The efficacy of Cary Blair medium was compared with that of Selenite 'F'in the isolation of enteropathogens from 805 cases of diarrhoea. It was shown that use of the Cary Blair medium resulted in a significantly higher rate of isolation. Not only were organisms found which were not isolated from the Selenite 'F' but there was a much higher isolation rate of Salmonella from Cary Blair medium althougn Selenite 'F' is generally considered as an enrichment medium for
Salmonella. The findings indicate that it would be advantageous to introduce Cary Blair medium as the sole transport medium for the isolation of enteropathogensfrom cases ofdiarrhoea.
A prospective clinical study comparing 74 cases of rotavirus-associated diarrhoea and 100 cases of non-rotavirus-associated diarrhoea revealed a higher incidence of vomiting to be the only significant difference in the former. Bloody stools were seen in about 5-10%, fever in about two-thirds and respiratory symptoms in a quarter of cases regardless of aetiology. The overwhelming majority had mild dehydration of the isonatremic type. Hypokalemia was noted in a quarter of the cases in both groups.
Keywords: General Hospital Kuala Lumpur
Plesiomonas shigelloides was isolated from 5 (2.1%) of the 234 children with diarrhoea and none of the 230 controls. In one child, the organism was found in association with Salmonella. Two strains had Shigella sonnei phase I antigen. All the strains were susceptible to the aminoglycosides, cephalosporins, nalidixic acid, nitrofurantoin, chloramphenicol and cotrimoxazole; but resistant to the penicillins. Alkaline peptone water enrichment subcultured to desoxycholale citrate agar proved to be a useful method for isolating this organism from faeces. As the roie of P. shigelloides in causing gastrointestinal disease remains controversial, further studies are necessary to determine its enteropathogenicily.
Over a period of 2 months, 35 of 69 (51%) cases of juvenile diarrhoea studied in eastern Malaysia were associated with rotavirus excretion; rotavirus associated diarrhoea occurred most commonly in the 6-24 month age group. Polyacrylamide gel electrophoresis (PAGE) of genome ribonucleic acid showed that only 4 rotavirus electropherotypes could be detected. Of those, 2 predominated and 2 were detected only once each; one of these may have been a reassortment of the two predominant electropherotypes. Analysis of the clinical features of patients excreting rotavirus subgroup 1 or 2, determined by PAGE, demonstrated that rotavirus subgroup 1 was associated with more hypotonic dehydration and need for intravenous therapy: lethargy was significantly more common among those excreting rotavirus subgroup 2.
The prevalence of Enterotoxigenic Escherichia coli (ETEC) in 433 stool samples from diarrhoeal cases of all ages was studied using two commercially available test kits for the detection of heat labile toxin (LT) and the infant mouse assay for the heat stable toxin (ST). 16 samples (3.7%) were positive for ETEC, of which nine were producing ST alone, six LT alone and only one was producing both LT and ST. Although the percentage of isolation rate was low, its occurrence was almost as common as the Shigella spp and Salmonella spp in the same study. Of the two test kits examined, the Phadebact ETEC-LT Test 50 (Pharmacia Diagnostics, Uppsala, Sweden) was found to be more suitable for use in a routine diagnostic laboratory. Ten out of 12 (83%) of the strains tested were resistant to one or more antibiotics.
The group A rotavirus staphylococcal co-agglutination test was evaluated and its sensitivity and specificity compared with an in-house enzyme-linked immunosorbent assay (ELISA) and a commercial latex agglutination test (Rotalex). In addition, the storage stability of the staphylococcal reagents was ascertained. Examination of 136 clarified suspensions of diarrhoeal faeces by the staphylococcal co-agglutination test revealed a high proportion of false positives (26%) and uninterpretable results (34%) due to non-specific agglutination. Non-specific agglutination could be removed effectively by prior absorption of the clarified faecal specimens with unsensitized staphylococci. The staphylococcal co-agglutination test was less sensitive and specific than the in-house enzyme-linked immunosorbent assay but was comparable to the Rotalex slide latex agglutination test. The staphylococcal reagents have a shelf life of at least 29 weeks.
