmonella Infantis, belonging to the ST 32 and one S. Derby, belonging to ST 40. Twenty-one isolates with different antibiotics resistance profiles from the most prevalent serovars were selected for PFGE analysis. Serovar S. Typhimurium (n = 11) revealed 4 pulsotypes and 1 cluster and S. 1.4,5,12:i:- (n = 10) revealed 5 pulsotypes and 4 clusters. The high prevalence of the pathogen, with its high rates of antibiotics resistance and belonging to genetic groups that are often associated with disease in humans, shows that the production chain of pork is a potential source of infection in salmonellosis cases. Therefore, effective preventive measures for pathogen control are needed to reduce the risk of foodborne diseases., (Copyright © 2020 Elsevier B.V. All rights reserved.)

The aim of this work was to verify the occurrence, quantification, pulse types, and antimicrobial susceptibility profiles of Salmonella sp. isolated from chicken meat produced and marketed in the state of Paraná, considered to be the state with the highest production of poultry meat in Brazil. Ninety-five of 300 (31.5%) frozen cuts of chicken were found to contain Salmonella sp., and 98 different isolates of Salmonella sp. were cultured from the positive samples. Quantification showed low Salmonella sp. loading, ranging from 0.12 to 6.4 MPN/g. The antimicrobial resistance test was performed against 16 agents from 6 different classes. All isolates were sensitive to meropenem, imipenem, chloramphenicol, and amikacin. The highest resistance rates were observed for nalidixic acid (95%), tetracycline (94%), doxycycline (94%), ampicillin (87%), amoxicillin with clavulanic acid (84%), ceftriaxone (79%), and ciprofloxacin (76%). A total of 84 (85.7%) of the isolates were identified with a multidrug resistant profile, 13 of which were found to have encoding genes extended-spectrum beta-lactamase (ESBL), especially bla CTX-M-2 e bla TEM-1 . The major serovars identified were S. Typhimurium (43%) and S. Heidelberg (39%). The third most isolated serovar was S. Ndolo (6%), without previous reports of its presence in poultry meat in Brazil. Molecular characterization of S. Typhimurium and S. Heidelberg isolates by pulsed field gel electrophoresis (PFGE) showed a clonal relationship between all isolates of the same serovar (genetic similarity greater than 80%). Isolates of S. Typhimurium and S. Heidelberg with 100% similarity were found in up to five different geographic regions of the state, showing the potential for the spread of this pathogen in the Paraná poultry chain. Epidemiological surveys like this are important to understand the dynamics of dissemination and to monitor the prevalence of pathogens in the final products of poultry chains. In addition, to know the resistance profile of strains of Salmonella sp. present in food that contributes to the adoption of faster and more effective therapeutic measures, when necessary.

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., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Introduction: Salmonella is a major cause of foodborne disease, and poultry products are important contributors to the transmission of this zoonotic pathogen. Although considered to be rare in most countries, Salmonella Corvallis has been reported in specific geographic areas isolated from both human and non-human sources. The aim of this study was to report the occurrence, the antimicrobial resistance profiles including the extended-spectrum beta-lactamase (ESBL) production, and the clonal relatedness of S. Corvallis strains., Methodology: A total of 132 fragments of poultry carcasses from a slaughterhouse in São Paulo State, Brazil, were collected at different stages of the manufacturing process (post-bleeding, post-plucking, and post-chilling) and analyzed for the presence of Salmonella. Antimicrobial resistance was determined by disc diffusion method and Etest. Clonal relatedness was determined by pulsed-field gel electrophoresis (PFGE)., Results: Among the 272 Salmonella strains recovered, fourteen were S. Corvallis. Ten (71.4%) showed ESBL production and resistance to at least three antimicrobial agents. Nalidixic acid resistance and reduced ciprofloxacin susceptibility was verified in four (28.6%) strains. PFGE analyses showed that all the S. Corvallis strains belonged to the same pulsotype., Conclusion: This study identified genetically related S. Corvallis strains exhibiting ESBL production and reduced susceptibility to quinolone. The results suggest the need to improve the sanitary conditions in the slaughterhouse. Moreover, from a public health perspective, continuous surveillance on Salmonella is needed to control the dissemination of this important zoonotic pathogen and its resistance determinants.