Saxitoxin as a toxic principle of a freshwater puffer, Tetraodon fangi, in Thailand.

Saxitoxin was identified in a freshwater puffer, Tetraodon fangi, which caused food poisoning in Thailand. Tetrodotoxin, a puffer toxin, was not detected in the species by the HPLC-fluorometric analysis, showing that tetrodotoxin is absent or under any detectable level. The result of this study shows that saxitoxin can be a major toxin in puffer.

Demographic data on Salmonella enteritidis infection in Thailand, 1990-1995.

The data for the comprehensive analysis of Salmonella enteritidis infection was based on the information recorded in the request form submitted for Salmonella typing and the results of serotyping at the WHO National Salmonella and Shigella Center, Department of Medical Sciences, Ministry of Public Health, Thailand during 1990-1995. Fifty-one cases of S. enteritidis (SE) infection were confirmed in 1990. The morbidity being markedly increased each year from 1991 to 1995, with 105, 307, 471, 659 and 877 cases being identified, respectively. Among the isolates of Salmonella spp, SE was the most common serotype during 1993-1995. The cases were mostly predominant in Bangkok and then in southern, northeastern, central and northern regions, respectively. The morbidity rates per 100,000 population per year of SE infection in 1990-1995 were 0.09, 0.18, 0.53, 0.8, 1.11 and 1.47, respectively. Analysis of the infection rate by sex and age demonstrated that the incidence in males was higher than in females. Adult patients were more frequently found than adolescent patients. The organism was found in feces, blood, pus, urine, cerebrospinal fluid and sputum, accounting for 41.7, 35.8, 5.5, 2.5, 1.7 and 0.4%, respectively. The average extraintestinal isolation index was 0.52.

Prevalence of salmonellae in broiler, layer and breeder flocks in Thailand.

Salmonellae were detected in thirteen broiler flocks, 15 layer flocks and 7 parent breeder flocks in Thailand from October 1991 to August 1992. Salmonellae were isolated from samples of feed, drinking water, cloacal swabs, faeces and litter from all broiler and breeder flocks, and 87% of the layer flocks. From broiler flocks, litter samples were more frequently contaminated than other samples, while feed left over in the layer house and drinking water in the parent breeder house were the most commonly contaminated. Of the total of 1,488 samples examined from all flocks, salmonellae were recovered from samples of litter (42%), water in drinking troughs (36%), feed left over in the feed trays (28%), water in the main tanks (17%), cloacal swabs (13%) and stock feed (8%). The most common serovars associated with the broiler, layer and parent breeder flocks were Salmonella blockley, S. weltevreden and S. amsterdam respectively.

Detection of salmonellae in hen eggs in Thailand.

Two thousand four hundred and ninety eggs were collected from retail markets in 6 provinces and from laying hen farms in 3 provinces. Eggs were pooled in groups of 3 to obtain 830 samples for testing. Isolation of salmonellae was made from both egg shell and egg contents. Eggs from retail markets were contaminated with salmonellae on egg shells (13.2%) and in egg contents (3.9%). Three (0.4%) samples yield positive both on egg shells and in egg contents. Of the 86 samples from laying hen farms, salmonellae were found on egg shells and in egg contents, 3.5% and 1.2%, respectively. From the 134 strains tested, twenty-four serotypes were confirmed. Salmonella cerro, S. amsterdam and S. typhimurium were predominantly encountered, 4.8%, 4.3% and 1.4%, respectively. Only two samples were contaminated with S. enteritidis, one each from open market and laying hen farm, one on egg shells and the other in egg content respectively.

Incidence of salmonellae in duck eggs in Thailand.

Detection of salmonellae was performed on egg shells and egg contents of duck eggs. Five hundred and sixty-four tested samples were came from 1,128 eggs, 2 eggs in each sample. Eggs were collected from retail markets in Bangkok, Chon Buri, Chachoengsao, Lop Buri, Ang Thong and Nakhon Ratchasima provinces during January through June 1992. The percentage of salmonellae contamination on the egg shells only, egg contents only and both shells and contents were 12.4%, 11% and 0.2%, respectively. Twenty three serotypes were identified from the 133 salmonellae isolates. The common serotypes found from duck eggs were Salmonella typhimurium, S. cerro, S. tennessee, S. amsterdam, S. agona and S. infantis accounting for 5.5%, 4.1%, 2.8%, 2.1%, 1.4% and 1.1%, respectively.

Determination of pyridonecarboxylic acids in plasma by reverse-phase high-performance liquid chromatography.

