Background and Aim: Antimicrobial resistance (AMR) in foodborne bacteria presents a significant threat to public health, especially in countries with intensive livestock production systems. Pig farming is a major source of animal protein in Thailand and is recognized as an important reservoir of antimicrobial-resistant bacteria. Escherichia coli is commonly used as an indicator organism for monitoring AMR, including extended-spectrum β-lactamase (ESBL) production and pathogenic potential. This study aimed to assess the frequency of AMR, multidrug-resistant (MDR), ESBL determinants, and virulence genes in E. coli isolates collected from slaughterhouses and fresh markets in central Thailand. Materials and Methods: A total of 498 archived E. coli isolates were analyzed, including 236 isolates from slaughterhouses (feces and carcasses) and 262 isolates from fresh markets (pork and cutting boards). Antimicrobial susceptibility testing was performed against 18 antimicrobial agents using the disk diffusion method. MDR was defined as resistance to three or more antimicrobial classes. ESBL production was identified through phenotypic confirmatory tests, and ESBL-producing isolates were screened for blaTEM, blaCTX-M, and blaSHV genes by multiplex polymerase chain reaction. All isolates were further examined for select virulence genes linked to major E. coli pathotypes. Results: Overall, 97.4% of E. coli isolates showed resistance to at least one antimicrobial agent, and 87.3% were classified as MDR. ESBL-producing E. coli made up 23.5% of all isolates, with a significantly higher prevalence in slaughterhouses compared to fresh markets (p < 0.05). Among ESBL producers, 97.4% exhibited MDR phenotypes. Most (89.7%) of the ESBL-producing isolates carried at least one bla gene, with blaTEM being the most common, followed by blaCTX-M. Virulence genes were detected at a low frequency (3.2%), mainly involving eaeA, lt, and stp. Conclusion: The high prevalence of AMR, MDR, and ESBL-producing E. coli throughout the pork production chain highlights slaughterhouses and fresh markets as key points for the spread of resistant bacteria. These findings emphasize the need for stronger antimicrobial stewardship, better hygiene practices, and ongoing AMR surveillance within the One Health approach to reduce public health risks linked to pork consumption.

BACKGROUND:Livestock-associated MRSA (LA-MRSA) clonal complex (CC) 398 is primarily found among pigs across Europe. However, CC398 has also been sporadically identified in several Asian countries, including Thailand. This study aimed to examine the drivers contributing to the emergence of LA-MRSA CC398 in Thailand's swine industry. METHODS:Whole-genome sequencing data of 18 LA-MRSA CC398 isolates from pigs, retail pork and swine workers in Thailand were analysed. Additionally, a total of 1197 qualified genomes from various sources in 24 countries were retrieved from Pathogenwatch. Subsequently, two SNP-based phylogenetic trees were reconstructed using maximum likelihood (n = 1215) and Bayesian inference (n = 168). RESULTS:Our findings revealed that Staphylococcus aureus isolates with the CC398-SCCmec Vc (5C2&5)-t034 genotype were closely related to European isolates, including those from Denmark. In contrast, S. aureus isolates belonging to the CC398-composite SCCmec-t034 formed a phylogenetically distinct cluster. CONCLUSIONS:This study reports that the CC398-SCCmec Vc (5C2&5)-t034 genotype identified in Thai pigs may have originated from Danish swine populations, possibly introduced into Thailand through international livestock movement. The CC398-composite SCCmec-t034 genotype was also detected in domestic pigs; however, it appears to have evolved independently from the CC398-SCCmec Vc (5C2&5)-t034 genotype. Bayesian phylogenetic analysis estimates that the common ancestor of the composite genotype emerged earlier than that of the CC398-SCCmec Vc (5C2&5)-t034 genotype, indicating a separate evolutionary origin.

