Analysis of the spike, ORF3, and nucleocapsid genes of porcine epidemic diarrhea virus circulating on Thai swine farms, 2011–2016

Porcine epidemic diarrhea virus (PEDV) outbreaks on pig farms have caused significant economic loss in the swine industry since it was first reported in Thailand a decade ago. Anecdotal evidence suggests that PEDV is now endemic in this region, therefore genome information of circulating PEDV is important for molecular surveillance and evaluation of potential benefits of field vaccination. Here, we characterized PEDV infection on commercial Thai swine farms by screening 769 samples of feces and small intestinal contents from pigs with diarrhea between 2011 and 2016. Using reverse-transcription polymerase chain reaction targeting the spike (S) gene, 153 PEDV-positive samples were further subjected to analysis of the open reading frame 3 and nucleocapsid (N) genes. Comparison of 95 samples in which nucleotide sequencing was successfully obtained for all three genes revealed evolutionary diversity among the Thai PEDV strains. Phylogenetic analyses suggest that although some Thai strains changed little from years past, others resembled more closely to the recent strains reported in China. Interestingly, eight Thai PEDV strains possessed amino acid deletions in the N protein. The PEDV sequence divergence may be responsible for driving periodic outbreaks and continued persistence of PEDV on commercial swine farms. Our findings provide important insight into regional PEDV strains in circulation, which may assist future inclusions of suitable strains for future PEDV vaccines

Environmental survival, role of exoprotein ApxIV and live vaccination studies with Actinobacillus pleuropneumoniae

EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Effect of on growth performance, diarrhea incidence, fecal bacterial population and intestinal morphology of suckling pigs challenged with F4 enterotoxigenic

Objective Gut health improvements were monitored with respect to growth performance, diarrhea incidence, fecal bacterial population and intestinal morphology of suckling pigs orally supplemented with live Lactobacillus salivarius (L. salivarius) oral suspensions and challenged with F4+ enterotoxigenic Escherichia coli (ETEC). Methods Two groups of newborn pigs from 18 multiparous sows were randomly designated as non-supplemented (control: n = 114 piglets) and L. salivarius supplemented groups (treatment: n = 87 piglets). Treatment pigs were orally administered with 2 mL of 109 colony-forming unit (CFU)/mL L. salivarius on days 1 to 3, then they were orally administered with 5 mL of 109 CFU/mL L. salivarius on days 4 to 10, while those in control group received an equal amount of phosphate buffered saline solution. On day 24 (2 weeks post supplementation), one pig per replicate of both groups was orally administered with 108 CFU/mL F4+ ETEC, then they were euthanized on day 29 of experiment. Results Results revealed that pigs in treatment group had a statistically significant increase in average daily gain, body weight and weight gain, and tended to lower diarrhea throughout the study. Numbers of Lactobacillus population in feces of treatment pigs were higher than control pigs, especially on day 10 of study. Numbers of total bacteria in intestinal contents of control pigs were also increased, but not Coliform and Lactobacillus populations. Histological examination revealed statistically significant improvements of villous height and villous/crypt ratio of duodenum, proximal jejunum and distal jejunum parts of treatment pigs compared with controls. Duodenal pH of treatment group was significantly decreased. Conclusion Oral supplementation of live L. salivarius during the first 10 days of suckling pig promoted growth performance and gut health, reduced diarrhea incidence, increased fecal Lactobacillus populations and improved intestinal morphology

Effect of on growth performance, diarrhea incidence, fecal bacterial population and intestinal morphology of suckling pigs challenged with F4 enterotoxigenic

Objective Gut health improvements were monitored with respect to growth performance, diarrhea incidence, fecal bacterial population and intestinal morphology of suckling pigs orally supplemented with live Lactobacillus salivarius (L. salivarius) oral suspensions and challenged with F4+ enterotoxigenic Escherichia coli (ETEC). Methods Two groups of newborn pigs from 18 multiparous sows were randomly designated as non-supplemented (control: n = 114 piglets) and L. salivarius supplemented groups (treatment: n = 87 piglets). Treatment pigs were orally administered with 2 mL of 109 colony-forming unit (CFU)/mL L. salivarius on days 1 to 3, then they were orally administered with 5 mL of 109 CFU/mL L. salivarius on days 4 to 10, while those in control group received an equal amount of phosphate buffered saline solution. On day 24 (2 weeks post supplementation), one pig per replicate of both groups was orally administered with 108 CFU/mL F4+ ETEC, then they were euthanized on day 29 of experiment. Results Results revealed that pigs in treatment group had a statistically significant increase in average daily gain, body weight and weight gain, and tended to lower diarrhea throughout the study. Numbers of Lactobacillus population in feces of treatment pigs were higher than control pigs, especially on day 10 of study. Numbers of total bacteria in intestinal contents of control pigs were also increased, but not Coliform and Lactobacillus populations. Histological examination revealed statistically significant improvements of villous height and villous/crypt ratio of duodenum, proximal jejunum and distal jejunum parts of treatment pigs compared with controls. Duodenal pH of treatment group was significantly decreased. Conclusion Oral supplementation of live L. salivarius during the first 10 days of suckling pig promoted growth performance and gut health, reduced diarrhea incidence, increased fecal Lactobacillus populations and improved intestinal morphology

