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Mycoplasma gallisepticum (MG) is one of the most economically important pathogens worldwide. MG affects the respiratory system and impairs growth performance in poultry. In developing countries, the most widely used technique to identify MG is the conventional PCR assay. In this study, 24 MG isolates collected from Thailand farms with unvaccinated chickens during 2002-2020 were characterized by gene-targeted sequencing (GTS), followed by phylogenetic analysis using unweighted pair group method with arithmetic mean. These 24 Thai MG isolates differed from vaccine strains, including the F, ts-11 and 6/85 strains. One isolate showed 99.5-100% genetic similarity to the F strain with 4 partial gene analyses. This result may have been due to contamination from vaccinated flocks because the F strain is the most commonly used vaccine strain in Thailand. However, the GTS analysis using the partial MG genes in this study showed that the isolates could be grouped into different patterns based on individual gene sequences. The phylogenetic analysis of partial mgc2, gapA, pvpA and lp gene sequences classified the Thai MG isolates into 7, 11, 7 and 2 groups, respectively. In conclusion, at least 2 partial MG genes, especially partial gapA and mgc2 genes, are needed to differentiate MG isolates., (© 2022. The Author(s).)

Salmonella spp. is an important foodborne pathogen associated with consumption of contaminated food, especially food of livestock origin. Antimicrobial resistance (AMR) in Salmonella has been reported globally and increasing AMR in food production is a major public health issue worldwide. The objective of this study was to describe the genetic relatedness among Salmonella enterica isolates, which displayed identical DNA fingerprint profiles. Ten S. enterica isolates were selected from meat and human cases with an identical rep-PCR profile of serovars Rissen (n = 4), Weltevreden (n = 4), and Stanley (n = 2). We used long-read whole genome sequencing (WGS) on the MinION sequencing platform to type isolates and investigate in silico the presence of specific AMR genes. Antimicrobial susceptibility testing was tested by disk diffusion and gradient diffusion method to corroborate the AMR phenotype. Multidrug resistance and resistance to more than one antimicrobial agent were observed in eight and nine isolates, respectively. Resistance to colistin with an accompanying mcr-1 gene was observed among the Salmonella isolates. The analysis of core genome and whole genome MLST revealed that the Salmonella from meat and human salmonellosis were genetically related. Hence, it could be concluded that meat is one of the important sources for Salmonella infection in human., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Salmonella enterica subsp. enterica serotype Rissen is the predominant serotype found in Thai pork production and can be transmitted to humans through contamination of the food chain. This study was conducted to investigate the genetic relationships between serovar Rissen isolates from all levels of the pork production chain and evaluate the ability of the in silico antimicrobial resistance (AMR) genotypes to predict the phenotype of serovar Rissen. A total of 38 serovar Rissen isolates were tested against eight antibiotic agents by a disk diffusion method and the whole genomes of all isolates were sequenced to detect AMR genetic elements using the ResFinder database.A total of 86.84% of the isolates were resistant to tetracycline, followed by ampicillin (78.96%) and sulfonamide-trimethoprim (71.05%). Resistance to more than one antimicrobial agent was observed in 78.95% of the isolates, with the most common pattern showing resistance to ampicillin, chloramphenicol, streptomycin, sulfonamide-trimethoprim, and tetracycline. The results of genotypic AMR indicated that 89.47% of the isolates carried tet(A), 84.22% carried bla TEM-1B , 78.95% carried sul3, and 78.95% carried dfrA12. The genotypic prediction of phenotypic resistance resulted in a mean sensitivity of 97.45% and specificity of 75.48%. Analysis by core genome multilocus sequence typing (cgMLST) demonstrated that the Salmonella isolates from various sources and different locations shared many of the same core genome loci. This implies that serovar Rissen has infected every stage of the pork production process and that contamination can occur in every part of the production chain., (Copyright © 2019. Published by Elsevier B.V.)

Human salmonellosis is a major public health problem worldwide. Infections can pass to humans by contact with contaminated substances in the food chain. This study aimed to determine the prevalence and contamination levels of Salmonella isolated from pork, chicken and beef sold in different types of retail stores in Chiang Mai and Lamphun provinces and to investigate the genetic relatedness among Salmonella isolates in food chains in that area. A total of 360 meat samples from supermarkets, mini-grocery stores and fresh markets were obtained. Salmonella Rissen and S. Weltevreden were found in all meat sample types and in human cases. The overall prevalence of Salmonella in the chicken, pork and beef samples was 34.17%, 32.50% and 3.33%, respectively. Quantitatively, Salmonella contamination was highest in pork (1.24 log 10 MPN/g), followed by chicken (1.08 log 10 MPN/g), and beef (0.75 log 10 MPN/g). The highest frequency of Salmonella contamination was found at the fresh markets (85.71%), whereas the highest quantity of contamination level was from mini-grocery stores (1.27 log 10 MPN/g). The rep-PCR analysis results revealed that some of the Salmonella from meat samples and human cases were identical clones., (© 2019 Blackwell Verlag GmbH.)