Motorcycle taxis are popular transportation in areas with heavy traffic in Thailand. In this study, we recruited motorcycle taxi drivers in six central provinces in Thailand between January and March 2023 and measured their particulate matter (PM) and PM-bound polycyclic aromatic hydrocarbon (PAH) exposures using personal air sampling. We found that the PM 10 and PM 2.5 concentrations measured by personal air sampling were independent of those monitored at air quality monitoring stations or by area air sampling devices. Among the six provinces, motorcycle taxi drivers in Pathum Thani were exposed to the highest mean concentration of PM 10 (224.9 µg/m 3 ), PM 2.5 (410.9 µg/m 3 ), PM 10− bound total PAH (38.4 ng/m 3 ), and PM 2.5 -bound total PAH (36.9 ng/m 3 ). Four workstations (PTT-1 to PTT-4) using 22 samples of PM₁₀ and 25 samples of PM₂.₅ personal air samplers showed unexpectedly higher PM₂.₅ than PM₁₀, likely due to route-specific environmental factors, as drivers follow variable routes determined by passenger destinations and daily demand. The incremental lifetime cancer risk of PM 10− bound PAH and PM 2.5 -bound PAH in Pathum Thani were 4.5 × 10 −8 and 7.8 × 10 −8 , respectively, which were acceptable levels. None of the individuals’ lung function parameters was significantly correlated with the individuals’ concentrations of PM 10 , PM 2.5 , PM 10− bound total PAH, or PM 2.5 -bound total PAH. However, province averages of PM 10 -bound total PAH exposure of motorcycle taxi drivers were positively correlated with the proportions of participants who answered symptoms of chronic bronchitis in the province. The causal relationship between motorcycle taxi drivers’ PM and PM-bound PAH exposure in Pathum Thani and their respiratory symptoms needs to be further investigated.

Background and Aim: Salmonella contamination in eggs poses a significant public health risk, particularly in alternative egg production systems where contamination and antimicrobial resistance remain underexplored. This study aimed to determine the occurrence of Salmonella contamination in three different egg production systems in Phayao, Thailand, and analyze serovar diversity, antimicrobial resistance, virulence genes, and genetic profiles. Materials and Methods: A total of 750 eggs were sampled from cage, free-range, and organic egg production systems, purchased from supermarkets in Phayao Province. Eggshells and contents were separately analyzed using conventional microbiological methods to isolate Salmonella. Phenotypic identification, serotyping, and antimicrobial susceptibility testing were performed. Genotypic characterization, including virulence and antimicrobial resistance gene detection, was conducted using polymerase chain reaction. Multilocus sequence typing (MLST) was employed to determine genetic diversity. Results: Salmonella contamination was detected in three eggshell samples (0.4%), with one positive sample from each production system. The identified serovars were Salmonella Mbandaka (cage eggs), Salmonella Corvallis (free-range eggs), and Salmonella Cerro (organic eggs). Antimicrobial resistance was observed in only one isolate, S. Mbandaka, which exhibited resistance to sulfamethoxazole/trimethoprim and carried the sul1 and sul2 genes. All Salmonella isolates harbored virulence genes (invA, sopB, and stn). MLST analysis identified three distinct sequence types (ST413, ST1541, and ST1593) corresponding to the detected serovars. Conclusion: This study demonstrates a low occurrence of Salmonella contamination in eggshells across different production systems, with no contamination detected in egg contents. The presence of distinct serovars and genetic types suggests varying contamination sources. Although antimicrobial resistance was minimal, the presence of virulence genes in all isolates highlights the potential risk of infection. Continuous monitoring and improved biosecurity measures in egg production and distribution are recommended to enhance food safety and public health.

Antimicrobial resistance (AMR) is on one of the global priority challenges. This study explored the impact of diet alteration on AMR bacteria through metagenomic analysis during the annual vegetarian festival in Thailand in October 2019. The study investigated the effects of a 10-day shift from a regular to a vegetarian diet by collecting urban sewage from Nakhon Sawan, Surat Thani, and Bangkok before, during, and after the festival. Additionally, faecal samples from individuals in the northern city were analyzed. Using shotgun metagenomic sequencing, the samples were mapped against bacterial, AMR genes, and carbohydrate-active enzymes databases. The results revealed significant changes in AMR gene abundance and increased carbohydrate metabolism genes in sewage samples from all three cities during the festival. There was also a notable shift in the composition and diversity of bacterial species, particularly in the northern city. The total abundance of AMR genes increased during the vegetarian festival across all locations. This study highlights the correlation between a population's vegetarian diet and increased AMR in Thailand. It also demonstrates that metagenomic analysis of sewage can effectively assess the impact of dietary changes on bacterial communities and AMR at a population level, providing valuable insights for public health strategies.

