Antimicrobial resistance profiling and molecular typing of ruminant-borne isolates of Clostridium perfringens from Xinjiang, China.

OBJECTIVES: Clostridium perfringens (C. perfringens) can cause intestinal diseases in livestock and humans, which seriously threatens the healthy development of animal husbandry and human food safety. Here, the characteristics of antimicrobial resistance and molecular typing of ruminant-borne strains of C. perfringens in Xinjiang, China were explored and profiled. METHODS: A total of 307 clinical feces collected from ruminants (cattle and sheep) with diarrheal symptoms were screened for C. perfringens. The recovered isolates were characterized in respect to their antimicrobial resistance pattern and molecular typing. RESULTS: A total of 109 isolates of C. perfringens were isolated from 307 clinical feces of ruminants, most of which displayed the multidrug resistance (MDR) phenotype. Demonstration of the quinolone-resistance gene was the highest among the isolates (70.6%). The multiplex PCR typing based on toxin genes showed that type A and type D strains made up 82.6% (90/109) and 17.4% (19/109), among which, the isolates carrying ß2 gene occupied 43.3% (39/90) of type A strains and 31.6% (6/19) of type D strains. These isolates were divided into 6 genotypes (I-VI) by enterobacterial repetitive intergenic consensus sequence-based PCR (ERIC-PCR) method. A total of 33 ST types (ST1-ST33) were identified by multilocus sequence typing (MLST) method. CONCLUSION: C. perfringens isolates with multidrug resistance (MDR) were frequent and circulating in ruminants. Among them, type A-Ⅰ-ST19 was the dominant genotype of C. perfringens, displaying obvious genetic diversity. This study provided important epidemiological data for the risk assessment of food safety associated with ruminant-borne C. perfringens in Xinjiang, China.

Molecular detection and genetic variability of Ehrlichia canis in pet dogs in Xinjiang, China.

BACKGROUND AND AIM: As a tick-borne zoonotic pathogen, Ehrlichia canis has already posed a threat to public health and safety. This study aimed to clarify the prevalence and molecular characteristics of E. canis in pet dogs in Xinjiang, China. MATERIALS AND METHODS: A total of 297 blood samples of pet dogs and 709 skin ticks (Rhipicephalus sanguineus sensu lato) were subjected to molecular detection using PCR for E. canis 16S rRNA gene, and then, positive samples were amplified, sequenced, and phylogenetically analyzed for E. canis gp36 gene. RESULTS: The PCR detection showed that the positive rate of PCR was 12.12% (36/297) in blood samples and 15.23% (108/709) in tick samples, respectively. Based on the phylogenetic analysis of E. canis gp36 protein, these E. canis strains in different geographical regions of the world can be divided into Genogroup I and Genogroup II. Among them, the Xinjiang epidemic strain XJ-6 and 533, 36, 1055, Kasur1, and Jake strains were clustered into subgroup 1.1 of Genogroup I, while the XJ-2, XJ-21, and XJ-35 strains and the TWN1, TWN4, CM180, and CM196 strains were closely related and belonged to subgroup 2.2 of Genogroup II, displaying high genetic diversity. CONCLUSION: This is the first study focusing on the molecular epidemiology of E. canis infection in pet dogs, which revealed that E. canis infection had been occurred in Xinjiang, China. More importantly, this study confirmed that the substantial variability in immunoreactive protein gp36 from E. canis strains circulating in pet dogs.

Molecular Detection and Genetic Diversity of porcine Circovirus Type 3 in Commercial Pig Farms in Xinjiang Province, China.

INTRODUCTION: Porcine circovirus type 3 (PCV3) is a newly discovered porcine circovirus. The molecular characteristics and genetic evolution of PCV3 in Xinjiang province, China still being unclear, the aim of the study was their elucidation. MATERIAL AND METHODS: A total of 393 clinical samples were collected from pigs on commercial farms in nine different regions of Xinjiang and phylogenetic analysis based on full-length Cap genes was performed. RESULTS: The prevalence at farm level was 100%, while in all the tested samples it was 22.39%. Nine PCV3 strains were detected in Xinjiang province and they shared 98.9-99.3% nucleotide and 97.5-100.0% Cap gene amino acid sequence identities with other epidemic strains from China and abroad. Compared with other epidemic strains of PCV3, there were 26 base mutation sites in the Cap gene in the nine Xinjiang strains, resulting in the mutation of amino acids at positions 20, 24, 75, 77, 108, 111 and 206. Phylogenetic analysis showed that these strains can be divided into two different genetic groups, to the first of which five strains affiliated and divided between subgroups 1.1 and 1.2, and to the second of which the other four strains affiliated and similarly divided between subgroups 2.1 and 2.2. CONCLUSION: PCV3 circulates widely among commercial pig farms in Xinjiang province, China, and displays obvious genetic diversity. The results provide epidemiological information useful for the prevention and control of PCV3 infection in the pig industry.

Impact of rli87 gene deletion on response of Listeria monocytogenes to environmental stress.

Listeria monocytogenes (LM) is a zoonotic pathogen that widely adapts to various environments. Recent studies have found that noncoding RNAs (ncRNAs) play regulatory roles in LM responses to environmental stress. To understand the role of ncRNA rli87 in the response regulation, a rli87 deletion strain LM-Δrli87 was constructed by homologous recombination and tested for stress responses to high temperature, low temperature, high osmotic pressure, alcohol, acidity, alkaline and oxidative environments, along with LM EGD-e strain (control). The results showed that compared with LM EGD-e, LM-Δrli87 grew faster (P < 0.05) at low temperature (30 °C), high temperature (42 °C), and in alkaline condition (pH = 9), similarly (P > 0.05) in acidic and high osmatic pressure (10% NaCl) conditions. When cultured in medium containing 3.8% ethanol, the growth was not significantly different between the two strains (P > 0.05). When cultured at pH 9, they had similar growth rates in the first 5 h (P > 0.05), but the rates were significantly different after 6 h (P < 0.05). The expression of rsbV, rsbW, hpt, clpP, and ctsR was upregulated in LM-∆rli87 compared with LM EGD-e at pH 9, indicating that the rli87 gene regulated the expression of the five genes in alkaline environment. Our results suggest that the rli87 gene has an important regulatory role in LM's response to temperature (30 and 42 °C), alkaline stresses.