Prevalence and antimicrobial resistance of Salmonella spp. isolated from chicken meat in upper northeastern Thailand

Foodborne disease associated with Salmonella spp. occurs in some parts of the world, including Thailand. The present study aimed to determine prevalence, antimicrobial resistance, and serotypes of Salmonella spp. isolated from chicken meat in upper northeastern Thailand. A total of 326 swab samples of fresh chicken meat were collected from wet markets in Khon Kaen, U-don Thani, Nong Khai, Loei, Kalasin, Maha Sarakham, and Bueng Kan Provinces, northeastern Thailand, between August and November 2019. All samples were analyzed for Salmonella spp. using the ISO 6579:2002/AMD 1:2007 method. The isolates were tested for antimicrobial susceptibility using the Kirby-Bauer method, and the serotypes of isolates positive were identified. The overall prevalence of Salmonella spp. isolated from chicken meat was 36.2% (118/326), and prevalence in the provinces was as follows: U-don Thani, 70.9%; Bueng Kan, 66.67%; Khon Kaen, 45.9%; Kalasin, 31.25%; Nong Khai, 29.8%; Maha Sarakham, 26.42% and Loei, 12.5%. Resistance was highest for nalidixic acid at 31%, followed by ampicillin (24%), tetracycline (19%), sulfamethoxazole trimethoprim (8%), norfloxacin (5%), ciprofloxacin (4%), amoxicillin (4%), and chloramphenicol (1%). However, all isolates were susceptible to ceftazidime. Twenty-seven serotypes were detected, with the Corvallis, Singapore, Kentucky and Agona serotypes being the most common. Salmonella spp. were detected in a large percentage of the swab samples of chicken meat in every city, indicating a high level of contamination of chicken meat. Given the high resistance of Salmonella strains to some antibiotics, it may be beneficial to find other drugs for salmonellosis treatment and to use antibiotics more wisely

Dissemination of clonal Salmonella enterica serovar Typhimurium isolates causing salmonellosis in Mauritius

Salmonella enterica serotype Typhimurium is one of the leading causes of salmonellosis in Mauritius, where it has also been associated with outbreaks of foodborne illness. However, little is known about its molecular epidemiology in the country. This study was therefore undertaken to investigate the clonality and source of Salmonella Typhimurium in Mauritius by studying human, food, and poultry isolates by pulsed-field gel electrophoresis (PFGE) and antibiotic minimum inhibitory concentration determination. Forty-nine isolates collected between 2008 and 2011 were analyzed, including 25 stool isolates from foodborne illness outbreaks and sporadic gastroenteritis cases, four blood isolates, one postmortem colon isolate, 14 food isolates, and five poultry isolates. All isolates were pansusceptible to the 16 antibiotics tested, except for two isolates that were resistant to sulfamethoxazole and trimethoprim. Overall characterization of the isolates by PFGE digested with XbaI and BlnI resulted in eight different patterns. The largest of the clusters in the composite dataset consisted of 20 isolates, including two raw chicken isolates, four poultry isolates, and nine human stool isolates from two outbreaks. A second cluster consisted of 18 isolates, of which 12 originated from human blood and stool samples from both sporadic and outbreak cases. Six food isolates were also found in this cluster, including isolates from raw and grilled chicken, marlin mousse, and cooked pork. One poultry isolate had a closely related PFGE pattern. The results indicate that one clone of Salmonella Typhimurium found in poultry has been causing outbreaks of foodborne illness in Mauritius and another clone that has caused many cases of gastrointestinal illness and bacteremia in humans could also be linked to poultry. Thus, poultry appears to be a major reservoir for Salmonella Typhimurium in Mauritius. Initiating on-farm control strategies and measures against future dissemination may substantially reduce the number of cases of salmonellosis in the country

Characterization of Salmonella enterica serovar Enteritidis isolates recovered from blood and stool specimens in Thailand

<p>Abstract</p> <p>Background</p> <p>Bacteremia due to <it>Salmonella</it> spp. is a life-threatening condition and is commonly associated with immune compromise. A 2009 observational study estimated risk factors for the ten most common non-typhoidal <it>Salmonella</it> (NTS) serovars isolated from Thai patients between 2002–2007. In this study, 60.8% of <it>Salmonella enterica</it> serovar Enteritidis isolates (n = 1517) were recovered from blood specimens and infection with <it>Salmonella</it> serovar Enteritidis was a statistically significant risk factor for bacteremia when compared to other NTS serovars. Based on this information, we characterized a subset of isolates collected in 2008 to determine if specific clones were recovered from blood or stool specimens at a higher rate. Twenty blood isolates and 20 stool isolates were selected for antimicrobial resistance testing (MIC), phage typing, PFGE, and MLVA.</p> <p>Result</p> <p>Eight antibiogrammes, seven MLVA types, 14 <it>Xba</it>I/<it>Bln</it>I PFGE pattern combinations, and 11 phage types were observed indicating considerable diversity among the 40 isolates characterized. Composite analysis based on PFGE and MLVA data revealed 22 genotypes. Seven of the genotypes containing two or more isolates were from both stool and blood specimens originating from various months and zones. Additionally, those genotypes were all further discriminated by phage type and/or antibiogramme. Ninety percent of the isolates were ciprofloxacin resistant.</p> <p>Conclusions</p> <p>The increased percentage of bloodstream infections as described in the 2009 observational study could not be attributed to a single clone. Future efforts should focus on assessing the immune status of bacteriaemic patients and identifying prevention and control measures, including attribution studies characterizing non-clinical (animal, food, and environmental) isolates.</p