Extraintestinal pathogenic Escherichia coli (ExPEC), especially uropathogenic E. coli (UPEC) are responsible for urinary tract infections (UTIs), while diarrheagenic E. coli (DEC) cause foodborne illnesses. These pathogenic E. coli are a serious threat to human health and a public concern worldwide. However, the evidence on pork E. coli (PEC) harboring UPEC virulence-associated genes is currently limited. Therefore, this study aimed to determine the phylogroups, virulence genes, and their association between PEC and UPEC from UTI patients. In this study, 330 E. coli were obtained from archived stock culture isolated from pork (PEC; n = 165) and urine of patients with UTIs (UPEC; n = 165) during 2014-2022. Phylogroups, UPEC- and diarrheagenic E. coli (DEC) associated virulence genes were assessed using PCR assays. The results showed that phylogroups A (50.3%), and B1 (32.1%) were commonly found among PEC whereas phylogroups B2 (41.8%), and C (25.5%) were commonly detected in the UPEC. PEC and UPEC carried similar virulence-associated genes with different percentages. The most frequent UPEC virulence-associated gene among UPEC, and PEC strains was fimH, (93.3%, and 92.1%), followed by iucC (55.2%, and 12.7%), papC (21.8%, and 4.2%), afaC (22.4%, and 0%), hlyCA (17%, and 0.6%), cnf (16.4%, and 0.6%), and sfa/focDE (8.5%, and 4.8%). Additionally, 6 of 27 UPEC virulence-associated gene patterns were found in both PEC and UPEC strains regardless of phylogroups. Furthermore, the DEC virulence-associated genes were found in only 3 strains, one from PEC harboring eae, and two from UPEC carried fimH-bfpA or afaC-CVD432 indicating hybrid strains. Cluster analysis showed a relationship between PEC and UPEC strains and demonstrated that PEC harboring UPEC virulence-associated genes in pork may be associated with UPEC in humans. Food safety and hygiene practices during pork production chain are important procedures for minimizing cross-contamination of these strains that could be transmitted to the consumers.

Vibrio parahaemolyticus (V. parahaemolyticus) is commonly found in seawater and seafood products, but evidence is limited of its presence in seafood marketed in locations very distant from coastal sources. This study determined the prevalence and characterization of V. parahaemolyticus in seafood from markets in landlocked Phayao province, Northern Thailand. Among 120 samples, 26 (21.7%) were positive for V. parahaemolyticus, being highest in shrimp (43.3%), followed by shellfish (36.7%), and squid (6.7%), but was not found in fish. V. parahaemolyticus comprised 33 isolates that were non-pathogenic and non-pandemic. Almost all isolates from shrimp and shellfish samples were positive for T3SS1. Only five isolates (15.2%) showed two antimicrobial resistance patterns, namely, kanamycin-streptomycin (1) carrying sul2 and ampicillin-kanamycin-streptomycin (4) that carried tetA (2), tetA-sul2 (1), as well as one negative. Antimicrobial susceptible V. parahaemolyticus isolates possessing tetA (67.9%) and sul2 (3.5%) were also found. Six isolates positive for integron class 1 and/or class 2 were detected in 4 antimicrobial susceptible and 2 resistant isolates. While pathogenic V. parahaemolyticus was not detected, contamination of antimicrobial resistance V. parahaemolyticus in seafood in locations distant from coastal areas requires ongoing monitoring to improve food safety in the seafood supply chain.

