Salmonella prevalence in meat at retail markets in Pakse, Champasak Province, Laos, and antimicrobial susceptibility of isolates.

Non-typhoidal Salmonella is one of the most common causes of human gastroenteritis worldwide and most human outbreaks are associated with the consumption of contaminated food. However, there are no reports on Salmonella contamination in market meat in Laos. The objective of this study was to determine the prevalence of Salmonella in meat samples in Pakse, Champasak Province, Laos, as well as the antimicrobial susceptibility of isolates. The prevalence of Salmonella was 82% in beef, 93% in pork and 80% in buffalo meat. In total, 80 isolates and 11 serovars were found, including serovars Stanley (n=15), Anatum (n=14), Derby (n=11), Rissen (n=9) and Amsterdam (n=7). The drug susceptibility of 60 strains against 10 antimicrobial agents was tested. The 60 isolates examined were sensitive to ciprofloxacin (100% susceptible), norfloxacin (100%), cefotaxime (95%), nalidixic acid (90%) and chloramphenicol (88%), but were resistant to streptomycin (67% resistant), tetracycline (67%) and ampicillin (63%). Of the isolates, 73% were multidrug-resistant. These findings indicate a high Salmonella prevalence in market meat in Pakse. Therefore, programmes to control Salmonella contamination are needed.

Salmonella prevalence in slaughtered buffaloes and pigs and antimicrobial susceptibility of isolates in Vientiane, Lao People's Democratic Republic.

This is the first report regarding isolation of Salmonella from cecum samples of buffaloes and pigs and characterization of the isolates in Laos. The organisms were isolated from 8% (4/50) of buffaloes and 76% (37/49) of pigs. In buffaloes, 3 animals harbored serotype 9,12: -:1,5, and 1 animal harbored both S. Derby and S. Javiana. In pigs, the most predominant serotypes were S. Derby (51%) followed by S. Anatum (45%), S. Weltevreden (15%) and S. Stanley (5%). The buffalo isolates were susceptible to the antimicrobials tested, whereas the pig isolates showed 10 resistance patterns to 1-5 antibiotics. Of the 59 pig isolates, the resistance rates to tetracycline, streptomycin, ampicillin, sulfamethoxazole-trimethoprim, chloramphenicol, amoxicillin-clavulanic acid and nalidixic acid were 24%, 22%, 14%, 5%, 2%, 2% and 2%, respectively. The results suggest that pigs and buffaloes harbor Salmonella, with a higher prevalence especially in pigs, and all the isolates showed sensitivity to cefotaxime, norfloxacin and ciprofloxacin.

Prevalence of Campylobacter spp. in slaughtered cattle and buffaloes in Vientiane, Lao People's Democratic Republic.

This is the first report regarding isolation of Campylobacter in caecum and bile samples obtained from ruminants in Vientiane, Lao PDR. Campylobacter was isolated from 3 (1.6%) of the 184 caecum samples and 1 (1.0%) of the 100 bile samples obtained from buffaloes. Three of the 4 isolates were determined to be C. jejuni, which was detected in 2 caecum samples and 1 bile sample; the other caecum sample contained C. fetus. Campylobacter was not isolated from any of the 82 cattle caecum samples. Our results suggest that cattle and buffaloes may not be important sources of Campylobacter food poisoning in Lao PDR.

Salmonella contamination in pigs at slaughter and on the farm: a field study using an antibody ELISA test and a PCR technique.

An antibody ELISA test and a PCR method for identifying the risk of Salmonella contamination were compared in a field study on the same lots of animals in a slaughterhouse. The results were compared to investigations carried out on two farms with different prevalences of Salmonella antibody-positive animals. Salmonella antibody ELISA testing was carried out on all 383 meat juice samples derived from the diaphragm pillar muscle of each pig. Salmonella DNA analysis was performed by PCR technique on small intestine samples with lymph nodes from all 383 pigs, and on tonsils from the last 129 pigs. The 383 animals tested came from 32 different pig farms. Furthermore, the herd antibody blood serum status against Salmonella spp. of weaners was determined on two selected pig fattening farms, one with low and one with high seroprevalence in meat juice. A total of 7.0% (ELISA cut-off OD% > or =40) of the slaughtered pigs from 6 of 32 fattening farms were seropositive. Salmonella DNA was found in 16.4% of the jejunum/lymph nodes (383 animals) and in 15.5% of the tonsils (129 animals). Salmonella DNA was found in the jejunum/lymph nodes of 41% of the seropositive pigs. However, serotitres were also positive in only 17.5% of all pigs positive in the jejunum DNA test. Two farms were selected for further investigation: farm 13 (F13), with a high prevalence of seropositive pigs, 29.0%, Category II; and F11, with 9.4%, Category I. However, categorization according to the blood serum tests of the fattening pigs after on-farm testing was very different: F13 had 5% positive animals (Category I); and F11, 23.3% (Category II). The study led to the following results and recommendations: First, ELISA tests are useful for the detection of farms that are regularly contaminated with Salmonella, but such tests cannot give information on the infectious status of a single animal (or a group) at the point of slaughter. Second, it is crucial that management measures are taken to prevent the spread of infections by trade and transport: piglets should be supplied exclusively by a single, well-known producer, and finishers should be tested serologically on farm before going to slaughter. Third, ELISA tests and the PCR method are suitable for the detection of Salmonella and are recommended as analytical tools for all pork quality control programmes. Fourth, animals from suspicious farms should always be slaughtered at the end of the slaughter day, followed by thorough cleaning and disinfection.