Antimicrobial resistance in Salmonella enteritidis strains isolated from broiler carcasses, food, human and poultry-related samples

Exploring of spectrum beta lactamase producing multidrug-resistant Salmonella enterica serovars in goat meat markets of Bangladesh

The emergence of Salmonella enterica serovars that produce extended-spectrum beta-lactamase and exhibit multi-drug resistance (MDR) poses a substantial global threat, contributing to widespread foodborne illnesses and presenting an alarming issue for public health. This study specifically concentrated on the isolation and identification of ESBL-resistant genes (bla TEM, bla SHV, bla CTX-M1, bla CTX-M2, bla CTX-M9, MultiCase ACC, MultiCase MOX, MultiCase DHA, bla OXA) and the antibiogram profiling of Salmonella enterica serovars found in goat meat samples procured from retail outlets in Bangladesh. During the research in the Sylhet district of Bangladesh, researchers gathered a total of 210 samples of goat meat from 13 different Upazilas. Primarily, cultural and biochemical methods were used for isolation of bacteria from the selected samples. Salmonella enterica serovars Typhimurium and Enteritidis, along with three ESBL-resistant genes, were identified through polymerase chain reactions (PCRs). The disk diffusion test was used to determine antimicrobial susceptibilities. Out of 210 samples analysed, Salmonella spp. was detected in 18.10 % (38 out of 210), with S. Enteritidis and S. Typhimurium found in 9.05 % (19 out of 210) and 5.24 % (11 out of 210) of the samples, respectively. A total of 72.73 % (8/11) of S. Enteritidis and 100 % (19/19) of S. Typhimurium isolates were positive by Multidrug-resistant patterns. The positive outcomes were found of S. Typhimurium tested 63.16 % (12 out of 19) for the bla TEM gene and 21.05 % (4/19) for the bla SHV, gene. The study proposes that the retail goat meat market channel could be a prominent transmission way of ESBL-producing MDR Salmonella enterica serovars, representing a significant public health hazard.

Salmonella spp. in Domestic Ruminants, Evaluation of Antimicrobial Resistance Based on the One Health Approach-A Systematic Review and Meta-Analysis

Salmonella spp. pose a global threat as a leading cause of foodborne illnesses, particularly prevalent in the European Union (EU), where it remains the second cause of foodborne outbreaks. The emergence of antimicrobial resistance (AMR) in Salmonella spp. has become a critical concern, complicating treatment strategies and escalating the risk of severe infections. The study focuses on large and small ruminants, identifying a prevalence of Salmonella spp. in slaughterhouses and revealing varied AMR rates across antimicrobial families throughout a meta-analysis. Also, comparison with AMR in human medicine was carried out by a systematic review. The results of the present meta-analysis displayed a prevalence of Salmonella spp. in large and small ruminants at slaughterhouses of 8.01% (8.31%, cattle; 7.04%, goats; 6.12%, sheep). According to the AMR of Salmonella spp., 20, 14, and 13 out of 62 antimicrobials studied were classified as low (<5%), high (>5% but <10%), and very high (>10%), respectively. Salmonella spp. did not display AMR against aztreonam, mezlocillin, ertapenem, meropenem, cefoxitin, ceftazidime, levofloxacin, tilmicosin, linezolid, fosfomycin, furazolidone, quinupristin, trimethoprim and spectinomycin. In contrast, a prevalence of 100% of AMR has been described against ofloxacin, lincomycin, and cloxacillin. In the context of the main antibiotics used in the treatment of human salmonellosis, azithromycin was shown to have the highest resistance among Salmonella spp. isolates from humans. Regarding cephalosporins, which are also used for the treatment of salmonellosis in humans, the prevalence of Salmonella spp. resistance to this class of antibiotics was similar in both human and animal samples. Concerning quinolones, despite a heightened resistance profile in Salmonella spp. isolates from ruminant samples, there appears to be no discernible compromise to the efficacy of salmonellosis treatment in humans since lower prevalences of AMR in Salmonella spp. isolated from human specimens were observed. Although the resistance of Salmonella spp. indicates some degree of concern, most antibiotics are not used in veterinary medicine. Thus, the contribution of cattle, sheep and goats to the rise of antibiotic resistance of Salmonella spp. and its potential impact on public health appears to be relatively insignificant, due to their low prevalence in carcasses and organs. Nevertheless, the observed low prevalence of Salmonella spp. in ruminants at slaughterhouse and the correspondingly low AMR rates of Salmonella spp. to key antibiotics employed in human medicine do not indicate that ruminant livestock poses a substantial public health risk concerning the transmission of AMR. Thus, the results observed in both the meta-analysis and systematic review suggests that AMR is not solely attributed to veterinary antibiotic use but is also influenced by factors such as animal health management (i.e., biosecurity measures, prophylactic schemes) and human medicine.

Evaluation of the in vitro and in vivo efficiency of in-feed bacteriophage cocktail application to control Salmonella Typhimurium and Salmonella Enteritidis infection in broiler chicks

RESEARCH HIGHLIGHTS

Bacteriophage (BP) cocktail was partially resistant to different temperatures and pH values.The BP cocktail showed lytic effects on different Salmonella isolates.The BP cocktail reduced Salmonella colonization in the internal organs of broilers.

Anti-Salmonella Defence and Intestinal Homeostatic Maintenance In Vitro of a Consortium Containing Limosilactobacillus fermentum 3872 and Ligilactobacillus salivarius 7247 Strains in Human, Porcine, and Chicken Enterocytes

Limosilactobacillus fermentum strain 3872 (LF3872) was originally isolated from the breast milk of a healthy woman during lactation and the breastfeeding of a child. Ligilactobacillus salivarius strain 7247 (LS7247) was isolated at the same time from the intestines and reproductive system of a healthy woman. The genomes of these strains contain genes responsible for the production of peptidoglycan-degrading enzymes and factors that increase the permeability of the outer membrane of Gram-negative pathogens. In this work, the anti-Salmonella and intestinal homeostatic features of the LF3872 and LS7247 consortium were studied. A multi-drug resistant (MDR) strain of Salmonella enteritidis (SE) was used in the experiments. The consortium effectively inhibited the adhesion of SE to intact and activated human, porcine, and chicken enterocytes and reduced invasion. The consortium had a bactericidal effect on SE in 6 h of co-culturing. A gene expression analysis of SE showed that the cell-free supernatant (CFS) of the consortium inhibited the expression of virulence genes critical for the colonization of human and animal enterocytes. The CFS stimulated the production of an intestinal homeostatic factor-intestinal alkaline phosphatase (IAP)-in Caco-2 and HT-29 enterocytes. The consortium decreased the production of pro-inflammatory cytokines IL-8, TNF-α, and IL-1β, and TLR4 mRNA expression in human and animal enterocytes. It stimulated the expression of TLR9 in human and porcine enterocytes and stimulated the expression of TLR21 in chicken enterocytes. The consortium also protected the intestinal barrier functions through the increase of transepithelial electrical resistance (TEER) and the inhibition of paracellular permeability in the monolayers of human and animal enterocytes. The results obtained suggest that a LF3872 and LS7247 consortium can be used as an innovative feed additive to reduce the spread of MDR SE among the population and farm animals.

