Pawin Padungtod

Campylobacter in Food Animals and Humans in Northern Thailand

Cross-sectional, longitudinal, and case-control studies were conducted to describe the epidemiology of Campylobacter in chickens, swine, dairy cows, farm workers, nonfarm residents, and children with diarrhea. Samples were collected in Chiang Mai and Lamphung provinces of northern Thailand from 2000 through 2003. A total of 2,360 samples were processed. Results from the cross-sectional study indicated that the prevalences of Campylobacter in chickens at the farm, slaughterhouse, and market were 64, 38, and 47%, respectively. In swine, the prevalences at the farm, slaughterhouse, and market were 73, 69, and 23%, respectively. Campylobacter prevalence was 14% in dairy cows and 5% in raw milk. The prevalence of Campylobacter on farms was lower in environmental samples than in samples collected from live animals. No Campylobacter isolates were obtained from healthy nonfarm residents, but isolates were obtained from 5 and 18% of farm workers and children with diarrhea, respectively. The prevalence of Campylobacter in pigs in the longitudinal study was 61% at the farm, 46% at the slaughterhouse, and 33% at the market. The majority of Campylobacter isolates from chickens (52%), swine (98%), and farm workers (66%) were Campylobacter coli, whereas the majority of isolates from dairy cows (63%) and children with diarrhea (62%) were Campylobacter jejuni. Most Campylobacter isolates from diarrheal children had single-strand conformation polymorphism profiles similar to those of isolates from chickens. None of the risk factors for infection in children with diarrhea were significantly associated with the isolation of Campylobacter.

Serotypes, Antimicrobial Susceptibility, and gyr A Gene Mutation of Campylobacter jejuni Isolates from Humans and Chickens in Thailand

In Thailand, 51% (36/70) Campylobacter jejuni isolates from humans and 68% (47/69) isolates from poultry were classified into 10 Penner serotypes (serotype B, C, R, E, G, A, K, D, I, and L) and 9 serotypes (serotype A, C, I, K, B, E, S, D, and L), respectively. The rate of antimicrobial drug resistance to nalidixic acid, ciprofloxacin, ampicillin, tetracycline, and erythromycin shown by human isolates were 96%, 96%, 29%, 57%, and 14%, while that shown by poultry isolates were 77%, 77%, 22%, 26%, and 17%, respectively. All quinolone‐resistant strains contained a mutation in the gyrA gene (T86→I86), suggesting that the strains were already widespread in Thailand.

A cross-sectional study of Salmonella in pre-slaughter pigs in a production compartment of northern Thailand.

A cross-sectional study was conducted to determine the prevalence of Salmonella and to associate management factors in fattening pigs in a production compartment of northern Thailand. A total of 194 fecal samples and 166 environmental samples were collected from 22 fattening pig herds for isolation and identification of Salmonella. An additional 427 serum samples were collected from the same herds to determine Salmonella antibodies using ELISA. A questionnaire was used to collect management factors likely to be associated with Salmonella identification. Prevalence of Salmonella in each sample and its confidence interval was adjusted for clustering by herds using linearization technique. A generalized estimating equation was used to determine the odds ratio and significance level for each management factor in a logistic regression model. Salmonella was found in all 22 study pig herds with a fecal sample prevalence of 63% (95%CI: 56-69%) and a serum sample prevalence of 72%. However, isolation results were not significantly different from ELISA results. The most isolated serotype was Salmonella Rissen (49%) followed by Salmonella Typhimurium (19%), Salmonella Stanley (12%) and Salmonella Weltevreden (4%) being significantly different in the different specimens collected (p=.024). The final logistic regression model with isolation results as outcome showed that medium herd size (OR=2.32, p=0.003), quality certification according to the Department of Livestock Development standard (OR=1.88, p=0.000), use of effective microorganisms (OR=1.51, p=0.022), slurry waste management (OR=2.17, p=0.000) and less number of pigs per pen (OR=1.12, p=0.000) were significantly associated with positive Salmonella isolation; with positive ELISA results, however, only the use of effective microorganisms was significantly associated (OR=2.63, p=0.011).

Prevalence of Salmonella in retail chicken meat in Hanoi, Vietnam.

