Distribution,quantitative load and characterization of Salmonella associated with swine farms in upper-northern Thailand

This study was conducted to analyze the prevalence and quantitative loads of Salmonella spp. on pig farms in Chiang Mai, Lamphun, Thailand to assess loading levels before slaughtering. The serotype diversity, antimicrobial-resistance pattern and pulse-field type of Salmonella spp. were also characterized to assess the dynamic propagation of the pathogen. The Salmonella-positive prevalence was 246/805 (30.56%), and the quantitative loads varied from 1.48~4.04 Log₁₀MPN/g, with a mean ± standard deviation of 2.11 ± 0.57. AMP/S/TE (ampicillin/streptomycin/tetracycline) was the highest frequency antimicrobial resistance pattern found in this study. In addition, Salmonella Rissen was the primary serotype in this region. PFGE results indicated the occurrence of infection by cross contamination among pig farms. Our study showed that pork is easily contaminated with this pathogen. Farm control programs must be based on strict biosecurity and hygienic measures, which could further reduce the contamination pressure at slaughterhouses or retail shops.     

Occurrence and characterization of livestock-associated methicillin-resistant Staphylococcus aureus in pig industries of northern Thailand

This study was conducted to determine the prevalence of livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) in pigs, farm workers, and the environment in northern Thailand, and to assess LA-MRSA isolate phenotypic characteristics. One hundred and four pig farms were randomly selected from the 21,152 in Chiang Mai and Lamphun provinces in 2012. Nasal and skin swab samples were collected from pigs and farm workers. Environmental swabs (pig stable floor, faucet, and feeder) were also collected. MRSA was identified by conventional bacterial culture technique, with results confirmed by multiplex PCR and multi locus sequence typing (MLST). Herd prevalence of MRSA was 9.61% (10 of 104 farms). Among pigs, workers, and farm environments, prevalence was 0.68% (two of 292 samples), 2.53% (seven of 276 samples), and 1.28% (four of 312 samples), respectively. Thirteen MRSA isolates (seven from workers, four from environmental samples, and two from pigs) were identified as Staphylococcal chromosomal cassette mec IV sequences type 9. Antimicrobial sensitivity tests found 100% of the MRSA isolates resistant to clindamycin, oxytetracycline, and tetracycline, while 100% were susceptible to cloxacillin and vancomycin. All possessed a multidrug-resistant phenotype. This is the first evidence of an LA-MRSA interrelationship among pigs, workers, and the farm environment in Thailand.     

Antimicrobial resistance and genotypic characterization of coagulase-negative staphylococci over the dry period

Coagulase-negative staphylococci (CNS) have become the most frequently isolated organisms from bovine intramammary infections in recent years. While antimicrobial resistance (AR) is not considered a major problem among mastitis pathogens, concerns over emerging AR in general are increasing worldwide. Little information exists about the association between AR and one of the most common mastitis control measures, antibiotic dry cow therapy. The primary objective of the current study was to determine the prevalence of AR in CNS isolated before and after antimicrobial dry cow therapy. An additional objective was to genotypically characterize selected CNS isolates using pulsed-field gel electrophoresis (PFGE), to assess diversity and persistence of organisms over the dry period. Resistance against 10 antimicrobials was determined using a broth microdilution method and compared between CNS isolates collected at dry-off and at calving and from cows treated or not treated with intramammary antimicrobial products at dry-off (752 cows in total). Results suggested that increasing age of a cow and dry cow treatment when combined with high milk somatic cell count at dry-off and positive clinical mastitis history, were associated with increased AR to most beta-lactam antimicrobials and sulfadimethoxine. PFGE results suggested considerable diversity among the tested isolates as well as some clusters within cows and herds. PFGE would be useful in distinguishing between potentially persisting infections and cures and reinfections with different CNS strains.     

Comparison of Campylobacter contamination levels on chicken carcasses between modern and traditional types of slaughtering facilities in Malaysia

A total of 360 samples including fresh fecal droppings, neck skins, and swab samples was collected from 24 broiler flocks and processed by 12 modern processing plants in 6 states in Malaysia. Ninety samples from 10 traditional wet markets located in the same states as modern processing plants were also collected. Microbiological isolation for Campylobacter was performed following ISO 10272-1:2006 (E). The overall rate of contamination for Campylobacter in modern processing plants and in traditional wet markets was 61.1% (220/360) and 85.6% (77/90), respectively. Campylobacter jejuni was detected as the majority with approximately 70% for both facilities. In the modern processing plants, the contamination rate for Campylobacter gradually declined from 80.6% before the inside-outside washing to 62.5% after inside-outside washing and to 38.9% after the post chilling step. The contamination rate for Campylobacter from processed chicken neck skin in traditional wet markets (93.3%) was significantly (P<0.01) higher than in modern processing plants (38.9%).     