Antimicrobial Susceptibility of Salmonella Isolated from Chickens and Humans in Wau, South Sudan

Background. Salmonella infections are a public health problem across the globe. In South Sudan, there is little information regarding the prevalence and antibiotic resistance patterns of Salmonella. Therefore, this study assessed the prevalence and antimicrobial susceptibility of Salmonella isolates from chickens and humans in South Sudan. Fecal samples were collected and cultured on Xylose Lysine Deoxycholate Agar for the isolation of Salmonella and confirmed using biochemical tests and PCR through the amplification of the invA gene. A total of 417 fecal samples were examined, of which 270 (64.7%) were chicken cloacal swabs while 147 (35.3%) were humans’ stool specimens. Results. Eleven (11) Salmonella isolates were isolated from humans while nine were from chickens. All 11 isolates from humans were susceptible to sulfamethoxazole-trimethoprim, chloramphenicol, streptomycin, cefotaxime, nalidixic acid, and gentamicin. However, 4 (36.7%) isolates showed resistance to ciprofloxacin, 2 (18.9%) to ampicillin, and 1 (9.1%) to tetracycline. All chicken isolates were susceptible to chloramphenicol, streptomycin, sulfamethoxazole-trimethoprim, ciprofloxacin, cefotaxime, nalidixic acid, and gentamicin but showed resistance to tetracycline 2 (22.2%) and ampicillin 1 (11.1%). Conclusion. Antimicrobial resistant isolates were isolated in both chickens and humans. Further, MDR isolates were found in both chicken and human samples, and this is a public health concern. This, therefore, calls for concerted efforts to educate producers and consumers on public health, food safety, food hygiene in food production, and enhancement of surveillance programmes on zoonotic bacteria and antimicrobial susceptibility.

Emergence, Dissemination and Antimicrobial Resistance of the Main Poultry-Associated Salmonella Serovars in Brazil

Salmonella infects poultry, and it is also a human foodborne pathogen. This bacterial genus is classified into several serovars/lineages, some of them showing high antimicrobial resistance (AMR). The ease of Salmonella transmission in farms, slaughterhouses, and eggs industries has made controlling it a real challenge in the poultry-production chains. This review describes the emergence, dissemination, and AMR of the main Salmonella serovars and lineages detected in Brazilian poultry. It is reported that few serovars emerged and have been more widely disseminated in breeders, broilers, and layers in the last 70 years. Salmonella Gallinarum was the first to spread on the farms, remaining as a concerning poultry pathogen. Salmonella Typhimurium and Enteritidis were also largely detected in poultry and foods (eggs, chicken, turkey), being associated with several human foodborne outbreaks. Salmonella Heidelberg and Minnesota have been more widely spread in recent years, resulting in frequent chicken/turkey meat contamination. A few more serovars (Infantis, Newport, Hadar, Senftenberg, Schwarzengrund, and Mbandaka, among others) were also detected, but less frequently and usually in specific poultry-production regions. AMR has been identified in most isolates, highlighting multi-drug resistance in specific poultry lineages from the serovars Typhimurium, Heidelberg, and Minnesota. Epidemiological studies are necessary to trace and control this pathogen in Brazilian commercial poultry production chains.

Characterisation of Salmonella Enteritidis ST11 and ST1925 Associated with Human Intestinal and Extra-Intestinal Infections in Singapore

Salmonella Enteritidis is a major foodborne pathogen worldwide. In this study, a total of 276 S. enteritidis isolates, collected between 2016 and 2017 from human, food and farm/slaughterhouse samples, were studied to enhance the understanding of the epidemiology of human salmonellosis in Singapore. Results showed all 276 isolates belonged either to ST1925 (70.3%) or ST11 (29.7%), with ST11 being significantly more frequent in extra-intestinal isolates and chicken isolates. Food isolates, most of which were from poultry, showed the highest prevalence of resistance (33–37%) against beta-lactams or beta-lactams/beta-lactamase inhibitor combination (ampicillin, piperacillin and ampicillin/sulbactam). The analysis showed the detection of genes associated with resistance to aminoglycoside genes (99.6%), tetracycline (55.1%), and beta-lactams (14.9%) of all isolates. Nine types of plasmids were found in 266 isolates; the most common incompatibility group profiles were IncFIB(S)-IncFII(S)-IncX1 (72.2%) and IncFIB(S)-IncFII(S) (15.8%). Most plasmid harbouring isolates from chicken (63.6%, 14/22) and from human (73.8%, 175/237) shared the same plasmid profile (IncFIB(S)-IncFII(S)-IncX1). SNP analysis showed clustering of several isolates from poultry food products and human isolates, suggesting phylogenetic relatedness among these isolates. Lastly, this study provides important epidemiological insights on the application of phenotypic and next-generation sequencing (NGS) tools for improved food safety and public health surveillance and outbreak investigation of S.enteritidis.

Inoculation of Weaned Pigs by Feed, Water, and Airborne Transmission of Salmonella enterica Serotype 4,[5],12:i:

ABSTRACT

Salmonella enterica serotype 4,[5],12:i:- (STM) has become an increasing problem for food safety and has been often detected in swine products. Weanling pigs were exposed to STM-contaminated feed, water, or air to determine possible STM transmission routes. A control group of pigs was included. STM was monitored daily in feces and rectal and nasal swabs. STM colonization was most prevalent in tissues from tonsil, lower intestine, and mesenteric lymph nodes. No differences in lesion severity were observed between inoculated and control pigs. Contaminated feed, water, and aerosolized particles caused infection in weaned pigs; however, no STM colonization was observed in skeletal muscle destined for human consumption. Based on the results from this study, STM contamination in pork products most likely results from cross-contamination of meat by digesta or lymph node tissue during processing.

HIGHLIGHTS

CRISPR-Cas System: An Adaptive Immune System’s Association with Antibiotic Resistance in Salmonella enterica Serovar Enteritidis

Several factors are involved in the emergence of antibiotic-resistant bacteria and pose a serious threat to public health safety. Among them, clustered regularly interspaced short palindromic repeat- (CRISPR-) Cas system, an adaptive immune system, is thought to be involved in the development of antibiotic resistance in bacteria. The current study was aimed at determining not only the presence of antibiotic resistance and CRISPR-Cas system but also their association with each other in Salmonella enteritidis isolated from the commercial poultry. A total of 139 samples were collected from poultry birds sold at the live bird markets of Lahore City, and both phenotypic and genotypic methods were used to determine antimicrobial resistance. The presence of the CRISPR-Cas system was determined by PCR, followed by sequencing. All isolates of S. enteritidis (100%) were resistant to nalidixic acid, whereas 95% of isolates were resistant to ampicillin. Five multidrug-resistant isolates (MDR) such as S. enteritidis isolate (S. E1, S. E2, S. E4, S. E5, and S. E8) were found in the present study. The CRISPR-Cas system was detected in all of these MDR isolates, and eight spacers were detected within the CRISPR array. In addition, an increased expression of CRISPR-related genes was observed in the standard strain and MDR S. enteritidis isolates. The association of the CRISPSR-Cas system with multiple drug resistance highlights the exogenous acquisition of genes by horizontal transfer. The information could be used further to combat antibiotic resistance in pathogens like Salmonella.

Whole-Genome Analysis of Multidrug-Resistant Salmonella Enteritidis Strains Isolated from Poultry Sources in Korea

The Salmonella Enterica subsp. Enterica serovar Enteritidis is one of main serovars isolated from human patients with food poisoning and poultry without clinical signs. Consumption of poultry products contaminated with Salmonella Enteritidis is a common source of human salmonellosis; 82 Salmonella spp. were isolated from 291 samples of retail chicken meat, 201 one-day-old chicks, 30 internal organs of chickens, 156 chicken eggs, 100 duck eggs, 38 straw bedding samples, 18 samples of retail duck meat, and 19 swab samples from slaughterhouses in 2019 and 2020. An antibiotic susceptibility test was performed for all isolates, revealing 33 multidrug-resistant (MDR) strains. The whole genome of 33 MDR strains isolated in 2019 and 2020 and 10 strains isolated in 2011, 2012, and 2017 was sequenced using the MinION sequencing protocol. Within these 43 samples, 5 serovars were identified: S. Enteritidis, S. Agona, S. Virchow, S. Albany, and S. Bareilly. The most common serovar was S. Enteritidis (26/43), which showed the highest resistance to ampicillin (100%), followed by nalidixic acid (90%) and colistin (83%). Core genome multilocus sequence typing analysis showed that the S. Enteritidis strains isolated from different sources and in different years were clustered together. In addition, the S. Enteritidis strains isolated since 2011 consistently harbored the same antibiotic resistance patterns.

