Mycobacterium leprae particle agglutination in diagnosis and monitoring of treatment of leprosy.

IgM antibody levels against PGL-1 antigen were measured by M. leprae particle agglutination (MLPA) in 156 untreated leprosy patients. The seropositivity rate was much higher in newly untreated MB patients (84.7%) than in PB patients (19.7%). The mean MLPA titers in MB and PB declined significantly after 1 month of MDT (p < 0.001). Seropositivities in control serum specimens were 11.3 per cent in active pulmonary tuberculosis patients, 2.6 per cent in dermatologic patients and 4.4 per cent in a healthy population, in low titers. The study confirms that, anti PGL-1 assay using MLPA is a sensitive and specific diagnostic tool for the diagnosis of leprosy especially MB patients. Additionally, it provides an alternative tool in monitoring leprosy patients under MDT.

DNA amplification for detection of leprosy and assessment of efficacy of leprosy chemotherapy.

Polymerase chain reaction (PCR) for the detection of Mycobacterium leprae was applied to fresh skin biopsies and slit-skin smears from 122 untreated leprosy patients. The PCR positivity rates in biopsies were 95.6% in multibacillary (MB) cases and 44.2% in paucibacillary (PB) cases. Following 1 month of treatment, MB cases declined by 54.3% and PB cases by 61.8% of initial values. Six-month values also declined from initial positivity rates to 50.3% and 53.8% of initial values in MB and PB, respectively. Larger declines in the rate of positivity were seen for skin-smear samples at 1 and 6 months in both MB and PB, but overall PCR positivity rates were lower than biopsy rates for M. leprae.

Ofloxacin containing combined drug regimens in the treatment of multibacillary leprosy.

The results of ofloxacin containing combined drug regimens in the treatment of 60 multibacillary leprosy cases from January 1989 to June 1995 are reported. The objective of the trial is to compare the antileprotic property of ofloxacin and rifampicin in multibacillary leprosy patients and to study the killing rate of M. leprae by ofloxacin and rifampicin before mass treatment can be recommended. The complications and side-effects of ofloxacin and rifampicin were of a mild nature and both drugs were well tolerated. Moderate to marked clinical improvement was noticed in a short period with ofloxacin containing regimens in multibacillary leprosy patients. No persisters were detected in any of the 33 specimens (of mouse footpads) that had been obtained after treatment for 6 months. Ofloxacin if added to the currently used WHO recommended MB-MDT regimen may shorten the duration of treatment. Ofloxacin, therefore, may be considered as a suitable alternative in suspected/proven rifampicin resistant cases and where rifampicin is contraindicated. The results were evaluated on the basis of the clinical conditions, mycobactericidal effectiveness, signs of drug toxicity and side effects.

Use of NASBA RNA amplification for detection of Mycobacterium leprae in skin biopsies from untreated and treated leprosy patients.

This study was performed to assess the value of NASBA RNA amplification of a 16S rRNA target for the detection of presumably viable Mycobacterium leprae in sections of skin biopsies from leprosy patients. The NASBA positivity rate was 90.4% (84/93) for untreated multibacillary (MB) patients [bacterial index (BI) > or = 2] and 16.7% (8/48) for the untreated paucibacillary (PB) patients (BI < 2). NASBA positivity showed a good concordance with the presence of solidly stained M. leprae [morphological index (MI)] in skin biopsies from leprosy patients, but no relationship could be demonstrated between the strength of the NASBA signals and the BI. Furthermore, the usefulness of the detection of 16S rRNA by NASBA to monitor the efficacy of leprosy treatment was investigated using an additional 154 biopsy specimens analyzed from 80 MB patients during the course of treatment. The NASBA positivity rate declined during treatment. A significant decrease was observed after only 1-3 months. These results favor the view that detection of RNA by NASBA may reflect the viability of M. leprae.

Anti-PGL-1 antibody levels in Thai leprosy patients.

Phenolic glycolipid - 1 (PGL-1) is a Mycobacterium leprae specific cell wall component. It is an immunodominant antigen and can induce a strong humoral immune response. IgM antibody levels against PGL-1 were measured in Thai leprosy patients between October 1992-April 1994 by a commercially available M. leprae particle agglutination test (MLPA). The percentage of seropositivity was much higher in newly untreated multibacillary (MB) patients (83.9%) than in paucibacillary (PB) patients (17.8%). Antibody levels in the MB group varied in the range 32-8,192, whereas they varied in the range 32-256 in the PB group. Patients being treated with multidrug therapy (MDT) were 68.3% and 19.4% seropositive in the MB and PB groups, respectively. Seropositivities in control serum specimens were 11.3% in active pulmonary tuberculosis patients, 2.6% in dermatologic patients and 4.4% in a healthy population. In conclusion, the anti-PGL-1 assay using MLPA appears to be a sensitive and specific diagnostic tool for the diagnosis of MB patients. Additionally, it may provide an alternative to the BI determination in monitoring MB patients under MDT, and also in the surveillance of such patients after MDT.

Combined chemotherapy trials with regimens containing ofloxacin and rifampicin for multibacillary leprosy patients.

The results of combined chemotherapy trials with regimens containing ofloxacin and rifampicin for the treatment of 60 multibacillary leprosy cases from January 1989 to September 1995 was reported. Clinical improvement was achieved by all regimens from the end of the first month. Most patients continued to improve for 3 years. Bacterial indices were gradually reduced during the treatment. Patients on regimens containing rifampicin were clear of M. leprae at the end of the 5th year. The complications and side-effects of ofloxacin and rifampicin were trivial and both drugs were well tolerated. Ofloxacin added to the current WHO recommended M.B.-MDT regimen may shorten the duration of treatment. Ofloxacin may be an alternative in suspected/proven rifampicin resistant cases or rifampicin contraindicated.

Detection of Mycobacterium leprae infection by PCR.

PCR amplification of the 531-bp fragment of the Mycobacterium leprae pra gene in fresh biopsy and slit skin smear samples was evaluated for its usefulness in the detection of leprosy bacilli in patients in Thailand. In multibacillary patients, 87.1% (27 of 31) of biopsy specimens and 41.9% (13 of 31) of slit skin smear specimens were positive by PCR, whereas in paucibacillary patients, 36.4% (8 of 22) of biopsy specimens and 18.2% (4 of 22) of slit skin smear specimens yielded detectable PCR amplification. Compared with other diagnostic procedures, PCR showed a clear advantage over both microscopic examination of slit skin smears and serologic detection of anti-phenolic glycolipid 1 antibody, especially in paucibacillary patients when bacterial indexes were 0 and seropositivity was only 6.25%. PCR was also evaluated for its potential to help monitor bacterial clearance in some of these patients during chemotherapeutic treatment. The PCR results on slit skin smear samples at 1, 3, and 6 months of chemotherapy showed that the number of PCR-positive cases of both multibacillary and paucibacillary types decreased sequentially. The results of this study are encouraging. However, investigation of a larger number of clinical specimens with an improvement in PCR methods, especially on slit skin smears, needs to be done before PCR can be established as a diagnostic procedure for leprosy patients and subclinical cases or as a tool for drug assessment.