<div>Background: Streptococcus suis is a zoonotic pathogen closely related to the respiratory tract of swine. Paeonol is a traditional Chinese medicine with antibacterial effect. This study demonstrated the effect of paeonol on biofilm formation and the expression of virulence factors of Streptococcus suis.&nbsp; 
 
Methods: The minimum inhibitory concentration (MIC) of paeonol on Streptococcus suis was determined by double dilution method. Crystal violet staining method was used to determine the effect of paeonol on the biofilm formation. The effects of paeonol on the morphology and structure of Streptococcus suis biofilm were observed by field emission scanning electron microscopy (FE-SEM). Real-time quantitative PCR (qRT-PCR) was used to detect the expression levels of Streptococcus suis related virulence factors under sub-MIC (1/4 MIC, 1/8 MIC) paeonol. 
 
Result: The results showed the effect of 1/4 MIC and 1/8 MIC paeonol on biofilm formation and mature biofilm was significant (*P&lt;0.05). Under the action of paeonol, the biofilm structure becomes sparse. qRT-PCR results showed that 1/8 MIC paeonol inhibits bacterial adhesion by up-regulating the expression of mrp virulence genes, thereby inhibiting the formation of Streptococcus suis biofilm.</div>

Effects of Paeonol Sub-inhibitory Concentration on Streptococcus suis Biofilm and Expression of Virulence Genes

To investigate the seroprevalence of Streptococcus&nbsp;suis&nbsp;(S. suis) in Tibetan pigs on Tibetan plateau of China, a total of 454 serum samples were collected from December 2014 to January 2015 and analyzed by enzyme linked immunosorbent assay (ELISA) for Streptococcus antibodies. The seroprevalence was found to be 61.79% (95% CI 55.4-67.9), 57.81% (95% CI 50.5-64.9) and 62.50% (95% CI 35.4-84.8) in Tibetan counties of Nyingchi, Mainling and Gongbo&rsquo;gvamda respectively; and 61.34% (95% CI 54.1-68.2) of females and 59.23 % (95% CI 53.0-65.3) of males were found to be positive for S. suis. These findings suggested a high seroprevalence of S. suis in Tibet pigs triggering a public concern.

Seroprevalence of Streptococcus suis in Tibetan pigs in Tibet, China

<div>Streptococcus suis (S. suis) is a major pathogen causing economic losses to the swine industry. Norfloxacins are usually used at sub-MIC (Minimum Inhibitory Concentration) doses to prevent S. suis infection. This study demonstrates the effect of norfloxacin sub-MIC on biofilm formation and virulence gene expression in S. suis.It was found that 1/4 MIC of norfloxacin increased biofilm formation in S. suis, the biofilms formed contained a higher number of viable bacteria. Additionally, bacterial growth rates were inhibited at 1/2 MIC of norfloxacin. Furthermore, the mRNA level of S. suis virulence gene cps, ef, sly, fpbs, gdh and gapdh increased by real-time PCR, while the virulence gene mrp decreased at 1/4 MIC. In conclusion, Norfloxacin sub-MICs affects biofilm formation and virulence gene expression in S. suis. These findings suggest that investigating the effect of the administration of antibiotics sub-MICs on bacterial biofilms and infection may lead to the development of future antibiotic treatments modalities.</div>

<div>Norfloxacin Sub-Inhibitory Concentration Affects Streptococcus suis Biofilm Formation and Virulence Gene Expression</div>

<div>Background: Among various diseases, respiratory disease is considered a leading cause of mortality in pigs. Streptococcus suis affects respiratory tract and causes pneumonia as an opportunistic pathogen, that impairs animal health and lowers individual and herd performance in swine. Therefore, it becomes important to have an insight of bacterial pneumonia with special reference to Streptococcus suis in pig, so that control measures could be practiced effectively. 
 
