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Biomedical subjects

R J Gilbert

Publications and source records attributed to R J Gilbert.

At least 145 records · Page 8Linked to original sources
PubMed1977

ICMSF methods studies. VIII. Comparative study for the enumeration of Clostridium perfringens in foods.

Four methods were compared in an international comparative study for the enumeration of Clostridium perfringens: the SFP (Shahidi-Ferguson perfringens) agar (A), TSC (tryptose-sulfite-cycloserin) agar (B), SC (sulfite-cycloserine) agar (C), and neomycin blood agar (D) methods. The confirmed C. perfringens counts were slightly lower for D than for A-C. The percentages of presumptive colonies confirmed as C. perfringens were essentially the same in each method. The relative numbers of nonspecific colonies were the lowest in C, followed by B, D, and A. The methods were also compared for simplicity and for aspects associated with the recognition and selection of presumptive colonies.

Agar↗
PubMed1976

Identification of a novel enterotoxigenic activity associated with Bacillus cereus.

A strain of Bacillus cereus isolated from a food poisoning outbreak characterized by vomiting has been shown to be capable of causing vomiting when cultures grown on rice, but not other media, were fed to Rhesus monkeys. In contrast, a strain isolated from a diarrhoeal outbreak produced diarrhoea, but not vomiting, when grown on various media in similar feeding trials. Furthermore, culture filtrates from the diarrhoeal strain caused fluid accumulation in ligated rabbit ileal loops whereas those from the vomiting strain did not. It is proposed that at least two enterotoxins are involved, one responsible for the vomiting and one for the diarrhoeal symptoms.

Animals↗
PubMed1975

Bacillus cereus food poisoning: a provisional serotyping scheme.

A provisional serotyping scheme for Bacillus cereus has been developed. Eighteen selected cultures of B. cereus isolated from foods and clinical specimens were used to prepare agglutinating sera against the flagellar antigen. There were no significant cross-reactions between the sera. The sera were used to type 137 isolates of B. cereus from 34 British and Australian incidents of food poisoning associated with the consumption of cooked rice. The majority of the isolates from samples of food (56 of 84; 66-7%) and from clinical specimens (43 of 53; 81-1%) were of H-serotype 1. Types 1, 3 and 5 were isolated from foods, clinical specimens or both, obtained from 31 of the 34 episodes. Sixty-six isolates of B. cereus were obtained from 63 samples of uncooked long-grain rice. The majority of the isolates (38 of 66; 57-6%) were untypable and types 1, 3 and 5 made up only 5 of 66 (7-5%) of the total. The results support the theory that B. cereus may cause two distinct forms of foodborne illness. Strains from incidents of food poisoning characterised by a longer incubation period and with diarrhoea as the main symptom have provided serotypes 2, 6, 8, 9 and 10, whereas those causing the rice-associated emetic illness are usually serotypes 1, 3 or 5.

Agglutination↗
PubMed1974

The survival and growth of Bacillus cereus in boiled and fried rice in relation to outbreaks of food poisoning.

A number of outbreaks of food poisoning attributed to Bacillus cereus have been reported recently and all have been associated with cooked rice usually from Chinese restaurants and ;take-away' shops.Tests were made to assess the heat resistance of B. cereus spores in aqueous suspension, the growth of the organism in boiled rice stored at temperatures in the range 4-55 degrees C., and the effect of cooking and storage on the growth of the organism in boiled and fried rice. The spores of B. cereus survived cooking and were capable of germination and outgrowth. The optimum temperature for growth in boiled rice was between 30 degrees and 37 degrees C. and growth also occurred during storage at 15 degrees and 43 degrees C.To prevent further outbreaks it is suggested that rice should be boiled in smaller quantities on several occasions during the day, thereby reducing the storage time before frying. After boiling the rice should either be kept hot (> 63 degrees C.) or cooled quickly and transferred to a refrigerator within 2 hr. of cooking. Boiled or fried rice must not be stored under warm conditions especially in the range 15-50 degrees C.

Bacillus cereus↗
PubMed1972

Serological detection of enterotoxin in foods implicated in staphylococcal food poisoning.

Two methods are described for the extraction of enterotoxin from foods incriminated in incidents of staphylococcal food poisoning. Enterotoxin was detected serologically in 12 of 24 food samples from 20 separate incidents: eight samples contained enterotoxin A, three contained D and one both A and B. The amount of enterotoxin in nine foods, based on 100% recovery, varied from 0.02 to 0.09 mug./g.Data are also given on the numbers of Staphylococcus aureus isolated from samples of food from 39 food poisoning incidents. Colony counts varied between 7.5 x 10(5) and 9 x 10(9)/g. with a median value of 7 x 10(7)/g.

Cell Count↗
PubMed1971

The survival of salmonellas on finger-tips and transfer of the organisms to foods.

The survival of salmonellas on the finger-tips is considered with reference to the ease with which they can be transferred to food by handling.Escherichia coli and several Salmonella serotypes were shown to survive on the finger-tips for various periods of time, for example, S. anatum could be recovered 3 hr. after artificially contaminating them with between 500 and 2000 organisms. S. anatum could also be recovered from the finger-tips after contaminating them with more than 6000 organisms followed by a 15 sec. hand-wash 10 min. later. Similarly, the survivors from minimal inocula of less than 100 S. anatum/finger-tip were, after 10 min., still capable of infecting samples of corned beef and ham. E. coli was isolated from the finger-tips of 13 of 110 butchers soon after they had left the meat line at a meat products factory, but was not detected on the finger-tips of 100 volunteers at the Central Public Health Laboratory.The implications of the present findings to the spread of salmonellas from raw to cooked foods, and the relevance of this to outbreaks of Salmonella infection in the general population and in hospitals, are discussed.

Cross Infection↗
PubMed1970

Comparison of materials used for cleaning equipment in retail food premises, and of two methods for the enumeration of bacteria on cleaned equipment and work surfaces.

There is no official scheme for testing disinfectants and detergent/disinfectants for use in the retail food trade and few recommended procedures have been given for the cleaning of equipment with these agents. Therefore, field trials were carried out in a large self-service store. Comparisons were made of the various cleaning efficiencies, as determined by bacterial plate counts, of detergent and disinfectant solutions and machine cleaning oils applied with either clean cloths or disposable paper towels to items of equipment. The most satisfactory results were always obtained when anionic detergent (0.75% w/v) and hypochlorite (200 p.p.m. available chlorine) solutions were applied in a ;two-step' procedure.Tests were made to compare the calcium alginate swab-rinse and the agar sausage (Agaroid) techniques for the enumeration of bacteria on stainless steel, plastic, formica and wooden surfaces before and after a cleaning process. Although recovery rates were always greater by the swab-rinse technique, the agar sausage technique was considered to be a useful routine control method for surface sampling.

Bacteria↗