The VP4 genetic groups of 151 field strains of human rotaviruses obtained from infants and young children with diarrhea from four locations in Malaysia were analyzed. The strains were adapted to growth in tissue culture and studied further by molecular hybridization of northern blotted RNA to PCR-generated cDNA probes representing amino acids 84-180 of the KU strain VP4, 83-181 of the DS-1 strain VP4, and 83-180 of either the 1076 or K8 strain VP4, representing VP4 genetic groups 1-4 (P1A, P1B, P2, and P3), respectively. The majority (79% of the field strains hybridized with the KU VP4 genetic group 1 probe and were associated with G1, G3, G4, untypable, or mixed G serotypes. VP4 genetic group 1 (P1A) strains were the most common in all locations in Malaysia between 1978-1988. Three strains which exhibited G3 and subgroup I specificity hybridized with the K8 VP4 genetic group 4 probe. These three VP4 genetic group 4 (P3) strains were detected in two different years and locations, extending the initial detection of this VP4 genetic group (the K8 strain) in Japan to a larger geographical area of Asia.
Approximately 57% of clinical and 33% of poultry isolates examined produced a cytotoxin. Cytotoxic activity was detected in 25 (50%) isolates of Campylobacter of which 12 were isolated from bloody diarrhea and 9 from watery stools. The cytotoxin titers were low, ranging from 2 to 16. The crude filtrates from 50 Campylobacter isolates showed no cytotoxic effect in Vero cells, no fluid accumulation in suckling mice and no hemolytic activity.
By means of the gentamicin HEp-2 cell invasion assay, it was demonstrated that 82% of the Campylobacters tested were cell-invasive, including 83% of isolates from bloody diarrhoea and 80% of isolates from watery diarrhoea. The large number of invasive strains from watery diarrhoea suggests the possible role of invasiveness in the production of watery diarrhoea. Whether this stage can progress further to more severe symptoms such as bloody diarrhoea remains to be elucidated. Whether this progression to bloody diarrhoea occurs as a result of toxin production is still debatable. In Vero cells, invasion was less efficient and intracellular multiplication was not observed.
A 57-year-old man, while on travel in Malaysia, suffered from diarrhea after he ate fruits. He developed limbs weakness without sensory disturbance after his return to Japan. Serum from the patient had high IgG anti-GM1 antibody titer. Campylobacter jejuni was isolated from his stool. The serotype belonged to PEN 5. The patient received double-filtration plasmapheresis 7 times during from days 6 to 17. Muscle strength began to recover gradually on day 10, and returned to normal 5 months after the onset of neurologic symptoms. Repeated neurophysiologic studies indicated that the axonal degeneration of motor nerves was predominant process. This case suggests that Guillain-Barré syndrome is a complication of traveler's diarrhea.
Aeromonas hydrophila strains obtained from diarrhoeal samples of human patients (19 isolates) and freshwater ponds (11 isolates) were analysed for siderophore production. Both clinical and environmental isolates showed significantly increased siderophore production under iron-limiting conditions both at 28 degrees C and at 37 degrees C. Clinical isolates consistently produced higher levels of siderophores than did the environmental isolates. The role of plasmids in moderating siderophore production was studied after curing with acridine orange. Treatment with acridine orange for 24 h removed the larger plasmids but the smaller plasmids (< 5 MDa), more common in the environmental isolates, were resistant to curing. As found in the untreated isolates, the cured clinical isolates produced higher mean levels of siderophores than the cured environmental isolates. Siderophore production in A. hydrophila was significantly influenced by iron-limiting cultural conditions and the source of isolates, but plasmid content and growth temperature at 28 degrees C or 37 degrees C had little effect on production. The basis for the greater production of siderophores in clinical isolates than in environmental isolates needs further study.