Methods: Detailed post mortem examination was carried out on 180 pigs. Bacterial isolation was carried out from 127 (70.55%) lungs samples with pneumonic lesions. Further, suspected colonies of S. suis were subjected to Polymerase Chain Reaction for detection of glutamate dehydrogenase gene. Phylogenetic analysis was carried out for the positive S. suis samples.</div>

<div> 
Results: Bacteria isolated were Pasteurella multocida (34.44%), S. suis (28.89%), E. coli (16.67%), Staphylococcus spp. (14.44%), Klebsiella spp. (3.33%) and Salmonella spp. (2.22%). Out of 26 suspected S. suis colonies subjected to Polymerase Chain Reaction, 17 isolates with amplicon size 688 bp were confirmed to be positive for glutamate dehydrogenase gene. The Phylogenetic analysis of glutamate dehydrogenase gene of S. suis from pigs of Assam showed percent identity above 99% with Germany, Canada and China strain of S. suis.&nbsp;</div>

Molecular Detection and Characterization of Streptococcus suis Isolated from Pneumonic Lungs of Pigs

<div style="text-align: justify;">Brucella spp. is the causative agent of brucellosis, an extremely important disease worldwide. Innate immune cells detect pathogens via repeated cellular patterns (PAMPs) such as the Brucella suis (B. suis) lipopolysaccharide (LPS) coat on Gram-negative bacteria, which act as an important virulence factor of Brucella. B.suis LPS may be an issue for pro-inflammatory cytokine induction such as interleukin-1 (IL-1), interleukin-18 (IL-18) and interleukin-1&acirc; (IL-1&acirc;), which released from immune cells to mediate downstream inflammatory effects. To elucidate the mechanism of how B.suis LPS affects the secretion of IL-1, IL-18 and IL-1&acirc; in macrophages. We identified the up-regulation of caspase-11 in a porcine alveolar macrophages (PAM) cells stimulated with B.suis LPS. Furthermore, specific small interfering RNA (siRNA) targeting caspase-11 effectively inhibited B.suis LPS stimulated IL-1, IL-18 and IL-1&acirc; release from PAM. The results indicated that the concentrations of IL-1, IL-18 and IL-1&acirc; of caspase-11 siRNA pretreated group were lower than that of control significantly. Caspase-11 plays an important role in IL-1, IL-18 and IL-1&acirc; secretion from porcine alveolar macrophage cells stimulated with Brucella suis LPS, and these findings might aid our understanding of the pathogenic mechanisms of Brucella and provide an entirely new innate immune response mechanism underlying macrophages dysfunction during Brucella infection.</div>

Caspase-11 plays an important role in IL-1, IL-18 and IL-1&acirc; secretion from porcine alveolar macrophage cells stimulated with Brucella suis LPS

<div style="text-align: justify;">Skin diseases can have an adverse impact on the production in a swine herd by causing decrease in growth rate and feed efficiency. Sarcoptes scabiei var. suis is one of the most common causes of mange in domestic and wild pigs. Keeping this point in view, a study on seroprevalence and dermatopathology of Sarcoptes scabiei var. suis infestation in the pig population of Tripura has been undertaken. The presence of anti Sarcoptes antibodies (Immunoglobulin G) was detected by commercially available kit. In the present study, 189 pigs (11.81%) were found to be seropositive against Sarcoptes scabiei infestation out of 1600 screened pigs. Thirty one pigs out of 189 were found to be clinically positive and confirmed by microscopic examination. Examination of the skin scraping revealed various developmental stages viz., egg, larva, protonymph and adult of Sarcoptes mite. Occurrence of sarcoptic mange was found to be highest in young age group (67.72%, 128/189), male pigs (56.08%, 106/189) and Large White Yorkshire breed (47.08%). The highest and lowest occurrence of sarcoptic mange was noticed in winter (41.27%) and monsoon (7.94%) season, respectively. Clinical lesions were distributed most commonly in ear pinna (87.10%, 27/31) region. The presence of anti Sarcoptes antibodies was found to be highest in pigs having severe generalized skin lesions (70.0%). Histopathology of skin biopsy revealed a tunnel like ulcerated lesion in the skin with severe inflammatory cell infiltration in the core. The present study shows the high seroprevalence of Sarcoptes scabiei var. suis in pigs in Tripura state and recommends for proper control measures. However, epidemiological studies involving larger population are required for comprehensive results.</div>

