Melioidosis: when in doubt leave the quinolone alone!
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Biomedical subjects
Publications and source records attributed to L R Ashdown.
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OBJECTIVE: To report the first human case of autochthonous melioidosis in temperate Australia (latitude 31 degrees 10'S) and to describe the extent of the presence of the causative agent, Pseudomonas pseudomallei, in southwest Western Australia. CLINICAL FEATURES: A 45-year-old man living on a hobby farm was admitted to hospital for investigation of lung lesions, weight loss and low grade fevers. P. pseudomallei was cultured from material from an aspiration biopsy of a mediastinal mass. INTERVENTION AND OUTCOME: The patient was successfully treated with a regimen of ceftazidime and trimethoprim-sulfamethoxazole. A review of epidemiological data showed that, since 1967, P. pseudomallei has been cultured from animals and soil in a region 50-250 km north-west of Perth, Western Australia, and that pockets of endemicity are found in the districts of Toodyay (where our patient's farm was), Chittering, Ballidu, Gidgegannup, Badgingarra, and Wongan Hills. CONCLUSION: The persistence of the bacterium in animals and soil in south-west Western Australia demonstrates abundantly that P. pseudomallei can exist opportunely beyond its traditional tropical habitat. It is likely that there will be further clinical cases of melioidosis originating in this region, and that the boundaries of endemicity in Australia will expand further.
OBJECTIVE: To describe the clinical presentation, diagnosis and management of strongyloidiasis in northern Queensland, and to identify predisposing factors for this infection. DESIGN: A five-year retrospective study of medical records of all cases diagnosed in a regional hospital microbiology laboratory, with follow-up by interview where possible. SETTING: The Townsville General Hospital. PATIENTS: A total of 14 cases of strongyloidiasis were identified, with patients ranging in age from 7 months to 59 years. RESULTS: Infected patients included nine Aborigines and two Vietnamese refugees, both high-risk groups. Of three Caucasians diagnosed, one was a war veteran, but the other two did not have significant travel histories; all three had lived or worked under insanitary conditions. In only one case was strongyloidiasis suspected; in most, it was diagnosed because of diarrhoea or blood eosinophilia which could not be related to the presenting illness. Thiabendazole treatment was effective in most cases. CONCLUSION: In northern Australia, strongyloidiasis can be acquired locally by Caucasians who live in unhygienic circumstances. It should be suspected in any person with unexplained abdominal pain, diarrhoea, cutaneous symptoms or blood eosinophilia, and the laboratory must be informed of the provisional diagnosis.
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Human infection with Pseudomonas pseudomallei, the causative agent of melioidosis, typically produces subclinical disease and an asymptomatic carrier state; occasionally clinical illness, frequently with a fatal outcome, may occur. Consequently, to help protect staff from laboratory-acquired melioidosis, microbiological and biomedical laboratories must have adequate facilities for safe work procedures and laboratory staff must engage in safe work practices. Recommendations from a melioidosis-endemic, diagnostic laboratory for the prevention of laboratory-acquired infection with this bacterium are essentially Category 3 (Advisory Committee on Dangerous Pathogens), Risk Group 3 (Australian Standards) or Biosafety Level 2 (National Institutes of Health) precautions. These include safeguards for centrifugation, prohibiting the 'sniff' test and the use of a biological safety cabinet for sputum processing, for subculture of stock strains, for preparation of antigen and for research studies but not for routine diagnostic techniques with P. pseudomallei.
The Minitek disc system was utilized for the differentiation of Pseudomonas pseudomallei, the causative agent of melioidosis, from Ps. cepacia. The system was simple to use, inexpensive, and furnished rapid, clear-cut test results after 4 h. This procedure is suitable for differentiating soil bacteria presumptively identified as Ps. pseudomallei, Ps. cepacia or flavobacteria, and for the rapid confirmation of the presumptive identification of either Ps. pseudomallei or Ps. cepacia obtained by commercial identification-kit systems in the clinical laboratory.
