Flagella Phenotypic Variations of ST34 Type Salmonella Typhimurium and Variants.

Salmonella enterica serovar Typhimurium and its variants are the most common serotypes of human salmonellosis cases. Serotyping Salmonella Typhimurium and its variants has always been challenging. Our previous work found that among 14 Salmonella Typhimurium and variant strains, some different antigenic formulas had 100% pulsed-field gel electrophoresis (PFGE) similarity. The 14 strains were sorted into 3 groups; in each group, the different antigenic formulas had the same PFGE patterns. This phenomenon suggested that different antigenic formula identification might originate from a common ancestor subtyped by PFGE. To assess whether the serotyping method on Salmonella Typhimurium and variant strains reflected the genetic relationship, we improved the discrimination for the phylogenetic relationship among the 14 Salmonella Typhimurium and variant strains using Fourier-transform infrared spectroscopy (FTIR) and whole-genome multilocus sequence typing (wgMLST). We compared the wgMLST assay of 14 Salmonella Typhimurium and variant strains from this study with 50 public ST34 strain data of Salmonella Typhimurium and variant strains. We also compared flagella (H antigen)-related genes based on the whole genome of 14 strains and the other 293 ST34 public database for further understanding of this question. The phylogenetic results (PFGE) showed no regularity between the antigenic formulas and genotypes. The results of the higher discrimination power assays (FTIR and whole-genome multilocus sequence typing) also showed no regularity between the antigenic formulas and genotypes (or phenotypes). The 58 flagella encoding genes of different antigenic formulas were sorted into 13 patterns. However, a similar phenomenon was found: the same flagella encoding gene patterns could express different antigenic formulas. In conclusion, there is no consistency between the antigenic formulas and phylogenetic relationships among ST34 Salmonella Typhimurium and variant strains, even in flagella antigenic formula and flagella encoding genes.

Spotted Fever Group Rickettsia Infection of Cats and Cat Fleas in Northeast Thailand.

Rickettsia species cause rickettsioses, which are zoonotic diseases found worldwide, and are transmitted by arthropods such as lice, fleas, ticks, and mites. In Thailand, flea infestations are common among cats and dogs. This study aimed at determining the exposure to spotted fever group rickettsiae (SFGR) of cats in surrounding areas of Rajabhat Maha Sarakham University, Muang district, Maha Sarakham province and rickettsial infection among cat fleas, Ctenocephalides felis, collected from dogs of the surrounding area of Waeng Noi district, Khon Kaen province. Forty-two cat sera were assessed for IgG antibody titers against SFGR by a group-specific enzyme-linked immunosorbent assay. The prevalence of seroreactive cats was 4.76% (2/42). DNA preparations from 23 individual cat fleas from three dogs were assessed by Rickettsia genus-specific, group-specific, and species-specific quantitative real-time PCR (qPCR) assays. Positive results were confirmed by ompB gene fragment sequencing. Twenty-one of 23 cat fleas were positive for Rickettsia asembonensis, and the other two DNA preparations were negative for rickettsial DNA. This study's finding indicates that companion cats and dogs in Northeast Thailand are exposed to SFGR and that exposure may be due to infection with R. asembonensis, an organism known to infect humans, monkeys, and dogs. Clinicians for humans and animals in Northeast Thailand should be aware of rickettsial infections among their patients.

Risk of Antimicrobial Resistant Non-Typhoidal Salmonella during Asymptomatic Infection Passage between Pet Dogs and Their Human Caregivers in Khon Kaen, Thailand.