<div style="text-align: justify;">Seroprevalence and Dermatopathology of Sarcoptes scabiei var. suis Infestation in Pigs</div>

<div>Background: Bovine mastitis is a multifactorial and is one of the most challenging disease. It can be caused by many different bacterial species, the most common of which are Staphylococcus species and Streptococcus species. The prevalence of different species varies temporally, geographically and also due to control measures adopted in herds. The present study is on the biofilm forming Streptococcus uberis causing mastitis and the effect of antibiofilm agents on the antimicrobial resistance of the microorganisms.&nbsp; 
 
Methods: The isolates were identified by Polymerase chain reaction (PCR). Two antibiofilm agents, resveratrol and ursolic acid (UA) each at two concentrations (30 &mu;g/ml, 100 &mu;g/ml) were used for the study. Biofilm formation and rate of biofilm inhibition was detected using quantitative microtiter plate (MTP) assay and biofilm gene (lux S) was detected using PCR. The isolates treated with antibiofilm agents were subjected to standard disc diffusion test with 7 antibiotics and the change in antibiotic resistance was studied.&nbsp; 
 
Result: The mean&plusmn;SE values of inhibition rates of 29 S. uberis isolates by 30 &mu;g/ml UA, 100 &mu;g/ml UA, 30 &mu;g/ml resveratrol, 100 &mu;g/ml resveratrol were 33.96&plusmn;3.17%, 57.40&plusmn;2.8%, 31.35&plusmn;3.12% and 46.28&plusmn;3.47%, respectively. Biofilm inhibiting agents along with all antibiotics had reduced antimicrobial resistance by 1.5-2 times on in vitro antibiotic resistance testing by disc diffusion at 100 &mu;g/ml concentration. The antibiofilm agents were found to be very effective to control antibiotic resistance of S. uberis from mastitic milk samples in vitro.</div>

​Efficacy of Resveratrol and Ursolic Acid on Biofilm Inhibition and Antimicrobial Resistance of Streptococcus uberis

<div>Background: Streptococcus uberis (S. uberis) is an environmental pathogen causing mastitis in Dairy cattle. It causes recurrent mastitis and reduction in milk production in livestock causing economic loss. The prevalence of S. uberis intramammary infections is due to ability of the organism to form biofilm in udder tissue. The present study is on in-vitro biofilm production, the correlation of luxS gene and the biofilm formation in S. uberis.&nbsp; 
 
Methods: A total of 91 mastitic milk samples were collected from cattle and buffaloes brought at Veterinary Hospitals and farms in Krishna, Guntur and West Godavari districts, Andhra Pradesh. The identification of the culture isolates was based on cultural and biochemical characteristics and confirmed by Polymerase Chain Reaction (PCR). The Streptococcus species cultures showing greyish, pinpointed colonies and/or aesculin hydrolysis on Edwards medium were further identified by various biochemical tests viz., catalase test, ninhydrin test, sodium hippurate hydrolysis test and type of haemolysis on 7% sheep blood agar. Confirmation of the isolates by PCR was followed by detection of biofilm formation using qualitative Congo red agar (CRA) method, quantitative microtiter plate (MTP) assay and biofilm gene (luxS) was detected using PCR. 
 
Conclusion: From this study it is suggestable that for biofilm study both phenotypic and genotypic methods should be taken together which can be influenced by various other factors also. MTP assay was a good choice for quantitative biofilm determination, which was giving a more accurate and understandable results. The results express that any of the isolates without luxS didn&rsquo;t produce a strong biofilm and it is concluded that there may be other genes for regulation of biofilm production and/or luxS gene has a regulatory role for one or more genes related to biofilm formation in S. uberis.</div>

<div>luxS Gene and Biofilm Formation in Streptococcus uberis Isolated from Bovine Mastitis Cases</div>

<div>Background:&nbsp;The major mastitis-producing organisms are Staphylococcus aureus, Streptococcus agalactiae, Streptococcus dysgalactiae, Streptococcus uberis and Escherichia coli. Molecular characterization of the major bacterial pathogens for some genes responsible for their virulence should be considered the reduction of risk factors responsible for the presence and spread of contagious pathogens through milk. 
 
