SUMMARYThe purpose of this study was to investigate carriage of intestinal spirochaetes by selected population groups in Western Australia. Stool specimens from 293 rural patients with gastrointestinal disorders, and from 227 healthy migrants from developing countries were cultured. Spirochaete isolates were identified using PCR, and typed by pulsed field gel electrophoresis (PFGE). Brachyspira aalborgi was not isolated. Brachyspira pilosicoli was recovered from 15 rural patients, all Aboriginal. Prevalence was 9n9 % in 151 Aboriginals and 0 % in 142 non-Aboriginals. Carriage of B. pilosicoli amongst migrants was 10n6 % (24\227). Carriage was significantly increased in Aboriginal children aged 2-5 years (P l 0n0027) and in migrant individuals from the Middle East and Africa (P l 0n0034). Carriage was significantly associated with detection of faecal protozoa in both Aboriginals (P l 0n0021) and migrants (P l 0n012). PFGE results indicated that the B. pilosicoli strains were genetically diverse.
An automated ribotyping device (RiboPrinter) was used to determine the ribotypes of a collection of Burkholderia pseudomallei isolates. In a preliminary evaluation with the restriction enzymes BamHI and EcoRI, the protocol with EcoRI was more discriminating. The reproducibilities of the ribotypes obtained with EcoRI (EcoRI ribotypes) were determined by testing three levels of bacterial loads. The performance of the manufacturer's software was assessed by comparing the machine-optimized ribotypes with the type determined from the original gel image analyzed with Bionumerics software. The library of B. pseudomallei EcoRI ribotypes was then compared with the ribotypes obtained by DNA macrorestriction analysis of XbaI digests by pulsed-field gel electrophoresis. The typeability of B. pseudomallei by EcoRI ribotyping was 100%, and the discrimination index was 0.94. The slightly greater discrimination provided by DNA macrorestriction analysis (0.96) was achieved at the expense of a significantly longer processing time of 6 days, although the method was only half the cost of automated ribotyping. Typeability by macrorestriction analysis was lower (97%) unless a thiourea step was added to neutralize the action of Tris-dependent endonucleases. The digital record of B. pseudomallei isolates analyzed thus far provides a useful resource for future epidemiological studies and will help shorten the response time in the event of a further melioidosis outbreak or the deliberate release of B. pseudomallei as a biohazard.
Abstract. Septicemic melioidosis is often fatal despite treatment with antibiotics such as ceftazidime to which Burkholderia pseudomallei, the causal pathogen, is sensitive in vitro. We report a near-fatal case of septicemic melioidosis with persistent B. pseudomallei bacteremia despite intravenous ceftazidime in which combination therapy with meropenem and ciprofloxacin, splenectomy and correction of metabolic acidosis allowed for hospital discharge. The choice of antibiotic agents was supported by intracellular minimum inhibitory concentration analysis using B. pseudomallei co-culture in Acanthamoeba trophozoites. The patient's B. pseudomallei isolates were indistinguishable by pulsed-field gel electrophoresis from clinical and environmental isolates previously analyzed during investigation of a Western Australian melioidosis outbreak. A combination of antibiotics known to possess intracellular activity against B. pseudomallei, surgery and supportive critical care may provide a means of improving the probability of survival in persistent septicemic melioidosis.
A cluster of three cases of listeriosis cases occurred against a background of endemic listeriosis in Western Australia. Human and environmental isolates of Listeria monocytogenes obtained during the outbreak investigation were rapidly subtyped by automated ribotyping using an EcoRI protocol and a RiboPrinter. DNA macrorestriction analysis by pulsed-field gel electrophoresis (PFGE) was used to confirm the relatedness of isolates. Serogroup 1/2 predominated among the food samples and the four clinical isolates from the outbreak cluster were also of this serogroup. All isolates from chicken material were serogroup 1/2 and indistinguishable by ribotype pattern. PFGE subdivided strains of this ribotype into four subtypes. The preliminary analysis had an immediate impact on hypothesis generation, environmental health investigations, environmental specimen collection and initial control measures. Sufficient typing data to guide environmental health and disease control initiatives was generated in less than one week by combining automated ribotyping with PCR-based detection of L. monocytogenes in suspect foodstuffs and an L. monocytogenes DNA probe. There were no further cases of bacteriologically confirmed listeriosis in Western Australia for six months after completion of the investigation.
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