Effects of climatic elements on Salmonella contamination in broiler chicken meat in Japan

Geographical variation in antimicrobial resistant Salmonella Schwarzengrund from chicken meat in Japan

Chicken meat is a major source of foodborne salmonellosis. In Japan, fluoroquinolones and third-generation cephalosporins are the first- and second-choice treatments for Salmonella gastroenteritis, respectively. We investigated the prevalence and antimicrobial resistance of Salmonella in 154 chicken meat products from Hokkaido (42), Tohoku (45), Kanto (5), and Kyushu (62), Japan. Salmonella was isolated from 133 products (86.4%). High resistance rates were observed for streptomycin (56.5%), tetracycline (50.7%), and kanamycin (47.8%), while all isolates were susceptible to cefazolin, cefotaxime, gentamicin, ciprofloxacin, colistin, and chloramphenicol. The most common serovar, Salmonella Schwarzengrund (83.3%), showed clear regional differences in multidrug resistance: 100% in Kyushu, 41.5% in Tohoku, and 0% in Hokkaido. These findings highlight significant geographical variation in antimicrobial resistance among Salmonella Schwarzengrund isolates.

Determination of Antimicrobial Resistance Megaplasmid-Like pESI Structures Contributing to the Spread of Salmonella Schwarzengrund in Japan

BACKGROUND/OBJECTIVES

The acquisition of antimicrobial resistance by foodborne pathogens is a serious human health concern. In Japan, combinations of antimicrobial resistance genes in Salmonella from chicken meat were common among several serovars. Therefore, we hypothesized that different S. enterica serovars share a common antimicrobial resistance plasmid.

METHODS

Antimicrobial resistance transfer was tested in S. Infantis and S. Schwarzengrund, the major serovars used as donors. The plasmid structure was determined by subjecting S. Infantis Sal_238 and S. Schwarzengrund Sal_249 to short- and long-read sequencing.

RESULTS

The high homology between pSal_249Sch and pSal_238Inf suggests they have a common ancestor. Because the sequences of pSal_238Inf and pSal_249Sch were highly homologous to pESI (a plasmid for emerging S. Infantis), pSal_238Inf and pSal_249Sch were identified as pESI-like plasmids. S. Schwarzengrund is the third Salmonella serovar to expand its distribution related to pESI-like plasmid acquisition. Core-genome multilocus sequence-type analysis revealed that S. Schwarzengrund isolates with pESI-like plasmids from Japan (core-genome sequence-type [cgST] 167363 and cgST287831), the UK (cgST167363), and the USA (cgST167363, cgST196045, and cgST287831) were closely related; they are also suggested to share a common ancestor. The transfer of antimicrobial resistance was observed in combinations of both serovars. Specifically, the tentative plasmid sequence obtained via short-read sequencing, PCR, and conjugation experiments identified deletions of antimicrobial resistance genes (aadA, sul1, and tetA), class 1 integron, mercury resistance operon, and/or plasmid transfer region in the pESI-like plasmid.

CONCLUSION

These data on the structural diversity of pESI-like plasmids suggest that some time has passed since S. Schwarzengrund acquired them.

Multi-locus sequence typing of Salmonella enterica isolates from dog treats and raw meat-based dog food in Japan

OBJECTIVE

Salmonella is an important zoonotic foodborne pathogen which is recognized as a major public health concern worldwide. Salmonella contamination are highly prevalent in dog treats and raw meat-based dog food (RMBDs). And dog treats and raw meat-based dog food are often implicated as main sources of human infection. Many epidemiological studies have focused on the characteristics of Salmonella in many countries. But there are no such reports in Japan. This study was conducted to investigate the genetic characteristics of Salmonella using multi-locus sequence typing (MLST).

RESULTS

Fourteen Salmonella isolates were assigned to 8 sequence types: ST19, ST26, ST32, ST34, ST241, ST469, ST864 and ST1861. The most common types were ST32 and ST34 (21%, n = 3). The second most common types were ST26 and ST469 (14%, n = 2).

