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

In Silico Detection of Integrons and Their Relationship with Resistance Phenotype of Salmonella Isolates from a Brazilian Pork Production Chain

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.

Multi-locus sequence typing, antimicrobials resistance and virulence profiles of Salmonella enterica isolated from bovine carcasses in Minas Gerais state, Brazil

The aim of this study was to identify virulence and antimicrobial resistance profiles and determine the sequence type (ST) by multilocus sequence typing (MLST) of Salmonella enterica isolates from bovine carcasses from slaughterhouse located in Minas Gerais state, Brazil, and its relationship with bovine isolates obtained on the American continent based on sequence type profile. The MLST results were compared with all Salmonella STs associated with cattle on American continent, and a multi-locus sequence tree (MS tree) was built. Among the 17 S. enterica isolates, five ST profiles identified, and ST10 were the most frequent, grouping seven (41.2%) isolates. The isolates presented 11 different profiles of virulence genes, and six different antibiotics resistance profiles. The survey on Enterobase platform showed 333 Salmonella STs from American continent, grouped into four different clusters. Most of the isolates in the present study (13/17), were concentrated in a single cluster (L4) composed by 74 STs. As a conclusion, five different STs were identified, with ST10 being the most common. The isolates showed great diversity of virulence genes and antibiotics resistance profiles. Most of the isolates of this study were grouped into a single cluster composed by 74 STs formed by bovine isolates obtained on the American continent.

Antibiotic Resistance Profile of Salmonella sp. Isolates from Commercial Laying Hen Farms in Central-Western Brazil

Microbial resistance to antibiotics poses a significant threat to both human and animal health, necessitating international efforts to mitigate this issue. This study aimed to assess the resistance profiles of Salmonella sp. isolates and identify the presence of intl1, sul1, and blaTEM resistance genes within antigenically characterized isolates, including Agona, Livingstone, Cerro, Schwarzengrund, Salmonella enterica subsp. enterica serotype O:4.5, Anatum, Enteritidis, Johannesburg, Corvallis, and Senftenberg. These isolates underwent susceptibility testing against 14 antibiotics. The highest resistance percentages were noted for sulfamethoxazole (91%), sulfonamides (51%), and ceftiofur (28.9%), while no resistance was observed for ciprofloxacin. Salmonella Johannesburg and Salmonella Corvallis showed resistance to one antibiotic, whereas other serovars were resistant to at least two. Salmonella Schwarzengrund exhibited resistance to 13 antibiotics. The intl1 gene was detected in six out of the ten serovars, and the sul1 gene in three, always co-occurring with intl1. The blaTEM gene was not identified. Our findings highlight the risk posed by the detected multiple resistances and genes to animal, human, and environmental health. The multidrug resistance, especially to third-generation cephalosporins and fluoroquinolones, highlights the need for stringent monitoring of Salmonella in laying hens. The potential of the environment, humans, eggs, and their products to act as vectors for antibiotic resistance represents a significant concern for One Health.

Effect of ginger essential oil and 6-gingerol on a multispecies biofilm of Listeria monocytogenes, Salmonella Typhimurium, and Pseudomonas aeruginosa

The objective of this study was to evaluate the potential antimicrobial and antibiofilm effect of ginger essential oil (GEO) and 6-gingerol on a multispecies biofilm formed by Listeria monocytogenes, Salmonella Typhimurium, and Pseudomonas aeruginosa on a polypropylene surface. The minimum inhibitory concentration concentrations obtained for GEO were 100 and 50 mg/mL and for 6-gingerol 1.25 mg/mL. Sessile cell counts ranged within 5.35-7.35 log CFU/cm2 in the control biofilm, with the highest sessile growth at 72 h. GEO treatments acted on the total population regardless of concentration at 1 and 48 h. L. monocytogenes behaved similarly to the total population, showing GEO action at 1 h and keeping the same pattern at 48, 72, and 96 h. Better action on S. Typhimurium was obtained at times of 1, 72, and 96 h. P. aeruginosa showed logarithmic reduction only when treated with GEO 50 mg at 24 h. As for 6-gingerol, in general, there was no significant action (p > 0.05) on the evaluated sessile cells. GEO showed antimicrobial activity against L. monocytogenes, S. Typhimurium, and P. aeruginosa, acting as an inhibitor of biofilm formation. As for 6-gingerol, it was considered a possible antimicrobial agent but without efficacy during biofilm formation.