An allelopathic substance isolated from Zanthoxylum limonella Alston fruit

Bioassay-guided fractionation of the ethyl acetate extract of the Zanthoxylum limonella Alston fruits led to the isolation of a phenolic compound named xanthoxyline. The allelopathic effects of xanthoxyline were evaluated on Chinese amaranth (Amaranthus tricolor L.) and Barnyardgrass (Echinochloa crus-galli (L.) Beauv.) under laboratory conditions. At a concentration of 2500 μM, xanthoxyline completely inhibited seed germination and growth of Chinese amaranth, while this compound showed a significantly inhibitory effect on seed germination of Barnyardgrass by 43.59% and inhibited shoot and root length by 71.56% and 87.48%, respectively. To determine the mechanism through which xanthoxyline exerts its toxicity, the cytogenetic bioassay was conducted. Roots of Allium cepa L. (onion) were treated with a series of concentrations, ranging from 15.625 to 125 μM for 18 h. Cytogenetic studies of onion roots showed a decrease of the mitotic index in the exposed roots dependent on the concentration of xanthoxyline. Likewise, the mitotic phase index was altered in onion incubated with xanthoxyline. Analyses of the abbreviation types showed spindle disturbances at late prophase, sticky metaphase, c-mitosis, non-oriented chromosome at metaphase, sticky anaphase, delayed anaphase and diagonal at telophase for the onion roots exposed to xanthoxyline.     

A Cross‐Sectional Study of Hepatitis E Virus Infection in Healthy People Directly Exposed and Unexposed to Pigs in a Rural Community in Northern Thailand

A cross‐sectional study of the association between occupational pig exposure and hepatitis E virus (HEV) infection in adult pig farmers and the general population who were not directly exposed to pigs was conducted in Nan Province, Thailand, from November 2010 to April 2011. All participants were interviewed to provide information on their job history, eating habits and other potential confounders. The prevalence of anti‐HEV immunoglobulin G antibodies (IgG) among 513 subjects was 23.0%. Hand washing with water and soap was associated with a lower seroprevalence of HEV infection, whereas living in an area with frequent flooding (OR 1.64, 95% CI: 1.00–2.68) and consuming internal pig organs more than twice per week (OR 3.23, 95%CI: 1.15–9.01) were both associated with a higher seroprevalence of anti‐HEV IgG. There was no association between HEV seroprevalence and frequent, direct occupational pig contact.     

Effect of atorvastatin on oxidative stress and inflammation markers in myxomatous mitral valve disease in dogs: A comparison of subclinical and clinical stages

Myxomatous mitral valve disease (MMVD) is the most common acquired cardiac disorder found in dogs. The disease process can lead to heart failure (HF) and has been found to be associated with oxidative stress and inflammation. Statins exert antioxidant and anti‐inflammatory effects in human HF patients. However, the beneficial effects of statins in MMVD dogs are still unclear. Thirty MMVD dogs were enrolled in the study and were divided into two groups: MMVD without HF dogs (n = 15) and MMVD with HF dogs (n = 15). Atorvastatin (8 mg kg^?1 day^?1) was administered orally to all dogs for 4 weeks. All dogs underwent physical examination and cardiac examination at the beginning and end of the experiment, including baseline values for hematology, blood chemistry profile, lipid profile, N‐terminal pro B‐type natriuretic peptide, oxidative stress marker (8‐isoprostane), and inflammatory marker (tumor necrosis factor alpha). The results showed that atorvastatin reduced plasma cholesterol levels in both groups. In addition, plasma concentrations of 8‐isoprostane, tumor necrosis factor alpha, and N‐terminal pro B‐type natriuretic peptide were significantly lower after atorvastatin administration, but only in MMVD dogs in the HF group. Atorvastatin found to be associated with possible antioxidant and inflammatory effects in dogs with HF secondary to MMVD. The potential benefits of statins in dogs with HF merits further investigation in larger, placebo‐controlled studies.     

Quantification and rep‐PCR characterization of Salmonella spp. in retail meats and hospital patients in Northern Thailand

Human salmonellosis is a major public health problem worldwide. Infections can pass to humans by contact with contaminated substances in the food chain. This study aimed to determine the prevalence and contamination levels of Salmonella isolated from pork, chicken and beef sold in different types of retail stores in Chiang Mai and Lamphun provinces and to investigate the genetic relatedness among Salmonella isolates in food chains in that area. A total of 360 meat samples from supermarkets, mini‐grocery stores and fresh markets were obtained. Salmonella Rissen and S. Weltevreden were found in all meat sample types and in human cases. The overall prevalence of Salmonella in the chicken, pork and beef samples was 34.17%, 32.50% and 3.33%, respectively. Quantitatively, Salmonella contamination was highest in pork (1.24 log₁₀MPN/g), followed by chicken (1.08 log₁₀MPN/g), and beef (0.75 log₁₀MPN/g). The highest frequency of Salmonella contamination was found at the fresh markets (85.71%), whereas the highest quantity of contamination level was from mini‐grocery stores (1.27 log₁₀MPN/g). The rep‐PCR analysis results revealed that some of the Salmonella from meat samples and human cases were identical clones.