Of 46 patients with clinical melioidosis, 35 (22 culture-positive and 13 culture-negative) had relatively uneventful disease courses, with elevated serum C-reactive protein (CRP) concentrations (greater than 5 mg/dl) that decreased with the commencement of appropriate antibiotic therapy, and continued to show an uninterrupted decrease (mean 29.4 days, range 12-52 days) to the normal range (less than 1 mg/dl), with resolution of their infections. In five culture-positive patients with complicated disease courses, CRP concentrations remained elevated (greater than 5 mg/dl) until the underlying disorders were successfully managed, or until the antibiotic regimen was changed, and CRP values then decreased to the normal range. During surveillance, elevated CRP concentrations (greater than 10 mg/dl) led to the diagnosis of reactivation of infection in three afebrile patients, while the serum CRP values in other patients remained within the normal range in the absence of intercurrent complications. The CRP estimations may be helpful in ascertaining active infection in patients with low serum levels of specific IgM antibody, and serial measurements of serum CRP in patients with clinical melioidosis may be useful in determining the optimal duration of treatment and for detecting occult or unresolved infection with Pseudomonas pseudomallei.
By using enzyme immunoassay and immunofluorescence antigen detection techniques on sputum specimens, four of 260 patients with pulmonary infection resident in tropical Queensland were found to be infected with Chlamydia. All four chlamydial infections were community-acquired and there was no history of close contact with birds by any of the four patients. One woman was deemed to be suffering with Chlamydia pneumonia, while the role of the organism in the pathogenesis of respiratory disease in the other three patients was indeterminate. At present, the incidence of pulmonary chlamydial infection in the population of tropical Queensland does not warrant routine testing, but investigations for these organisms should be undertaken in patients who present to their physicians with atypical pulmonary infection or whose clinical conditions are refractory to penicillin/ampicillin therapy.
OBJECTIVE: To report the success of hyperbaric oxygen therapy in the treatment of Nocardia brasiliensis mycetoma. We believe this to be only the second report in the medical literature of hyperbaric oxygen therapy used in the therapy of nocardial disease. CLINICAL FEATURES: A 78-year-old man presented to a general hospital outpatient clinic after eight months with a painless swollen left foot. There was no significant medical history, no trauma had occurred, and no foreign body had been detected. The dorsum of the foot had a discharging sinus, from which N. brasiliensis was isolated. INTERVENTIONS: After unsuccessful treatment with surgical debridement and high-dose antibiotic therapy, hyperbaric oxygen therapy was administered in a multiplace recompression chamber (one hour of treatment at 1.8 atmospheres absolute followed by a 30 minute "ascent" to surface pressure). A total of 19 treatments were administered. OUTCOME: Successful healing of an N. brasiliensis mycetoma of the left foot. CONCLUSION: In this case of N. brasiliensis mycetoma involving the lower extremity, the conventional management of surgery and antibiotic therapy was unsuccessful, and only with the addition of hyperbaric oxygen therapy did clinical recovery occur.
Salmonella virchow is the second most commonly isolated salmonella serotype from human sources in Australia, and overseas studies indicate that S. virchow is a significant cause of extraintestinal salmonellosis. The successful management of three infants, two with septicaemia and one with leptomeningitis and septicaemia due to S. virchow, is described. A review of the Townsville General Hospital laboratory records (1978-1988) showed that, among other aspects, S. virchow accounted for 46% of all salmonella septicaemias, further exemplifying the invasive propensity of this serotype. Information obtained from various sources, after crude analyses, demonstrates that more than 90% of S. virchow infections in humans in Australia occur in Queensland, and that most (greater than 78% in 1987) of those infections in Queensland come from a coastal zone north of Bundaberg, with the highest concentration (0.4 per 1000 persons) occurring in the Cairns region.