Methods: The two hundred milk samples were collected from cows and buffaloes of four different tehsils of the Sirohi district of Southern Rajasthan. Out of 200 milk samples, 74 milk samples that were found positive for SCM were cultured for primary isolation of predominant bacterial pathogens. Out of these 74 positive samples, total of 97 isolates were recovered from these milk samples either as a single or mixed infection. To genotypically characterize&nbsp;S. aureus&nbsp;isolates, genes encoding virulence determinants (spa-IgG-binding and Coa), Staphylococ cal enterotoxins (bac and bca) and E. coli Shiga toxins (stx1 and stx2) were investigated. 
 
Result: The etiological prevalence of SCM caused by different bacteria was,&nbsp;S. aureus, (27%),&nbsp;Streptococcus spp. (15%) and E. coli (6.5%) respectively either as single and or as mixed infections. All S. aureus isolates were tested by PCR for the presence of the spa gene and coa gene results revealed that 40 isolates (74.0%) carried both spa (IgG-binding) and coa gene. 11 isolates of S. agalactiae (36.6%) carried the bca gene. The bca gene codes for Alpha-C protein, a surface protein that helps the bacteria to enter the host cells. E. coli isolates were also screened for the presence of virulence gene stx1&nbsp;and stx2 gene. Out of 13 isolates tested, 6 isolates harboured both stx1 and stx2 genes.</div>

Analysis of Virulence Genes of Staphylococcus aureus, Streptococcus, E. coli Isolated from Bovine Subclinical Mastitis

<div>Bovine mastitis is one of the common diseases resulting in high economic losses in the dairy industry. Streptococcus uberis, the environmental or contagious pathogen, is one of the most frequently identified bacteria causing clinical and subclinical mastitis. Antimicrobials are commonly used to control bacterial infections in dairy cattle. The emergence of antimicrobial resistance (AMR) bacteria made the treatment of this disease by antimicrobials a challenge. Currently, AMR is a global threat to both human and animal health. This review summarizes the AMR profiles of S. uberis collected worldwide between the years 2000-2020. Most of the studies included in this review were from Europe, Estonia, Canada, Danish, Switzerland and Czech. In general, S. uberis is highly susceptible to &beta;-lactam antimicrobials, whereas resistance to tetracyclines, macrolides, aminoglycosides antimicrobials occurred in most countries. The isolates against most antimicrobials presented an increasing pattern over time. It highlights that monitoring the AMR of S. uberis is crucial to reduce the public health crisis.</div>

Effects of Paeonol Sub-inhibitory Concentration on Streptococcus suis Biofilm and Expression of Virulence Genes

Seroprevalence of Streptococcus suis in Tibetan pigs in Tibet, China

Norfloxacin Sub-Inhibitory Concentration Affects Streptococcus suis Biofilm Formation and Virulence Gene Expression

Molecular Detection and Characterization of Streptococcus suis Isolated from Pneumonic Lungs of Pigs

Caspase-11 plays an important role in IL-1, IL-18 and IL-1â secretion from porcine alveolar macrophage cells stimulated with Brucella suis LPS

Seroprevalence and Dermatopathology of Sarcoptes scabiei var. suis Infestation in Pigs

Efficacy of Resveratrol and Ursolic Acid on Biofilm Inhibition and Antimicrobial Resistance of Streptococcus uberis

luxS Gene and Biofilm Formation in Streptococcus uberis Isolated from Bovine Mastitis Cases

Analysis of Virulence Genes of Staphylococcus aureus, Streptococcus, E. coli Isolated from Bovine Subclinical Mastitis

Antimicrobial Resistance of Streptococcus uberis Isolated from Bovine Mastitis: A Review