Characterization of microbial ecology, Listeria monocytogenes, and Salmonella sp. on equipment and utensil surfaces in Brazilian poultry, pork, and dairy industries

This study aimed to evaluate the level of counting by indicator microorganisms, identify the microbial ecology, detect Listeria monocytogenes and Salmonella sp., and determine the presence of virulence genes and biofilm formation. A total of 480 samples were collected from the surfaces of the equipment and utensils using sterile swabs for the detection of L. monocytogenes and Salmonella sp. and counting mesophilic aerobes, Enterobacteriaceae, Escherichia coli, and Pseudomonas sp. The microbial ecology was evaluated by sequencing the 16S rRNA gene. Genes for virulence and biofilm formation were analyzed and adhesion capacity was evaluated for L. monocytogenes and Salmonella sp. The mesophilic aerobe count was the highest in the dairy processing facility, followed by the pork and poultry slaughterhouses. L. monocytogenes was detected in all facilities, with the highest detection in the pork slaughterhouse, followed by the poultry and dairy facilities. Salmonella sp. was only detected in the dairy. Isolates of L. monocytogenes and Salmonella sp. showed poor adhesion to polystyrene surfaces, virulence genes, and biofilm formation. The frequent contaminants in the slaughterhouses were Pseudomonas, Acinetobacter, and Aeromonas in poultry, Acinetobacter, Pseudomonas, and Brevundimonas in pork, and Pseudomonas, Kocuria, and Staphylococcus in dairy. Our results provide useful information to understand the microbiological risks associated with contamination.

Comprehensive profiling of serotypes, antimicrobial resistance and virulence of Salmonella isolates from food animals in China, 2015-2021

Introduction

Salmonella is a ubiquitous foodborne pathogen and mainly transmitted to human farm-to-fork chain through contaminated foods of animal origin.

Methods

In this study, we investigated the serotypes, antimicrobial resistance and virulence of Salmonella from China.

Results

A total of 617 Salmonella isolates were collected from 4 major food animal species across 23 provi nces in China from 2015-2021. Highest Salmonella prevalence were observed in Guangdong (44.4%) and Sandong (23.7%). Chickens (43.0%) was shown to be the major source of Salmonella contamination, followed by pigs (34.5%) and ducks (18.5%). The number of Salmonella increased significantly from 5.51% to 27.23% during 2015-2020. S. Derby (17.3%), S. Enteritidis (13.1%) and S. Typhimurium (11.4%) were the most common serotypes among 41 serotypes identifiedin this study. Antibiotic susceptibility testing showing that the majority of the Salmonella isolates were resistant to neomycin (99.7%), tetracycline (98.1%), ampicillin (97.4%), sulfadiazine/trimethoprim (97.1%), nalidixic acid (89.1%), doxycycline (83.1%), ceftria xone (70.3%), spectinomycin (67.7%), florfenicol (60.0%), cefotaxime (52.0%) and lomefloxacin (59.8%). The rates of resistance to multiple antibiotics in S. Derby and S.Typhimurium were higher than that in S. Enteritidis. However, the rate of resistance to fosfomycin were observed from higher to lower by S. Derby, S. Enteritidis, and S. Typhimurium. Biofilm formation ability analysis found that 88.49%of the Salmonella were able to produce biofilms, of which 236 Salmonella isolates were strong biofilm producer. Among the 26 types of antibiotics resistance genes (ARGs) were identified in this study, 4 ARGs (tetB,sul2,aadA2, and aph(3')-IIa) were highly prevalent. In addition, 5 β-lactam resistance genes (bla _TEM, bla _SHV, bla _CMY-2, bla _CTX-M, and bla _OXA) and 7 quinolone resistance genes (oqxA, oqxB, qnrB, qnrC, qnrD, qnrS, and qeqA) were detected among these isolates. 12 out of 17 virulence genes selected in this study were commonly presented in the chromosomes of tested isolate, with a detection rate of over 80%, including misL, spiA, stn, pagC, iroN, fim, msgA, sopB, prgH, sitC, ttrC, spaN.

Discussion

This study provided a systematical updating on surveillance on prevalence of Salmonella from food animals in China, shedding the light on continued vigilance for Salmonella in food animals.