A simple qualitative and quantitative determination for pyridonecarboxylic acids including nalidixic acid (NA), oxolinic acid (OA) and pipemidic acid (PPA) in chicken plasma was carried out by microbiological, spectrophotometric, thin-layer chromatographic (TLC) and reverse-phase high-performance liquid chromatographic (HPLC) methods. As a test organism for bacteriological bioassay, Bacillus subtilis ATCC-6633 was the most sensitive of seven organisms investigated. Using the cup and the disc methods, a standard curve was obtained by determining the relationship between various drug concentrations and the diameter of the inhibition zone. The three drugs had two strong UV absorbance wavelengths (257 and 330 nm) on spectrophotometry. TLC analysis using a silica gel 60 F254 plate was investigated, and a solution of methanol:chloroform:acetic acid (3:1:1, v/v/v) was found to be the most suitable solvent for separation. The minimum concentration of drug detectable by this method was 0.5 microgram/ml for NA, 0.075 microgram/ml for OA and 0.39 microgram/ml for PPA. For HPLC analysis, a solution of acetonitrile:0.2 M phosphoric acid (1:1, v/v) was superior, and simultaneous determination of all three drugs was possible under the HPLC conditions used. The lowest measurable amount of drug in chicken plasma was 0.01 microgram/g. Recovery from extracts spiked with each drug at a known concentration was close to 100% for NA and OA, but only about 50% for PPA.

The occurrence of salmonellae in bean sprouts in Thailand.

Detection of Salmonella spp. in 344 samples of bean sprouts was attempted by pre-enriched in buffered peptone water (BPW) or lactose broth (LB) at 37 degrees C, followed by selective enrichments, selenite cystein broth (SCB) and Rappaport medium (RV) at 43 degrees C. Four selective media, bismuth sulphite agar (BSA), brilliant green agar (BGA), Salmonella-Shigella agar (SSA) and MacConkey agar (MA) were used for isolation. Salmonellae were isolated from 30 (8.7%) samples. They were serotypes lexington (56.7%), orion (16.7%), senftenberg (16.7%), tennessee (3.3%), poona (3.3%) and weltevreden (3.3%). Pre-enrichment in LB, followed by enrichment in SCB and streaking on to BSA gave the highest recoveries. Fifteen of 30 strains isolated were sensitive to all 14 antibiotics tested. Seven strains were resistant to one, and a strains showed multiple resistance to 2-4 antimicrobial agents.

A continuous, simple and rapid method for the detection, extraction and identification of residual antibacterial agents in meat.

Most antibacterial agents produced larger inhibition zones and showed lower detectable concentrations on minimal medium (MM) seeded with Bacillus subtilis than on Mueller-Hinton medium. After simple extraction, using a small amount of acetonitrile, from an agar block inside the inhibitory zone produced by each antibacterial agent, identification was carried out by reverse-phase high-performance liquid chromatography (HPLC). It is recommended that for inspection of residues MM is superior as a bioassay medium. The continuous, simple and rapid method described may be useful for routine laboratory testing of residual antimicrobial agents in food.

A reverse-phase high-performance liquid chromatographic determination of nicarbazin residues in eggs.

A reverse-phase high-performance liquid chromatographic (HPLC) method was employed for analysis of nicarbazin [1:1 mixture of 4,4'-dinitrocarbanilide (DNC) and 2-hydroxy-4, 6-dimethyl-pyrimidine] in chicken eggs. Nicarbazin residues were analysed by determining the DNC of nicarbazin. HPLC of the DNC portion of nicarbazin was performed with a reverse-phase mu-Bondapak C18 column, using a mobile phase of acetonitrile-water (7:3, v/v). A variable-wavelength detector set at 340 nm, 0.02 AUFS, and a recorder set at 4 mm/min were used for the detection. The standard curve for nicarbazin was linear within the range 0.05-2.0 micrograms/ml. The recovery of nicarbazin added to eggs was 90.2%. The detection limit of nicarbazin in this analytical method was 0.005 micrograms/ml. Nicarbazin was detected in 10% of eggs obtained by feeding chickens with a diet contaminated with nicarbazin within the range 0.07 to 1.39 micrograms/g, but it was not detected in eggs obtained commercially.

Characteristics of Pasteurella multocida isolated from humans, swine and poultry in Thailand.

Pasteurella multocida is a pathogen of animals and humans. Most of the patients have been associated with animals but many cases had not contacted them. The failure to diagnose P. multocida infections is mostly due to misidentification on gram stained smears and inadequate laboratory identification techniques. In order to compile detailed characteristics of the organism we studied the physical and biochemical properties of 70 isolates of P. multocida - 17 human, 23 swine and 30 poultry. All isolates produced catalase, oxydase, indol, nitrate reduction and ornithine decarboxylase. They failed to produce urease, gelatinase, methyl red, acetoin and could not grow on MacConkey agar, SS-agar, in nutrient broth with 0% or 6% NaCl. With respect to fermentable sugars, all isolates consistantly produced acid from glucose, mannitol and mannose. None of the cultures fermented lactose, maltose and dulcitol. Marked variations in the patterns of fermentation of arabinose and xylose were found. The characteristics tested are important to facilitate identification of P. multocida but could not be used to differentiate the host of the bacterium.

