Pulsed-field gel electrophoresis as an epidemiologic tool in the investigation of laboratory acquired Salmonella typhi infection.

Strains of Salmonella typhi implicated in two separate cases of laboratory acquired infection from patients and the medical laboratory technologists who processed the patients' samples were analysed by pulsed-field gel electrophoresis. Although all four isolates were of bacteriophage type E1, PFGE was able to demonstrate that the strains responsible for the two laboratory acquired cases were not genetically related. The PFGE patterns of the isolates from the MLTs were found to be identical to those of the corresponding patients after digestion with restriction enzyme AvrII. This provided genetic as well as epidemiological evidence for the source of the laboratory acquired infections.

Development and preliminary evaluation of an IgM dot-immunobinding assay (IgM-DIA) for rapid serodiagnosis of scrub typhus infection.

An IgM dot-immunobinding assay (IgM-DIA) was developed for the diagnosis of scrub typhus infection. The whole cell antigens of Karp, Kato and Gilliam strains of Rickettsia tsutsugamushi were immobilized onto nitrocellulose paper and reacted with patients sera. The presence of IgM R. tsutsugamushi specific antibody in the patient sera could be detected by the observation of a visible brown dot on the nitrocellulose paper. The IgM-DIA has a sensitivity of 90.4% and specificity of 81.4% as compared to the indirect immunoperoxidase test. The IgM-DIA is rapid, simple, cost-effective, does not require microscope or incubator. It is recommended as a rapid screening test for the diagnosis of scrub typhus infection in the field or rural area within the hyperendemic region.

In-vitro susceptibility of Pseudomonas pseudomallei isolated in Malaysia to some new cephalosporins and a quinolone.

The current drugs recommended for treatment of melioidosis are tetracycline, chloramphenicol and cotrimoxazole. Unfortunately these drugs are not the drug of choice in an acutely ill patient with septicaemia prior to the availability of laboratory results. With the discovery of the new cephalosporins which have a broad spectrum of activity clinicians are using them either alone or in combination with other antibiotics in such critical situations. Hence, an in-vitro study was carried out on the susceptibility of 41 strains of P. pseudomallei isolated in Malaysia, to these new cephalosporins and a new quinolone. The results showed that all the cephalosporins tested had some activity on the strains tested, with ceftazidime being the most active drug. Pefloxacin had very poor activity. However, further clinical studies are required to determine the duration, dosage and in-vivo activity of the antibiotics.

Enterotoxin production by Staphylococcus aureus strains isolated from humans, foods and animals in Malaysia.

Enterotoxin production by strains of Staphylococcus aureus isolated from human, food and animal sources was investigated. Of the 130 isolates studied, 27 (20.8%) were found to be enterotoxigenic. The most common enterotoxin detected from human sources was enterotoxin C whereas enterotoxin B occurred more frequently in staphylococcal strains of food origin. The 2 enterotoxigenic strains, from animals isolated from a dog and a goat, produced enterotoxins A and C, respectively. Enterotoxin E was not detected alone from any of the enterotoxigenic strains studied, but occurred together with other enterotoxins. The need to detect enterotoxin in staphylococcal strains and in suspected foods for the confirmation of staphylococcal food poisoning is discussed.