Evaluation of the performance of an in-house duplex PCR assay targeting the IS6110 and rpoB genes for tuberculosis diagnosis in Cameroon.

BACKGROUND: Tuberculosis (TB) remains a major public health concern in many low-income countries accounting for approximately two-thirds of deaths in people living with human immunodeficiency virus (HIV) infection. With prompt, accurate and appropriate treatment, almost all TB disease can be cured. The present study was to evaluate the diagnostic performance of an in-house duplex PCR (D-PCR) using IS1610 and rpoB specific primers in sputum samples from TB suspected patients. METHODS: A hospital-based cross-sectional study was conducted at the Limbe and Buea Regional Hospitals of the South West Region of Cameroon from June 2016 to April 2017. Sputum samples, decontaminated with hypertonic saline/sodium hydroxide solution were centrifuged and pellets processed for smear microscopy, culture and DNA extraction. Suspected inhibition was resolved by serial dilution of genomic DNA. Results were compared to culture as gold standard as well as a Composite Reference Standard (CRS). RESULTS: A total of 129 participants aged between 5 to 82 years were enrolled in to the study. The median age of the participants was 37 years (interquartile range, IQR: 27-50 years), with 54.3% being male. Forty-seven samples (36.4%) were positive by direct sputum microscopy, 49 (38%) by microscopy after concentration, 51 (39.5%) by culture and 62 (40.1%) by D-PCR. PCR inhibition was resolved in 85.7% (18/21) of the samples that had inhibition. The overall sensitivity, specificity, positive and negative predictive values, positive and negative likelihood ratios and area under the curve AUC) of the D-PCR was 93.5, 94, 94, 94%, 15.6, 0.005 and 89.0% respectively using CRS as reference. The sensitivities of D-PCR observed among different sample categories were 95.7, 87.5 and 87.5% for smear-and culture-positives, smear-negative/culture-positive, and clinically diagnosed cases respectively. CONCLUSION: IS1610 and rpoB duplex PCR using relatively cheap decontamination and DNA extraction methods in addition to simple serial dilutions to resolve PCR inhibition shows high sensitivity in the diagnosis of paucibacillary tuberculosis.

Characterization and assessment of HBV chronically infected patients: Identification of those eligible for treatment in the South West region of Cameroon.

BACKGROUND: The management of patients with chronic hepatitis B infection is quite complex because it requires an in-depth knowledge of the natural history of the disease. This study was aimed at characterizing HBV infected patients in order to determine the phase of the infection and identify the proportion eligible for treatment using 3 different guidelines. METHODS: HBV chronically infected patients (negative for HIV and HCV) were enrolled and the following tests were done for them: ALT, AST, HBV viral load, HBV serologic panel and Full blood count. APRI score was calculated for all patients. These patients were classified into immunotolerant, immune clearance, immune control and immune escape phases of the infection. The WHO and the 2018 AASLD criteria was also used to identify those who need treatment. Patients were clinically examined for signs and symptoms. Questionnaire was administered to all participants to ascertain their treatment status. Statistical analysis was done using SPSS version 21. RESULTS: A total of 283 participants (101 females and 182 males) with a mean age of 31.3±8.5 were enrolled. Fifty-two (18.4%) were eligible for treatment (Immune clearance and immune escape phases) and they recorded a significantly higher mean APRI score (0.71±0.51) as compared to those in the immune control and immune tolerant phase (0.43±0.20). Based on WHO and AASLD criteria, 12(4.2%) and 15 (5.3%) were eligible for treatment respectively and these were all subsets of the 52 cases mentioned above. Six (2.1%) and 29 (10.2%) of those identified under the immune control phase were on tenofovir and traditional medication respectively. CONCLUSION: Considering treatment for patients in the immune clearance and immune escape phases of the infection can be a reliable strategy to implement in our setting as this may probably tie with considerations from other treatment guidelines. Fifty-two (18.4%) patients were eligible for treatment and none of them were among the 2.1% of patients put on Tenofovir based treatment. This calls for the need for more trained health experts to periodically assess patients, implement an adequate treatment guideline and place the right patients on treatment in Cameroon.