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ABSTRACT. Streptococcus suis (S. suis) is an emerging zoonotic pathogen causing significant economic losses in the swine industry. Here, we investigated the antimicrobial susceptibility, associated antibiotic-resistant determinants and sequence type (ST) of S. suis isolates from diseased pigs in China from 2008 to 2010. Serotype 2 was the most frequently observed strain (n=95) among the 106 S. suis strains collected, followed by serotypes 3 (n=3), 5 (n=3), 4 (n=2), 7 (n=1), 11 (n=1) and 28 (n=1). Multilocus sequence typing analysis revealed that ST1 (n=21) and ST7 (n=74) were the predominant STs, and serotype 2 was found to be significantly correlated with ST7 (P=0.017, Fisher's exact test) and CC1 (P=0.024, Fisher's exact test). The antimicrobial susceptibility results indicated that the antibiotic resistance rate was highest for tetracycline (99.1%), followed by azithromycin (68.9%), erythromycin (67.9%), clindamycin (67.9%), trimethoprim/ sulfamethoxazole (16%), levofloxacin (2.8%), chloramphenicol (1.9%), cefaclor (0.9%) and ceftriaxone (0.9%). Antibiotic-resistant genes tet(40), erm(B), mef(A/E) and msr(D) could be detected, and several tandem organizations of antibiotic resistance genes were also found in this study. In conclusion, S. suis strains isolated from diseased pigs in China were less diverse and multi-drug resistant. Streptococcus suis, an emerging zoonotic pathogen, can cause infections of both pigs, and occasionally, human beings; such infections include meningitis, septicemia, pneumonia, endocarditis and arthritis [14,20]. Thirty-three serotypes (types 1-31, 33 and 1/2) have been described based on capsular polysaccharides, and serotype 2 is considered to be the most pathogenic as well as the most prevalent capsular type in diseased pigs. Control of the disease by antimicrobials has generally been ineffective, partly because of increased resistance by S. suis to antimicrobials.Tetracycline and erythromycin are two antimicrobials that are extensively used for therapy, prophylaxis and growth promotion, and subsequently, associated resistance has been widely reported at a high rate in S. suis strains isolated from pigs and human beings [3,10,18]. However, mechanisms, which contribute to the tetracycline and macrolide resistance in Chinese S. suis strains, are still poorly understood. Besides, although several approaches have been used to characterize S. suis isolates from diseased pigs in limited geographic regions in China [13,22], knowledge about the current epidemiological status of S. suis in Chin is still limited. Therefore, in this study, we investigated the antimicrobial resistance patterns, tetracycline and erythromycin resistance genes, Serotypes and STs of S. suis isolated from diseased pigs in central and eastern regions of China. MATERIALS AND METHODS Bacterial strains and antimicrobial susceptibilities:All strains (n=106) used in this study were obtained from samples of different tissues (lung, brain, joint, heart and blood) isolated from diseased pigs from 14 provinces in central an...

Streptococcus suis serotype 2 (SS2) infection is a major cause of sudden death in pigs and is of concern for humans as it has strong zoonotic capabilities. Developing novel effective vaccines would be beneficial to control SS2 infection. HP0272 is a novel immunogenic surface protein; its protective efficacy remains to be evaluated. The present mouse model found that the purified recombinant HP0272 could elicit a significant humoral antibody response, and to confer complete protection against a lethal dose of SS2 infection. In addition, real-time PCR confirmed that in vivo-induced antigen existed in most SS2 field pathogenic strains, and in half of all reference strains of different serotypes of S. suis. The results indicate that HP0272 has the potential as an effective component of a new vaccine.

It remains an unsolved problem to quantify a natural microbial community by rapidly and conveniently measuring multiple species with functional significance. Most widely used high throughput next-generation sequencing methods can only generate information mainly for genus-level taxonomic identification and quantification, and detection of multiple species in a complex microbial community is still heavily dependent on approaches based on near full-length ribosome RNA gene or genome sequence information. In this study, we used near full-length rRNA gene library sequencing plus Primer-Blast to design species-specific primers based on whole microbial genome sequences. The primers were intended to be specific at the species level within relevant microbial communities, i.e., a defined genomics background. The primers were tested with samples collected from the Daqu (also called fermentation starters) and pit mud of a traditional Chinese liquor production plant. Sixteen pairs of primers were found to be suitable for identification of individual species. Among them, seven pairs were chosen to measure the abundance of microbial species through quantitative PCR. The combination of near full-length ribosome RNA gene library sequencing and Primer-Blast may represent a broadly useful protocol to quantify multiple species in complex microbial population samples with species-specific primers.

This paper proposes the combination of headspace-gas chromatography-ion mobility spectrometry (HS-GC-IMS) and chemometrics as a method to detect the age of Chinese liquor (Baijiu). Headspace conditions were optimized through single-factor optimization experiments. The optimal sample preparation involved diluting Baijiu with saturated brine to 15% alcohol by volume. The sample was equilibrated at 70 °C for 30 min, and then analyzed with 200 μL of headspace gas. A total of 39 Baijiu samples from different vintages (1998–2019) were collected directly from pottery jars and analyzed using HS-GC-IMS. Partial least squares regression (PLSR) analysis was used to establish two discriminant models based on the 212 signal peaks and the 93 identified compounds. Although both models were valid, the model based on the 93 identified compounds discriminated the ages of the samples more accurately according to the goodness of fit value (R2) and the root mean square error of prediction (RMSEP), which were 0.9986 and 0.244, respectively. Nineteen compounds with variable importance for prediction (VIP) scores > 1, including 11 esters, 4 alcohols, and 4 aldehydes, played vital roles in the model established by the 93 identified compounds. Overall, we determined that HS-GC-IMS combined with PLSR could serve as a rapid and accurate method for detecting the age of Baijiu.