Rapid detection of ethambutol-resistant Mycobacterium tuberculosis in clinical specimens by real-time polymerase chain reaction hybridisation probe method

Background

Early diagnosis of drug resistance (DR) to ethambutol (EMB) in tuberculosis (TB) remains a challenge. Simple and reliable method (s) are needed for rapid detection of DR Mycobacterium tuberculosis (MTB) in clinical specimens.

Objectives

The aim of this study was to design fluorescence resonance energy transfer hybridisation probe-based real-time polymerase chain reaction (PCR) method for the early detection of EMB-resistant MTB direct from clinical sputa.

Materials and Methods

Primers and probes were designed against 306 codon of embB gene which is commonly associated with EMB resistance. A comparative study was done between Lowenstein-Jenson (L-J) proportion and hybridisation probe-based real-time PCR method for susceptibility testing. DNA sequencing was used in nine representative isolates to validate the efficiency of real-time PCR method to detect emb306 mutation of MTB.

Results

A total of 52 clinical sputum samples and corresponding culture isolates (from category II pulmonary TB cases) were included in this study. Out of 52 MTB isolates, 32 and 20 were resistant and susceptible to EMB, respectively, as determined by L-J proportion method. Real-time PCR showed 95% specificity, 75% sensitivity and 82.69% accuracy when compared with L-J proportion method. A 100% of concordance was observed by validating the real-time PCR results with DNA sequencing.

Conclusions

Our real-time PCR hybridisation probe method promises for rapid detection of EMB-resistant MTB directly from clinical specimens. However, future studies and modifications of method by incorporating other potential loci along with targeted mutation (emb306) are still required to increase the sensitivity of method.

Human immunodeficiency virus and hepatitis B virus co-infections among tuberculosis patients attending a Model Rural Health Research Unit in Ghatampur, North India

INTRODUCTION

This prospective cross-sectional hospital-based study was carried out in order to assess the prevalence of human immunodeficiency virus (HIV) and hepatitis B virus (HBV) infections among patients with active tuberculosis (TB) disease attending an Outpatient Department (OPD) at the Model Rural Health Research Unit in Ghatampur, a rural village in Kanpur district.

MATERIALS AND METHODS

The socio-demographic features and clinical profile of the TB patients were analysed in the context of symptoms at the time of testing. The HIV and HBV status were determined and correlated with clinical features at the time of testing.

RESULTS

In our study, the prevalence of HIV infection among TB patients is 1.48% (18/1215) and that of HBsAg reactivity was found to be 2.96% (36/1215). During 2007-2010, the HIV-positivity varied between 1.5% and 1.45% whereas HBV reactivity ranged between 2.4% and 3.63%.A substantial percentage of the TB patients attending the OPD in Ghatampur harbour HIV and HBV infections, which otherwise would remain undiagnosed without serological screening.

CONCLUSION

Co infection with HBV among TB patients potentiate the risk of anti-tuberculous therapy-induced hepatotoxicity, therefore, exercising caution and carefully monitoring the patients for drugs associated hepatotoxicity is essential. There is an urgent need to perform population-based surveys of HIV and hepatitis infections among TB patients to assess the true extent of the problem. Efforts should be made to make physicians aware of the peculiarities and manage these patients effectively.

Evaluation of the diagnostic value of immunocytochemistry and in situ hybridization in the pediatric leprosy

Leprosy is characterized by a long and variable incubation period and a chronic clinical course. Diagnosis of leprosy is essentially based on clinical features. Although the majority of cases can be diagnosed clinically yet alternative methods for diagnosis are required especially for early cases. Immunocytochemistry and in situ hybridization can be a valuable tool for diagnosis for early cases. The present study is aimed to assess the diagnostic value of immunocytochemistry and in situ hybridization in cytological specimens and to compare these techniques with Z.N. staining. This prospective study was carried out in 26 patients below 18 years of age of leprosy. Clinical examination of each patient was done and categorized according to IAL. After taking consent, three skin smears was taken, one for Z.N. staining and remaining two for immunocytochemistry and in situ hybridization respectively. Routine skin smear examination by Z.N. staining method confirmed the diagnosis in 4/26 (15.83%) and these belonged to BB, BL category. Immunocytochemistry showed positivity in 10/15 (66.6%) in BT and 72.7% in BB/BL leprosy. Immunocytochemistry improved the diagnosis by 53.85%, and the results were statistically significant (p < 0.01). In situ hybridization showed the positive results in 80% cases of BT leprosy and 90.9% cases of BB/BL leprosy. In situ hybridization improved the diagnosis by 70% in comparison to ZN staining and the results were statistically significant (p < 0.01). This study supports that immunocytochemistry and in situ hybridization enhance the diagnosis of leprosy when compared to routine skin smears stained by Z.N staining. They are important diagnostictoolsfor definitive diagnosis in early as well as established cases of leprosy.

Clinical and histopathological evaluation of the effect of addition of immunotherapy with Mw vaccine to standard chemotherapy in borderline leprosy

This study reports detailed analysis of clinical parameters and clearance of granuloma in borderline leprosy patients treated with immunotherapy and chemotherapy. It aims to assess the additive effect of immunotherapy (Mwvaccine) with standard MDT on clinical status of untreated borderline leprosy cases and on granuloma fraction of untreated borderline leprosy cases. Patients attending the OPD were serially recruited in two groups. A total of 150 cases in one treatment (trial) group (Mw vaccine plus MDT) and 120 cases in another treatment (control) group (MDT only) of border line leprosy have been included. After the formal written consent, detailed clinical examination, charting, smear examination of all untreated borderline patients of both groups was done, biopsies were taken from the active lesions of all patients of both groups at start of therapy and every six month thereafter till the completion of therapy. The same procedure was repeated every six months during the follow-up period. Standard MDT was given to all the patients of both groups according to type of disease. Mw vaccine 0.1 ml (0.5 x 10(9) bacilli) was injected intra-dermally at the start of therapy and every six months in addition to chemotherapy to the treatment group. The BT cases were followed up after 6 doses of MDT and 2 doses of Mw vaccine, and, the BB, BL cases were followed up after 24 doses of MDT plus 5 doses of Mw vaccine. Clinically, greater and faster improvement was observed in all the clinical parameters, faster attainment of smear negativity and two episodes of lepra reaction occurred in cases treated with combined chemotherapy and immunotherapy, as compared to controls (chemotherapy alone) wherein clinical improvement was slower in all parameters, slower attainment of smear negativity in bacillary index and seven showed the occurrence of reactions, histipathologically in addition to more rapid clearance of granuloma in immunotherapy treated group, a significant finding was an increase in the epithelioid cells population in this group. This suggests a possible immunoactivation of the macrophages especially in BB/BL immunotherapy group. Overall comparison of regression induced by chemotherapy alone with that induced by combined chemotherapy and immunotherapy shows a greater reduction in clinical parameters as well as granuloma fraction in BT cases as well as in BB/BL cases. This trial shows the potential usefulness of this approach of addition of immunotherapy to standard chemotherapy in borderline leprosy cases which leads to in faster recovery from disease reduced chances of reactions and faster granuloma clearance. Such information is expected to be useful in improving the immunotherapeutic approaches for treatinggranulomatous conditions in general and in leprosy in particular.