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One hundred clinical isolates of Pseudomonas pseudomallei from humans were tested for their ability to produce extracellular, biologically active substances which are thought to contribute to the virulence of Pseudomonas species. All isolates produced at least on extracellular enzyme; 91 strains were positive for lecithinase, lipase, and protease; but none was positive for elastase. Ninety-three strains produced a hemolysin which was detectable around the heavy growth on saline-washed sheep erythrocyte brain heart infusion agar but not demonstrable around individual colonies or in broth culture filtrate. In contrast, a hemolysin which was cytolytic around individual colonies of P. pseudomallei on the assay plate and in broth culture filtrate was exhibited by four strains. By using one of these four isolates as the test strain, the latter hemolysin was characterized further. It was heat labile, most active in an acid environment (pH 5.5), and cytolytic in broth culture filtrate for a variety of animal and human erythrocytes. Sterols, particularly cholesterol and 7-dehydrocholesterol, inhibited its hemolytic activity, but the activity was not enhanced by reducing agents or suppressed by reagents which modify sulfhydryl-activated hemolysins. A nonhemolytic mutant of the test strain of P. pseudomallei retained the extracellular enzymes of its parent, indicating that the hemolysin was not a lecithinase, lipase, or protease.
Three selective isolation media and the paraffin baiting technique were compared with conventional culture (Sabouraud dextrose agar without antibiotic supplement) for the ability to grow and detect nocardiae from simulated sputum specimens. Modified Thayer-Martin medium, incorporating vancomycin, colistin, nystatin and trimethoprim as selective agents, produced the highest recovery rate and with the greatest suppression of normal respiratory tract flora. A clinical evaluation using a screening programme devised for a busy diagnostic microbiology laboratory was performed on 1600 sputum specimens. Inoculating sputum on modified Thayer-Martin medium and extending the initial incubation period of 3 days at 35 degrees C under 10% carbon dioxide to a further 3 weeks at room temperature in a candle jar, led to the diagnoses, which otherwise would have been missed, of pulmonary nocardiosis in 3 patients and pulmonary infections due to Neisseria meningitidis, Pseudomonas cepacia, and Serratia marcescens in a further 22 patients.
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Thirteen cases of granuloma inguinale were diagnosed in just over a twelve-month period at the Australian Government Health Laboratory and the General Hospital, Townsville. Seven patients were males, four of whom were immates of Her Majesty's Prison, Townsville. Two of the patients were married, and two were sisters. All the female patients were pregnant at the time of diagnosis. The provisional diagnosis was confirmed by the presence of intracytoplasmic Donovan bodies in crushed tissue smears stained with Wright's stain and pinacyanole. The diagnosis of granuloma inguinale could not be reliably made from sections of formalin-fixed tissue alone. The clinical findings, methods of laboratory diagnosis, management and treatment of this disease are also described with an added emphasis on treatment during pregnancy.
Ninety-one strains of Pseudomonas pseudomallei were tested in the API 20E system and in equivalent conventional tests. Except for utilisation of citrate there was good correlation between API and conventional tests. Seven-digit profiles were constructed from each strain after 48 hours' incubation, and numerical codes 2 006 727, 2 206 706, 2 206 707, and 2 206 727 accounted for 77% of strains tested. API 20 E, in combination with tests for heat stability of alkaline phosphatase, resistance to colistin and gentamicin, oxidative attack only of glucose, and acid from maltose, was found to provide a simple method for positive identification of all strains of this organism in two days.
A selective medium consisting of trypticase soy agar with 4% glycerol, 5 mg/l crystal violet, 50 mg/l neutral red and 4 mg/l of gentamicin was devised for isolation of Pseudomonas pseudomallei from clinical specimens. Absorption of neutral red was found to be suitable for differentiating this organism from other bacteria, while gentamicin was effective in selecting Ps. pseudomallei from organisms commonly found in clinical material. The medium was more suitable for screening clinical specimens than MacConkey's agar with colistin-S because it was more selective and allowed multiple specimens to be inoculated on a single plate. Eight thousand clinical specimens from an area endemic for melioidosis were screened on the selective medium. This resulted in the recovery of 8 isolates of Ps. pseudomallei that would not have been detected using routine culture media alone.