Article

Utility of Quantitative Polymerase Chain Reaction in Leptospirosis Diagnosis: Association of Level of Leptospiremia and Clinical Manifestations in Sri Lanka

Division of Infectious Diseases, Department of Medicine, School of Medicine, University of California San Diego, La Jolla, CA 92093-0741, USA.
Clinical Infectious Diseases (Impact Factor: 8.89). 02/2012; 54(9):1249-55. DOI: 10.1093/cid/cis035
Source: PubMed

ABSTRACT

Quantitative polymerase chain reaction (qPCR), despite cost and logistical challenges, has the potential to provide accurate and timely diagnosis for leptospirosis at the point-of-care in endemic areas. We studied optimal sample types for qPCR, timing of sampling, and clinical manifestations in relation to quantitative leptospiremia.
A new qPCR assay using pathogenic Leptospira-specific 16S ribosomal RNA (rRNA) gene Taqman primers and an optimized temperature stepdown protocol was used to analyze patient blood samples. Serum was compared with whole blood as sample source. Quantitative leptospiremia was compared with clinical manifestations of leptospirosis and outcome.
The diagnostic sensitivity of qPCR of whole blood and serum was 18.4% (95% confidence interval [CI]: 9.97%-31.4%) and 51.0% (95% CI: 37.5%-64.4%) respectively. The qPCR on suspected cases confirmed infection in 58 of 381 cases (15.2%). Of these, 6 cases confirmed by nested polymerase chain reaction (PCR) and sequencing were serologically negative using a standard but not regionally optimized microscopic agglutination test panel. The bacterial load in serum/blood ranged from 10(2) to 10(6) Leptospira/mL. Median leptospiral load for uncomplicated, renal failure, myocarditis, and multi-organ failure patients were 8616, 11007, 36100, and 15882 Leptospira/mL respectively. The qPCR window of positivity ranged from day 2 to day 15; sensitivity of qPCR was not affected by the length of the interval between the onset of symptoms and sample collection (P = .328).
Quantitative PCR shows potential as a valid diagnostic test with a wider window of positivity than previously thought. Quantitative leptospiremia in serum/whole blood samples did not directly correlate with clinical manifestations of outcome in this patient population.

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Available from: Suneth Buddhika Agampodi
    • "The advantage of these tests compared to MAT is that detection of genomic material can be done at a very early stage of the illness without having to wait for antibody development. In Sri Lanka, Agampodi et al.[26]used quantitative PCR to amplify 16 s rRNA, and found that sensitivity was much better when serum was used as the source than whole blood (51 vs 18%). Quantitative leptospiraemia correlated with myocarditis, renal failure and multi organ failure. "
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    ABSTRACT: The role of corticosteroids in the treatment of severe leptospirosis is unclear. The rationale for their use is that, in severe leptospirosis, there is a severe immunological response that is harmful to the host resulting in multi-organ dysfunction, which is potentially offset by the nonspecific immunosuppression of high dose steroids. We conducted a systematic review of studies that have assessed the use of high dose corticosteroids in patients with severe leptospirosis by searching MEDLINE and Scopus SciVerse without any language or time restrictions. We identified five studies, including one open randomized clinical trial, which had assessed the use of high dose steroids in severe leptospirosis. Four studies demonstrated a benefit of corticosteroids in treating severe disease with pulmonary involvement when administered early in the course of the disease, but these studies had several methodological constraints as highlighted in the text. Only the randomized controlled trial study showed that corticosteroids are ineffective and may increase the risk of nosocomial infections. There is no robust evidence to suggest that high dose corticosteroids are effective in severe leptospirosis, and a well-designed randomized clinical trial is needed to resolve this.
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