Salmonella Characterization in Poultry Eggs Sold in Farms and Markets in Relation to Handling and Biosecurity Practices in Ogun State, Nigeria

Salmonella remains one of the notable food-borne bacterial pathogens. It is associated with poultry and poultry products including eggs. This study investigated Salmonella distribution in eggshell and content, their antimicrobial resistance pattern, and the possible risk factors driving contamination in Ogun State, Nigeria. A total of 500 eggs (5 eggs pooled into one sample) were collected and culturally examined for the presence of Salmonella serovars. Isolates were further characterized biochemically using Microbact 20E (Oxoid) and Antimicrobial susceptibility determined by the Kirby-Bauer disk diffusion method. A total of 14 Salmonella isolates spread across 10 serovars were recovered from the 100 pooled egg samples; 10 (10%) from the market and 4 (4%) farms, 13(13%) eggshell, and 1(1%) egg content. All tested serovars were susceptible to ampicillin, chloramphenicol, florfenicol, and kanamycin. Resistance was mostly observed in sulfamethoxazole 8 (80%), followed by ciprofloxacin 5 (50%) and tetracycline 3 (30%). Sales of eggs in the market appear to be a strong factor encouraging contamination in addition to poor biosecurity and unhygienic handling of eggs on the farm.

Isolation, identification, molecular detection and sensitivity to antibiotics of Salmonella from cattle faeces

The present study was designed with the aim of isolation and identification of Salmonella by con-ventional culture method and their confirmation by polymerase chain reaction (PCR). Antibacte-rial sensitivity study of isolated Salmonella from cattle faeces was also performed. During the study period of July 2017 to June 2018, a total of 200 faecal samples were collected from different government and private farms in Sylhet district of Bangladesh. Out of 200 samples, 24 (12%) were found to be positive for Salmonella by conventional culture methods. Among the twenty four suspected colonies of Salmonella, seventeen were confirmed by biochemical test and same number was detected by PCR estimating a prevalence of 8.5% (17/200). The prevalence was high-er in calves under 1 year of age (16%) compared with older animals (11.25% of 1–2 years; 10% of above 2 years of age) but without statistically significant differences (χ2=4.835, P=0.089). Moreo-ver, in diarrhoeic animals the prevalence was significantly higher (32.14%, χ2=49.414, P<0.01) than in apparently healthy animals (8.72%). The antibiotic sensitivity test showed that highest number of Salmonella isolates were sensitive to ciprofloxacin (100%), gentamicin (100%) and neomycin (100%). On the other hand, significantly high resistance of Salmonella isolates was detected to erythromycin (100%), amoxicillin (100%), cotrimoxazole (81.48%), streptomycin (62.96%) followed by tetracycline (55.56%).

Insights into the Oxidative Stress Response of Salmonella enterica serovar Enteritidis Revealed by the Next Generation Sequencing Approach

As a facultative intracellular pathogen, Salmonella Enteritidis must develop an effective oxidative stress response to survive exposure to reactive oxygen species within the host. To study this defense mechanism, we carried out a series of oxidative stress assays in parallel with a comparative transcriptome analyses using a next generation sequencing approach. It was shown that the expression of 45% of the genome was significantly altered upon exposure to H₂O₂. Quantitatively the most significant (≥100 fold) gene expression alterations were observed among genes encoding the sulfur utilization factor of Fe-S cluster formation and iron homeostasis. Our data point out the multifaceted nature of the oxidative stress response. It includes not only numerous mechanisms of DNA and protein repair and redox homeostasis, but also the key genes associated with osmotic stress, multidrug efflux, stringent stress, decrease influx of small molecules, manganese and phosphate starvation stress responses. Importantly, this study revealed that oxidatively stressed S. Enteritidis cells simultaneously repressed key motility encoding genes and induced a wide range of adhesin- and salmonellae-essential virulence-encoding genes, that are critical for the biofilm formation and intracellular survival, respectively. This finding indicates a potential intrinsic link between oxidative stress and pathogenicity in non-typhoidal Salmonella that needs to be empirically evaluated.

Frequency of Antimicrobial Resistance Genes in Salmonella From Brazil by in silico Whole-Genome Sequencing Analysis: An Overview of the Last Four Decades

Salmonella is a leading human pathogen and a significant public health concern worldwide. Massive food production and distribution have contributed to this pathogen dissemination, which, combined with antimicrobial resistance (AMR), creates new control challenges in food safety. The development of AMR is a natural phenomenon and can occur in the bacterial evolutionary process. However, the overuse and the misuse of antimicrobial drugs in humans and in animals have increased AMR selective pressure. In Brazil, there is an accuracy lack in AMR frequency in Salmonella because too many isolates are under-investigated for genetic and phenotypic AMR by the Brazilian health authorities and the research community. This underreporting situation makes the comprehension of the real level of Salmonella AMR in the country difficult. The present study aimed to use bioinformatics tools for a rapid in silico screening of the genetic antimicrobial resistance profile of Salmonella through whole-genome sequences (WGS). A total of 930 whole-genome sequences of Salmonella were retrieved from the public database of the National Biotechnology Information Center (NCBI). A total of 65 distinct resistance genes were detected, and the most frequent ones were tet(A), sul2, and fosA7. Nine point mutations were detected in total, and parC at the 57 position (threonine → serine) was the highest frequent substitution (26.7%, 249/930), followed by gyrA at the 83 position (serine → phenylalanine) (20.0%, 186/930) and at the 87 position (aspartic acid → asparagine) (15.7%, 146/930). The in silico prediction of resistance phenotype showed that 58.0% (540/930) of the strains can display a multidrug resistance (MDR) profile. Ciprofloxacin and nalidixic acid were the antimicrobial drugs with the highest frequency rates of the predicted phenotype resistance among the strains. The temporal analysis through the last four decades showed increased frequency rates of antimicrobial resistance genes and predicted resistance phenotypes in the 2000s and the 2010s when compared with the 1980s and 1990s. The results presented herein contributed significantly to the understanding of the strategic use of WGS associated with in silico analysis and the predictions for the determination of AMR in Salmonella from Brazil.

A Dynamic Method for Broad-Spectrum Bacteriophage Cocktail Formulation Against Poultry-Associated Salmonella enterica

Background: Poultry products are the largest food category linked to salmonellosis in Canada. Bacteriophages (phages) have been proposed as a novel antimicrobial in the poultry industry due to their documented ubiquity, efficacy, and safety benefits. Materials and Methods: A library of 78 lytic phages was rapidly screened against 50 prominent poultry-associated Salmonella enterica isolates procured from British Columbia, Canada. Results: A phage cocktail was successfully formulated using only three sewage-isolated phages (SE4, SE13, and SE20) to achieve broad-spectrum antimicrobial efficacy across all S. enterica serovars. Highly promising phages were also characterized using one-step growth curves and transmission electron microscopy. Conclusion: Relative host efficiency is a new agar-based semiquantitative metric developed here for the rapid comparison of different phages against a panel of known bacterial targets.

