Characterization of the Leptospira interrogans S10-spc-alpha operon.

A ribosomal protein gene cluster from the spirochaete Leptospira interrogans was characterized. This locus is homologous to the Escherichia coli S10, spc, and alpha operons. Analysis of L. interrogans RNA showed that the ribosomal protein genes within this cluster are co-transcribed, thus forming an operon. Two transcription initiation sites were mapped by primer extension, upstream of fus, the first gene in this cluster, and sequences from this region provided promoter activity in E. coli. Transcription terminates near a predicted stem-loop structure following rplQ, the last gene in the cluster. These data suggest that two promoters upstream of fus direct transcription of this 17.5-kb ribosomal protein gene cluster. Comparison of the L. interrogans S10-spc-alpha cluster to homologous loci from Borrelia burgdorferi and Treponema pallidum provided evidence that this region of the genome underwent several rearrangements during spirochaete evolution.

Detection of leptospires in urine by PCR for early diagnosis of leptospirosis.

We tested urine samples from patients at different stages of current leptospirosis and thereafter to determine whether use of the PCR for detection of leptospires in urine can be a valuable alternative to culturing. The procedure of DNA extraction and subsequent PCR applied to 15 freshly voided urine samples proved to be twice as sensitive as culturing. Overall, we were able to detect leptospires in approximately 90% (26 of 29) of the urine samples. Urine and serum samples were obtained from seven patients, before the eighth day of illness. Although it is generally assumed that leptospiruria starts approximately in the second week of illness, we were able to detect leptospires in all of these early urine samples. In contrast, only two of seven corresponding serum samples gave positive PCR results, which suggests that PCR analysis of urine can be more successful for early diagnosis of leptospirosis than PCR analysis of serum. Urine samples from six patients who had been treated with antibiotics at the time of illness were positive by PCR, implying that the patients were still shedding leptospires in their urine despite treatment. Some of these samples were even taken years after the infection, indicating that shedding of leptospires in urine may last much longer than is generally assumed. We conclude that detection of leptospires in urine with PCR is a promising approach for early diagnosis of leptospirosis and may also be useful in studying long-term shedding.