Geographical Variation of Antimicrobial Resistance of Salmonella in Japanese Chicken

Chicken is a potent source of Salmonella infection in humans. Occasionally, patients with severe Salmonella enteritis require antimicrobial therapy. Antimicrobials are used to prevent and treat bacterial infections in broiler and breeder farms. Herein, we investigated the prevalence and antimicrobial resistance of Salmonella in 337 vacuum-packed chicken breast products manufactured in Japan between June and December 2021. Salmonella was isolated from 287 samples (85.2%). Among the products from Eastern Japan, the lowest Salmonella prevalence was observed in those processed in September (65.6%), which was significantly (p < 0.05) lower than that in November or December. Among the products from Western Japan, the lowest Salmonella prevalence was observed in those processed in August (61.9%), which was significantly (p < 0.05) lower than that in June, November, and December. The most frequent serovar was Salmonella Schwarzengrund (223 isolates), followed by S. Infantis (53 isolates), S. Manhattan (9 isolates), and S. Enteritidis (1 isolate). High rates of antimicrobial resistance were observed for streptomycin (64.5%), kanamycin (50.2%), tetracycline (65.2%), nalidixic acid (11.5%), and trimethoprim (35.9%). Resistance rates against these five antimicrobials in S. Schwarzengrund isolates were markedly higher in the isolates from Western Japan than in those from Eastern Japan. All 287 Salmonella isolates were susceptible to ciprofloxacin which belongs to fluoroquinolones and cefotaxime which belongs to third-generation cephalosporins. Salmonella prevalence in chicken products in Japan was found to be extremely high; therefore, chicken meat should be thoroughly heated before consumption. In Japan, fluoroquinolones and third-generation cephalosporins are recommended as the first- and second-choice antimicrobials for patients with severe Salmonella enteritis, respectively. The results of this study show that administering fluoroquinolones or third-generation cephalosporins is an effective option for patients with Salmonella enteritis caused by consuming chicken meat, and efficient strategies for Salmonella management on broiler farms and chicken-processing plants need to be developed.

Salmonella Prevalence and antibiotic resistance profile in raw poultry meat sold in North Lebanon: Insights from the COVID-19 pandemic and economic crisis

Salmonella-related foodborne illness is a significant public health concern, with the primary source of human infection being animal-based food products, particularly chicken meat. Lebanon is currently experiencing a dual crisis: the COVID-19 pandemic and an unprecedented economic crisis, which has resulted in substantial challenges to the public health system and food safety. This study aims to assess the prevalence and antibiotic resistance profile of Salmonella in raw poultry meat sold in North Lebanon during this dual crisis. A cross-sectional study was carried out between May 2021 and April 2022 across six different districts in North Lebanon. A total of 288 whole, unprocessed chickens were examined. The isolation and identification of Salmonella isolates were done based on cultural and biochemical properties. All isolates were subjected to antimicrobial susceptibility testing and phenotypic assays for Extended-Spectrum Beta-lactamase (ESBL) detection. The prevalence of Salmonella in raw poultry meat purchased in North Lebanon reached 18.05 % (52/288). The dry season and chilled chicken were significantly associated with an increased risk of Salmonella contamination (P < 0.05). Additionally, 34.61 % of the isolates were potential ESBL producers, and 57.69 % exhibited multidrug resistance (MDR). This study highlights the existence of MDR in chicken meat in North Lebanon, posing a potential health risk if undercooked chicken meat is consumed. This emphasizes the importance of the implementation of preventive strategies and hygienic procedures throughout the food chain to reduce the risk of Salmonella spp. contamination in chicken meats and its potential transmission to humans.

Predictive modeling of Salmonella spp. growth behavior in cooked and raw chicken samples: Real-time PCR quantification approach and model assessment in different handling scenarios

The increasing prevalence of Salmonella contamination in poultry meat emphasizes the importance of suitable predictive microbiological models for estimating Salmonella growth behavior. This study was conducted to evaluate the potential of chicken juice as a model system to predict the behavior of Salmonella spp. in cooked and raw chicken products and to assess its ability to predict cross-contamination scenarios. A cocktail of four Salmonella serovars was inoculated into chicken juice, sliced chicken, ground chicken, and chicken patties, with subsequent incubation at 10, 15, 20, and 25°C for 39 h. The number of Salmonella spp. in each sample was determined using real-time polymerase chain reaction. Growth curves were fitted into the primary Baranyi and Roberts model to obtain growth parameters. Interactions between temperature and growth parameters were described using the secondary Ratkowsky's square root model. The predictive results generated by the chicken juice model were compared with those obtained from other chicken meat models. Furthermore, the parameters of the chicken juice model were used to predict Salmonella spp. numbers in six worst-case cross-contamination scenarios. Performance of the chicken juice model was evaluated using the acceptable prediction zone from -1.0 (fail-safe) to 0.5 (fail-dangerous) log. Chicken juice model accurately predicted all observed data points within the acceptable range, with the distribution of residuals being wider near the fail-safe zone (75%) than near the fail-dangerous zone (25%). This study offers valuable insights into a novel approach for modeling Salmonella growth in chicken meat products, with implications for food safety through the development of strategic interventions. PRACTICAL APPLICATION: The findings of this study have important implications in the food industry, as chicken juice could be a useful tool for predicting Salmonella behavior in different chicken products and thus reducing the risk of foodborne illnesses through the development of strategic interventions. However, it is important to recognize that some modifications to the chicken juice model will be necessary to accurately mimic all real-life conditions, as multiple factors particularly those related to food processing can vary between different products.

