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.
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.
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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.
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The development of a human milk bank with nursing mothers as donors of human milk is described. Breast milk is collected manually, and as aseptically as possible, by the mother in the privacy of her home, and the milk is transported frozen to the milk bank by a member of the Nursing Mothers' Association of Australia. A sample of expressed milk is also collected and sent to the Microbiology Department of the Australian Government Health Laboratory for bacteriological examination. The milk bank is suitably located in the paediatric ward of the Townsville General Hospital. Human milk which has been classed as bacteriologically safe is given untreated to hospitalized infants in preference to formula milk. The result is a human milk bank which is administered under medical and microbiological control.
A case of neonatal osteomyelitis and meningitis caused by group B streptococci is reported; the organism isolated was found to be similar or the same as an organism cultured form the maternal vagina. The clinical course and management is also described.
Pseudomonas pseudomallei was recovered from urine specimens of two patients who acquired the organism after they were admitted to a hospital in a region in which it is endemic. Both patients were diabetic and both had urethral catheters passed while they were hospitalized. samples of soil taken from the hospital grounds yielded an isolate of P. pseudomallei that was identical biochemically and by antibiogram to the two isolates recovered from the urine specimens of the two patients. The two patients stayed in wards located in separate hospital blocks, which were geographically distinct but connected by a walkway. The relevant clinical histories of the two patients and the epidemiologic and microbiologic characteristics of the P. pseudomallei isolates were studied. Sera from both patients showed a significant rise in titers of antibody specific for P. pseudomallei. These two patients are considered to represent the first reported cases of hospital-acquired infection due to P. pseudomallei.