Study of the antibiotic residues in poultry meat in some of the EU countries and selection of the best compositions of lactic acid bacteria and essential oils against Salmonella enterica

In this study, the presence of antibiotics (ANB) residues was evaluated in poultry meat purchased from German and Lithuanian markets. In addition, the antimicrobial activity of 13 lactic acid bacteria (LAB) strains, 2 essential oils (EO) (Thymus vulgaris and Origanum vulgare L.), and their compositions were tested for the purpose of inhibiting antibiotic-resistant Salmonella spp. ANB residues were found in 3 out of the 20 analyzed poultry meat samples: sample no. 8 contained enrofloxacin (0.46 μg/kg), sample no. 14 contained both enrofloxacin and doxycycline (0.05 and 16.8 μg/kg, respectively), and sample no. 18 contained enrofloxacin (2.06 μg/kg). The maximum residue limits (MRLs) for the sum of enrofloxacin and ciprofloxacin and for doxycycline in the poultry muscle are 100 μg/kg. Finally, none of the tested poultry meat samples exceeded the suggested MRLs; however, the issue of ANB residues still requires monitoring of the poultry industry in Germany, Poland, and Lithuania, despite the currently established low ANB concentrations. These findings can be explained by the increased use of alternatives to ANB in the poultry industry. Our results showed that an effective alternative to ANB, which can help to reduce the occurrence of antibiotic-resistant salmonella, is a composition containing 1.0% of thyme EO and the following LAB strains: Lactobacillus plantrum LUHS122, Enteroccocus pseudoavium LUHS242, Lactobacillus casei LUHS210, Lactobacillus paracasei LUHS244, Lactobacillus plantarum LUHS135, Lactobacillus coryniformins LUHS71, and Lactobacillus uvarum LUHS245, which can be recommended for poultry industry as components of feed or for the treatment of surfaces, to control the contamination with Salmonella strains. However, it should be mentioned that most of the tested LAB strains were inhibited by thyme EO at the concentrations of 0.5 and 1.0%, except for LUHS122, LUHS210, and LUHS245. Finally, it can be noted that the agents responsible for the inhibitory effect on Salmonella are not the viable LAB strains but rather their metabolites, and further studies are needed to identify which metabolites are the most important.

Antimicrobial Resistance in Nontyphoidal Salmonella Isolates from Human and Swine Sources in Brazil: A Systematic Review of the Past Three Decades

Salmonella is the leading cause of foodborne illnesses worldwide. The widespread use of antimicrobials as prophylactic, therapeutic, and growth promoters in both livestock and human medicine has resulted in selective pressure regarding antimicrobial-resistant (AMR) bacteria. This systematic review summarizes phenotypic antimicrobial resistance profiles in Salmonella isolates from human and swine sources between 1990 and 2018 in Brazil. The 20 studies that matched the eligibility criteria-isolates from pigs and humans from Brazil, between 1990 and 2016, containing information on the number of Salmonella isolates, and applying the disk diffusion susceptibility method-were included. During the assessed period, Salmonella strains isolated from swine sources displayed the highest resistance rates for tetracycline (20.3%) and sulfonamides (17.4%). In contrast, human isolates displayed the highest resistance rates against ampicillin (19.8%) and tetracycline (17%). Salmonella Typhimurium was the most frequent AMR isolate from both swine and human sources, corresponding to 67% of all isolates. From 2001 to 2005, tetracycline and ampicillin were the top antimicrobial resistance compounds, and the most frequently detected in swine and human sources, respectively. A total of 63 and 58 multiple drug resistance profiles were identified in swine and human isolates, respectively. Antimicrobial resistance has decreased throughout the 1990-2016 period, except for gentamicin and nalidixic acid in swine and human isolates, respectively. The results indicate that Salmonella isolated from human and swine display resistance against clinically important antimicrobials, indicating that swine are possibly one of the main vectors for spreading human salmonellosis in Brazil.

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.

Egg Production in Poultry Farming Is Improved by Probiotic Bacteria

Antimicrobial resistance (AMR) is one of the most serious threats for human health in the near future. Livestock has played an important role in the appearance of antibiotic-resistant bacteria, intestinal dysbiosis in farming animals, or the spread of AMR among pathogenic bacteria of human concern. The development of alternatives like probiotics is focused on maintaining or improving production levels while diminishing these negative effects of antibiotics. To this end, we supplied the potential probiotic Enterococcus faecalis UGRA10 in the diet of laying hens at a final concentration of 10⁸ Colony Forming Units per gram (CFU/g) of fodder. Its effects have been analyzed by: (i) investigating the response of the ileum and caecum microbiome; and (ii) analyzing the outcome on eggs production. During the second half of the experimental period (40 to 76 days), hens fed E. faecalis UGRA10 maintained egg production, while control animals dropped egg production. Supplementation diet with E. faecalis UGRA10 significantly increased ileum and caecum bacterial diversity (higher bacterial operational taxonomic unit richness and Faith’s diversity index) of laying hens, with animals fed the same diet showing a higher similarity in microbial composition. These results point out to the beneficial effects of E. faecalis UGRA10 in egg production. Future experiments are necessary to unveil the underlying mechanisms that mediate the positive response of animals to this treatment.

Spread of the serotypes and antimicrobial resistance in strains of Salmonella spp. isolated from broiler

Serotypes and antimicrobial susceptibility of Salmonella's isolates from broiler production chain were determined. A total of 239 isolated strains from chicken, carcasses, breeding environments, and slaughter was analyzed by disk diffusion test, in the period of 2009 to 2010. For antibiotics with a high number of resistant strains, the minimal inhibitory concentration (MIC) was performed. We identified 24 serotypes, being the most frequent, Minnesota (31.4%) and Infantis (22.6%). The highest percentages of resistance were obtained for sulfonamide (42.7%), followed by tetracycline with 37.6% and amoxicillin with 27.6%. From the total, 32 resistance profiles were identified, being 60.7% of the strains were resistant to at least one antibiotic. Of these, 31.7% of the isolates showed multidrug resistance profiles belonging to serovar Minnesota, Saintpaul, and S. enterica. The highest resistance was found in isolates from slaughterhouse (66.9%) and aviary (58.7%). A large number of strains showed MIC above the maximum tested concentration for the antibiotics amoxicillin and sulfamethoxazole. The high number of Salmonella's resistant strains indicates the need for prudent use of these drugs in poultry production in order to reduce the occurrence and spread of antibiotic resistance profiles, and the risk that multiresistant strains isolated from broilers may pose a risk to human health.

Occurrence, antimicrobial resistance and whole-genome sequencing analysis of Salmonella isolates from chicken carcasses imported into Iraq from four different countries

Salmonella is a major cause of human foodborne illnesses worldwide; however, little is known about its occurrence and genomic characteristics in food sources in many developing countries. This study investigates the occurrence, serotypes distribution, antimicrobial resistance, and multilocus sequence types (ST) of Salmonella isolated from 400 imported frozen chicken carcasses sold in the markets of Thi-Qar, south-eastern Iraq. Salmonella was detected in 46 out of 400 tested samples [11.5% (95% confidence interval: 8.5%-15.0%)]. S. Typhimurium was the most abundant (30.4%) among 14 different serotypes recovered from the tested frozen carcasses. Antimicrobial resistance was most frequently detected against tetracycline (84.4%), nalidixic acid (80.4%), streptomycin (69.6%) and trimethoprim/sulfamethoxazole (65.2%). Whole-genome sequencing (WGS) analysis revealed that 18 isolates harbored four β-lactamase resistance genes, with bla_CARB-2 was the most commonly (14/18) detected. It was possible to identify 8 multilocus sequence types from the WGS analysis of 40 out of the 46 Salmonella isolates; with ST-11 (among S. Enteritidis) and ST-19 (among S. Typhimurium) were the most frequently detected. These results add to our understanding of the global epidemiology of Salmonella. Our work stands as one of the first reports on WGS analysis of Salmonella from retail chicken in a Middle-Eastern country. Results from this study could be valuable for guiding an informed import risk analysis aiming at reducing the exposure risk from Salmonella through imported chicken carcasses into Iraq. This work demonstrates the value of WGS as a promising tool for supporting evidence-based food safety hazard characterization.

