Evaluation of the polymerase chain reaction for early diagnosis of leptospirosis.

Early diagnosis of leptospirosis is important because severe leptospiral infection can run a fulminant course. The polymerase chain reaction (PCR) was evaluated for the detection of leptospires in clinical samples from patients with acute leptospiral infection. Blood and urine samples from 71 patients with leptospirosis were examined by PCR, culture or serology. Samples from 44 (62%) patients with the diagnosis of leptospirosis were positive by PCR as compared to 34 (48%) by culture. The presence of leptospires was demonstrated by PCR in 13 patients before the development of antibodies, as well as in two patients who were seronegative during their illness and at autopsy. Samples from 16 patients without leptospirosis were seronegative and culture negative, and also negative by PCR. We conclude that PCR is a rapid, sensitive and specific means of diagnosing leptospiral infection, especially during the first few days of the disease.

Simple method for production of internal control DNA for polymerase chain reaction assays for leptospira spp. - abstract

A simple and highly versatile one-step method for the production of internal control DNA for an established polymerase chain reaction assay for Leptospira interrogans is described. The internal control was produced from DNA of serovar bim, and is amplified with the same primers used routinely in our PCR assays. The inclusion of the internal control in the reaction mixture did not affect the efficacy of amplification of the target DNA. The method is simple and rapid and should be adaptable to most PCR assays for Leptospira spp. (AU)

Use of the polymerase chain reaction for rapid diagnosis of leptospirosis - abstract

Leptospirosis is endemic in Barbados with 97 percent of severe cases caused by three serovars of leptospira interrogans. Early diagnosis is important since the disease can run a fulminant course and patients may die before the appearance of characteristic clinical manifestations of Leptospirosis and/or leptospiral antibodies are detected, and therefore the disease may go unrecognized. In this study, the potential of the polymerase chain reaction (PCR) was explored for the early diagnosis of leptospirosis, with a view to detecting leptospirosis within the first ten days of the onset of the disease. Blood and urine samples from 83 patients with leptospirosis admitted to the Queen Elizabeth Hospital, Barbados, between January 1990 and December 1992, were examined serologically, by culture and by PCR. The mortality rate during the study period was 8.4 percent. PCR was more often positive than culture for the detection of leptospires in proven cases by antibody titre and detected the presence of leptospires in sera before the development of antibodies. As culture can take up to 13 weeks, it does not contribute to an early diagnosis. Seroconversion usually occurs on about the seventh day of the disease, thus diagnosis by serology can take a week or more to be decisive. PCR, on the day of admission, and the characterization of PCR products by Southern hybridization can be completed within one or two subsequent days. PCR is potentially a valuable addition to the diagnostic process in leptospirosis (AU)