Pulmonary melioidosis presenting with right paratracheal mass.

A rare case of pulmonary melioidosis is reported. The patient was a 62-year-old man presenting with subacute fever, dry cough, and significant weight loss. A chest x-ray revealed a right paratracheal mass. The findings from fiberoptic bronchoscopy were a blunt carina and normal tracheobronchial tree. The patient had an underlying disease of poorly controlled diabetes mellitus, heavy smoking, and heavy alcoholic drinking. One of the two cultured blood specimens grew B. pseudomallei. The pathological finding of transbronchial biopsy at the apical segment of the right upper lung showed lymphocytic infiltrates. He was treated with two weeks of intravenous ceftazidime plus cotrimoxazole followed by 5 months of oral doxycycline plus cotrimoxazole. Clinical symptoms significantly improved and the right paratracheal mass disappeared.

Seroprevalence of melioidosis in dairy cattle in Chiang Mai Province, northern Thailand.

The seroprevalence of melioidosis in dairy cattle in Chiang Mai Province was investigated using of the indirect hemagglutination antibody (IHA) method. Two hundred and fifty-three samples were tested for serum antibodies to Burkholderia pseudomallei. The samples were from a total population of 8,688 dairy cattle in the province; random sampling, stratified by the location of cattle, was used. The seroprevalence was determined as 2% at 1:40 cut-off value, which was estimated to equate to 0.3% to 3.7% (95% CI). This report of relatively low disease prevalence in the animal population corresponds to other prevalence studies of the agent in the environment and the human population in the region. The prevalence is markedly different to that reported from northeastern Thailand, where the disease is highly endemic.

Retrospective study on the diagnostic value of IgG ELISA, dot immunoassay and indirect hemagglutination in septicemic melioidosis.

Three serological methods for diagnosis of melioidosis were compared with the culture method currently used as the "gold standard". The diagnostic values of the serological methods were evaluated retrospectively in 306 patients residing in an endemic area. The enzyme-linked immunosorbent assay (ELISA), using affinity purified antigen for detecting specific IgG antibody, showed a slightly higher specificity (86.0%) than the dot immunoassay (DOT) (84.0%) and both were superior to indirect hemagglutination (IHA) (72.0%). The sensitivity of DOT (96.4%) and ELISA (85.7%) were considerably higher than that of IHA (50.0%). The primary benefit of the high negative predictive value of both ELISA (96.4%) and DOT (99.0%) in an area of high prevalence is the ability to rule out most of the non-melioidosis patients.

Burkholderia pseudomallei-specific recombinant protein and its potential in the diagnosis of melioidosis.

Melioidosis is an important public health problem in Southeast Asia and Northern Australia. This disease is caused by the gram-negative bacilli, Burkholderia pseudomallei. Wide spectra of clinical manifestations are observed in melioidosis ranging from asymptomatic to septicemic infection. Although serodiagnostic methods of melioidosis have been improved significantly in recent years, a highly specific diagnostic test that can differentiate asymptomatic seropositive individuals and melioidosis patients remains to be the subject of current investigations. In this study, a B. pseudomallei-specific gene, pBps-1, expressing a novel 18.7 kDa recombinant protein was selected from genomic libraries of two B. pseudomallei virulent isolates by using pooled sera from septicemic melioidosis patients. Nucleotide sequence analysis demonstrated that this gene is unique and does not show substantial similarity with any known genes in the Genbank database. The Bps-1 recombinant protein was evaluated for its potential in serodiagnosis of melioidosis by Western blot analysis. A high degree of specificity was demonstrated using sera from healthy individuals in the endemic (98.5%) and non-endemic areas (100%), with moderate sensitivity (69.7%) in melioidosis patients. The study demonstrated that this approach can be used to obtain highly specific recombinant antigens such as that described in the present report. A combination of such antigens should provide materials for successful serodiagnosis of melioidosis in the endemic areas.

The 1990-1991 outbreak of melioidosis in the Northern Territory of Australia: clinical aspects.

From November 1990 to June 1991, 33 cases of acute melioidosis were diagnosed in tropical Northern Territory, Australia during an exceptionally wet monsoon. Eighteen (55%) were alcoholic, 16 (48%) diabetic and only 4 (12%, all survivors) had no risk factors. Twenty-seven (82%) were considered recent infection, with an incubation period of 3-21 days (mean 14) documented in eight cases with presumed cutaneous inoculation. Fourteen patients presented with pneumonia (4 septicemic) and of 11 others with septicemia 4 had genitourinary foci. Three of 4 with splenic abscesses required splenectomy. Three had only skin/soft tissue infection. One patient with brainstem encephalitis needed prolonged ventilation. Overall mortality was 36% (12 cases, including three relapses), despite therapy with ceftazidime and intensive care facilities. Pseudomonas pseudomallei is the commonest diagnosed cause of fatal bacteremic pneumonia at Royal Darwin Hospital and emphasis is placed on early appropriate antibiotic therapy and compliance with maintenance therapy for at least three months.