Introduction: Vibrio parahaemolyticus is a common pathogen that can cause seafood-borne gastroenteritis in humans. We determined the prevalence and characteristics of V. parahaemolyticus isolated from clinical specimens and oysters in Thailand. Methodology: Isolates of V. parahaemolyticus from clinical specimens (n = 77) and oysters (n = 224) were identified by biochemical testing, polymerase chain reaction (PCR) assays, and serotyping. The toxin genes, antimicrobial resistance, and β-lactamase production were determined. Results: A total of 301 isolates were confirmed as V. parahaemolyticus by PCR using specific primers for the toxR gene. The majority of clinical isolates carried the tdh+/trh− genotype (82.1%), and one of each isolate was tdh−/trh+ and tdh+/trh+ genotypes. One isolate from oyster contained the tdh gene and another had the trh gene. Twenty-six serotypes were characterized among these isolates, and O3:K6 was the most common (37.7%), followed by OUT:KUT, and O4:K9. In 2010, most clinical and oyster isolates were susceptible to antibiotics, with the exception of ampicillin. In 2012, clinical isolates were not susceptible to cephalothin (52.4%), streptomycin (95.2%), amikacin (66.6%), kanamycin (61.9%), and erythromycin (95.2%), significantly more frequently than in 2010. More than 95% of isolates that were not susceptible to ampicillin produced β-lactamase enzymes. Conclusions: We found toxin genes in two oyster isolates, and the clinical isolates that were initially determined to be resistant to several antibiotics. Toxin genes and antimicrobial susceptibility profiles of V. parahaemolyticus from seafood and environment should be continually monitored to determine the spread of toxin and antimicrobial resistance genes.

Exposure to outdoor air pollutants, particularly respirable particulate matter (RPM), can cause adverse health outcomes. The cross-sectional study aimed to assess motorcycle taxi driver’s health risk from exposure to RPM. A total of 153 motorcycle taxi drivers were recruited in Bangkok and five adjacent provinces during May and June 2022. The standardized questionnaire for data collection contained exposure time (hour/day), frequency of exposure (days/years), duration of exposure (year), body weight (kg), and averaging time (days). The average RPM concentration from six provinces were assessed personal air sampling pumps and ranged from 0.006-0.031 mg/m3. Bangkok showed the highest average RPM concentration (0.031 mg/m3), followed by Pathumthani (0.028 mg/m3), Samut Prakan (0.009 mg/m3), Nakhon Pathom (0.008 mg/m3), Nonthaburi (0.007 mg/m3), and Samut Sakhon (0.006 mg/m3), respectively. The Hazard Quotient (HQ) values for a non-carcinogenic risk to human health caused by RPM exposure in each province indicated a negligible risk (HQ=0.005-0.028). HQ averages (HQ=0.013) from all provinces were also at an acceptable level (≤1). Not all motorcycle taxi drivers are safe from RPM exposure, although their exposure is within acceptable limits depending on their individual susceptibility. Therefore, this is the first report on quantifying exposure to RPM from personal air sampling and health risk assessment among motorcycle taxi drivers. These findings would be useful information for further preventing and controlling ambient air pollution including policies and strategies to mitigate the risks for motorcycle-taxi drivers and the other exposed populations.

The motorcycle taxi drivers of Bangkok and adjacent provinces in Thailand may have been heavily exposed to ambient air pollution and the impact of this on their lungs has been neither documented nor studied. In this study, we recruited a total of 343 motorcycle taxi drivers in Bangkok and adjacent provinces in Thailand and their lung function parameters were analyzed using spirometry in May and June 2022. Of these, 153 participants were selected and their exposure to respirable dust during working was measured by personal air sampling. Respirable dust concentrations collected with personal air sampling suggested that motorcycle taxi drivers working at workstations where they were exposed to respirable dust at high concentrations tended to have a low percent predicted FEV1. Twelve% and 7.3% of motorcycle taxi drivers recruited in this study had the symptoms of chronic bronchitis and acute bronchitis, respectively. These results suggested that some motorcycle taxi drivers around Bangkok and adjacent provinces had a high risk of occupational exposure to ambient air pollution. The government needs to establish a medical check-up system for motorcycle taxi drivers to monitor their health status.

This study delved into the antimicrobial potential of hydrolysates from adzuki bean and mung bean protein concentrates, created using Alcalase and Flavourzyme enzymes. Targeting common foodborne pathogens (Salmonella Typhimurium, Salmonella Enteritidis, Vibrio parahaemolyticus, Staphylococcus aureus, and Bacillus subtilis) and Escherichia coli, the research underscored the crucial role of peptidase in generating antibacterial peptides. Fractions F-2 of Flavourzyme hydrolysed adzuki bean (ABF) and F-4 of Flavourzyme hydrolysed mung bean (MBF) showed the highest antibacterial activity against S. Typhimurium and S. aureus, respectively, whereas F-2 of Alcalase hydrolysed mung bean (MBA) exhibited very poor activity against S. aureus. TripleTOF LC-MS/MS analysis revealed small cationic antibacterial peptides, with lysine being prominent against S. aureus and proline-proline against S. Typhimurium. These findings highlighted the significant contribution of protease enzymes in fostering antibacterial peptide production, offering valuable insights for developing effective antimicrobial agents in the context of food safety.