Salmonella Derby from pig production chain over a 10-year period: antimicrobial resistance, biofilm formation, and genetic relatedness

The aim of this study was to evaluate 140 Salmonella Derby isolates collected over a 10-year period from porcine origins (environment, pig carcass, lymph nodes, intestinal content, and pork) for their phenotypic and genotypic antimicrobial resistance, their ability to produce biofilm, and their genetic relatedness. The minimum inhibitory concentration (MIC) was determined using microdilution broth method and antimicrobial resistance genes were investigated by PCR. The quantification of biofilm formation was performed in sterile polystyrene microtiter plates. Genetic relatedness was determined by Xba-I macrorestriction analysis. The highest frequencies of non-wildtype (nWT) populations were observed against tetracycline (75.7%), streptomycin (70%), and colistin (11.4%), whereas wildtype populations were observed against ciprofloxacin, ceftazidime, and gentamicin. The resistance genes found were blaTEM (ampicillin), aadA variant (streptomycin/spectinomycin), tetA (tetracycline), and floR (florfenicol). On 96-well polystyrene microtiter plate, 68.6% of the isolates proved to be biofilm producers. Among 36 S. Derby isolates selected to PFGE analysis, 22 were clustered with 83.6% of similarity. Additionally, 27 isolates were clustered in 11 pulsotypes, which presented more than one strain with 100% of similarity. Most of S. Derby isolates were able to form biofilm and were classified as nWT or resistant to tetracycline, streptomycin, and colistin. PFGE allowed the identification of closely related S. Derby isolates that circulated in pig slaughterhouses and pork derived products along a decade.

Critically Important Antimicrobial Resistance Trends in Salmonella Derby and Salmonella Typhimurium Isolated from the Pork Production Chain in Brazil: A 16-Year Period

Knowledge about antimicrobial resistance in Salmonella is relevant due to its importance in foodborne diseases. We gathered data obtained over 16 years in the southern Brazilian swine production chain to evaluate the temporal evolution of halo for carbapenem, and the MIC for third-generation cephalosporins, fluoroquinolone, and polymyxin in 278 Salmonella Derby and Typhimurium isolates. All antimicrobial resistance assays were performed in accordance with EUCAST. To assess the diameter halo, we used a mixed linear model, and to assess the MIC, an accelerated failure time model for interval-censored data using an exponential distribution was used. The linear predictor of the models comprised fixed effects for matrix, serovar, and the interaction between year, serovar, and matrix. The observed halo diameter has decreased for ertapenem, regardless of serovars and matrices, and for the serovar Typhimurium it has decreased for three carbapenems. The MIC for ciprofloxacin and cefotaxime increased over 16 years for Typhimurium, and for Derby (food) it decreased. We did not find evidence that the MIC for colistin, ceftazidime, ciprofloxacin (Derby), or cefotaxime (food Typhimurium and animal Derby) has changed over time. This work gave an overview of antimicrobial resistance evolution from an epidemiological point of view and observed that using this approach can increase the sensitivity and timeliness of antimicrobial resistance surveillance.

Occurrence and Distribution of Antibiotic-Resistant Staphylococcus aureus in a Brazilian Pork Production Chain

ABSTRACT

Here we characterized the distribution and the antibiotic resistance of staphylococci from a Brazilian pork production chain. Samples (n = 1,114) from pig farms, pig lots, and slaughterhouses, located in two Brazilian states (Minas Gerais and Paraná), were subjected to coagulase-positive Staphylococcus enumeration. S. aureus isolates (n = 251) from this collection were further characterized for their resistance to oxacillin, cefoxitin, vancomycin, and tetracycline through phenotypic and molecular assays. Coagulase-positive Staphylococcus counts from pig farms were higher compared with other samples (P < 0.05). Other counts were relatively low but were present in all production stages. S. aureus isolates were commonly resistant to oxacillin and cefoxitin (54 of 73, 74.0%), qualifying them as methicillin-resistant S. aureus, but PCR assays indicated that few harbored the expected antimicrobial resistance genes (femB, mecA, and mecC). Lower frequencies of vancomycin and tetracycline resistance were found (6.8 to 37.0%). PCR sensitivity (34.5 to 86.7%) and specificity (26.6 to 85.0%) for detection of antibiotic resistance genes varied based on the assessed antibiotic. Antibiotic-resistant staphylococci are widely distributed in the Brazilian pork production chain, and methicillin-resistant S. aureus can become a potential health and economic impediment for the Brazilian pork industry.