Histological diagnosis of early and suspicious leprosy by in situ PCR

Leprosy is a chronic mycobacterial disease whose diagnosis is primarily based on clinico-pathological examination and supported by slit skin smears for the presence of acid fast bacilli (AFB). However, definitive diagnosis of early leprosy and those suspected to have the disease but not histologically confirmed pose major public health problems. The present study reports the utility of the in situ Polymerase Chain Reaction amplification (PCR) directed at a 530bp fragment of DNA encoding the 36kd antigen of the causative Mycobacterium leprae for the diagnosis of such patients using skin biopsies of lesions. Twenty five adult patients (aged 15-50yrs) each from the clinical categories of Early and clinically Suspect leprosy were selected for the study after obtaining permission. They had solitary lesions, which were negative for AFB on slit skin smear examination. Routine histopathology confirmed the diagnosis of leprosy in 8/25 (32%) cases in the category of Early leprosy with AFB being seen in 2 biopsies, and in 5/25(20%) cases of Suspect leprosy with AFB being seen in a solitary case. The Direct in situ PCR procedure which was performed in the histologically unconfirmed cases improved the diagnosis with positive results observed in 12/17 (70.6%) cases of Early (p=0.001) and in 12/20 (60%) cases of Suspect Leprosy (p=0.005 indicating the usefulness of the Direct in situ PCR to establish the diagnosis of leprosy in histologically doubtful cases.

Evaluation of diagnostic role of in situ PCR on slit-skin smears in pediatric leprosy

A large proportion of early cases of leprosy in children remain AFB negative in skin smears. Such cases required additional techniques to confirm the diagnosis. In situ PCR on slit- skin smears is minimally invasive and less cumbersome as compared to skin biopsies. This study was initiated in our institute with the objective to evaluate the diagnostic value of in situ PCR on slit- skin smears in pediatric leprosy. A total of 25 cases of leprosy below 16 years of age were included in the study. After detailed history and thorough clinical examination, informed consent was obtained from the parents of children for slit- skin smears from lesion sites for AFB staining and for in situ PCR technique. Cases were clinically categorized according to IAL classification into indeterminate (I), tuberculoid tuberculoid (TT), borderline tuberculoid (BT), borderline borderline (BB), borderline lepromatous (BL) and lepromatous (LL). Most of the patients (76%) were between 9-16 years of age and 64% of the cases had history of contact with leprosy patients within the family. Skin smears were positive for AFB in only 20% of the cases. On applying in situ PCR, it was observed that 62.5% cases of I/TT/BT/BB category and 88.8% of BL/LL category gave positive signals. Overall in situ PCR confirmed the diagnosis in 72% cases while by slit smears diagnosis was confirmed in only 20% of cases. Further, out of 20 skin smear negative cases, 13 were positive by in situ PCR. Specificity of the signals of in situ PCR was established by demonstrating the absence of signals in nonleprosy dermatological conditions of vitiligo and P.alba. This study supports the potential usefulness of in situ PCR on slit- skin smears of early pediatric leprosy cases. This strategy will be especially useful in cases where skin smears are negative and in those cases where skin biopsy can not be done either because of unusual locations of lesions or because of sensitive age of the patients.

Study of rifampicin resistance and comparison of dapsone resistance of M. leprae in pre- and post-MDT era

The aim of this study to study the drug resistance patterns of dapsone (pre- and post-MDT) and rifampicin (post-MDT era). All the 84 patients from pre-MDT period (1985-1990) and 77 patients for post-MDT period (1990-2002) reporting to a tertiary care hospital-NJIL & OMD, Agra and referred for drug susceptibility testing were included in the study. Drug resistance was studied by mouse foot pad method. Dapsone resistance was high during pre-MDT era i.e. 8.3% (medium) and 19.1% (high) with an overall dapsone resistance of 27.4%. During the post-MDT era, the dapsone resistance was low i.e. 1.3% (medium) and 3.9% (high) respectively (overall dapsone resistance-5.2%). While no comparison with pre-MDT era is available, the rifampicin resistance in these selected self-reporting cases during the post-MDT era was comparatively rather high (9.1%). MDT appears to have been useful in reducing the prevalence of dapsone resistance in leprosy patients reporting to a tertiary care hospital.

Potential of a metabolic gene (accA3) of M. leprae as a marker for leprosy reactions

Understanding the mechanism(s) of reactions in leprosy remains a challenging task for both clinicians and basic scientists. While there is some understanding of host processes associated with different type of lepra reactions, there is very little information about bacterial factors triggering these inflammatory processes. This study is continuation of our earlier research programme on leprosy genomics in which significant transcription of 11 genes was observed during active disease and these included accA3 gene. In present study, we have investigated the potential of this gene or its gene product as molecular and or immunological marker for studying the reactions. Using quantitative Real-Time RT-PCR significant higher expression (mean log2 ratio=3.39) of accA3 was observed in specimens from leprosy reaction cases compared with cases without reactions. in silico homology model of this protein was analyzed for hydrophilic and B-cell epitope regions. Peptides with maximum antigenecity were selected, cloned, expressed and used to study sero-reactivity across the disease spectrum by indirect ELISA. While sero-reactivity was observed in leprosy cases the antibody levels did not vary significantly between the patient/s of same clinical type with and without reaction thereby indicating the limitation of this approach for this purpose. Measurement of transcription of this gene has, thus, potential as a molecular marker for monitoring the reactions.

In vitro effect of fluoroquinolones against Mycobacterium tuberculosis isolates from Agra & Kanpur region of north India

BACKGROUND & OBJECTIVE

Fluoroquinolones (FQs) are important drugs used for treatment of drug resistant tuberculosis and are also now being considered as first line drugs to shorten the duration of treatment of tuberculosis (TB). In order to find out useful FQs for treatment of tuberculosis, the comparative efficacy of five FQs, namely, ofloxacin (OFL), ciprofloxacin (CIP), sparfloxacin (SPX), gatifloxacin (GAT) and levofloxacin (LEVX) was studied against Mycobacterium tuberculosis (MTB) isolates obtained from both treated and untreated patients from Agra and Kanpur regions of north India.

