The prevalence of intermediately virulent Rhodococcus equi isolates from pig submaxillary lymph nodes from four slaughterhouses in Nakhonpathom province, Thailand, was investigated. The isolates were tested for the presence of virulence plasmids and the 20-kDa virulence-associated protein antigen (VapB) gene by PCR. Of the 734 submaxillary lymph nodes tested, 19 (2.6%) produced positive cultures of R. equi. All 19 isolates were positive for the VapB gene and contained virulence plasmids that were identified as type 1 (six isolates), type 6 (two isolates), type 7 (one isolate), type 16 (two isolates), and a new variant (eight isolates). Based on the restriction digestion patterns of the plasmid DNAs, we tentatively designated the variant as type 18. Investigation of the prevalence and plasmid profiles of VapB-positive R. equi in pigs should be extended throughout Thailand to evaluate potential sources of zoonotic infections.

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Background and Aim: Salmonella enterica is an important foodborne pathogen and is recognized as a major public health issue. The emergence of multidrug-resistant (MDR) S. enterica represents a major challenge for national public health authorities. We investigated the distribution of serovars and antimicrobial resistance of S. enterica isolates from clinical swine samples stored at the Veterinary Diagnostic Laboratory, Faculty of Veterinary Medicine, Kasetsart University from 2016 to 2017. Materials and Methods: Clinical samples were collected and subjected to standard microbiological techniques outlined in the Manual of Clinical Microbiology to identify Salmonella serovars. Susceptibility to antimicrobials was tested by the Kirby–Bauer disk diffusion method using a panel of 14 antimicrobials. Results: A total of 144 Salmonella isolates were identified and the dominant serovar was Salmonella Choleraesuis (66.67%), followed by monophasic Salmonella Typhimurium (18.75%), S. Typhimurium (9.03%), and Rissen (5.56%). The isolates displayed high resistance rates to ampicillin (AMP [100%]), amoxicillin (AX [100%]), tetracycline (TE [100%]), cefotaxime (CTX [89.58%]), ceftriaxone (CRO [87.50%]), chloramphenicol (C [82.64%]), gentamicin (CN [79.17%]), nalidixic acid (NA [72.92%]), and ceftazidime (CAZ [71.53%]). All isolates were MDR, with 29 distinct resistance patterns. The dominant MDR pattern among serovars Choleraesuis and Rissen exhibited resistance to 9 antimicrobials: ( R7-14 AMP-AX-CAZ-CRO-CTX-NA-C-CN-TE). However, all tested isolates were susceptible to AX/ clavulanic acid and fosfomycin. Conclusion: High resistance levels to the third generation of cephalosporins such as CAZ, CRO, and CTX highlight the need for careful and reasonable usage of antimicrobials in animals and humans, especially for S. Choleraesuis infections.

In this study, 22 bacterial isolates from swine necropsy specimens, which were biochemically identified as Streptococcus suis and other Streptococcus species, were re-examined using species-specific PCR for authentic S. suis and 16S rRNA gene sequencing for the verification of the former judge. Identification of S. suis on the basis of biochemical characteristics showed high false-positive (70.6%) and false-negative (60%) rates. The authentic S. suis showed various capsular polysaccharide synthesis gene types, including type 2 that often isolated from human cases. Five of 22 isolates did not even belong to the genus Streptococcus . These results suggested that the misidentification of the causative pathogen in routine veterinary diagnosis could be a substantial obstacle for the control of emerging infectious diseases.

screened for resistance SNPs at the following gene targets by pyrosequencing: PfATPase6 (atpase6), chloroquine resistance transporter (pfcrt), cytochrome b (cytb), dihydrofolate reductase-thymidylate synthase (dhfr), dihydropteroate synthetase (dhps), and multidrug resistance protein (mdr1). Isolates were also screened for mutations of the kelch13 propeller region (kelch13) by Sanger sequencing. Mutation prevalence was calculated and compared across time periods.Results: Two-hundred, twenty-three unique isolates of P. falciparum were identified from 2008-2009 (n = 75), 2013-2014 (n = 79) and 2017-2018 (n = 69). Of 223 isolates, 126 had a documented travel history, with most (88%) imported from sub-Saharan Africa. Significant decreases in mutant genotypes from 2008-09 to 2013-14 for mdr1 N86Y (p < 0.001), D1246Y (p = 0.007), pfcrt K76T (p = 0.032) were observed. Similarly, significant decreases in mutant allelic frequencies were observed from 2013-14 to 2017-18 for mdr1 N1042D (p = 0.0065); and cytB Y268NSC (p = 0.0038) and mdr1 N86Y (p = 0.003) across the three time frames. Significant increases in mutant allelic frequencies for pfcrt C72S (p = 0.027); dhfr A16 V (p = 0.01), C50R (p = 0.04); dhps K540E (p < 0.001), A581G (p < 0.001), A613S (p < 0.001), and mdr1 N1042D (p < 0.001) were observed between 2008-09 and 2013-14. A significant increase in mutant allelic frequencies for atpase6 was observed from 2013-14 and 2017-18 (p < 0.0001). Kelch13 mutations were not identified in any isolate between 2008-09 and 2013-14, including the 4 imported from southeast Asia. Conclusion:Mutant genotypes for several molecular markers of drug resistance were highly prevalent among P. falciparum isolates imported to Ontario, especially mutations in dhfr conferring resistance to proguanil. Our observation of minor genotypes confirms the heterogeneous nature of infection, which may lead to differential drug resistance levels and therapeutic failure. Atpase6 has shown significantly increases in mutant allelic frequencies associated with artemisinin resistance and warrants sustained surveillance.