Paucibacillary Leprosy: Reappraisal using Ziehl-Neelsen staining of slit skin smears and 16S rRNA Real Time Polymerase Chain Reaction of nasal swabs
Background: Leprosy is diagnosed by cardinal signs. Classiﬁcation of paucibacillary (PB) and multibacillary (MB) leprosy is based on the number of skin lesions and nerve involvement. Objective: The study was conducted to determine the role played by acid fast bacilli (AFB) positivity of slit skin smear (SSS) in clinical classiﬁcation. Methodology: SSSs and nasal swab smears (NSSs) were stained by Ziehl-Neelsen staining. RNAs was extracted from 120 NSSs. NSSs and SSSs were examined by microscopy and M. leprae viability in NSS was determined by real time polymerase chain reaction (RT-PCR). NSSs from 50 healthy individuals were used as controls. Results: Group-A PB cases, classiﬁed simply by presenting with ,5 patches, showed the presence of AFB in NSSs (7·5%) and SSSs (15%). Group-B PB cases, classiﬁed on the basis of a negative skin smear were AFB negative. Control group NSSs were AFB negative. RT-PCR of NSSs of PB cases of Group A and Group B were 65% and 87% positive for viable M. leprae respectively. All NSSs were positive for 16S rRNA gene with variable copy numbers. It was noted that 3 SSSs negative AFB cases from Group-A were positive for AFB in NSS. It was also observed that 6 SSSs positive AFB (Group-A) cases were negative for AFB in NSS. It was interesting to note that none of the patients in Group-A was AFB positive in both NSS and SSS. However, all of these patients were positive for 16S rRNA qPCR in NSSs. Conclusion: Our ﬁndings strongly suggest immediate inclusion of AFB staining of SSS for classiﬁcation of leprosy.