Genomic diversity of Salmonella enterica isolated from raw chicken at retail establishments in Mexico

The genomic diversity of circulating non-typhoidal Salmonella in raw chicken was investigated in three states of central Mexico. A total of 192 S. enterica strains from chicken meat samples collected at supermarkets, fresh markets, and butcher shops were analyzed by whole-genome sequencing. The serovar distribution, occurrence of genes encoding for antimicrobial resistance, metal resistance, biocide resistance, plasmids and virulence factors, and clonal relatedness based on single nucleotide polymorphism (SNP) analysis were investigated. Serovars Infantis, Schwarzengrund and Enteritidis predominated among twenty identified. The distribution of serovars and proportion of AMR genes was different according to the state, year, season, and retail establishment (p < 0.001). Genes encoding metals resistance were identified in all the strains. A total of 145 virulence genes were identified and strains were classified into 32 virulotypes; serovars Infantis, Typhimurium, and Enteritidis showed the highest number of virulence genes. The strains matched 34 SNP clusters in the NCBI Pathogen Detection server and 59 %, which corresponded to Infantis, Schwarzengrund, Saintpaul, and Enteritidis, were associated with five major clusters and matched with chicken, environmental and clinical isolates from at least three countries. These results provide useful information to understand the epidemiology of Salmonella, conduct microbial risk assessment, and design risk-based control measures.

Role of multidrug resistance and co-resistance on a high percentage of streptomycin resistance in Escherichia coli isolated from chicken meats in Japan

We focused on streptomycin resistance because of the high percentage of streptomycin-resistant Escherichia coli concerning the amount used of streptomycin. Antimicrobial resistance and horizontal transfer were identified in 117 isolates of coliform bacteria from chicken meat to identify the factors that increase streptomycin resistance. Escherichia (45 isolates) was the predominant genus. Most streptomycin-resistant Escherichia isolates were resistant to other antimicrobials (17/18), suggesting that using various antimicrobials could select streptomycin-resistant Escherichia isolates. Resistance was transferred from 7 out of the 18 streptomycin-resistant isolates. The transconjugants acquired strA/strB (7/7), blaTEM (5/7), aphA1 (5/7), tetB (3/7), dfrA14 (1/7) and/or dfrA17 (1/7). The co-resistance of streptomycin resistance with other resistances would also increase streptomycin resistance.

The phenotypic and genotypic antimicrobial resistance patterns of Salmonella isolated from chickens and meat at poultry slaughterhouses in Japan and Thailand

Background and Aim

Poultry meat is a popular food consumed globally. However, poultry farming is a source of Salmonella contamination which causes human salmonellosis. This study aimed to estimate the prevalence and antimicrobial resistance (AMR) of Salmonella among chickens and meat at poultry slaughterhouses in province study areas in Thailand and Japan.

Materials and Methods

Chicken meat and feces samples were collected in Thailand and Japan. In Nakhon Ratchasima Province, Thailand, 558 samples were obtained from slaughterhouses from January 2021 to March 2022. In Gifu Prefecture, Japan, 140 samples (70 each of intestinal contents and meat) were purchased from slaughterhouses from June to October 2022. For Salmonella detection, the samples were cultivated according to the International Organization for Standardization 6579:2002/AMD 1:2007 method and confirmed using polymerase chain reaction (PCR) and agglutination tests for serotyping. Isolated Salmonella were tested for AMR to nine antibiotics using the disk diffusion method. Selected phenotypic multidrug-resistant (MDR) isolates were evaluated for AMR genes (AMRGs) using PCR.

Results

Salmonella prevalence from chickens and meat at slaughterhouses in Thailand and Japan was 41.2% and 40.7%, respectively. All the Salmonella isolates in Japan were serotyped as Schwarzengrund, and no Salmonella isolates were resistant to the nine antibiotics tested. In contrast, most of the Thai Salmonella isolates from chicken cloacal swabs and meat were resistant to doxycycline (78.3%) and colistin (63.5%). The prevalence of MDR Salmonella (MDRS) in chickens and meat from Thailand and Japan was 29.1% (67/230) and 0% (0/57), respectively. However, the most frequent AMRGs found in MDRS in Thailand were extended-spectrum beta-lactamase-Temoneira (ESBL-TEM) (45.1%). All isolated Salmonella from Japan revealed a class 1 integron gene (Int-1).