Antimicrobial Susceptibility of <i>Streptococcus suis</i> Isolated from Diseased Pigs in Thailand, 2018–2020

Streptococcus suis is a porcine and zoonotic pathogen that causes severe systemic infection in humans and pigs. The treatment of S. suis infection relies on antibiotics; however, antimicrobial resistance (AMR) is an urgent global problem, pushing research attention on the surveillance of antibiotic-resistant S. suis to the fore. This study investigated the antimicrobial susceptibility of 246 S. suis strains isolated from diseased pigs in Thailand from 2018–2020. The major sources of S. suis strains were lung and brain tissues. PCR-based serotyping demonstrated that the most abundant serotype was serotype 2 or ½, followed by serotypes 29, 8, 9, and 21. To the best of our knowledge, this is the first report describing the distribution of AMR S. suis serotype 29 in diseased pigs. The antimicrobial susceptibility test was performed to determine the minimum inhibitory concentrations of 35 antimicrobial agents. The results showed that important antimicrobial agents for human use, amoxicillin/clavulanic acid, daptomycin, ertapenem, meropenem, and vancomycin, were the most effective drugs. However, a slight decrease in the number of S. suis strains susceptible to amoxicillin/clavulanic acid and vancomycin raised awareness of the AMR problem in the future. The data indicated a tendency of reduced efficacy of available veterinary medicines, including ampicillin, cefepime, cefotaxime, ceftiofur, ceftriaxone, chloramphenicol, florfenicol, gentamicin, penicillin, and tiamulin, for the treatment of S. suis infection, thus emphasizing the importance of the prudent use of antibiotics. The widespread of multidrug-resistant S. suis strains was identified in all serotypes and from different time periods and different regions of the country, confirming the emergence of the AMR problem in the diseased pig-isolated S. suis population

Relationship between Penicillin-Binding Proteins Alterations and β-Lactams Non-Susceptibility of Diseased Pig-Isolated <i>Streptococcus suis</i>

Streptococcus suis is a zoonotic pathogen causing disease in both animals and humans, and the emergence of increasingly resistant bacteria to antimicrobial agents has become a significant challenge globally. The objective of this study was to investigate the genetic basis for declining susceptibility to penicillin and other β-lactams among S. suis. Antimicrobial susceptibility testing and penicillin-binding proteins (PBP1a, PBP2a, PBP2b, and PBP2x) sequence analysis were performed on 225 S. suis isolated from diseased pigs. This study found that a growing trend of isolates displayed reduced susceptibility to β-lactams including penicillin, ampicillin, amoxicillin/clavulanic acid, and cephalosporins. A total of 342 substitutions within the transpeptidase domain of four PBPs were identified, of which 18 substitutions were most statistically associated with reduced β-lactams susceptibility. Almost all the S. suis isolates which exhibited penicillin-non-susceptible phenotype (71.9%) had single nucleotide polymorphisms, leading to alterations of PBP1a (P409T) and PBP2a (T584A and H588Y). The isolates may manifest a higher level of penicillin resistance by additional mutation of M341I in the 339STMK active site motif of PBP2x. The ampicillin-non-susceptible isolates shared the mutations in PBP1a (P409T) and PBP2a (T584A and H588Y) with additional alterations of PBP2b (T625R) and PBP2x (T467S). The substitutions, including PBP1a (M587S/T), PBP2a (M433T), PBP2b (I428L), and PBP2x (Q405E/K/L), appeared to play significant roles in mediating the reduction in amoxicillin/clavulanic acid susceptibility. Among the cephalosporins, specific mutations strongly associated with the decrease in cephalosporins susceptibility were observed for ceftiofur: PBP1a (S477D/G), PBP2a (E549Q and A568S), PBP2b (T625R), and PBP2x (Q453H). It is concluded that there was genetically widespread presence of PBPs substitutions associated with reduced susceptibility to β-lactam antibiotics