HIGHLIGHTS

Characterization of Salmonella enterica Contamination in Pork and Poultry Meat from São Paulo/Brazil: Serotypes, Genotypes and Antimicrobial Resistance Profiles

Salmonellosis is a zoonosis of major relevance to global public health. Here we present the assessment of Salmonella enterica contamination in pork and poultry meat sold at retail markets in São Paulo, Brazil. A total of 780 meat samples (386 poultry meat and 394 pork samples) were collected from 132 markets. From these, 57 samples (7.3%) were positive for S. enterica isolation, including 32 (8.3%) poultry meat and 25 (6.3%) pork samples. S. enterica isolates were further characterized for serotyping, antimicrobial resistance and genotyping by amplified fragment length polymorphism and pulsed field gel electrophoresis. Antimicrobial resistance analysis demonstrated two main profiles: pork isolates were more resistant to macrolides, β-lactams, tetracycline, phenicols, and fluoroquinolones, and poultry meat isolates presented higher resistance to fluoroquinolones, sulfonamides, tetracycline, and β-lactams. A total of 72.4% of poultry meat isolates were identified as S. Heidelberg, while most of pork isolates were S. Typhimurium (31.7%) and S. Give (16.7%). Genotyping resulted in most clusters consisting exclusively of pork or poultry meat, no cross-contamination was detected, and a tendency to differentiate isolates according to their serotypes and markets of origin. High resistance rates to critically important antimicrobials reinforce the importance of controlling Salmonella contamination in meat production chains.

Anti-microbial resistance of Salmonella isolates from raw meat-based dog food in Japan

Background

Salmonella contamination of raw meat‐based diets (RMBDs) for pets poses a major public health concern but has not been investigated in Japan.

Objective

To investigate Salmonella contamination in RMBDs for dogs marketed in Japan and the anti‐microbial resistance profiles of the Salmonella isolates.

Methods

Sixty commercial RMBD samples were collected in the Okayama and Osaka Prefectures, Japan, between December 2016 and March 2017. The obtained Salmonella isolates were serotyped, their anti‐microbial resistance patterns were determined, and the anti‐microbial‐resistant isolates were screened for the presence of resistance genes by polymerase chain reaction.

Results

Salmonella enterica subsp. enterica was detected in seven of the 60 RMBD samples. Among them, five isolates were identified as S. Infantis (n = 3), S. Typhimurium (n = 1) and S. Schwarzengrund (n = 1), while the serotypes of two isolates were unable to be identified. All isolates were susceptible to ampicillin, cefazolin, cefotaxime and gentamycin. Two isolates were resistant to more than one anti‐microbial agent; one of the S. Infantis isolates was resistant to streptomycin, kanamycin, tetracycline and trimethoprim, while the S. Typhimurium isolate was resistant to nalidixic acid, ciprofloxacin and chloramphenicol. The S. Schwarzengrund isolate was resistant to tetracycline. Additionally, the S. Typhimurium isolate harboured the anti‐microbial resistance gene gyrA with a mutation corresponding to Ser‐83→Phe amino acid substitution.

Conclusion

The study findings suggest that RMBDs for dogs marketed in Japan can be a potential source of Salmonella infection for dogs and humans including infections caused by quinolone‐resistant isolates.

The current study's objective was to determine the prevalence of Salmonella contamination in RMBD for dogs and the antimicrobial resistance profiles of these isolates. Therefore, the incidence of Salmonella contamination in RMBD for dogs currently sold in Japan was surveyed. Salmonella was detected in seven of the 60 raw food samples.

Prevalence, serovar distribution, and antibiotic resistance of Salmonella spp. isolated from pork in China: A systematic review and meta-analysis

The epidemiological characteristics of Salmonella spp. in pork have been widely studied in China, but the results remain inconsistent. This study aimed to summarize the epidemiological characteristics of Salmonella spp. isolated from pork, including its prevalence, serovar distribution, and antibiotic resistance rate. We systematically reviewed published studies on Salmonella spp. isolated from pork in China between 2000 and 2020 in two Chinese and three English databases and quantitatively summarized its prevalence, serovar distribution, and antibiotic resistance using meta-analysis methods. Furthermore, we conducted subgroup analysis and meta-regression to explore the source of the heterogeneity from historical changes and regional difference perspectives. Ninety-one eligible studies published between 2000 and 2020 were included. The meta-analysis showed that the pooled prevalence of Salmonella isolated from pork was 0.17 (95% CI: 0.14, 0.20), with a detected growing trend over time. For the proportions of serovars, Derby (0.32, 95% CI: 0.26, 0.38), Typhimurium (0.10, 95% CI: 0.07, 0.15) and London (0.05, 95% CI: 0.03, 0.08) were dominant in these studies. The antibiotic resistance rates were high for tetracycline (0.68, 95% CI: 0.59, 0.77), sulfisoxazole (0.65, 95% CI: 0.45, 0.83), ampicillin (0.43, 95% CI: 0.34, 0.53), streptomycin (0.42, 95% CI: 0.29, 0.56), and sulfamethoxazole (0.42, 95% CI: 0.25, 0.60). The results of this study revealed a high prevalence, the regional characteristics of serovar distribution, and the severe challenges of antibiotic resistance of Salmonella originating from pork in China, suggesting the potential increasing risk and disease burden. Therefore, it is necessary to improve the prevention and control strategies of Salmonella in pork.