Toxicity of the freshwater puffer fish Tetraodon fangi and T. palembangensis from Thailand.

Toxicity of the freshwater puffer Tetraodon fangi and T. palembangensis from Amphur Chumpuang, Nakorn Ratchasima Province, Thailand (where food poisoning due to T. fangi recently occurred) was monitored from December 1988 through October 1989. The puffer were toxic throughout most of the year. There was marked variation in amounts of toxins among individuals and with the time of collection. The highest toxicity levels for T. fangi were found in skin (813 mouse units per g) following by eggs (336), muscle (331), liver (209) and intestine (159). Corresponding values for T. palembangensis were 907, 332, 282, 225 and 143 mouse units/g, respectively.

Food poisoning due to consumption of the freshwater puffer Tetraodon fangi in Thailand.

In October 1988, food poisoning due to the freshwater puffer Tetraodon fangi occurred. Six out of eight people who consumed spicy soup (Tom Yam) of puffer developed clinical signs of tetrodotoxin intoxication. The incubation period varied from 30 min to 3 hr and there were no deaths. Puffers were collected one week after the occurrence of the food poisoning and their content of toxin was determined. All organs of puffer were toxic with skin having the highest toxicity followed by gonad, muscle, liver and intestine.

Protogonyaulax cohorticula, a toxic dinoflagellate found in the Gulf of Thailand.

Two clones of Protogonyaulax cohorticula were isolated from the Gulf of Thailand. The extracts of these clones killed mice with typical signs of paralytic shellfish poisoning. The toxicities corresponded to those of strongly toxic clones of P. tamarensis. In the HPLC and electrophoretic analyses, gonyautoxins and saxitoxin were detected. About 80% of the toxins consisted of gonyautoxin I. These results show that P. cohorticula is a toxic species of Protogonyaulax and that it is at least one of the causative organisms of paralytic shellfish poisoning in Thailand.

Studies on mycobacteria isolated from animals, with special reference to the agglutination test.

Ninety-three strains of slowly-growing mycobacteria were studied biochemically. Ninety of these were isolated from animals (pigs, cattle, dog and poultry) and three from dust and sawdust-bedding in a pighouse. One strain from a lymph node of a pig was identified as M. gordonae. Ninety-two strains fitted into the M. aviam-intracellulare complex. Of the 92 biochemically confirmed M. avium-intracellulare strains, 78 were tested serologically ad modum Schaefer. Of 73 strains from pigs, one was serotype 1, fifty serotype 2 and eight serotype 8, while two could not be type and twelve were autoagglutinable. Three strains from pighouse environment were serotype 8 and two from cattle and a dog were both serotype 2. A slight modification of Schaefer's agglutination method, using smaller amounts of antigen and antiserum, was developed.

An epizootic of Mycobacterium intracellulare, serotype 8 infection in swine.

Eight strains of mycobacteria isolated from tuberculous lymph nodes of swine were identified as Mycobacterium intracellulare, serotype 8. The infected swine were borne in a large breeding herd and as 8 weeks old piglets distributed to a number of farms for fattening. Autopsy material from the breeding herd, incriminated as the primary source of M. intracellulare, serotype 8 infection, has not been available for bacteriological examination, but none of a number of sows slaughtered showed any visible lesions. The organism, however, was isolated from sawdust-bedding and dust collected in pigpens. Eight samples of water collected from the well and several pipelines and taps of the automatic watering system in the infected pigpens all turned out negative. Results of medical examination of 7 farmworkers from farm G excluded the possibility of a human source of infection. Altogether 799 out of about 2000 piglets raised at farm G. and distributed for fattening to 7 different farms were detained for tuberculosis-like lesions when slaughtered some three months later. In none of the seven farms did spread of the infection occur, and despite no special measures of segregation and disinfection were taken, the M. intracellulare infection left the premises with the last pig from farm G. Neither in sow herd G. animal to animal infection seemed important. Following a rigid practice of cleaning and disinfection of the sow pens in between each litter, the infection which apparently had persisted in the environment for about nine months, disappeared and the sow herd could be saved.

Inactivation of enterovirus by glutaraldehyde.

A study on the rate of inactivation by glutaraldehyde of coxsackievirus was conducted using different concentrations, temperatures, and pH values. It was found, that 2 percent glutaraldehyde at pH 7.4 and 25 C, as recommended for a sporicide, reduced the titer of infectious virus by 2 log10U in 1 min or less. The reduction was not negatively affected by high concentrations of organic matter (serum and animal spillings) in the reaction mixtures.