A comparison of two molecular methods for diagnosing leptospirosis from three different sample types in patients presenting with fever in Laos.

OBJECTIVES: To compare two molecular assays (rrs quantitative PCR (qPCR) versus a combined 16SrRNA and LipL32 qPCR) on different sample types for diagnosing leptospirosis in febrile patients presenting to Mahosot Hospital, Vientiane, Laos. METHODS: Serum, buffy coat and urine samples were collected on admission, and follow-up serum ∼10 days later. Leptospira spp. culture and microscopic agglutination tests (MAT) were performed as reference standards. Bayesian latent class modelling was performed to estimate sensitivity and specificity of each diagnostic test. RESULTS: In all, 787 patients were included in the analysis: 4/787 (0.5%) were Leptospira culture positive, 30/787 (3.8%) were MAT positive, 76/787 (9.7%) were rrs qPCR positive and 20/787 (2.5%) were 16SrRNA/LipL32 qPCR positive for pathogenic Leptospira spp. in at least one sample. Estimated sensitivity and specificity (with 95% CI) of 16SrRNA/LipL32 qPCR on serum (53.9% (33.3%-81.8%); 99.6% (99.2%-100%)), buffy coat (58.8% (34.4%-90.9%); 99.9% (99.6%-100%)) and urine samples (45.0% (27.0%-66.7%); 99.6% (99.3%-100%)) were comparable with those of rrs qPCR, except specificity of 16SrRNA/LipL32 qPCR on urine samples was significantly higher (99.6% (99.3%-100%) vs. 92.5% (92.3%-92.8%), p <0.001). Sensitivities of MAT (16% (95% CI 6.3%-29.4%)) and culture (25% (95% CI 13.3%-44.4%)) were low. Mean positive Cq values showed that buffy coat samples were more frequently inhibitory to qPCR than either serum or urine (p <0.001). CONCLUSIONS: Serum and urine are better samples for qPCR than buffy coat, and 16SrRNA/LipL32 qPCR performs better than rrs qPCR on urine. Quantitative PCR on admission is a reliable rapid diagnostic tool, performing better than MAT or culture, with significant implications for clinical and epidemiological investigations of this global neglected disease.

Falciparum malaria as a cause of fever in adult travellers returning to the United Kingdom: observational study of risk by geographical area.

BACKGROUND: The probability that a returned traveller with a history of fever has malaria is likely to vary by geographical area, but this has not been quantified in travellers. AIM: To collect data on prevalence of malaria in outpatients returning with a fever or history of fever from malaria-endemic countries, at the point of presentation for a malaria test. DESIGN: Observational retrospective study. Consecutive patients presenting to an unselected 'walk-in' clinic for returned travellers. RESULTS: Of 2867 patients meeting inclusion criteria, 337 (11.8%) had malaria, 89.5% originating in sub-Saharan Africa. Of travellers returning from sub-Saharan Africa excluding South Africa with fever/history of fever, 291/1497 had malaria (19.4%, 95% CI 17-21%). A high proportion was visiting friends and relatives. In those from other areas the proportions were: 16/707 (2.3%, 95% CI 1.5-3.8) from Indian subcontinent/Southeast Asia; 2/143 (1.4%) from Southern America; 4/129 (3.1%) from South Africa; 1/44 (2.3%) from North Africa; and 8/41 (19.5%) from Oceania. Compared to other malaria-endemic regions, African travel gave an adjusted odds ratio of 7.8 (95% CI 5.4-11.2, P < 0.0001). Only 45.1% of malaria cases had a fever (> or =37.5 degrees C) at the time of presentation. Only 3% of all diagnoses of malaria had no history of fever. In 28% of cases parasite count increased in the initial 24 h of antimalarial treatment. CONCLUSION: The likelihood that a patient with fever returning from Africa has malaria is high (around 1 in 5), and is significantly lower from other areas. Absence of fever at presentation does not exclude malaria.

Physician-initiated courtesy MODS testing for TB and MDR-TB diagnosis and patient management.

SETTING: Laboratorio de Investigación de Enfermedades Infecciosas, Universidad Peruana Cayetano Heredia (UPCH) and government health centres, Lima, Peru. OBJECTIVE: To evaluate the contribution of unselected (courtesy) microscopic observation drug susceptibility (MODS) testing to the diagnosis and/or drug susceptibility testing (DST) of tuberculosis and their subsequent impact upon patient management. DESIGN: Retrospective database analysis and case note review of MODS culture-positive cases. RESULTS: Mycobacterium tuberculosis was isolated in 28.9% of 225 samples (209 patients); 22.2% of 63 positive cases were multidrug-resistant. In 58 MODS culture-positive cases with follow-up data available, MODS provided culture confirmation of diagnosis, DST or both in 82.8%, before any standard method. In 41.4%, this result should have prompted a modification in patient management. Delays between laboratory result and initiation or change of treatment, where applicable, took on average 42 and 64 days, respectively, of which a delay of respectively 17 and 48 days occurred after the receipt of results by the health facility. CONCLUSION: MODS provides important data for clinical management within a meaningful timeframe and should contribute positively to patient outcomes due to earlier initiation of appropriate therapy. Although clinicians may successfully select patients likely to benefit from MODS, ongoing work is required to identify optimal implementation of the assay and to reduce logistical and health system derived delays.