METHODS

A total of 162 MTB isolates [including 110 MTB isolates obtained from untreated patients (Cat-I) and 52 isolates from treated patients (Cat-II)] were tested for their susceptibilities to FQs using standard minimum inhibitory concentration (MIC) method on Löwenstein-Jensen medium.

RESULTS

Keeping in view the therapeutically achievable drug levels, it was found that in Cat-I 97.2 per cent (107/110) isolates were sensitive to GAT, 89 per cent (98/110) to LEVX at 1 microg/ml whereas 92.7 per cent (102/110) isolates were inhibited by OFL at 2 microg/ml and 73.6 per cent (81/110) to SPX at 0.5 microg/ml. Only 63.6 per cent (70/110) isolates were found to be sensitive to CIP at 2 microg/ml which increased to 89 per cent (98/110) at 4 microg/ml (higher than achievable peak serum level). On the other hand, among 52 isolates for Cat-II, 37 (71.2%) were found to be sensitive to GAT and 33 (63.5%) to LEVX at 1 microg/ml concentration, 28 (53.8%) to SPX at 0.5 microg/ml whereas 33 (63.5%) and 24 (46.2%) isolates were found to be sensitive to OFL and CIP at 2 microg/ml, respectively.

INTERPRETATION & CONCLUSION

It appears that GAT has higher activity against MTB isolates followed by OFL, LEVX and SPX whereas CIP showed the lowest activity. GAT was also found to be the most effective FQ against multi-drug resistant (MDR) isolates both from Cat-I and Cat-II patients. Thus, except CIP, other FQs showed potential to be included in the treatment regimens of tuberculosis including MDR-TB.

Development and evaluation of real-time RT-PCR assay for quantitative estimation of viable Mycobacterium leprae in clinical samples

Detection of live organisms by molecular methods has special significance in leprosy where causative organism can not be cultivated in vitro. Such techniques would be especially important for monitoring the progress of the disease. While real-time RT- PCR technology will be appropriate for this purpose, there is very little experience of use of such tools in leprosy. This study describes the development of a quantitative RT-PCR targeting 16S rRNA based on primers used in a semi quantitative RT-PCR and its application on clinical samples including slit scraping and biopsies. RNA was extracted from biopsies from 3 lepromatous leprosy (LL) cases and standard curve was generated by plotting crossing over point against the dilutions of input RNA quantity (number of bacilli used for RNA extraction). Real-time RT-PCR was performed for quantitative detection of live M. leprae in 28 slit (13/28 smear positive) scrappings and 32 biopsies (22/32 smear positive). Number of viable bacteria as estimated by solid stained bacilli and real-time PCR correlated (no difference p>0.05). The test achieved a theoretical analytical sensitivity limit of up to single live bacillus even considering 11.3% efficiency of RNA preparation which was calculated by spiking of known number of leprosy bacilli in non leprosy skin biopsies (PCR negative). All smear positive cases were positive by this assay. This assay appears to be a promising tool for detection and quantification of viable bacilli in selected clinical situations and should be of use even in smear negative cases also.

Long term follow-up results of 1 year MDT in MB leprosy patients treated with standard MDT + once a month Minocycline and Ofloxacin

BACKGROUND

This study was initiated in consultation with the National Leprosy Eradication Programme (NLEP) in mid nineties to try new treatment regimens for leprosy which were more robust in terms of control of reactions, long term relapses, operationally easier to undertake and feasible in field conditions. It was also envisaged to see if the addition of newer bactericidal drugs would be beneficial.

OBJECTIVES

(i) To test the feasibility, safety and response of the patients to the new regimen. (ii) To observe the incidence of reactions during and after stoppage of therapy, for a period of 8-10 years after release from treatment.

MATERIALS AND METHODS

A total of one hundred skin smear positive MB patients (15 LL, 35 BL and 50 BB) patients were included in this study. All the patients received the standard MDT + once a month supervised 100 mg of Minocycline and 400 mg of Ofloxacin for 12 months during the treatment phase. Thereafter, the treatment was stopped in all the patients which were followed-up on placebo (B complex tablets). Of these, 70 patients completed the treatment schedule of one year therapy and the post treatment follow-up of 9 to 10 years.

RESULTS

All the patients tolerated the drugs well. The clinical response of the patients to the treatment was very good of which 32.85% of cases had history of reactions before starting treatment. During treatment, the incidence of reactions increased marginally to 38.5%, but these were easily controlled with concurrent administration of steroids. After completion of treatment the incidence was much less i.e. 10% and 3% after 1 and 2 years of post treatment follow-up respectively. The overall relapse rate is 5.7% (4/70) with an incidence density of 0.05/100 patient years. Relapses were confirmed by clinical, bacteriological, molecular biological (rRNA probes and 36 kD targeting PCR) as well as ATP bioluminescence. The relapsed patients presented with the appearance of new lesions, slit-skin smears were again found to become positive after becoming negative. Three of the four cases who relapsed had the initial mean BI of 2 to 2.9+ whereas one had the initial mean BI of 1.5+. Also, 2 of the 4 relapsed patients had positive PCR signals at the time of stoppage of treatment.

CONCLUSION

The addition of Minocycline and Ofloxacin to the standard FDT has been observed to be a well tolerated. Overall as of now, the incidence of reactions observed with the newer treatment regimen is found to be significantly lower than that of 2 years fixed duration MB-MDT. The efficacy of this regimen regarding bacteriological clearance and relapse rates could not be compared due to non-availability of the results of experience with standard 1 year MDT regimen. However, this regimen appears to be operationally feasible and safe for the users.

Predominance of Mycobacterium fortuitum-chelonae complex in Ghatampur field area, endemic for leprosy

Non-tuberculous mycobacteria (NTM) are commonly found in the environment. As exposure to environmental mycobacteria has been reported to immunomodulatory in this study, the presence of environmental mycobacteria was investigated in soil, drinking water and drainage sample in Ghatampur, India, which is known for high endemicity for leprosy. Soil, drinking water from the hand pumps/wells and also drainage water collected in pools was collected in clean containers and cultured for environmental mycobacteria. Samples were processed according to the protocol established earlier. 69 soil, 62 drinking water and 31 drainage water samples were analysed from soil and water collected from 48 villages of this field area. After decontamination, cultures were set upon Lowenstein Jensen (LJ) medium. Mycobacteria were identified using biochemical tests and molecular techniques such as PCR-RFLP targeting hsp65 kD and rpoB region as well as 16S ribosomal sequencing in case of isolates showing variable biochemical features. NTM (non-tubercular mycobacteria) were isolated from 47.82% of soil samples, 20.69% of drinking water samples and 19.35% of the drainage water samples, overall mycobacteria could be isolated 52/162 of samples (32.09%). Among these mycobacteria, M. fortuitum-chelonae complex was predominant in this area; other species isolated were M. phlei, M. vaccae, M. terrae and M. flavescens. Relevance of exposure to these mycobacteria on endemicity needs to be studied by immunological and epidemiological parameters.

