VNTR typing of Mycobacterium leprae in South Indian leprosy patients.

OBJECTIVES: To study the suitability, stability and diversity of short tandem repeat (STR) genomic markers to elicit strain variation in the Mycobacterium leprae isolates within leprosy patients from Andhra Pradesh and Tamil Nadu states in South India. MATERIALS AND METHODS: Slit skin smear (SSS) samples were collected from lesions and various body sites of newly diagnosed leprosy patients. The SSSs from each patient were pooled, except in the case of five patients. Total DNA was extracted from SSS samples. M. leprae STRs were amplified from the DNA either by multiplex PCR (MP) or single PCR methods. The number of repeats for each STR locus (the STR allele) was obtained either by fragment length analysis (FLA) or by DNA sequencing of the PCR amplicons. RESULTS AND CONCLUSION: Multiplex PCR minimised the use of DNA and reagents, and together with FLA, was time and cost effective for STR strain typing. After examination of the isolates of South Indian origin at 13 STR loci, it was determined that the alleles for (AC)8b, (GGT)5, 6-3a (rpoT), 21-3, 27-5, and 23-3 were conserved in two study populations. In a family from Andhra Pradesh, the M. leprae STR patterns in two patients were identical in 16 of 18 loci which indicate a common source of infection. Fourteen of 15 STR loci showed no intra-patient variation in the five patients tested in Tamil Nadu. Altogether, these studies indicate the suitability of STR strain typing for assessing short-range transmission chains.

Validity of the WHO operational classification and value of other clinical signs in the classification of leprosy.

The objective of this study is to examine the validity of the WHO operational classification using skin smear results as the gold standard and explore the value of additional clinical signs independently and in combination with the WHO classification. Between 1985 and 2000, 5439 new untreated leprosy patients were registered at the Schieffelin Leprosy Research and Training Center, Karigiri. They were classified according to the Ridley Jopling classification as well as WHO operational classification based on the number of skin lesions. The sensitivity and specificity of the WHO operational classification tested, using skin smear results as the gold standard, was found to be 88.6% and 86.7% respectively. The Receiver Operator Characteristic (ROC) curve confirms that the best option for sensitivity and specificity is a cut off of 6 and more lesions for MB. The validity of the number of enlarged nerves and size of the largest skin lesion as independent criteria to classify patients was found to be poor. Addition of three enlarged trunk nerves to the WHO classification improved its sensitivity to 91.4%, while the specificity remained almost unchanged at 85.3%. Addition of the size of the largest skin lesion to the WHO classification reduced its validity considerably. The study concludes that the WHO recommendation of using six and more lesions for classifying a patient as MB is the best option available at the moment, and calls for further research to identify other clinical criteria that have a better validity and could be easily applied in the field.

Relapses in multibacillary patients treated with multi-drug therapy until smear negativity: findings after twenty years.

The Schieffelin Leprosy Research and Training Center at Karigiri, India participated in several of the World Health Organization (WHO) trials. The first trial on combined therapy in multi-bacillary leprosy was initiated in 1981. The main objectives of this field trial were to evaluate the efficacy of WHO recommended regimens in preventing relapses, especially drug resistance relapses. This paper reports on the relapses twenty years after patients were inducted into the WHO field trial. Between 1981 and 1982, 1067 borderline lepromatous and lepromatous patients were inducted into the WHO field trial for combined therapy in multi-bacillary leprosy trial. Among them, 357 patients were skin smear positive. During the follow-up in 2002, only 173 of them could be traced and assessed. The mean duration of follow-up was 16.4 +/- 1.83 years. Two patients relapsed 14 and 15 years after being released from treatment, the relapse rate being 0.07 per 100 person years follow-up. Drug susceptibility tests done on one of the relapsed patients revealed drug sensitive organisms to all multi-drug therapy drugs.

Secondary rifampin resistance following multi-drug therapy--a case report.

This is the first report of secondary resistance to rifampin following MDT in a patient with prolonged, but irregular treatment. Repeated mouse foot-pad studies demonstrated resistance to dapsone after several years of monotherapy, and following subsequent MDT the studies demonstrated the development of resistance to rifampin.