Bacilloscopy and polymerase chain reaction of slit-skin smears and anti-phenolic glycolipid-I serology for Hansen's disease diagnosis

Filipe Rocha Lima; Natália Aparecida de Paula; Mateus Mendonça Ramos Simões; Gabriel Martins da Costa Manso; Gustavo Sartori Albertino; Giovani Cesar Felisbino; Vanderson Mayron Granemann Antunes; Fernanda André Martins Cruz Perecin; Andrezza Telles Westin; Helena Barbosa Lugão; Marco Andrey Cipriani Frade

doi:10.3389/fmed.2022.972244

Bacilloscopy and polymerase chain reaction of slit-skin smears and anti-phenolic glycolipid-I serology for Hansen's disease diagnosis

Front Med (Lausanne). 2022 Aug 10:9:972244. doi: 10.3389/fmed.2022.972244. eCollection 2022.

Authors

Filipe Rocha Lima^{1

2}, Natália Aparecida de Paula^{1

2}, Mateus Mendonça Ramos Simões^{1

2}, Gabriel Martins da Costa Manso^{1

2}, Gustavo Sartori Albertino^{1

2}, Giovani Cesar Felisbino^{1

2}, Vanderson Mayron Granemann Antunes^{1

2}, Fernanda André Martins Cruz Perecin², Andrezza Telles Westin², Helena Barbosa Lugão², Marco Andrey Cipriani Frade^{1

2}

Affiliations

¹ Healing and Hansen's Disease Laboratory, Ribeirão Preto Medical School, University of São Paulo, São Paulo, Brazil.
² Dermatology Division, Department of Internal Medicine, National Referral Center for Sanitary Dermatology and Hansen's Disease, Clinical Hospital of the Ribeirão Preto Medical School, University of São Paulo, São Paulo, Brazil.

Abstract

The bacilloscopy of the slit-skin smear (SSS) is the exclusive laboratory test associated with dermato-neurological evaluation for Hansen's disease (HD) diagnosis; however, it is negative in the majority of PB or primary neural forms. Thus, a PCR technique involving different sequences and target genes has been performed with an aim to increase the sensitivity and specificity of M. leprae identification, especially in patients with low bacillary loads. Additionally, serological assays based on antibody response reflect infection levels and indicate that this could be a simpler, less invasive technique for estimating M. leprae exposure. Serological tests and PCR have been shown to be more sensitive and accurate than the SSS. Our study aimed to measure accuracy and performance among the SSS and PCR of dermal scrapings stored on filter paper and APGL-I serology for diagnosis in HD. A cross-sectional study analyzing the medical records (n = 345) of an HD outpatient-dermatology clinic from 2014 to 2021 was conducted. Accuracy performance parameters, correlation, and concordance were used to assess the value among the SSS, PCR, and APGL-I exams in HD. The SSS presented 24.5% sensitivity, 100% specificity, 37.4% accuracy, and the lowest negative predictive value (21.5%). The PCR assay had 41, 100, and 51% sensitivity, specificity, and accuracy, respectively. PCR and APGL-I serology increased the detection of HD cases by 16 and 20.6%, respectively. PCR was positive in 51.3% of patients when the SSS was negative. The SSS obtained moderate concordance with PCR [k-value: 0.43 (CI: 0.33-0.55)] and APGL-I [k-value: 0.41 (CI: 0.31-0.53)]. A moderate positive correlation was found between the APGL-I index and the bacillary index (r = 0.53; P < 0.0001). Thus, the use of the SSS is a low sensitivity and accuracy method due to its low performance in HD detection. The use of PCR and serological tests allows for a more sensitive and accurate diagnosis of patients.

Keywords: Hansen’s disease; PCR; bacilloscopy; diagnosis; serology; slit-skin smear.