Changing profile of disease in leprosy patients diagnosed in a tertiary care centre during years 1995-2000

A hospital based retrospective study was carried out to determine change in the profile of disease in leprosy patients taking 1995 as baseline and compared with the profile seen in year 2000. A total of 2149 and 1703 cases were studied respectively of year 1995 and 2000. Male to female ratio slightly increased from 2.95:1 in year 1995 to 3.4:1 in year 2000. Majority of patients were of borderline type in both years. Proportion of cases with MB leprosy was nearly same in females (60.8%) and males (63.1%) in year 1995 and in year 2000 (64.8% females and 67.6% males). Proportion of highly bacillary cases has decreased over the years in females (from 20.95% in 1995 to 11.7% in year 2000, p=0.03) as well as in males (from 25% in 1995 to 15.5% in year 2000, p=0.001). Incidence of total reactions increased from 27.6% to 35.4% over the years which is significant (p<0.01). Proportion of type 1 reactions were more in reproductive age group in females in both years (p<0.05) and of type 2 reactions were significantly (p > or = 0.05) more in males in both years. Incidence of disability (both grade 1 and grade 2) was significantly more in males than in females in both years (p > or = 0.04). Grade 1 disability has significantly increased over years in females from 10.11% to 14.8%(p<0.03) as well as in males from 13.27% to 21.3%(p<0.001). Onset of reactions was associated with pregnancy/lactation in 62% of cases and with menopause in 21% of cases in 2000, which suggests strong correlation with hormonal imbalance. To conclude while leprosy incidence has declined after MDT, recognition and management of reactions in women around changes in their hormonal levels should be properly monitored for early and effective management.

International open trial of uniform multi-drug therapy regimen for 6 months for all types of leprosy patients: rationale, design and preliminary results

OBJECTIVE

To describe the rationale, design and preliminary results of an open trial of 6 months uniform multi-drug therapy (U-MDT) for all types of leprosy patients assuming a cumulative relapse rate not exceeding 5% over 5 years of follow-up.

METHODS

We intended to recruit 2500 patients each in multi-bacillary (MB) and pauci-bacillary (PB) groups from India (five centres) and China (two centres). Standardized clinical criteria were used to assess skin lesions in the field.

RESULTS

A total of 2912 patients enrolled from November 2003 to May 2007 (India, 2746; China, 166). MB patients constituted 39% and 3% had grade 2 disability. During follow-up, 27 patients (0.9%) developed new lesions. Of these, 78% were on account of reactions. Six patients had clinically confirmed relapse. Clofazimine-related skin pigmentation was short-lived and was acceptable to patients. We analysed data for clinical status of skin lesions. About 2.9% of patients were lost to follow-up; 85.9% completed treatment, of whom 19% had inactive skin lesions. PB patients responded better than MB patients (27%vs. 6%; P < 0.001). At the end of the first (n = 2013) and second year (n = 807) of follow-up post-U-MDT, in 49% and 46% patients, lesions were inactive, respectively (59% and 57% in PB, 37% and 28% in MB; P < 0.001).

CONCLUSION

U-MDT appears to be promising with respect to clinical status of skin lesions.

PCR and in-situ hybridization for diagnosis of leprosy

OBJECTIVE

To assess the diagnostic value of Polymerase Chain Reaction (PCR) and in situ hybridization.

METHODS

This prospective study was carried out in 22 patients

RESULTS

The histopathological examination confirmed the clinical diagnosis in 27.2% cases only. In situ hybridization showed a positivity of 42.8% in early (I/BT) and 46.7% in BB/BL group. In situ hybridization thus enhanced the diagnosis by 18.1%. PCR targeting 36 kDa gene of M. leprae was performed on 15 cases. In these 15 cases, histopathology confirmed the diagnosis in 4 cases (26.6%) and PCR confirmed the diagnosis in 10 cases (66.6%), thus enhancing the diagnosis by 40%.

CONCLUSION

36 kDa PCR and in situ hybridization enhance the diagnosis of leprosy when compared to routine histopathology. They are important diagnostic tools for definitive diagnosis in early and doubtful cases of leprosy.

Immunogenetics of mycobacterial infections in the North Indian population

Several lines of evidence highlight the genetic basis of risk to develop mycobacterial diseases. Human leukocyte antigen (HLA)-DR2 alleles (DRB1*1501 and DRB1*1502) have been found to be strongly associated with mycobacterial disease, especially the more severe forms such as lepromatous leprosy and multidrug-resistant pulmonary tuberculosis. In this study, DNA-based high-resolution typing techniques of polymerase chain reaction-sequence-specific oligonucleotide probe were used to determine the distribution of HLA-DR/DQ alleles in patients with leprosy and pulmonary tuberculosis. Analysis of different DR2 subtypes based on valine/glycine dimorphism at codon beta86 in pocket 1 of HLA-DR showed an inverse relationship of DR2 alleles with V/G as the severity of disease increased both in leprosy and in pulmonary tuberculosis.

Recent advances in molecular biology of leprosy

The last three decades have witnessed rapid progress in understanding the molecular biology of Mycobacterium leprae. Following the availability of complete genome sequence of leprosy bacillus in 2001, things have drastically changed. With the information about genetic structure, several techniques have been developed for diagnosis, molecular epidemiology and also detection of drug resistance. With the decline in the prevalence of leprosy globally, there has been some reduction in interest in the molecular methods for diagnosis, yet molecular techniques for studying the transmission dynamics and detection of drug resistance continue to be relevant. Knowledge about complete genome sequence has made it possible to undertake studies that can improve our understanding of the structure and function of this enigmatic organism. Newer information emerging about biology of M. leprae would provide insight into mechanisms of its survival and persistence in host and is likely to lead to better diagnostics and also therapeutics for mycobacterial infections in general.