In vitro activity of Nigella sativa against antibiotic resistant Salmonella enterica

Salmonellosis is a major food-borne disease worldwide and antimicrobial resistance in Salmonella is a public health problem. Phytochemicals are alternative therapeutics to treat antibiotic resistant Salmonella. Biochemically identified Salmonella enterica of human and poultry origin (n = 10) were confirmed by polymerase chain reaction. Susceptibility to antibiotics was determined by Kirby Bauer disc diffusion method. In-vitro anti-salmonella activity of N. sativa essential oil and extracts (aqueous and methanol) was determined against antibiotic resistant isolates by well diffusion and micro broth dilution method. Cytotoxic potential of N. sativa was observed by MTT assay. In S. eneterica the highest resistance (100%) was detected against nalidixic acid and ampicillin followed by oflaxacin (80%), tetracycline, co-trimoxazole and amoxicillin (60%), ciprofloxacin (40%) and gentamicin (20%). Methanol extract of N. sativa produced zone of inhibition from 35 ± 1.00 to 17 ± 1.00 with mean MIC value ≥562.5 ± 384.1 μg/mL. Essential oil showed antibacterial activity with zone of inhibition from 20 ± 1.00 to 14 ± 1.00 mm and mean MIC value ≥1000.0 ± 322.7 μg/mL. Aqueous extract had no anti-salmonella activity. MTT results showed more than 50 percent cell survival at concentrations >625 and >1250 μg/mL for methanol extract and essential oil of N. sativa respectively; concentrations less than cytotoxic values required for anti-salmonella activity. It was concluded that N. sativa had in-vitro activity against S. enetrica and can be used as therapeutic.

Phenotypic and Molecular Characterization of Salmonella Enteritidis SE86 Isolated from Poultry and Salmonellosis Outbreaks

Salmonella Enteritidis remains a standout among the leading causes of foodborne diseases worldwide. Previous studies have demonstrated that a unique clonal group of Salmonella Enteritidis, named SE86, is involved in foodborne outbreaks in southern Brazil and is frequently identified among strains isolated from poultry. The aim of this study was to determine the influence of the isolation source (food products involved in salmonellosis outbreaks and poultry sources) on the phenotypic and molecular characteristics of Salmonella Enteritidis SE86. A biofilm formation assay, antimicrobial susceptibility test, polymerase chain reaction identification of virulence-associated genes, and phage type 4 (PT4) assessment were performed to characterize Salmonella Enteritidis SE86. The human strains presented less antimicrobial resistance than the poultry strains. Resistance to some substances was related to the isolation source of the strain. Strains of the same clonal group presented different biofilm production abilities. Biofilm formation was independent of the isolation source at all temperatures. Temperature influenced biofilm formation only by the poultry strains. Most of the investigated genes presented a high frequency and a regular distribution, regardless of the isolation source. The spvB, spiA, pagC, sipB, prgH, spaN, sitC, and lpfC genes were associated with the avian strains, whereas iroN was associated with the strains isolated from food products involved in salmonellosis outbreaks. Most strains belonged to PT4. No relationship was found between biofilm production and antimicrobial resistance or between the virulence profile and biofilm production or antimicrobial resistance.

Bacteriophages: the possible solution to treat infections caused by pathogenic bacteria

Since their discovery in 1915, bacteriophages have been used to treat bacterial infections in animals and humans because of their unique ability to infect their specific bacterial hosts without affecting other bacterial populations. The research carried out in this field throughout the 20th century, largely in Georgia, part of USSR and Poland, led to the establishment of phage therapy protocols. However, the discovery of penicillin and sulfonamide antibiotics in the Western World during the 1930s was a setback in the advancement of phage therapy. The misuse of antibiotics has reduced their efficacy in controlling pathogens and has led to an increase in the number of antibiotic-resistant bacteria. As an alternative to antibiotics, bacteriophages have become a topic of interest with the emergence of multidrug-resistant bacteria, which are a threat to public health. Recent studies have indicated that bacteriophages can be used indirectly to detect pathogenic bacteria or directly as biocontrol agents. Moreover, they can be used to develop new molecules for clinical applications, vaccine production, drug design, and in the nanomedicine field via phage display.

Antimicrobial Resistance in Nontyphoidal Salmonella Isolated from Human and Poultry-Related Samples in Brazil: 20-Year Meta-Analysis

Nontyphoidal Salmonella are one of the leading causes of foodborne diseases in the world. As poultry products are recognized as main sources of human salmonellosis, nontyphoidal Salmonella control has become a global issue for the poultry industry. The increasing antimicrobial resistance in poultry-related nontyphoidal Salmonella serovars is a global matter of concern. By monitoring the evolution of antimicrobial resistance, alternative treatments can be identified and possible restrictions in the treatment of systemic human salmonellosis foreseen. A meta-analysis was conducted to assess the profile and temporal evolution of the antimicrobial resistance of nontyphoidal Salmonella of poultry and human origin in Brazil, isolated in the period from 1995 to 2014. Four databases were researched; twenty-nine articles met the eligibility criteria and were included in the meta-analysis. In the nontyphoidal isolates of poultry origin, the highest levels of antimicrobial resistance were verified for sulfonamides (44.3%), nalidixic acid (42.5%), and tetracycline (35.5%). In the human-origin isolates, the resistance occurred mainly for sulfonamides (46.4%), tetracycline (36.9%), and ampicillin (23.6%). Twenty-two articles described results of antimicrobial resistance specifically for Salmonella Enteritidis, also enabling the individual meta-analysis of this serovar. For most antimicrobials, the resistance levels of Salmonella Enteritidis were lower than those found when considering all the nontyphoidal serovars. In the poultry-origin isolates, a quadratic temporal distribution was observed, with reduced resistance to streptomycin in Salmonella Enteritidis and in all nontyphoidal serovars, and a linear increase of resistance to nalidixic acid in Salmonella Enteritidis. In the human-origin isolates, a linear increase was identified in the resistance to nalidixic acid in Salmonella Enteritidis and in all the nontyphoidal isolates, and to gentamicin in Salmonella Enteritidis. Continuous monitoring of the development and spread of antimicrobial resistance could support the measurement of the consequences on poultry and human health.