To explore the risk of antimicrobial resistant (AMR) non-typhoidal Salmonella during asymptomatic infection passage between pet dogs and human caregivers in Khon Kaen, Thailand, one hundred forty paired fecal samples (n = 280) were obtained from companion dogs and their human caregivers, interviewed from 140 households during 2019-2020. The purified Salmonella isolates were serotype-identified and tested for antimicrobial resistance against ampicillin, ciprofloxacin, chloramphenicol, nalidixic acid, streptomycin, sulfamethoxazole-trimethoprim, and tetracycline. The homologous Salmonella isolate pairs (suggesting Salmonella infections may have been due to passage between each one of the pair, or derived from the same source) were subsequently characterized by serotype screening, pulsed field gel electrophoresis (PFGE), and Synchrotron Fourier transform infrared spectroscopy (SR-FTIR). The Salmonella prevalence observed in dogs, 12.86% (18/140), was not significantly different from that observed in humans, 17.86% (25/140) using McNemar's test. The AMR patterns (the patterns among the isolates of pet dogs and caregivers) and the serotypes (thirteen serotypes with 18 isolates from pet dogs plus thirteen serotypes with 25 isolates from humans) between pet dogs and humans were not significantly different using Pearson's chi-squared test. The homologous Salmonella isolates from the Salmonella-present households was 5.13% (2/39). This study demonstrated that the hypothesis that there is a high risk of Salmonella infection passage between dogs and humans with close contact in Khon Kaen is doubtful. Only 5.13% of homologous Salmonella isolates from Salmonella-present households were found in Khon Kaen, Thailand, although the prevalence of Salmonella-positive samples, serotypes, and antimicrobial resistance patterns were quite similar among the two populations.

Evaluation of the Containment of Antimicrobial-Resistant Salmonella Species from a Hazard Analysis and Critical Control Point (HACCP) and a Non-HACCP Pig Slaughterhouses in Northeast Thailand.

To evaluate the containment of antimicrobial-resistant (AMR) Salmonella contaminations of a HACCP slaughterhouse (HACCP SH) and a non-HACCP slaughterhouse (non-HACCPSH), 360 paired pig rectal (representing the farm pig status) and carcass samples (representing the contamination) were collected equally from the two slaughterhouses that serviced 6 and 12 farms, respectively, in Northeast Thailand (n = 720). The purified Salmonella isolates were serotype identified, antimicrobial susceptibility tested, and pulsed-field gel electrophoresis (PFGE) assessed. Four evaluations of two slaughterhouses were examined: (1) the means of slaughtering contamination rates (SCR) (to evaluate the contamination level by averaged farm SCRs): the HACCP SH decreased contamination (SCR: -48.89% ± 8.80%, n = 6), whereas the non-HACCP SH increased (SCR: 14.31% ± 9.35%, n = 12). (2) The serotype diversity: the HACCP SH decreased the diversity from the rectal group (110 isolates, 9 serotypes) to carcass group (23 isolates, 3 serotypes), whereas there was no decrease in the non-HACCP SH (rectal group (66 isolates, 14 serotypes) and carcass group (31 isolates, 10 serotypes)). (3) The AMR patterns: the HACCP SH decreased from rectal group (96 isolates, 7 patterns) to carcass group (22 isolates, 1 pattern), whereas there was no decrease from the non-HACCP SH rectal group (22 isolates, 7 patterns) to carcass group (48 isolates, 8 patterns). (4) The estimated indirect contamination rate (by serotype screening and PFGE confirmation): the HACCP SH was 60.87% (14/23), whereas the non-HACCP SH was 98.48% (65/66). This study indicates that both the slaughterhouses keep a high level of indirect contamination; the HACCP SH decreases Salmonella contaminations and reduces the AMR patterns, the non-HACCP SH increases contaminations.

Global distribution of Bartonella infections in domestic bovine and characterization of Bartonella bovis strains using multi-locus sequence typing.

Bartonella bovis is commonly detected in cattle. One B. bovis strain was recently isolated from a cow with endocarditis in the USA, suggesting its role as an animal pathogen. In the present study, we investigated bartonella infections in 893 cattle from five countries (Kenya, Thailand, Japan, Georgia, and Guatemala) and 103 water buffaloes from Thailand to compare the prevalence of the infection among different regions and different bovid hosts. We developed a multi-locus sequence typing (MLST) scheme based on nine loci (16S rRNA, gltA, ftsZ, groEL, nuoG, ribC, rpoB, ssrA, and ITS) to compare genetic divergence of B. bovis strains, including 26 representatives from the present study and two previously described reference strains (one from French cows and another from a cow with endocarditis in the USA). Bartonella bacteria were cultured in 6.8% (7/103) of water buffaloes from Thailand; all were B. bovis. The prevalence of bartonella infections in cattle varied tremendously across the investigated regions. In Japan, Kenya, and the Mestia district of Georgia, cattle were free from the infection; in Thailand, Guatemala, and the Dusheti and Marneuli districts of Georgia, cattle were infected with prevalences of 10-90%. The Bartonella isolates from cattle belonged to three species: B. bovis (n=165), B. chomelii (n=9), and B. schoenbuchensis (n=1), with the latter two species found in Georgia only. MLST analysis suggested genetic variations among the 28 analyzed B. bovis strains, which fall into 3 lineages (I, II, and III). Lineages I and II were found in cattle while lineage III was restricted to water buffaloes. The majority of strains (17/28), together with the strain causing endocarditis in a cow in the USA, belonged to lineage I. Further investigations are needed to determine whether B. bovis causes disease in bovids.