Association of variants in theIL12Bgene with leprosy and tuberculosis

There is a great range in outcomes after mycobacterial infections, and this is probably due to individual variation in immune responses. One of the key cytokine regulators of the immune response is interleukin (IL-) 12. The IL12B gene encodes the p40 chain of both IL-12 and IL-23 and it has two major variant sites at which different alleles are associated with increased levels of gene expression and with susceptibility to a range of immune-related diseases. We hypothesized that IL12B variants associated with increased expression would be as associated with susceptibility to persistent mycobacterial infection. We tested this hypothesis by genotyping Indian subjects, having either leprosy or tuberculosis (TB), as well as ethnically matched controls. Subjects with leprosy were less likely to have the 3'UTR genotype associated with lower IL12B expression (P= 0.001). Subjects with TB were not only more likely to have the high-expressing IL12B promoter genotype (P= 0.01) but also more likely to have this in the same haplotype with the high expressing 3'UTR allele (P= 0.0009). These results suggest these infectious diseases may be improved by modulating IL-l2p40 production.

Analysis of gene probes and gene amplification techniques for diagnosis and monitoring of treatment in childhood leprosy

Nucleic acid sequences of Mycobacterium leprae were detected using gene probes hybridizing with targeting ribosomal RNA (16S rRNA), ribosomal DNA (16S rDNA) and gene amplification techniques (PCR) in skin lesion of paediatric leprosy patients and the effect of treatment on the by these methods. Eighty paediatric leprosy patients were included in the study. Most cases (79%) were between 9 and 16 years of age. Cases were divided into three groups according to treatment status, viz. untreated (30), undergoing treatment (30), and at the end of treatment (20). Clinical and slit smear examination for acid fast bacilli (AFB) was performed and nucleic acids were extracted and fractionated from skin biopsies. M. leprae specific 16S rRNA and 16S rDNA was detected by hybridization with gene probes whereas the 36 kDa gene sequence was detected by a gene amplification assay (PCR). The cases were classified as paucibacillary (PB) and multibacillary (MB) by the standard criteria of WHO (1988). Positivity of 16S rRNA in PB cases decreased from 60% in untreated to 10.5% after 4-8 months of treatment whereas for 16S r DNA, it decreased from 50% to 21%, for PCR from 70% to 36.8% for the same specimen, and all became negative at 1 year. Similar trends were seen in MB cases where positivity in smear positive untreated cases decreased from 100% to 56.2% with 16S rRNA and 42.8% with 16S rDNA and PCR, respectively, after 9-12 months of treatment and all became negative at 2 years, except one case which remained positive with PCR. Similar results were observed in smear negative MB cases, 100% positivity detected by 16S r RNA and PCR, 75% detected by 16S rDNA decreased to zero after 9-12 months of therapy. This study suggests the potential usefulness of gene probes targeting 16S rRNA and 16S rDNA and PCR as supportive molecular tools for diagnosis of smear negative evolving MB disease and also monitoring the response to treatment, these observations however, needs to be validated in prospective follow up studies.

Detection of Mycobacterium leprae DNA from soil samples by PCR targeting RLEP sequences

Despite near elimination of leprosy as a public health problem, several problems in leprosy still remain. These include early detection, determining efficacy of the treatment and differentiating relapses from re-infection. These aspects have important impact on the patients undergoing treatment and also have a bearing on understanding transmission dynamics in the community. While early diagnosis and management do not need major technological inputs, various reports have suggested that M. leprae is found in the environment and may have a role in continued transmission of disease. In earlier studies from other parts of world the presence of M. leprae DNA in the environment has been investigated both by microbiological and molecular studies. In the present study, an attempt was made to extract M. leprae DNA from soil samples, which were collected from eighteen different locations including 3 from our Institute area and 15 from different villages of Ghatampur area. We optimized a protocol for the extraction of DNA and amplified a fragment of M. leprae using specific primers targeting RLEP sequences. It was found that 33.3% of these soil samples collected from areas inhabited by leprosy cases gave positive result for M. leprae specific DNA. The utility of this method needs to be explored on a larger scale to establish the presence of M.leprae in the environment, and its role in the spread of the disease.

Detection of M. leprae by reverse transcription- PCR in biopsy specimens from leprosy cases: a preliminary study

A reverse transcription (RT)-PCR assay targeting 16S rRNA of Mycobacterium leprae has been used to detect M.leprae specific nucleic acids. This study has been initiated to gain experience about detection of RNA from seven biopsy specimens by RT-PCR assay using species- specific primers described earlier. These biopsy specimens were from clinically confirmed and untreated leprosy cases belonging to BB and BL types. The earlier reported method was established in our laboratory. 171 bp fragment by RT-PCR was amplified from 4/7 cases. The positives results by RT-PCR were from the biopsies from fresh or short term treated cases whereas negative results were from specimens from long term treated cases showing clinical features of relapse. DNA targeting PCR (36 KDa) showed positivity in both groups. These results suggest that RT-PCR positivity possibly reflect the presence of viable organisms. Thus as earlier predicted RT-PCR assay may be useful for viability determinations for assessing the response to chemotherapy as well as presence of persisters in relapse cases.

Diagnostic value of in situ Polymerase Chain Reaction in leprosy

OBJECTIVE

This prospective study was carried out to assess the diagnostic value of in situ Polymerase Chain Reaction in leprosy, particularly in enhancing the histopathological diagnosis.

METHOD

Clinical examination of 20 patients (< 16 yr) was done and skin smear for AFB was prepared. Biopsy of lesion site was taken for histopathological examination and in situ PCR testing.

RESULTS

The histopathological examination confirmed the clinical diagnosis in 45% cases only; non-specific histopathology was reported in the remaining 55% cases. In situ PCR showed a positivity of 57.1% in early/localized form of leprosy (IIBT) and 61.5% in (BB/BL) group. When compared to histopathology examination, a significant enhancement of 15% in diagnosis was seen. With in situ PCR, the diagnosis could be confirmed in 4/11 (36.3%) cases with non-specific histopathological features, (which is common in early disease) in addition to confirmation of 8/9 (88.8%) histopathologically-confirmed tissue sections. Histopathology and in situ PCR, combined together, confirmed the diagnosis in 13/20 cases (65% of total cases).

CONCLUSION

Thus, in situ PCR is an important diagnostic tool especially in early and doubtful cases of leprosy.

Persister studies in leprosy patients after multi-drug treatment

Cutaneous biopsies were collected from leprosy patients who attended the out-patient department of the Institute for treatment at different intervals, i.e., 12 months, 18 months, 24 months, 36 months, and more after beginning the multi-drug treatment therapy (M.D.T.). The patients belonged to the two drug regimens; (i) standard multibacillary (MB) M.D.T. after 12, 24, and 36 months; or (ii) standard M.D.T. + Minocycline 100 mg once a month (supervised) + Ofloxacin 400 mg once a month supervised for 12 months Biopsies were processed for mouse footpad inoculation and for estimating ATP levels by bioluminescence assay as per established methods. Viable bacilli were observed in 23.5% up to 1 year, 7.1% at 2 years, and in 3.84% at 3 years of M.D.T. by MFP and 29.4%, 10.7%, and 3.84% by ATP assay in the M.D.T. group at the same time period, respectively, but not in M.D.T. + Minocycline + Ofloxacin group after one year. The overall percentage of persisters was 5.55% by MFP and 7.14% by ATP assay up to 3 years of treatment.