SEROVARS AND ANTIMICROBIAL RESISTANCE OF Salmonella spp. ISOLATED FROM TURKEY AND BROILER CARCASSES IN SOUTHERN BRAZIL BETWEEN 2004 AND 2006

Salmonella spp. causes diseases in fowls, when species-specific serovars (Salmonella Pullorum and S.Gallinarum) are present in flocks, and public health problems, when non-typhoid serovars are isolated, as well as possible bacterial resistance induced by the preventive and therapeutic use of antimicrobials in animal production. This study describes the serovars and bacterial resistance of 280Salmonella spp. strains isolated from turkey and broiler carcasses in Southern Brazil between 2004 and 2006. SalmonellaEnteritidis was the most prevalent serovar (55.7%), followed by Heidelberg (5.0%), Agona (4.3%), Bredeney (3.9%), Hadar (3.2%), and Typhimurium (2.9%). Tennessee and S. Enterica subspecies enterica(O: 4.5) were isolated only in turkeys, and Hadar (18.6%) was the most prevalent serovar in this species. Antimicrobial susceptibility tests were performed in 178 isolates (43 from turkeys and 135 from broilers). All isolates were sensitive to amoxicillin + clavulanic acid, polymyxin B, ciprofloxacin, and norfloxacin, and were resistant to bacitracin and penicillin. Broiler carcass isolates showed resistance to nalidixic acid (48.9%), nitrofurantoin (34.3%), neomycin (9.6%), tetracycline (5.2%), and kanamycin (8.9%); and turkey carcass isolates were resistant to nalidixic acid (62.8%), tetracycline (34.9%), and neomycin (30.2%), with a significant difference in turkeys when compared to broiler carcass isolates. These results indicate the need for judicious use of antimicrobials in livestock production, given that the serovars identified are potential causes of food poisoning.

Multidrug resistance and ESBL-producing Salmonella spp. isolated from broiler processing plants

The aim of this study was to investigate the occurrence of multidrug-resistant, extended spectrum beta-lactamase (ESBL) producing Salmonella spp. isolated from conveyor belts of broiler cutting rooms in Brazilian broiler processing plants. Ninety-eight strains of Salmonella spp. were analyzed. Multidrug resistance was determined by the disk diffusion test and the susceptibility of the isolated bacteria was evaluated against 18 antimicrobials from seven different classes. The double disk diffusion test was used to evaluate ESBL production. Of the 98 strains tested, 84 were multidrug resistant. The highest rates of resistance were against nalidixic acid (95%), tetracycline (91%), and the beta-lactams: ampicillin and cefachlor (45%), followed by streptomycin and gentamicin with 19% and 15% of strain resistance, respectively. By contrast, 97% of the strains were sensitive to chloramphenicol. 45% of the strains were positive for the presence of ESBL activity. In this study, high rates of multidrug resistance and ESBL production were observed in Salmonella spp.

Impacto da salmonelose na suinocultura e suas implicações em saúde pública

RESUMO: O objetivo deste trabalho foi mostrar a presença da Salmonella na cadeia de produção de suínos e o risco em potencial para a saúde pública. As bactérias do gênero Salmonella são importantes agentes causadores de doenças transmitidas por alimentos (DTAs) em humanos. Estima-se que cerca de 10% do total de casos de salmonelose sejam veiculados por produtos de origem suína. A transmissão ao homem pode ocorrer pelo contato direto com animais, tanto nas granjas quanto nos frigoríficos, mas principalmente devido à ingestão de alimentos contaminados. A infecção de lotes suínos pode ocorrer em qualquer fase zootécnica e o principal ciclo de infecção é fecal-oral, podendo a bactéria se alojar nos linfonodos e ser excretada quando o animal for submetido a um fator estressante, como o transporte e/ou o reagrupamento. O uso inadequado de antimicrobianos também gera cepas multirresistentes. Os equipamentos e utensílios, de uma forma geral, estão relacionados à contaminação cruzada, agindo como veículos de propagação do micro-organismo dentro da indústria. Para garantir a segurança alimentar do consumidor, conclui-se que cuidados como limpeza, desinfecção e biossegurança devem se iniciar na granja de criação, com a utilização correta de antibióticos, passando pelo transporte evitando a superlotação e com medidas higiênico-sanitárias rigorosas durante o abate desses animais.

Prevalence of drug resistance and virulence features in Salmonella spp. isolated from foods associated or not with salmonellosis in Brazil

Salmonella is the most common etiological agent of cases and outbreaks of foodborne diarrheal illnesses. The emergence and spread of Salmonella spp., which has become multi-drug resistant and potentially more pathogenic, have increased the concern with this pathogen. In this study, 237 Salmonella spp., associated or not with foodborne salmonellosis in Brazil, belonging mainly to serotype Enteritidis, were tested for antimicrobial susceptibility and the presence of the virulence genes spvC, invA, sefA and pefA. Of the isolates, 46.8% were sensitive to all antimicrobials and 51.9% were resistant to at least one antimicrobial agent. Resistance to more than one antimicrobial agent was observed in 10.5% of the strains. The highest rates of resistance were observed for streptomycin (35.9%) and nalidixic acid (16.9%). No strain was resistant to cefoxitin, cephalothin, cefotaxime, amikacin, ciprofloxacin and imipenem. The invA gene was detected in all strains. Genes spvC and pefA were found in 48.1% and 44.3% of strains, respectively. The gene sefA was detected in 31.6% of the strains and only among S. Enteritidis. Resistance and virulence determinants were detected in Salmonella strains belonging to several serotypes. The high rates of antibiotic-resistance in strains isolated from poultry products demonstrate the potential risk associated with the consumption of these products and the need to ensure good food hygiene practices from farm to table to reduce the spread of pathogens relevant to public health.

Ocorrência e perfil de resistencia antimicrobiana de sorotipos de Salmonella spp. isolados de aviários do Paraná, Brasil

O presente estudo foi conduzido para verificar o perfil de resistência de diferentes sorotipos de Salmonella spp. isolados em aviários de frango de corte frente a agentes antimicrobianos. Foram processados 342 suabes de arrasto provenientes de granjas avícolas do oeste do Paraná, no período de janeiro de 2010 a janeiro de 2011, sendo isoladas 39 amostras de Salmonella spp. Os sorotipos mais frequentes foram: S. Heidelberg, S. Mbandaka, S. Newport, S. Schwarzengrund, S. Enteritidis, S. Livingstone, S. Orion, S. Give e S. Infantis. A determinação do perfil de resistência para os 19 sorotipos de Salmonella identificados foi realizada em relação a 12 antimicrobianos comerciais. Os resultados indicam que 51% dos sorotipos de Salmonella apresentaram resistência a um ou mais antimicrobianos, com 12 diferentes padrões de resistência. O maior percentual de resistência foi verificado à tetraciclina (30,8%), e o menor à gentamicina e cloranfenicol (2,6%). Os níveis de resistência indicam que os antimicrobianos devem ser utilizados nos aviários de forma mais prudente, buscando, assim, minimizar a disseminação de cepas resistentes.

Isolation and identification of salmonella from curry samples and its sensitivity to commercial antibiotics and aqueous extracts of Camelia sinensis (L.) and Trachyspermum ammi (L.)

OBJECTIVE

To isolate Salmonella from curry samples and to evaluate the drug sensitivity of the food-borne Salmonella and its susceptibility to specific plant extracts.

METHODS

Salmonella was isolated from the curry samples by standard microbiological methods and was confirmed by biochemical tests. The antibiotic susceptibility test was conducted by disc diffusion method using commercially available antibiotics such as ampicillin, tetracycline, chloramphenicol, kanamycin, and penicillin. In addition, the susceptibility of the food-borne Salmonella was also evaluated against the aqueous extracts of Camelia sinensis (L.) Theaceae (tea leaves) and the Trachyspermum ammi (L.) Apiaceae ( ajwain or omum seeds).

RESULTS

Out of fifty curry samples, only seven samples were identified to have Salmonella contamination. The Salmonella isolates showed a significant drug resistance pattern except for kanamycin. The plant extracts showed a considerable antibacterial activity against the isolates, indicating the presence of antimicrobial principle which can be exploited after complete pharmacological investigations.

