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.     

石油降解混合菌剂的筛选及降解条件研究

为了获得石油高效降解混合菌剂及优化的降解条件,从油污土壤、含油废水及原油中经富集驯化分离得到细菌68株、真菌15株,放线菌6株;将所分离的菌株通过初筛、复筛及两两混合拮抗实验,筛选得到Y-4与Y-12及Y-4与Y-37两组石油高效降解混合菌剂,其对石油的降解率均超过60%。同时研究了不同的初始条件对各混合菌剂降解率的影响。结果表明,Y-4与Y-12组合在初始pH 8.0、转速160 r/min、种子液以1:1接种0.5 mL、30~35℃培养7天,Y-4与Y-37组合在初始pH 7.5、转速130~160 r/min、种子液以1:1接种0.5 mL、35℃培养7天,加入的初始原油量越少,基质营养越丰富,其降解率越高。通过实验可知,在适宜的条件下2种混合菌剂的降解率均较高,并且混合菌剂对石油的降解率要高于单菌剂。     

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.