BackgroundMobile phones are widely used and may cause bacterial pathogens to spread among various professionals. Staphylococcus aureus from the mobile phones can contaminate the hands of food vendors and food during the cooking or packaging process. This research aimed to determine the prevalence, enterotoxin genes, and antimicrobial resistance (AMR) profiles of S. aureus contaminating the vendors' mobile phones.MethodsIn this study, 266 mobile phone samples were randomly collected from food vendors selling food on walking streets (n = 139) and in food centers (n = 127) in Phayao province. All samples were identified as S. aureus by the conventional culture method and confirmed species-specific gene by polymerase chain reaction (PCR). Then, all identified S. aureus isolates were tested for antimicrobial susceptibility by broth microdilution method and for the presence of staphylococcal enterotoxin (SE) genes by PCR.ResultsThe results showed that 12.8% of the mobile phones collected were contaminated with S. aureus. Of 49 S. aureus isolates obtained, 30 (61.2%) were positive for SE genes. The most common SE gene was sea followed by sec, seb, sem, seq, and sel. Moreover, S. aureus was most frequently resistant to penicillin, followed by chloramphenicol and tetracycline, erythromycin, clindamycin, and gentamicin. Methicillin-resistant S. aureus (MRSA), vancomycin-resistant S. aureus (VRSA), and multidrug-resistant (MDR) strains were also detected.ConclusionsThis study showed that mobile phones were an intermediate surface for the transmission of S. aureus, including MDR variants. It indicates that hand hygiene and the decontamination of mobile phones are essential to prevent cross-contamination of S. aureus in food settings.

Outdoor air pollution is a leading cause of death and premature death globally. Motorcycle-taxi drivers were most at risk associated with occupational exposure to ambient air pollution in urban areas. Therefore, a cross-sectional study was conducted to determine the influencing factors and prediction of lung function impairment in 308 motorcycle-taxi drivers living in Bangkok and adjacent provinces between February and June 2022. The study design included: data collection using questionnaires applied from the Thai version of ATS-DLD-78A: American Thoracic Society Division of Lung Diseases and Department of Disease Control, Ministry of Public Health, Thailand; a collection of respirable dust, and ambient air pollution parameters measured by per-sonal air sampling pump and real-time air quality index (AQI) station, and lung function determined by the spirometer. The results showed that 14 factors were significantly associated with lung function impairment (p<0.05). Apparently, seven influencing factors showing the most association were included: gender, the height of the subjects, history of allergies, exposure to respirable dust, mask types, helmet types, and family history of lung disease. The lung function impairment of motorcycle-taxi drivers was significantly predicted in 28.1% by regression analysis of these seven variables (R2=0.281). Therefore, this is the first report on influencing factors and prediction of lung function impairment among motorcycle-taxi drivers. These findings would be very useful for preventing and controlling measure ambient air pollution, setting policies and strategies to mitigate the risks for motorcycle-taxi drivers and the other ex-posed population.

