Presence of viable Mycobacterium leprae in environmental specimens around houses of leprosy patients

PURPOSE

Leprosy is a chronic systemic infectious disease caused by Mycobacterium leprae, one of the first organisms to be established as the cause for disease in humans. Because of high prevalence pockets of leprosy in the endemic regions, it is necessary to identify the possible sources of M. leprae in the environment and its mode of transmission.

MATERIALS AND METHODS

Slit skin smears (SSSs) from lesions were collected in 70% ethanol from 50 leprosy cases staying in the leprosy resettlement village and hospital from a high endemic area. One hundred and sixty soil samples were collected from different areas around the leprosy hospital and from the resettlement village of cured leprosy patients where active cases also resided at the time of sample collection. M. leprae specific gene region (RLEP 129 bp) and 16S rRNA targets were used for polymerase chain reaction (PCR) based detection for the presence and viability of M. leprae. An rpoT region was also amplified to determine presence of numbers of 6 bp tandem repeats.

RESULTS

All the SSS samples collected from patients showed three copies of rpoT region (6 bp tandem repeat, an ancient Indian type). Fifty-two soil samples showed presence of M. leprae DNA whereas M. leprae specific 16S rRNA gene was amplified in sixteen of these samples. PCR amplification and fragment length analysis showed 91 bp, i.e., three copies of the rpoT 6 bp tandem repeats from soil samples and similar three copies observed in patient samples.

CONCLUSION

Presence of viable M. leprae in the soil having same rpoT genotype of M. leprae noted in patients suggests that it could be the same strain of M. leprae. M. leprae found in the soil could be the one that is excreted out by the patient. Significance of its viability in the environment and its pathogenicity with respect to transmission needs to be further explored. Findings of this study might provide possible insights for further exploration into understanding transmission patterns in leprosy and also will throw light on identifying potential for existence of extra human source or reservoirs of M. leprae, if any.

Follicular neoplasms of the thyroid. Decision tree approach using morphologic and morphometric parameters

OBJECTIVE

Fine needle aspiration of the thyroid is limited in differentiating hyperplastic nodular goiters from true follicular neoplasms and in separating follicular adenomas from follicular carcinomas. The present study was done to evaluate if a panel of morphologic and morphometric parameters of the thyroid and ploidy status, either alone or in combination, would help differentiate hyperplastic nodular goiters from follicular adenomas and carcinomas.

STUDY DESIGN

Fine needle aspiration smears of 75 cases classified as follicular neoplasms of the thyroid were studied for morphologic (cellularity, colloid and cellular patterns) and morphometric parameters (nuclear diameters and nucleoli).

RESULTS

Of the large number of parameters utilized in this study, only two of the cellular patterns (honeycomb and single dispersed) and the average maximum nuclear diameter showed trends in differentiating these lesions.

CONCLUSION

Based on these patterns and nuclear diameter (9 microns), we developed a decision tree classification that separated the benign from malignant lesions (follicular carcinomas) with a sensitivity and specificity of 92.8% and 57.4%, respectively.