ABSTRACT
BACKGROUND: In sub-Saharan Africa, a third of people starting antiretroviral therapy and majority of patients returning to HIV-care after disengagement, present with advanced HIV disease (ADH), and are at high risk of mortality. Simplified and more affordable point-of-care (POC) diagnostics are required to increase access to prompt CD4 cell count screening for ambulatory and asymptomatic patients. The Visitect CD4 Lateral Flow Assay (LFA) is a disposable POC test, providing a visually interpreted result of above or below 200 CD4cells/mm3. This study evaluated the diagnostic performance of this index test. METHODS: Consenting patients above 18years of age and eligible for CD4 testing were enrolled in Nsanje district hospital (Malawi), Gutu mission hospital (Zimbabwe) and Centre hopitalier de Kabinda (DRC). A total of 708 venous blood samples were tested in the index test and in the BD FACSCount assay (reference test method) in the laboratories (Phase 1) to determine diagnostic accuracy. A total of 433 finger-prick (FP) samples were tested on the index test at POC by clinicians (Phase 2) and a self-completed questionnaire was administered to all testers to explore usability of the index test. RESULTS: Among 708 patients, 67.2% were female and median CD4 was 297cells/mm3. The sensitivity of the Visitect CD4 LFA using venous blood in the laboratory was 95.0% [95% CI: 91.3-97.5] and specificity was 81.9% [95% CI: 78.2-85.2%]. Using FP samples, the sensitivity of the Visitect CD4 LFA was 98.3% [95% CI: 95.0-99.6] and specificity was 77.2% [95% CI: 71.6-82.2%]. Usability of the Visitect CD4 LFA was high across the study sites with 97% successfully completed tests. Due to the required specific multiple incubation and procedural steps during the Visitect CD4 LFA testing, few health workers (7/26) were not confident to manage testing whilst multi-tasking in their clinical work. CONCLUSIONS: Visitect CD4 LFA is a promising test for decentralized CD4 screening in resource-limited settings, without access to CD4 testing and and it can trigger prompt management of patients with AHD. Lay health cadres should be considered to conduct Visitect CD4 LFA testing in PHCs as well as coordinating all other POC quality assurance.
Subject(s)
CD4 Lymphocyte Count/methods , HIV Infections/diagnosis , Mass Screening , Adult , Female , HIV Infections/epidemiology , Humans , Malawi/epidemiology , Middle Aged , Point-of-Care Testing , Serologic Tests , Zimbabwe/epidemiologyABSTRACT
Background: The emergence and spread of drug-resistant Tuberculosis (TB) is a major public health threat. TB resistance originates in the course of treatment due to genomic mutations in Mycobacterium tuberculosis (MTB). An increase in new cases with drug-resistant TB could be an indicator of high levels of circulating resistant strains. This study was conducted to determine the occurrence and frequency of genomic mutations that mediate Isoniazid (INH) and Rifampicin (RIF) resistance among isolates from untreated TB cases in urban Blantyre, Malawi. Methods: A cross-sectional retrospective study was conducted on a panel of 141(n=141) MTB clinical isolates recovered between June 2010 and January 2012 from >2+ Ziehl-Neelsen smear positive new pulmonary-TB patients with no history of treatment. Frozen isolates were revived using the BACTEC MGIT detection system. DNA was extracted using GenoLyse DNA extraction kit and detection of genomic mutations was carried out using the GenoType MTBDRplus Ver 2.0 assay. Results: Out of the 141 isolates studied, 3 (2.1%) were found carrying mutations in the katG gene that confer resistance to Isoniazid (INH). No mutations were detected in the inhA promoter region gene that confer weak INH resistance or in the rpoB gene that confer Rifampicin resistance. All katG mutant genes had a S315T1 single point mutation, a genomic alteration that mediates high INH resistance. Conclusion: The katG mutant gene conferring resistance to INH was the only genomic mutation observed among the isolates studied and the frequency of occurrence was low. Our findings suggest low levels of circulating drug-resistant MTB strains in urban Blantyre, Malawi.