Vibrio parahaemolyticus is a Gram-negative, foodborne pathogenic bacterium that causes human gastroenteritis. This organism is ubiquitously present in the marine environment. ABSTRACT Vibrio parahaemolyticus is a Gram-negative, foodborne pathogenic bacterium that causes human gastroenteritis. This organism is ubiquitously present in the marine environment. Detection of V. parahaemolyticus in aquatic birds has been previously reported; however, the characterization of isolates of this bacterium recovered from these birds remains limited. The present study isolated and characterized V. parahaemolyticus from aquatic bird feces at the Bangpu Recreation Center (Samut Prakan province, Thailand) from 2016 to 2017, using multilocus sequence typing (MLST) and genome analysis. The results showed that V. parahaemolyticus was present in 34.9% (76/218) of the collected bird fecal samples. Among the ldh-positive V. parahaemolyticus isolates (n = 308), 1% (3/308) were positive for tdh, 1.3% (4/308) were positive for trh, and 0.3% (1/308) were positive for both tdh and trh. In turn, the MLST analysis revealed that 49 selected V. parahaemolyticus isolates resolved to 36 STs, 26 of which were novel (72.2%). Moreover, a total of 10 identified STs were identical to globally reported pathogenic strains (ST1309, ST1919, ST491, ST799, and ST2516) and environmental strains (ST1879, ST985, ST288, ST1925, and ST260). The genome analysis of isolates possessing tdh and/or trh (ST985, ST1923, ST1924, ST1929 and ST2516) demonstrated that the organization of the T3SS2α and T3SS2β genes in bird fecal isolates were almost identical to those of human clinical strains posing public health concerns of pathogen dissemination in the recreational area. The results of this study suggest that aquatic birds are natural reservoirs of new strains with high genetic diversity and are alternative sources of potentially pathogenic V. parahaemolyticus in the marine environment. IMPORTANCE To our knowledge, infection of foodborne bacterium V. parahamolyticus occurs via the consumption of undercooked seafood contaminated with pathogenic strains. Aquatic bird is a neglectable source that can transmit V. parahaemolyticus along coastal areas. This study reported the detection of potentially pathogenic V. parahamolyticus harboring virulence genes from aquatic bird feces at the recreational center situated near the Gulf of Thailand. These strains shared identical genetic profile to the clinical isolates that previously reported in many countries. Furthermore, the strains from aquatic birds showed extremely high genetic diversity. Our research pointed out that the aquatic bird is possibly involved in the evolution of novel strains of V. parahaemolyticus and play a role in dissimilation of the potentially pathogenic strains across geographical distance.

Background and Aim: Antimicrobial resistance (AMR) is a global problem that affects human and animal health, and eggs can act as a vehicle for pathogenic and non-pathogenic resistant bacteria in the food chain. Escherichia coli is an indicator of food contamination with fecal materials as well as the occurrence and levels of AMR. This study aimed to investigate the presence of AMR, integrons, and virulence genes in E. coli isolated from eggshell samples of three egg production systems, from supermarkets in Thailand. Materials and Methods: A total of 750 hen's egg samples were purchased from supermarkets in Phayao Province: Cage eggs (250), free-range eggs (250), and organic eggs (250). Each sample was soaked in buffered peptone water (BPW), and the BPW samples were incubated at 37°C for 18–24 h. All samples were tested for E. coli by the standard conventional culture method. Then, all identified E. coli were tested for antimicrobial susceptibility to 15 antimicrobial agents by the agar disk diffusion method. All E. coli strains were subsequently found to have virulence genes and Classes 1 and 2 integrons by polymerase chain reaction. Results: Among the eggshell samples, 91 samples were identified as having E. coli (cage eggs, 24 strains; free-range eggs, 27 strains; and organic eggs, 40 strains). Then, among the E. coli strains, 47 (51.6%) were positive for at least one virulence gene. The proportion of AMR in the eggshell samples was 91.2% (83/91), and streptomycin (STR), ampicillin (AMP), and tetracycline (TET) had a high degree of resistance. Among the E. coli strains, 27 (29.7%) strains were positive for class 1 or 2 integrons, and integron-positive strains were commonly found in STR-, AMP-, and TET-resistant strains. Multidrug resistance (MDR) was detected in 57.1% (52/91) of the E. coli strains, with STR-AMP-TET (5.5%) as the most frequent pattern. The proportion of MDR in cage eggs was 75.0% (18/24), which was higher than in both free-range and organic eggs. On the other hand, 53.2% (25/47) of E. coli carrying virulence genes had MDR, distributed across the production systems as follows: Cage eggs, 76.9% (10/13); free-range eggs, 63.6% (7/11); and organic eggs, 34.8% (8/23). Conclusion: Escherichia coli was detected in eggshell samples from all three egg production systems. The high level of virulence genes, AMR, and integrons indicated the possibility of dissemination of AMR among pathogenic and commensal E. coli through eggshells. These findings could be a major concern to farmers, food handlers, and consumers, especially regarding raw egg consumption.