Pathogenic potential and antibiotic resistance of Yersinia enterocolitica, a foodborne pathogen limited to swine tonsils in a pork production chain from Southern Brazil

In this study, we aimed to characterize the distribution of Yersinia enterocolitica in a pork production chain in Brazil, as well as the virulence profile and antibiotic resistance of the obtained isolates. Samples from 10 pig lots obtained from finishing farms (water, feed, and barn floors, n = 30), slaughterhouse (lairage floors, carcasses at four processing steps, tonsils, and mesenteric lymph nodes, n = 610), and processing (end cuts, processing environment, n = 160) were obtained in Paraná state, Brazil, and subjected to Y. enterocolitica detection by ISO 10,273. The obtained isolates were identified based on biochemical and molecular features (16 s rRNA, inv, bioserotyping) and subjected to PCR assays to detect virulence (ail, ystA, ystB, virF, myfA, fepA, fepD, fes, tccC, ymoA, hreP, and sat) and multidrug resistance-related genes (emrD, yfhD, and marC). Also, isolates were subjected to disk diffusion test to characterize their resistance against 17 antibiotics from 11 classes and to pulsed field gel electrophoresis (PFGE) after XbaI macro-restriction. Y. enterocolitica was detected in a single sample (tonsil), and the obtained three isolates were characterized as serotype O:3, harboring ail, ystA, virF, myfA, tccC, ymoA, hreP, emrD, yfhD, and marC, and resistant to all tested antibiotics. The three isolates presented identical macro-restriction profiles by PFGE, also identical to isolates obtained from Minas Gerais, other Brazilian state; one selected isolate was identified as biotype 4. Despite the low occurrence of Y. enterocolitica in the studied pork production, the virulence potential and the antibiotic resistance profiles of the isolates demonstrated their pathogenic potential, and the macro-restriction profiles indicate strains descending from a common subtype in the pork production chain of two Brazilian States.

Antimicrobial Susceptibility and Frequency of bla and qnr Genes in Salmonella enterica Isolated from Slaughtered Pigs

Salmonella enterica is known as one of the most common foodborne pathogens worldwide. While salmonellosis is usually self-limiting, severe infections may require antimicrobial therapy. However, increasing resistance of Salmonella to antimicrobials, particularly fluoroquinolones and cephalosporins, is of utmost concern. The present study aimed to investigate the antimicrobial susceptibility of S. enterica isolated from pork, the major product in Philippine livestock production. Our results show that both the qnrS and the bla_TEM antimicrobial resistance genes were present in 61.2% of the isolates. While qnrA (12.9%) and qnrB (39.3%) were found less frequently, co-carriage of bla_TEM and one to three qnr subtypes was observed in 45.5% of the isolates. Co-carriage of bla_TEM and bla_CTX-M was also observed in 3.9% of the isolates. Antimicrobial susceptibility testing revealed that the majority of isolates were non-susceptible to ampicillin and trimethoprim/sulfamethoxazole, and 13.5% of the isolates were multidrug-resistant (MDR). MDR isolates belonged to either O:3,10, O:4, or an unidentified serogroup. High numbers of S. enterica carrying antimicrobial resistance genes (ARG), specifically the presence of isolates co-carrying resistance to both β-lactams and fluoroquinolones, raise a concern on antimicrobial use in the Philippine hog industry and on possible transmission of ARG to other bacteria.