Analysis of quantitative relationship between viability determination in leprosy by MFP, ATP bioluminescence and gene amplification assay

Two hundred twenty-one untreated, borderline lepromatous/lepromatous (BL/LL) leprosy patients have been investigated for viability by the mouse foot pad method (MFP), adenosine triphosphate (ATP) and polymerase chain reaction (PCR). The biopsies were collected at the beginning of and 12/24 months after treatment. The patient group was treated with a) immunotherapy (BCG/Mw) + MDT; b) MDT + pyrazinamide; c) control MDT; d) MDT + minocycline 100 mg once a month supervised + ofloxacin 400 mg once a month supervised. Biopsies were divided in three parts for use in the mouse foot pad, molecular and ATP investigations. In untreated and treated patients (at 12 and 24 months), there was a general agreement among all three techniques, and PCR and ATP showed higher positivity as compared to MFP. Further, there was good correlation among the viable biomass estimated by bacillary ATP levels, PCR assay and growth in mouse foot pads. The positivity was observed by MFP as well as PCR assay (18-kDa and 36-kDa) from all of the specimens when the ATP content was more than 3.6 pg/million. When the ATP content was below 3.5 pg/million, the positive takes in MFP decreased but the PCR positivity correlated with ATP bioluminescence up to 0.04 pg/million. When the ATP content was even lower, the uptake in the MFP was possibly a matter of chance, while PCR positivity was observed in 96% of the cases. For specimens with undetectable ATP, positivity was seen in 1% of the cases, showing the inability of ATP bioluminescence method to detect low background due to host ATP. PCR signals in some cases could be due to the higher sensitivity of the method or persistence of DNA after bacterial death in some cases. On the whole, the PCR methods even though targeting DNA have shown good correlations with biomass which confirm their usefulness in monitoring therapeutic responses in leprosy.

Patients presenting with defined areas of sensory loss--a preliminary study

Thirty patients presenting with circumscribed areas of clearly demonstrable hypoesthesia were chosen from amongst those attending this Institute. Their history and clinical features were recorded, lepromin test was done for reading at four weeks, and peripheral part of the hypoesthetic area was biopsied for histopathology and immunostaining. The subjects were predominantly adult males with the symptomatic sites limited to the extremities. On routine histopathological examination of the symptomatic sites, the diagnosis of leprosy, using defined criteria, could be made in six cases (20%). Immunostaining of the remaining sections showing either no pathology or a nonspecific pathology revealed the presence of mycobacterial antigen in five of the 24 cases (20.83%). Overall, leprosy could be diagnosed in 11 of the 30 cases studied (36.66%). This study shows that leprosy may be an important cause of circumscribed areas of sensory deficit.

Effect of treatment on PCR positivity in multibacillary leprosy patients treated with conventional and newer drugs ofloxacin and minocycline

In order to develop objective criteria to monitor trends of therapeutic responses positivity of PCR signals and ATP assay methods has been compared in multibacillary (MB) leprosy patients. Biopsies from lesions of 95 BL/LL patients before and after one year of treatment with a new drug regimen comprising of conventional and newer drugs ofloxacin and minocycline have been studied. These biopsies were processed for bacillary ATP assay and PCR positivity for a 36 kDa gene target by earlier published methods. In the untreated patients bacillary ATP levels were detectable in all specimens and ranged from 0.02 to more than 36 pg/millions organisms. After one year of treatment ATP levels were not detectable in any of the 57 biopsies specimens available for analysis. However, PCR signals were detectable in 3 out of 57 biopsies. In two specimens signals were very weak detectable only by hybridization. It may be concluded that DNA based PCR assay may be useful in monitoring the trends of therapeutic responses in MB patients under treatment.

Assessment of viability by normal mouse foot-pad and bacillary ATP bioluminescence assay in multibacillary cases treated with an MDT regimen using conventional as well as newer drugs like minocycline and ofloxacin

The therapeutic effect of a drug regimen of conventional drugs as well as newer drugs like ofloxacin and minocycline in smear-positive multibacillary (MB) leprosy cases was assessed by mouse foot-pad and ATP bioluminiscence methods. Biopsies were taken before starting treatment and after one year of treatment. They were processed for viability assessment by normal mouse foot-pad inoculation and bacillary ATP assay techniques. The test regimen was quite effective in its anti-bacterial effect as it was found to result in loss of bacillary viability in all the cases, as assessed by both methods.

Chemotherapy trials in MB leprosy using conventional and newer drugs pefloxacin and minocycline

One hundred, untreated, smear positive BB, BL and LL patients were treated with a regimen comprising of once a month, supervised, 600 mg of Rifampicin+ 400 mg Ofloxacin + 100 mg of Minocycline in addition to self administered 100 mg dapsone and 50 mg of clofazimine daily for twelve months.The treatment was then stopped and patients were followed up on placebo. This study reports the preliminary results after 2.5 to 3.5 years of post treatment follow-up. The drugs were well tolerated, the clinical response to the treatment was very good, and there was no case of treatment failure. Bacteriologically 25 out of the total 70 patients available for follow- up were still positive at the end of one year of treatment. These patients continued to progress satisfactorily and four patients were still positive at the end of 2 years. No growth was observed in the normal mouse foot pad after one year of therapy. No bacillary ATP was detected in the biopsy tissues after one year. While no M. leprae specific rRNA was detectable in any of the specimens after one year of treatment, weak PCR signals were detectable in 3/57 specimens at that period. In the follow up available no patient has relapsed. The patients are being followed up on placebo and longer follow-up is required to draw firm conclusions.

Determination of circulating IgG subclasses against lipoarabinomannan in the leprosy spectrum and reactions

IgG subclasses against lipoarabinomannan of mycobacteria were analyzed in the sera of leprosy patients. Patients with active leprosy [tuberculoid and lepromatous, patients undergoing erythema nodosum leprosum (ENL) and reversal reactions] and inactive cases (tuberculoid and lepromatous who were cured after chemotherapy) were included in this study. Active lepromatous patients had higher levels of IgG subclasses, except IgG4, compared to active tuberculoid patients. Some of the inactive cases (lepromatous patients cured after chemotherapy) were positive for the IgG1, IgG2 and IgG3 subclasses. However, their levels are lower than active lepromatous cases. On the other hand, no difference in the subclass levels between the active and inactive tuberculoid groups could be observed. While a significant fall in the level of IgG3 in ENL was observed as compared to lepromatous leprosy without ENL, higher levels of IgG1 and IgG2 were found in patients with reversal reactions compared to their active counterparts without reactions.