Arcobacter butzleri is an emerging zoonotic food-borne and water-borne pathogen that can cause diarrhea in humans. The global prevalence of A. butzleri infection is underestimated, and little is known about their phenotypic and genotypic characterization. The aim of this study was to determine antimicrobial susceptibility (AST) profiles, detect related virulence genes, and classify sequence type (ST) of A. butzleri isolates obtained from human stool and food samples. A total of 84 A. butzleri isolates were obtained from human diarrheal (n = 25), non-diarrheal (n = 24) stool, and food (n = 35) samples in Thailand. They were evaluated for phenotypic identification by conventional microbiological procedures and AST by Kirby-Bauer disc diffusion method as well as virulence genes detection. Representative isolates from each origin were selected based on the presence of virulence genes and AST profiles to analyze genetic diversity by multilocus sequence typing (MLST). All isolates showed resistance to nalidixic acid 40.5% (34/84), ciprofloxacin 11.9% (10/84), azithromycin 8.3% (7/84), and erythromycin 3.6% (3/84). Regarding the ten virulence genes detected, cj1349, mviN and pldA had the highest prevalence 100% (84/84), followed by tlyA 98.8% (83/84), cadF 97.6% (82/84), ciaB 71.4% (60/84), hecA and hecB 22.6% (19/84), iroE 15.5% (13/84) and irgA 10.7% (9/84), respectively. Three virulence genes were present among A. butzleri isolates of human diarrheal stool and food samples, with a significant difference observed among isolates; hecB [36% (9/25) and 8.6% (3/35)], hecA [36% (9/25) and 5.7% (2/35)], and irgA [24% (6/25) and 2.9% (1/35)] (p < 0.05), respectively. The hecA and hecB virulence genes functions are related to the mechanism of hemolysis, while irgA supports a bacterial nutritional requirement. MLST analysis of 26 A. butzleri isolates revealed that 16 novel STs exhibited high genetic diversity. The results of this study is useful for understanding potentially pathogenic and antimicrobial-resistant A. butzleri in Thailand. The pathogenic virulence markers hecB, hecA, and irgA have the potential to be developed for rapid diagnostic detection in human diarrheal stool. No significant relationships among STs and sources of origin were observed. Little is known about A. butzleri, the mechanism of action of these virulence genes, is a topic that needs further investigation.

Vibrio parahaemolyticus (VP) is a major cause of gastroenteritis outbreaks in Thailand and other countries due to the consumption of contaminated and undercooked seafood. However, there have been few reports of the molecular epidemiology of VP isolates from asymptomatic seafood handlers. Here, we report the phenotypic and genetic characterization of 61 VP isolates obtained from asymptomatic workers in two seafood-processing plants. We found 24 O:K serotypes, of which O11:KUT, O1:KUT and O3:KUT were the dominant serotypes. Analysis by PCR showed that 12 isolates harbored either tdh or trh genes with the potential to be pathogenic VP strains. The presence of T3SS2α and T3SS2β genes was correlated with the presence of tdh and trh, respectively. Four tdh+ isolates were positive for pandemic marker. In this study, VP isolates were commonly resistant to ampicillin, cephazolin, fosfomycin and novobiocin. Phylogenetic analysis of VP1680 loci in 35 isolates from 17 asymptomatic workers, 6 gastroenteritis patients, 7 environmental samples and 5 genomes from a database showed 22 different alleles. Gene VP1680 was conserved in tdh+ isolates and pandemic strains, while that of trh + isolates was diverse. Asymptomatic workers carrying VP were the most likely source of contamination, which raises concerns over food safety in seafood-processing plants.