Abstract:  Infection with Salmonella (S.) is the most frequently reported cause of bacterial food‐borne illness worldwide. Poultry are a common source and, in recent years, much attention has been focused in determining the prevalence of Salmonella during the different stages in the poultry production chain. This article was designed to investigate the prevalence of Salmonella serovars in retail chicken meat sold in Hanoi. A total of 262 samples were randomly collected from retail markets and examined for the presence of Salmonella. Of these samples, 48.9% were found to be contaminated with Salmonella. Predominant serotypes were S. Agona, S. Emek, S. London. The prevalence of S. Enteritidis and S. Typhimurium was considered. These findings have highlighted the magnitude of Salmonella contamination in retail chicken meat in Hanoi. On the basis of these preliminary survey results, it is recommended that a cost‐effective monitoring and surveillance system for Salmonella should be established in Hanoi. This system should be augmented by good agricultural and hygienic practices and well‐designed longitudinal research activities on the whole poultry production chain.

Determination of ciprofloxacin and nalidixic acid resistance in Campylobacter jejuni with a fluorogenic polymerase chain reaction assay.

A fluorogenic polymerase chain reaction assay for the gyrA gene was used to determine the frequency of a Thr-86 mutation in Campylobacter jejuni isolates from food animals and humans in northern Thailand and to investigate the correlation between this mutation and bacterial resistance to fluoroquinolones. Eighty-four isolates of C. jejuni were used: 65 from healthy chickens on farms, 16 from chickens at the slaughterhouse, 1 from chicken meat at the market, and 1 from a healthy farm worker. The microbroth dilution technique was used for in vitro susceptibility testing. MIC breakpoints established by the National Antimicrobial Resistance Monitoring System were used to categorize the resistance of C. jejuni to ciprofloxacin and nalidixic acid. Sixty of the 84 C. jejuni isolates tested carried the Thr-86 mutation in the gyrA gene. All isolates with ciprofloxacin MICs of > or = 2 mg/liter carried the mutation, and no isolates with nalidixic acid MICs of < or = 16 mg/liter carried the Thr-86-to-Ile mutation. There was a very strong association between ciprofloxacin resistance and the presence of the mutation (kappa = 0.971, P < 0.01). The association between the presence of the Thr-86-to-Ile mutation and nalidixic acid resistance was weaker (kappa 0.859: P < or = 0.01).

A Cross-Sectional Study of Salmonella in Pork Products in Chiang Mai, Thailand

The occurrence of Salmonella in food of animal origin in Chiang Mai province was investigated by using a cross-sectional study during several phases of the pork production chain (cutting, transport, and retail) and of the environment in the cutting unit of a slaughterhouse. In total, 173 pork samples were obtained during the cutting phase, 173 samples from transported pork, 200 samples from retail products, and 300 samples from the slaughterhouse environment. Salmonella was detected in 55.5% of freshly cut pork, 70.5% of transported pork, and 34.5% of retail products. The five most prevalent Salmonella serotypes identified were Rissen (45.3%), Typhimurium (16.3%), Krefeld (10.6%), Stanley (6.3%), and Lagos (6.0%). Carcass contamination prior to cutting and in the slaughterhouse environment appeared to be important sources of Salmonella in transported pork and retail products. As Salmonella was also found during early stages of the slaughter process, attention should focus on all stages of the pork production chain to reduce contamination level and consumer risk of infection.

Genetic Similarity Using MLST Amongst Campylobacter jejuni Isolates from Children with Diarrhea Symptoms and Broilers

The aim of the present study was to investigate the genetic similarity amongst Campylobacter jejuni isolates from children with diarrhea symptoms and broilers in Chiang Mai, Thailand during 2002–2007. Sequence types of 12 isolates from children with symptoms of diarrhea and 9 isolates from broilers and other 42 Thai sequence types were determined by multilocus sequence typing. Cluster analysis was performed to determine the molecular relatedness of the isolates. Results showed diverse sequence types of C. jejuni isolated from both broilers and children. One isolate each from a broiler and a child shared a single sequence type (574). The majority of 13/16 sequence types belonged to previously reported sequence types in Thailand and two previously reported human sequence types were identified in broilers. The authors conclude that there is evidence of a genetic relationship between C. jejuni isolated from humans and broilers. MLST analysis of C. jejuni suggested that broilers are one of the sources of human infection in Chiang Mai, Thailand.