Conclusion

Phenotypic MDRS isolates from Thailand showed the greatest correlation to AMRG and ESBL-TEM. Although there were no phenotypic AMR Salmonella isolates found in Japan, they can be found associated with Int-1, which may carry other AMRGs within the gene cassettes.

Investigating the dynamics of Salmonella contamination in integrated poultry companies using a whole genome sequencing approach

The study of non-typhoid Salmonella in broiler integrations has been limited by the resolution of typing techniques. Although serotyping of Salmonella isolates is used as a traditional approach, it is not of enough resolution to clearly understand the dynamics of this pathogen within poultry companies. The aim of this research was to investigate the epidemiology and population dynamics of Salmonella serotypes in 2 poultry integrations using a whole genome sequencing approach. Two hundred and forty-three Salmonella isolates recovered from the broiler production chain of 2 integrated poultry companies were whole genome sequenced and analyzed with dedicated databases and bioinformatic software. The analyses of sequences revealed that S. Infantis was the most frequent serotype (82.3%). Most isolates showed a potential for resistance against medically important antibiotics and disinfectants. Furthermore, 97.5% of isolates harbored the pESI-like mega plasmid, that plays an important role in the global dissemination of AMR. SNP tree analysis showed that there were clones that are niche-specific while other ones were distributed throughout the broiler production chains. In this study, we demonstrated the potential of whole genome sequencing analysis for a comprehensive understanding of Salmonella distribution in integrated poultry companies. Data obtained with these techniques allow determination of the presence of genetic factors that play an important role in the environmental fitness and pathogenicity of Salmonella.

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.

Detection of microbial contamination in chicken meat from local markets in Surabaya, East Java, Indonesia

Background and Aim:

Chicken meat can be contaminated by microorganisms anywhere in the supply chain, from farm to market, and these microorganisms can be transmitted to humans through direct contact, contact with the environment, and food consumption. The microbial contamination has a serious impact on public health. This study aimed to analyze the microbial contamination of chicken meat sampled from local markets in Surabaya, East Java, Indonesia.

Materials and Methods:

A total of 60 samples of fresh chicken meat obtained from 10 traditional markets (six samples per market) were examined for the presence of bacteria. Staphylococcus aureus, Salmonella spp., and Escherichia coli were identified using Gram staining, culturing, and biochemical tests. The most probable number (MPN) method was used to identify E. coli.

Results:

Most chicken meat samples were positive for S. aureus (58.3%), Salmonella spp. (48.3%), and E. coli (40%). The samples were considered positive for E. coli if the MPN value was higher than 1×10¹ CFU/g.

Conclusion:

High microbial contamination was found in all the chicken meat sampled from local markets in Surabaya. Such contamination can lead to foodborne diseases so, proper hygiene and sanitation standards should be followed from slaughterhouses to the end-users.

Molecular Characteristics and Antimicrobial Resistance of Salmonella enterica Serovar Schwarzengrund from Chicken Meat in Japan

Our previous study revealed that Salmonella enterica serovar Schwarzengrund-contaminated areas of broiler chickens have expanded from West Japan to East Japan. The present study investigated the antimicrobial resistance and molecular characteristics of 124 S. Schwarzengrund isolates obtained from chicken meat produced in East and West Japan from 2008 to 2019. Comparing the isolates obtained in 2008 and 2015–2019, an increase in the proportion of those resistant to kanamycin [51.4–89.7% (p < 0.001)] was observed. In contrast, the proportion of isolates resistant to both streptomycin and tetracycline and those that harbored a 1.0-kb class 1 integron, aadA1, and tetA, significantly decreased from 100% in 2008 to 47.1% in 2015–2019 (p < 0.001). A 1.0-kb class 1 integron containing aadA1, harbored by 78 isolates, was different from that reported in globally distributed S. Schwarzengrund strains (1.9 kb, containing the dfrA12-aadA2 gene cassette). Twenty-five isolates from different product districts and years of isolation were typed as sequence type (ST) 241 with multilocus sequence typing. Our results suggest that S. Schwarzengrund, which contaminates chicken meat in Japan, shares a common ancestor regardless of the product district from 2008 to recent years. Moreover, S. Schwarzengrund ST241 may have spread from western to eastern Japan.