Systematic Review: Nontyphoidal Salmonella in Food from Latin America

In Latin America, nontyphoidal Salmonella (NTS) is one of the most important etiological agents of foodborne infections; it can survive in soil, water, and food even after processing. Here, we aimed to perform a systematic review by collecting data on the prevalence, serotypes, and antimicrobial resistance (AMR) of NTS isolated from different food products in Latin America, following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Out of 1766 studies screened, 244 reports from 13 Latin American countries were eligible. Among these, 182 reported NTS prevalence, 87 reported NTS serotypes, and 83 reported serotypes with AMR patterns. The NTS prevalence ranged from 0.005% to 93.3%, regardless of country and food. Meat showed the highest NTS prevalence. Enteritidis, Typhimurium, and Derby were the most frequently observed serotypes in different food products. The serotypes Enteritidis, Typhimurium, and Infantis, isolated from animal products, showed the highest AMR rate. The presence of NTS in fruits and vegetables, which are generally consumed raw or as ready-to-eat food, indicates a high risk of salmonellosis from consuming these foods. Thus, the reduction of this pathogen in the food chain requires a One Health approach, involving good agricultural and manufacturing practices, low antimicrobial use, and proper waste management.

Prevalence and Antimicrobial Resistance of Salmonella and Staphylococcus aureus in Fattening Pigs in Hubei Province, China

Pig is usually the carrier of Salmonella and Staphylococcus aureus, and can transmit the bacteria along the pork production chain to cause severe public health problems. In this study, we investigated the prevalence of Salmonella and S. aureus in fattening pigs in Hubei Province, China. The overall prevalence of Salmonella in rectal swab among 896 samples from 22 farms was 17.30%, and that of S. aureus in nasal swab among 814 samples from 20 farms was 28.26%. Antimicrobial resistance (AMR) analysis showed that 95.33% of the Salmonella strains exhibited resistance to more than three classes of antimicrobial agents tested. The highest resistance proportions were for chloramphenicol (100%), sulfamethoxazole/trimethoprim (SXT) (100%), and tetracycline (TET) (93.46%), while the lowest proportions were for cefotaxime (37.38%), gentamicin (GEN) (34.58%), and ciprofloxacin (24.30%). On the other hand, 98.42% of the S. aureus strains were resistant to more than three classes of antimicrobial agents tested. The most common resistance among the S. aureus strains was against SXT (100.00%), followed by TET (98.43%), erythromycin (91.34%), and clindamycin (91.34%), while the lowest frequent resistances were against GEN (34.65%) and oxacillin (16.54%). The prevalence and AMR of Salmonella and S. aureus exhibited an obvious diversity among different pig farms. Our results provided the epidemiological data for risk analysis of foodborne bacteria and AMR in pig farms.

Comparative Analysis Using Pulsed-Field Gel Electrophoresis Highlights a Potential Transmission of Salmonella Between Asymptomatic Buffaloes and Pigs in a Single Farm

Buffaloes and pigs play an important epidemiological roll in the Salmonella infection cycle, and asymptomatic animals can act as key component in the dissemination of the disease by horizontal, vertical, and cross-species transmission. Our study aimed and was able to confirm evidences of a cross-species transmission of Salmonella Agona between asymptomatic buffaloes and pigs. Also, we described Salmonella infection within the pig production phases, involving serotypes Agona, Senftenberg and Schwarzengrund. Rectal samples were collected from Jafarabadi buffaloes (n = 25) and Piau pigs (n = 32), located on a single farm. Salmonella Agona was isolated from lactating buffaloes, gilts, pregnant sows, and weaned pigs, Salmonella Schwarzengrund from lactating sows and Salmonella Senftenberg from gilts, pregnant sows, lactating sows, and weaned pigs. Pulsed-field Gel Electrophoresis protocol (PFGE) was performed and revealed four different profiles. Profile 1 (Salmonella Agona), isolated from a pregnant sow, a gilt and two lactating buffaloes, revealed a indistinguishable PFGE pattern, confirming evidences of potential cross-species transmission. Profile 2 (Salmonella Agona), 3 (Salmonella Senftenberg), and 4 (Salmonella Schwarzengrund), isolated from pigs, revealed important indistinguishable PFGE patterns, evidencing Salmonella infection within the pig production phases. Considering the epidemiological relevance of buffaloes and pigs in the cycle of Salmonella infection, confirmation of a potential cross-species transmission of Salmonella Agona and potential Salmonella infection within the pig production phases highlights the importance of the correct establishment of preventive health strategies in farms, in special the importance of avoiding contact between buffaloes and pigs, since cross-species transmission can occur, increasing the risk of spreading the disease.