Salmonella Serovars from Humans and Other Sources in Thailand, 1993–2002

We serotyped 44,087 Salmonella isolates from humans and 26,148 from other sources from 1993 through 2002. The most common serovar causing human salmonellosis in Thailand was Salmonella enterica Weltevreden. Serovars causing human infections in Thailand differ from those in other countries and seem to be related to Salmonella serovars in different food products and reservoirs

International Spread of Multidrug-resistant Salmonella Schwarzengrund in Food Products

This serovar was isolated from persons, food, and food animals in Thailand, Denmark, and the United States

Effectiveness of BOX-PCR in Differentiating Genetic Relatedness among Salmonella enterica Serotype 4,[5],12:i:- Isolates from Hospitalized Patients and Minced Pork Samples in Northern Thailand

Salmonella enterica Serotype 4,[5],12:i:-, a monophasic variant of S. Typhimurium, with high virulence and multidrug resistance is distributed globally causing pathogenicity to both humans and domesticated animals. BOX-A1R-based repetitive extragenic palindromic-PCR (BOX)-PCR proved to be superior to three other repetitive element-based PCR typing methods, namely, enterobacterial repetitive intergenic consensus (ERIC)-, poly-trinucleotide (GTG)5-, and repetitive extragenic palindromic (REP)-PCR (carried out under a single optimized amplification condition), in differentiating genetic relatedness among S. 4,[5],12:i:- isolates from feces of hospitalized patients (n=12) and isolates from minced pork samples of S. 4,[5],12:i:- (n=6), S. Typhimurium (n=6), and Salmonella Serogroup B (n=4) collected from different regions of northern Thailand. Construction of phylogenetic trees from amplicon size patterns allowed allocation of Salmonella isolates into clusters of similar genetic relatedness, with BOX-PCR generating more unique clusters for each serotype than the other three typing methods. BOX-, (GTG)5-, and REP-PCR indicated significant genetic relatedness between S. 4,[5],12:i:- isolates 1 and 9 from hospitalized patients and S. 4,[5],12:i:- isolate en 29 from minced pork, suggesting a possible route of transmission. Thus, BOX-PCR provides a suitable molecular typing method for discriminating genetic relatedness among Salmonella spp. of the same and different serotypes and should be suitable for application in typing and tracking route of transmission in Salmonella outbreaks

Quantitative Risk Assessment of Susceptible and Ciprofloxacin-Resistant Salmonella from Retail Pork in Chiang Mai Province in Northern Thailand

The adverse human health effects as a result of antimicrobial resistance have been recognized worldwide. Salmonella is a leading cause of foodborne illnesses while antimicrobial resistant (AMR) Salmonella has been isolated from foods of animal origin. The quantitative risk assessment (RA) as part of the guidelines for the risk analysis of foodborne antimicrobial resistance was issued by the Codex Alimentarius Commission more than a decade ago. However, only two risk assessments reported the human health effects of AMR Salmonella in dry-cured pork sausage and pork mince. Therefore, the objective of this study was to quantitatively evaluate the adverse health effects attributable to consuming retail pork contaminated with Salmonella using risk assessment models. The sampling frame covered pork at the fresh market (n = 100) and modern trade where pork is refrigerated (n = 50) in Chiang Mai province in northern Thailand. The predictive microbiology models were used in the steps where data were lacking. Susceptible and quinolone-resistant (QR) Salmonella were determined by antimicrobial susceptibility testing and the presence of AMR genes. The probability of mortality conditional to foodborne illness by susceptible Salmonella was modeled as the hazard characterization of susceptible and QR Salmonella. For QR Salmonella, the probabilistic prevalences from the fresh market and modern trade were 28.4 and 1.9%, respectively; the mean concentrations from the fresh market and modern trade were 346 and 0.02 colony forming units/g, respectively. The probability of illness (PI) and probability of mortality given illness (PMI) from QR Salmonella-contaminated pork at retails in Chiang Mai province were in the range of 2.2 &times; 10&minus;8&ndash;3.1 &times; 10&minus;4 and 3.9 &times; 10&minus;10&ndash;5.4 &times; 10&minus;6, respectively, while those from susceptible Salmonella contaminated-pork at retails were in the range 1.8 &times; 10&minus;4&ndash;3.2 &times; 10&minus;4 and 2.3 &times; 10&minus;7&ndash;4.2 &times; 10&minus;7, respectively. After 1000 iterations of Monte Carlo simulations of the risk assessment models, the annual mortality rates for QR salmonellosis simulated by the risk assessment models were in the range of 0&ndash;32, which is in line with the AMR adverse health effects previously reported. Therefore, the risk assessment models used in both exposure assessment and hazard characterization were applicable to evaluate the adverse health effects of AMR Salmonella spp. in Thailand