Molecular detection and identification of Bartonella species in rat fleas from northeastern Thailand.

The presence of Bartonella species in Xenopsylla cheopis fleas collected from Rattus spp. (R. exulans, R. norvegicus, and R. rattus) in Khon Kaen Province, Thailand was investigated. One hundred ninety-three fleas obtained from 62 rats, were screened by polymerase chain reaction using primers specific for the 16S-23S intergenic spacer region, and the presence of Bartonella DNA was confirmed by using the citrate synthase gene. Bartonella DNA was detected in 59.1% (114 of 193) of fleas examined. Sequencing demonstrated the presence of Bartonella spp. similar to B. elizabethae, B. rattimassiliensis, B. rochalimae, and B. tribocorum in the samples tested with a cutoff for sequence similarity ≥ 96% and 4 clustered together with the closest match with B. grahamii (95.5% identity). If X. cheopis proves to be a competent vector of these species, our results suggest that humans and animals residing in this area may be at risk for infection by several zoonotic Bartonella species.

Oxidative stress in cancer-bearing dogs assessed by measuring serum malondialdehyde.

BACKGROUND: Oxidative stress, an excess of reactive oxygen species (ROS), causes lipid peroxidation resulting in cell and tissue damages. It may be associated with the development and progression of cancers in dogs. Malondialdehyde (MDA), the end product of lipid peroxidation, is commonly used as a marker of oxidative stress. The objective of this study was to assess oxidative stress in cancer-bearing dogs by measuring serum MDA levels. All client-owned dogs underwent physical examination at the Veterinary Teaching Hospital, Faculty of Veterinary Medicine, Khon Kaen University to determine the health status with the owner's consent. Blood samples of cancer-bearing dogs (N = 80) and clinically normal dogs (N = 101) were obtained and subjected for determination of MDA levels. In addition, complete blood count, creatinine, and alanine aminotransferase were measured. RESULTS: Serum MDA was significantly higher in cancer-bearing dogs than in clinically normal dogs (mean ± SD, 4.68 ± 1.32 µmol/L vs 2.95 ± 0.61 µmol/L, respectively; p < 0.001). Packed cell volume (mean ± SD, 36.18 ± 7.65% vs 44.84 ± 5.54%), hemoglobin (mean ± SD, 11.93 ± 2.88 g% vs 15.17 ± 2.00 g%) and red blood cells (median (IQA), 6.05 (2.15) vs 8.09 (1.34)) were all significantly lower in cancer-bearing dogs than in clinically normal dogs. However, the reverse was true for white blood cells (median (IQA), 18.20 (11.95) vs 14.90 (5.10)). Neither creatinine nor alanine aminotransferase levels were significantly different between groups. CONCLUSIONS: This study supports the conclusion that oxidative stress is associated with many types of cancers in dogs, as serum MDA levels were significantly higher in cancer-bearing dogs compared to clinically normal dogs.

Molecular characterization of Thai Ehrlichia canis and Anaplasma platys strains detected in dogs.

Canine monocytic ehrlichiosis caused by Ehrlichia canis is of veterinary importance worldwide. In Thailand, there has been little information available on E. canis and its phylogeny. The objective of this study was to characterize and establish molecular structure and phylogeny of Thai Ehrlichia and Anaplasma strains. Genus-specific primers for Ehrlichia and Anaplasma were used to amplify the 16S rRNA gene from naturally infected canine blood samples, and these amplicon sequences were compared with other sequences from GenBank. Both homology and secondary structure analysis of 16S rRNA sequences indicated that they were novel E. canis and A. platys strains. Phylogenetic analysis revealed that the Thai E. canis strain was closely related and formed a single cluster with E. canis from different countries. A. platys found in this study showed close relationship with earlier report of A. platys from Thailand. To our knowledge this report represents the first molecular characterization of the nearly complete 16S rRNA gene from E. canis in dogs from Thailand.