CONCLUSIONS

The present study demonstrates the occurrence of Salmonella in the curry samples, and shows significant drug resistance against most of the commercially available antibiotics, except kanamycin. Antimicrobial effect of the plant extracts against the food-bone Salmonella suggests that dietary including medicinal herbs would be one strategy to manage food borne pathogens.

Soluble plantain nonstarch polysaccharides, although increasing caecal load, reduce systemic invasion of Salmonella Gallinarum in the chicken

Soluble plantain (Musa paradisiaca) nonstarch polysaccharides (NSPs) have previously been shown to prevent pathogenic interaction with the intestinal epithelium. Here, we examined whether plantain NSP could prevent the invasion of the intestinal mucosa by Salmonella enterica Gallinarum, a causative agent of fowl typhoid. In vitro assays using B1OXI cells were performed with monolayers pretreated with/without plantain NSP, before inoculation with Salm. Gallinarum 287/91. Chicks were fed from hatch on a pellet diet containing 50 mg day(-1) plantain NSP, followed by oral inoculation with Salm. Gallinarum 287/91 at the age of 6 days. Bacteria were enumerated from the liver, spleen and caecal contents 3 days postinfection. Adhesion and invasion of Salm. Gallinarum to B1OXI cells were inhibited by 10 mg ml(-1) plantain NSP (reduction in invasion 52%; 95% CI 27-77; P < 0.05). In vivo diet supplemented with 50 mg day(-1) plantain NSP reduced the invasion of Salm. Gallinarum in the chick liver (control 4.05 Log10 CFU g(-1) , SE 0.28, vs plantain 2.07 Log10 CFU g(-1) , SE 0.65; P < 0.01) and nonsignificantly in the spleen. Conversely, CFUs were significantly increased in the caeca (control 1.27 Log10 CFU g(-1), SE 0.65, vs plantain 6.04 Log10 CFU g(-1) , SE 0.17; P < 0.001). Plantain NSP feed reduced the systemic infection by Salm. Gallinarum and may have potential in reducing the impact of the disease in avian salmonellosis. The caveat is the increased caecal load of Salm. Gallinarum, although this may reflect both the reduced intestinal invasion and the bacterial multiplication in the caeca.

SIGNIFICANCE AND IMPACT OF THE STUDY

Nonstarch polysaccharide (NSP) derived from the plantain (Musa paradisiaca) inhibits interaction with epithelial cells by Salmonella enterica Gallinarum, a causative agent of the disease fowl typhoid. Incorporation of plantain NSP into the poultry feed reduced Salm. Gallinarum levels in the spleen and liver of chicks following experimental infection, although their numbers in the caeca increased. These data demonstrate that alternatives to antimicrobials such as NSP may be useful in the control of invasive salmonellosis in poultry.

Resistance to antimicrobial agents among Salmonella isolates recovered from layer farms and eggs in the Caribbean region

This investigation determined the frequency of resistance of 84 isolates of Salmonella comprising 14 serotypes recovered from layer farms in three Caribbean countries (Trinidad and Tobago, Grenada, and St. Lucia) to eight antimicrobial agents, using the disc diffusion method. Resistance among isolates of Salmonella was related to the country of recovery, type of sample, size of layer farms, and isolate serotype. Overall, all (100.0%) of the isolates exhibited resistance to one or more of seven antimicrobial agents tested, and all were susceptible to chloramphenicol. The resistance detected ranged from 11.9% to sulphamethoxazole-trimethoprim (SXT) to 100.0% to erythromycin. The difference was, however, not statistically significant (P = 0.23). Across countries, for types of samples that yielded Salmonella, significant differences in frequency of resistance were detected only to SXT (P = 0.002) in Trinidad and Tobago and to gentamycin (P = 0.027) in St. Lucia. For the three countries, the frequency of resistance to antimicrobial agents was significantly different for ampicillin (P = 0.001) and SXT (P = 0.032). A total of 83 (98.8%) of the 84 isolates exhibited 39 multidrug resistance patterns. Farm size significantly (P = 0.032) affected the frequency of resistance to kanamycin across the countries. Overall, among the 14 serotypes of Salmonella tested, significant (P < 0.05) differences in frequency of resistance were detected to kanamycin, ampicillin, and SXT. Results suggest that the relatively high frequency of resistance to six of the antimicrobial agents (erythromycin, streptomycin, gentamycin, kanamycin, ampicillin, and tetracycline) tested and the multidrug resistance detected may pose prophylactic and therapeutic concerns for chicken layer farms in the three countries studied.

Molecular characterization of Salmonella enterica serovar Enteritidis on retail raw poultry in six provinces and two National cities in China

One hundred and twenty six Salmonella Enteritidis isolates recovered from 1152 retail raw poultries were characterized by antimicrobial susceptibility test, pulsed-field gel electrophoresis (PFGE), presence of quinolone resistance (Qnr) associated genes, Class I integron, extended spectrum beta-lactamases (ESBLs) encoding genes, and mutations in quinolone resistance-determining region (QRDR) of GyrA and ParC. Resistance was most frequently found to nalidixic acid (88.1%), followed by to tetracycline (65.9%), sulfisoxazole (65.1%), and ampicillin (61.9%), and a less extent to cefoxitin (8.7%), gatifloxacin (8.7%), levofloxacin (7.9%), ceftriaxone (7.1%), and ceftiofur (6.3%). One hundred and twenty three (98.4%) isolates were resistant to at least one antibiotic, and 93 (74.4%) to at least four antibiotics. aac(6')-Ib-cr, qnrB, qnrA and qnrS genes were detected in 15 (11.9%), 11 (8.7%), 6 (4.8%) and 1 (0.8%) isolates, respectively. Amino acid substitutions of Ser83Tyr, Asp87Asn, Asp87Tyr, Asp87Gly and Ser83Phe/Asp87Asn were detected in QRDR of GyrA, Arg80Ser was the unique mutation in ParC. Eight isolates were detected with amino acid substitution both in GyrA and ParC. Three isolates carried Class I integron that harboring dfrA17-aadA5, dhfR1-aadA1, and dfrA1, respectively. Five isolates were detected carrying bla(TEM)-bla(ACC) (n = 1), bla(TEM) (n = 1), bla(TEM)-bla(OxA) (n = 3), respectively. Genetic diversities (D = 0.9255) were found among isolates based on PFGE analysis.

Comparative analysis of virulence and resistance profiles of Salmonella Enteritidis isolates from poultry meat and foodborne outbreaks in northern Jordan

This study was conducted to isolate Salmonella Enteritidis from poultry samples and compare their virulence and antibiotic resistance profiles to S. Enteritidis isolated from outbreaks in northern Jordan. Two hundred presumptive isolates were obtained from 302 raw poultry samples and were subjected to further analysis and confirmation. A phylogenic tree based on 16S rRNA sequencing was constructed and selected isolates representing each cluster were further studied for their virulence in normal adult Swiss white mice. The most virulent strains were isolated from poultry samples and had an LD 50 of 1.55 × 10 (5) CFU, while some of the outbreak isolates were avirulent in mice. Antibiotic resistance profiling revealed that the isolates were resistant to seven of eight antibiotics screened with each isolate resistant to multiple antibiotics (from two to six). Of the poultry isolates, 100%, 88.9%, 77.8%, 66.7%, and 50% showed resistance to nalidixic acid, ciprofloxacin, ampicillin, cephalothin, and cefoperazone, respectively. Two outbreak isolates were sensitive to all tested antibiotics, while 71.4% were resistant to cefoperazone and only 28.6% showed resistance to nalidixic acid. Salmonella outbreak isolates were genetically related to poultry isolates as inferred from the 16S rRNA sequencing, yet were phenotypically different. Although outbreak strains were similar to poultry isolates, when tested in the mouse model, some of the outbreak isolates were highly virulent while others were avirulent. This might be due to a variation in susceptibility of the mouse to different S. Enteritidis isolates.