Phenotypic and genotypic characterization of non-typhoidal Salmonella isolated from a Brazilian pork production chain

Pork products are important sources of foodborne non-typhoidal Salmonella in Brazil where antibiotics are commonly used throughout the pork production process and this has the potential to selectively favor antibiotic-resistant strains. We characterized the genotypic and phenotypic diversity of S. enterica isolates (n = 41) that were isolated in Brazil. Isolates were collected from ten swine farms and one slaughterhouse. Whole-genome sequencing and in silico serotyping demonstrated that the S. enterica serovar Typhimurium was the most common serotype (n = 17), but eight additional servoars were identified. Isolates presented high similarity based on comparison of DNA sequences (minimum of 89.6%), and sequence variation grouped according to serotype. Eight multilocus sequence types were identified with ST19 being most common (n = 21). Several plasmids replicons were detected, with Col (RNAI) the most abundant (n = 30), followed by IncR (n = 22), IncI1 (n = 10) and IncA/C2 (n = 10). Minimum inhibitory concentration assays showed that the principle resistance phenotypes were for streptomycin (90.2%), tetracycline (87.8%), ampicillin (80.5%), chloramphenicol (70.7%) and ciprofloxacin (51.2%). Only two isolates were resistant to third-generation cephalosporins and no isolates were resistant to two tested carbapenems. Twenty-six unique antimicrobial-resistance genes were identified with bla_TEM-1A and bla_TEM-1B likely responsible for most beta-lactam resistance and floR responsible for most chloramphenicol resistance. Six strains were positive for mcr-1. At the time of collection, the sampled farms were adding ciprofloxacin to feed and this may have contributed to the high prevalence of resistance to this antibiotic. The high number of multidrug resistant Salmonella and the presence of multiple resistant genes and plasmids emphasize the diversity of Salmonella in the studied pork chain, specially from serotype Typhimurium.

Bonelli R, A. Penna B, P. Albuquerque J, M. Souza R, M. F. Cerqueira A. Antimicrobial Resistance in Farm Animals in Brazil: An Update Overview

In animal husbandry, antimicrobial agents have been administered as supplements to increase production over the last 60 years. Large-scale animal production has increased the importance of antibiotic management because it may favor the evolution of antimicrobial resistance and select resistant strains. Brazil is a significant producer and exporter of animal-derived food. Although Brazil is still preparing a national surveillance plan, several changes in legislation and timely programs have been implemented. Thus, Brazilian data on antimicrobial resistance in bacteria associated with animals come from official programs and the scientific community. This review aims to update and discuss the available Brazilian data on this topic, emphasizing legal aspects, incidence, and genetics of the resistance reported by studies published since 2009, focusing on farm animals and derived foods with the most global public health impact. Studies are related to poultry, cattle, and pigs, and mainly concentrate on non-typhoid Salmonella, Escherichia coli, and Staphylococcus aureus. We also describe legal aspects of antimicrobial use in this context; and the current occurrence of genetic elements associated with resistance to beta-lactams, colistin, and fluoroquinolones, among other antimicrobial agents. Data here presented may be useful to provide a better understanding of the Brazilian status on antimicrobial resistance related to farm animals and animal-derived food products.

Antimicrobial Resistance in Farm Animals in Brazil: An Update Overview

In animal husbandry, antimicrobial agents have been administered as supplements to increase production over the last 60 years. Large-scale animal production has increased the importance of antibiotic management because it may favor the evolution of antimicrobial resistance and select resistant strains. Brazil is a significant producer and exporter of animal-derived food. Although Brazil is still preparing a national surveillance plan, several changes in legislation and timely programs have been implemented. Thus, Brazilian data on antimicrobial resistance in bacteria associated with animals come from official programs and the scientific community. This review aims to update and discuss the available Brazilian data on this topic, emphasizing legal aspects, incidence, and genetics of the resistance reported by studies published since 2009, focusing on farm animals and derived foods with the most global public health impact. Studies are related to poultry, cattle, and pigs, and mainly concentrate on non-typhoid Salmonella, Escherichia coli, and Staphylococcus aureus. We also describe legal aspects of antimicrobial use in this context; and the current occurrence of genetic elements associated with resistance to beta-lactams, colistin, and fluoroquinolones, among other antimicrobial agents. Data here presented may be useful to provide a better understanding of the Brazilian status on antimicrobial resistance related to farm animals and animal-derived food products.