Histology and immuno-histology of lesions clinically suspicious of leprosy

Forty-six patients presenting with lesions clinically suspicious of leprosy were selected among patients attending the outpatient department (OPD) of our Institute. The lesions were biopsied deeply for histological analysis. The cases chosen commonly belonged to the 20-35 years age group, were predominantly males, with rare cases of leprosy within the family (2/46, 4.35%). The clinical presentation in most of the cases was that of a solitary lesion, (44/46, 95.65%) located in one of the extremities (40/46, 86.95%). A positive Mitsuda reaction could be elicited in 40% of the cases. Routine histopathologic analysis using defined criteriae, has established the diagnosis of leprosy in 16/46 (34.78%) cases with positivity for acid-fast bacilli in 4 cases. The remaining cases (25/46, 54.35%) exhibited a non-specific histopathology with a perivascular/periadnexal mononuclear cell infiltrate, few (5/46, 10.86%) exhibited minimal or no histopathological features. The sections with nonspecific or minimal pathology when immunostained for the presence of mycobacterial antigen exhibited positivity in 11/30 (36.6%) cases. Presuming the features observed to be consequent to the presence of antigens nearby, the diagnosis of leprosy was significantly enhanced compared to the diagnosis achieved with routine histopathology alone.

Chemotherapy trial in paucibacillary leprosy using clofazimine

In a double blind study, 300 PB patients (smear negative, indeterminate, tuberculoid and borderline tuberculoid) were randomly allotted to two regimens, the control subjects (150 patients) receiving the standard WHO multidrug regimen of six doses of once a month rifampicin with daily dapsone therapy for six months, while the study group (150 patients) receiving 50 mg of clofazimine daily for six months in addition to the WHO regimen. After stoppage of therapy all the patients were followed up on placebo. The regimens were well tolerated. In 7.5% of patients on clofazimine containing regimen, the lesions showed persisting activity at the time of stoppage of therapy, compared with 16% on the control regimen. This activity subsided spontaneously, more rapidly, in the study group (80% compared with 30% in the control group) in six months. Two patients in the control group and one patient in the study group developed late reaction. There were no relapses in the study group, whereas, two patients have relapsed in the control group during a follow-up of 2.5 to 3.5 years.

Immune responses to recombinant proteins of Mycobacterium leprae

Identification of antigenic determinants of the polar immune response in leprosy may illuminate both protection and pathogenesis. Thirty subjects were studied (22 with polar disease and 8 healthy controls who were heavily exposed but disease-free) by assaying the proliferative, interferon (IFN)-gamma, and antibody responses to recombinant antigens of Mycobacterium leprae (10, 28, 36, and 65 kDa). The 10-kDa antigen elicited IFN-gamma production from all tuberculoid (TT) and borderline tuberculoid (BT) patients but little from controls, lepromatous (LL), or borderline lepromatous (BL) patients (P<.05). Production of 65-kDa-specific IFN-gamma was higher in TT/BT than in controls or LL/BL patients (P<.006). All subjects produced 65-kDa-specific antibody, but it was higher in LL/BL patients than in healthy controls, whose responses were higher than in TT/BT subjects (P=.035). The 36-kDa antibody responses were selectively increased in LL/BL subjects (P<.02). The intermediate phenotype of the controls suggests that M. leprae-specific production of IFN-gamma may contribute to pathology and to protection in leprosy.

Specificity and function of immunogenic peptides from the 35-kilodalton protein of Mycobacterium leprae

We identified a T-cell determinant of the 35-kDa antigen of Mycobacterium leprae which is discriminatory against cross-sensitization by its closely related homologue in Mycobacterium avium. From synthetic peptides covering the entire sequence, those with the highest affinity and permissive binding to purified HLA-DR molecules were evaluated for the stimulation of proliferation of peripheral blood mononuclear cells (PBMCs) from leprosy patients and healthy sensitized controls. Responses to the peptide pair 206-224, differing by four residues between M. leprae and M. avium, involved both species-specific and cross-reactive T cells. Lymph node cell proliferation in HLA-DRB1*01 transgenic mice was reciprocally species specific, but only the response to the M. leprae peptide in the context of DR1 was immunodominant. Of the cytokines in human PBMC cultures, gamma interferon production was negligible, while interleukin 10 (IL-10) responses in both patients and controls were more pronounced. IL-10 was most frequently induced by the shared 241-255 peptide, indicating that environmental cross-sensitization may skew the response toward a potentially pathogenic cytokine phenotype.

Detection of viable organisms in leprosy patients treated with multidrug therapy

Cutaneous biopsies were collected from multibacillary leprosy patients who attended the out-patient department of Jalma Institute for treatment at different time intervals, i.e. 6 months, 12 months, 18 months, 24 months, 30 months, 36 months and 42 months after starting multidrug therapy (MDT) when they were still skin smear positive. Biopsies were processed for inoculation into mouse foot pad (MFP) and estimation of bacillary ATP levels by bioluminescent assay (ATP assay) by earlier established procedures. Viable bacilli were detectable after 1 year (25% cases by MFP and 31% cases by ATP assay), 2 years (8% cases by MFP and 12% cases by ATP assay) and 3 years (4% cases by both MFP and ATP assays). Overall, the percentage of the persisters was 10% by MFP and 13% by ATP assay. It would be important to carry out surveillance studies in larger number of BL/LL cases to know the trends and also the resultant relapses.

A sequential study of circulating immune complexes, complement and immunoglobulins in borderline tuberculoid leprosy patients with and without reactions

Sequential estimates of the levels of circulating immune complexes (CIC), complement catabolic fragment C3d, complement-mediated immune complex solubilization (CMS) and immunoglobulins were made in 24 newly diagnosed with borderline tuberculoid leprosy over a 20 month period after initiation of chemotherapy. Fourteen of these patients had not suffered from reversal reactions either at the time of presentation or during the follow-up. The levels of CIC were evaluated in them from the third to the eleventh month after starting chemotherapy and immunoglobulin G (IgG) levels were evaluated up to eight months. The concentrations of C3d and immunoglobulins A (IgA) and M (IgM) were normal in these patients. The other ten patients had reversal reaction at the time of diagnosis which subsided by the third month after starting treatment. They did not have reversal reactions later. The levels of CIC and IgG were elevated and those of CMS were depressed throughout the study period. Serum C3d level was initially elevated but came down to normal by the third month while IgA and IgM levels were within normal limits. The relevance of these findings to the genesis of reversal reaction is discussed in this communication.