Salmonella causes foodborne disease outbreaks worldwide and raises concerns about public health and economic losses. To determine prevalence, serovar, antimicrobial resistance patterns, and the presence of extended-spectrum beta-lactamase (ESBL) genes in a cross-sectional study, 418 total samples from feces and carcasses (from three slaughterhouses) and pork and cutting boards (from four markets) were collected in a central Thailand province in 2017 and 2018. Of the 418 samples, 272 (65.1%) were positive for Salmonella. The prevalence of Salmonella-positive samples from markets (158 of 178; 88.8%) was significantly higher than that among samples from slaughterhouses (114 of 240; 47.5%) (P < 0.05). A total of 1,030 isolates were identified; 409 were assigned to 45 serovars, with Salmonella Rissen the most common (82 of 409; 20%). Two serovars, Salmonella Cannstatt and Salmonella Braubach, were identified for the first time in Thailand in market and slaughterhouse samples, respectively. Among 180 isolates representing 19 serovars, 133 (73.9%) exhibited multidrug resistance. Screening for ESBL production revealed that 41 (10.3%) of 399 isolates were ESBL positive. The prevalence of ESBL-producing Salmonella isolates was significantly higher among the market isolates (31 of 41; 75.6%) than among the slaughterhouse isolates in (10 of 41; 24.4%) (P < 0.05). In market samples, 24 (77.4%) of 31 isolates were recovered from pork and 7 (22.6%) were recovered from cutting boards. Nine ESBL-producing isolates carried single ESBL genes, either blaTEM (4 of 41 isolates; 9.8%) or bla(CTX-M) (5 of 41 isolates; 12.2%), whereas 11 (26.8%) carried both bla(TEM) and bla(CTX-M). No ESBL-producing Salmonella isolate carried the blaSHV gene. These results suggest that pigs, their flesh, and cutting boards used for processing pork could be reservoirs for widespread ESBL-producing Salmonella isolates with multidrug resistance and outbreak potential across the food chain.

Aims: WQ-3810 has strong inhibitory activity against Salmonella and other fluoroquinolone-resistant pathogens. The unique potentiality of this is attributed to 6-amino-3,5-difluoropyridine-2-yl at R1 group. The aim of this study was to examine WQ-3810 and its derivatives WQ-3334 and WQ-4065 as the new drug candidate for wild-type Salmonella and that carrying QnrB19. Materials and Methods: The half maximal inhibitory concentrations (IC50s) of WQ-3810, WQ-3334 (Br atom in place of methyl group at R8), and WQ-4065 (6-ethylamino-3,5-difluoropyridine-2-yl in place of 6-amino-3,5-difluoropyridine-2-yl group at R1) in the presence or absence of QnrB19 were assessed by in vitro DNA supercoiling assay utilizing recombinant DNA gyrase and QnrB19. Results: IC50s of WQ-3810, WQ-3334, and WQ-4065 against Salmonella DNA gyrase were 0.031 ± 0.003, 0.068 ± 0.016, and 0.72 ± 0.39 μg/mL, respectively, while QnrB19 increased IC50s of WQ-3810, WQ-3334, and WQ-4065 to 0.44 ± 0.05, 0.92 ± 0.34, and 9.16 ± 2.21 μg/mL, respectively. Conclusion: WQ-3810 and WQ-3334 showed stronger inhibitory activity against Salmonella Typhimurium DNA gyrases than WQ-4065 even in the presence of QnrB19. The results suggest that 6-amino-3,5-difluoropyridine-2-yl group at R1 is playing an important role and WQ-3810 and WQ-3334 to be good candidates for Salmonella carrying QnrB19.

Methicillin-resistant Staphylococcus aureus (MRSA) have been a major public health concern in humans. Among MRSA, livestock-associated (LA)-MRSA strains have always been associated with exposure to livestock or their products and have emerged in different countries globally. Although studies have identified LA-MRSA from healthy pigs and pork in Thailand, prevalence in slaughtered pigs is still unknown. In addition, there are few reports on the epidemiology and molecular characteristics of LA-MRSA in Thailand. Hence, this is the first report investigating the epidemiology and molecular characteristics of MRSA in individual slaughtered pigs and pork in Thailand. A total of 204 nasal swab and 116 retailed pork samples were collected from three slaughterhouses and four fresh markets, respectively. Individual samples were used for screening for MRSA and obtained isolates were examined for drug- resistance profiling for 12 antimicrobial agents of 10 drug classes. In addition, SCCmec typing and multi-locus sequence typing were conducted to obtain genotype profiles. MRSA were isolated from 11 and 52 nasal swab and pork samples, respectively. The prevalence was significantly higher in the pork than in the nasal swab samples (p-value < 0.05). A high prevalence of ST9-SCCmecIX and ST398-SCCmecV with high-level antimicrobial resistance from markets and slaughterhouses indicated the spreading of MRSA with these genotypes in the Thai swine processing chains and suggested the need for further investigation to determine a control.