Dietary supplementation with soluble plantain non-starch polysaccharides inhibits intestinal invasion of Salmonella Typhimurium in the chicken

Soluble fibres (non-starch polysaccharides, NSP) from edible plants but particularly plantain banana (Musa spp.), have been shown in vitro and ex vivo to prevent various enteric pathogens from adhering to, or translocating across, the human intestinal epithelium, a property that we have termed contrabiotic. Here we report that dietary plantain fibre prevents invasion of the chicken intestinal mucosa by Salmonella. In vivo experiments were performed with chicks fed from hatch on a pellet diet containing soluble plantain NSP (0 to 200 mg/d) and orally infected with S.Typhimurium 4/74 at 8 d of age. Birds were sacrificed 3, 6 and 10 d post-infection. Bacteria were enumerated from liver, spleen and caecal contents. In vitro studies were performed using chicken caecal crypts and porcine intestinal epithelial cells infected with Salmonella enterica serovars following pre-treatment separately with soluble plantain NSP and acidic or neutral polysaccharide fractions of plantain NSP, each compared with saline vehicle. Bacterial adherence and invasion were assessed by gentamicin protection assay. In vivo dietary supplementation with plantain NSP 50 mg/d reduced invasion by S.Typhimurium, as reflected by viable bacterial counts from splenic tissue, by 98.9% (95% CI, 98.1-99.7; P<0.0001). In vitro studies confirmed that plantain NSP (5-10 mg/ml) inhibited adhesion of S.Typhimurium 4/74 to a porcine epithelial cell-line (73% mean inhibition (95% CI, 64-81); P<0.001) and to primary chick caecal crypts (82% mean inhibition (95% CI, 75-90); P<0.001). Adherence inhibition was shown to be mediated via an effect on the epithelial cells and Ussing chamber experiments with ex-vivo human ileal mucosa showed that this effect was associated with increased short circuit current but no change in electrical resistance. The inhibitory activity of plantain NSP lay mainly within the acidic/pectic (homogalacturonan-rich) component. Supplementation of chick feed with plantain NSP was well tolerated and shows promise as a simple approach for reducing invasive salmonellosis.

Evaluation of virulence and antimicrobial resistance in Salmonella enterica serovar Enteritidis isolates from humans and chicken- and egg-associated sources

Salmonella enterica serovar Enteritidis is a leading cause of salmonellosis throughout the world and is most commonly associated with the consumption of contaminated poultry and egg products. Salmonella Enteritidis has enhanced ability to colonize and persist in extraintestinal sites within chickens. In this study, 54 Salmonella Enteritidis isolates from human patients (n=28), retail chicken (n=9), broiler farms (n=9), and egg production facilities (n=8) were characterized by antimicrobial susceptibility testing, plasmid analysis, genetic relatedness using XbaI and AvrII pulsed-field gel electrophoresis (PFGE), and the presence of putative virulence genes. Nine isolates were evaluated for their abilities to invade and survive in intestinal epithelial and macrophage cell lines. Overall, 56% (n=30) of isolates were resistant to at least one antimicrobial agent tested, yet no isolates showed resistance to more than three antimicrobials. All isolates carried a common ∼55-kb plasmid, with some strains containing additional plasmids ranging from 3 to 50 kb. PFGE analysis revealed five XbaI and AvrII clusters. There were significant overlaps in the PFGE patterns of the isolates from human, chicken, and egg houses. All isolates tested PCR positive for iacP, purR, ttrB, spi4H, rmbA, sopE, invA, sopB, spvB, pagC, msgA, spaN, orgA, tolC, and sifA, and negative for iss, virB4, and sipB. Of the isolates selected for virulence testing, those containing the iron acquisition genes, iutA, sitA, and iucA, and ∼50-kb plasmids demonstrated among the highest levels of macrophage and epithelial cell invasion, which may indicate their importance in pathogenesis.

Antimicrobial resistance and virulence profiles of Salmonella isolated from butcher shops in Minas Gerais, Brazil

Salmonella can contaminate finished products of butcher shops, mainly through cross-contamination of utensils exposed to raw materials. To identify the main sources of contamination with this foodborne pathogen in four butcher shop environments, surface samples were obtained from employees' hands, cutting boards, knives, floor of the refrigeration room, meat grinders, and meat tenderizers (32 samples per area) and analyzed for Salmonella using the International Organization for Standardization method 6579, with modifications. Suspect isolates were identified by PCR (targeting ompC), and confirmed Salmonella isolates were subjected to pulsed-field gel electrophoresis (after treatment with restriction enzyme XbaI), analyzed for the presence of virulence genes (invA, sefA, and spvC), and screened for resistance to 12 antimicrobials. Salmonella isolates was identified only on cutting boards (five samples) from three butcher shops. Fifteen isolates were confirmed as Salmonella belonging to four pulse types (similarity of 71.1 to 100%). The invA gene was detected in 13 isolates, and the sefA was found in 8 isolates; no isolate carried spvC. All tested isolates were resistant to clindamycin and sensitive to amikacin and cefotaxine, and all isolates were resistant to at least 3 of the 12 antimicrobials tested. The results indicate the importance of cutting boards as a source of Salmonella contamination in butcher shops. The presence of multidrug-resistant Salmonella strains possessing virulence genes highlights the health risks for consumers.

Phenotypic and genotypic features of antibiotic resistance in Salmonella enterica isolated from chicken meat and chicken and quail carcasses

One hundred and twenty-three Salmonella enterica isolated in Italy from chicken meat and carcasses and from quail carcasses were analyzed to determine their levels of antibiotic resistance using antibiograms (phenotypic method) and PCR amplification of antimicrobial resistance-associated genes (genotypic method). The isolates were screened for the ability to grow in the presence of antibiotics (ampicillin, gentamicin, sulfamethoxazole and tetracycline) and for the presence of the following genes: pse-1, ant (3")-Ia, qacEΔI and sul-1, tetA, tetB and tetG. The most frequently isolated serotypes in the sample set were S. Virchow (24.4%), S. Enteritidis (17.1%) and S. Typhimurium (15.4%). Of the isolates from chicken carcasses, 86.1% were resistant to tetracycline, while 30.5% of the identified isolates exhibited phenotypic multi-drug resistance to ampicillin, sulfamethoxazole and tetracycline; the multi-resistance pattern ant (3")-Ia/sul-1/tetA+tetB was detected in 11.1% of the isolates. Of the isolates from quail carcasses, 89.2% exhibited resistance to sulfamethoxazole, and 24.3% displayed phenotypic multi-drug resistance to ampicillin, gentamicin, sulfamethoxazole and tetracycline; a complete genotypic profile (pse-1, ant (3")-Ia, qacEΔI and sul-1, tetA, tetB and tetG) was obtained for 27.0% of the isolates. Among these isolates, S. Typhimurium exhibited the genotypes pse-1/ant(3")-Ia/sul-1/tetG and pse-1/ant(3")-Ia/sul-1/tetA+tetG. Of the isolates from chicken meat, 60.0% were resistant to tetracycline, and 36.0% exhibited a multi-drug resistance to ampicillin, sulfamethoxazole and tetracycline; only one isolate, S. Enteritidis, contained the complete genotypic pattern pse-1/ant(3")-Ia/sul-1/tetG. The majority of the isolates displaying multi-drug resistance to the three antibiotics were isolated from chicken meat (40.0%).