Microdensitometric scanning procedure for quantitative assessment of hybridization of rRNA targeting probes in leprosy

In order to develop an objective criteria of grading of positivity of hybridization signals of gene probes targeting rRNA, a microdensitometric scanning procedure was standardised. Ribosomal RNA was extracted from the bacilli harvested from biopsies of leprosy cases across the spectrum and blotted on nitro-cellulose membranes. M. leprae specific rRNA targeting oligonucleotide probes were end-labelled and hybridization was done by the technique standardised and published earlier. The autoradiographs were developed and microdensitometric scanning was done by altering different parameters. Positivity was graded in 5 grades and compared with visual positivity. Microdensitometric scanning procedure and 5 grade system appear to be useful and reproducible. Signals in paucibacillary specimens were in 2+ to 3+ grading range whereas those in multibacillary specimens varied in grades from 2+ to 5+. This approach appears to have potential usefulness for assessing the bacillary load (possibly viable) in the clinical specimens from leprosy cases.

Viability determination of M.leprae: comparison of normal mouse foot pad and bacillary ATP bioluminescence assay

Correlation between viability assessment by mouse foot pad and ATP bioluminescence was studied in biopsy specimens from multibacillary leprosy cases. Biopsies were processed for inoculation into mouse foot pad and estimation of bacillary ATP levels by bioluminescent assay by earlier established procedures. ATP content as pg/million bacilli was estimated and correlation was assessed with growth in the mouse foot pad. It was observed that when the ATP content was > 36 pg/million bacterial cells, (> 1% probable viables) there was growth in the mouse foot pad from all the specimens. Similar results were observed when the ATP content was in the range of 3.6 to 35.99 pg/million cells (0.1 to 1% probable viables). The positivity rates in the mouse foot pad decreased when the ATP content decreased further. No positive growth in the specimens below 0.04 pg/million bacilli (< 0.001% viable organisms) was observed. These findings show an overall correlation between viability assessed by mouse foot pad and ATP bioluminescence. These observations validate the concept of ATP content of viable unit of M.leprae being in the order of 10(-15) g/live cell which is in the same order of magnitude as a colony forming unit of cultivable mycobacteria.

Effect of trifluoperazine on in vitro ATP synthesis by Mycobacterium leprae

The effect of trifluoperazine (TFP), a calmodulin antagonist, was investigated on in vitro ATP levels of human derived Mycobacterium leprae. M. leprae were obtained from biopsies from multi-bacillary forms of leprosy and were incubated in a modified Dubos medium system which supports limited in vitro synthesis of M. leprae. This incubation was carried out in the absence and presence of different concentrations of trifluoperazine. Samples for estimation of bacillary ATP levels were taken at day 0 and at 14 days of incubation. TFP inhibited ATP levels in M. leprae and this inhibitory effect was marginal at 2.5 microg ml(-1) (35% inhibition), highly significant at 5 microg ml(-1) (87% inhibition) and almost total at 10 microg ml(-1) (98.5% inhibition). This compound appears to have potential as an anti-leprotic drug and also as a broad spectrum anti-mycobacterial agent in view of its anti-tubercular activity reported earlier.

Levels of IgG subclasses in active and inactive cases in the disease spectrum of leprosy

The present study was carried out to establish the role of IgG subclasses in leprosy. IgG subclasses to Mycobacterium leprae sonicated antigens (MLSA) and phenolic glycolipid-I (PGL-I) were determined in 124 patients with active leprosy across the disease spectrum and in 76 cases with inactive disease after completion of chemotherapy. IgG2 antibodies were found to be the predominant subclass across the disease spectrum. Lepromatous patients showed elevated levels of IgGI. IgG3 antibody levels were higher in lepromatous than that in tuberculoid patients. Patients with erythema nodosum leprosum showed a significant fall in IgG3 antibody to MLSA. While chemotherapy induced a reduction in IgG1, IgG2 and IgG3 to PGL-I in almost all types of leprous patients, for MLSA the reduction was noticed for these subclasses only in lepromatous patients. IgG4 responses to these antigens were low through out the disease spectrum and did not alter with chemotherapy.

Study of gene probes in childhood leprosy

The objective was to detect nucleic acids of M. leprae in skin lesions of leprosy patients and study the effect of treatment on these nucleic acids, using r-RNA gene probes, using a cross sectional study. The study was carried out at Department of Paediatrics, S.N. Medical College, Agra and Department of Microbiology, Central JALMA Institute for leprosy, Agra. The study included 32 cases of leprosy less than 16 years of age, divided into 3 groups viz. without treatment (12 cases), in middle of treatment (11 cases) and at the end of treatment (9 cases). All cases were subjected to a detailed history and thorough clinical examination. All of them had smear examination and lepromin test done and their skin biopsies were subjected to gene detection. Nucleic acids were isolated from skin biopsies of all cases by standard procedure. After dot blotting of these nucleic acids, they were hybridised with radioactive (p32) r-RNA probes. The results were interpreted after getting the X-ray films processed with background signals from controls. Majority of cases were between 13-16 years of age. As age advanced, the disease moved from tuberculoid end of spectrum towards lepromatous end (p < 0.05). Majority of paucibacillary (PB) cases were lepromin positive while majority of multibacillary (MB) cases were lepromin negative (p < 0.05). In specimens of untreated cases, 50% of PB specimens and 87.5% of MB specimens were positive for r-RNA probes. In multibacillary type 100% smear positive specimens and 67% smear negative specimens were positive for r-RNA probes. In patients during the middle of treatment positivity for r-RNA decreased and 20% of PB specimens and 16.6% MB specimens were positive. At the end of treatment (1 year for PB cases and 2 years for MB cases), the results of r-RNA were negative, which indicated that the treatment regimens used in the study were effective. This study supports the usefulness of r-RNA probes as a diagnostic and therapeutic tool in childhood leprosy.

Viability of M. leprae while undergoing laboratory procedures

Studies were carried out to assess whether various methodological procedures adopted while conducting experiments, or, maintaining M. leprae under different conditions affected the number of organisms made available or their viability. Results of mouse foot-pad experiments showed that bacilli survived for one day at 37 degrees C, 7 days at 20 degrees to 30 degrees C and for 90 days in lyophilized conditions. Repeated daily exposure of the material preserved in refrigerator at +4 degrees C, to room temperatures showed that bacilli survived for only up to five days; whereas, with single exposure they survived up to 14 days. M. leprae were found to lose infectivity after 30 minutes of exposure to various disinfectants and ultra violet light. Centrifugation at high speed did not affect the viability of M. leprae.