An investigation of fingerstick blood collection for point-of-care HIV-1 viral load monitoring in South Africa.

BACKGROUND: Viral load (VL) quantification is an important tool in determining newly developed drug resistance or problems with adherence to antiretroviral therapy (ART) in HIV-positive patients. VL monitoring is becoming the standard of care in many resource-limited settings. Testing in resource-limited settings may require sampling by fingerstick because of general shortages of skilled phlebotomists and the expense of venepuncture supplies and problems with their distribution. OBJECTIVE: To assess the feasibility and ease of collecting 150 µL capillary blood needed for the use of a novel collection device following a classic fingerstick puncture. METHODS: Patients were recruited by the study nurse upon arrival for routine ART monitoring at the Themba Lethu Clinic in Johannesburg, South Africa. Each step of the fingerstick and blood collection protocol was observed, and their completion or omission was recorded. RESULTS: One hundred and three patients consented to the study, of whom three were excluded owing to the presence of callouses. From a total of 100 patients who consented and were enrolled, 98% of collection attempts were successful and 86% of participants required only one fingerstick to successfully collect 150 µL capillary blood. Study nurse adherence to the fingerstick protocol revealed omissions in several steps that may lower the success rate of capillary blood collection and reduce the performance of a subsequent VL assay. CONCLUSION: The findings of this study support the feasibility of collecting 150 µL of capillary blood via fingerstick for point-of-care HIV-1 VL testing in a resource-limited setting.

High incidence of latent tuberculous infection among South African health workers: an urgent call for action.

SETTING: In South Africa, health care workers (HCWs) are at two-fold greater risk of acquiring tuberculosis (TB) disease than the general population. Few studies have evaluated the risk of incident tuberculous infection. OBJECTIVE: To determine the incidence and risk factors for latent tuberculous infection (LTBI) among HCWs and to compare the results of the interferon-gamma release assay (IGRA) with those of the tuberculin skin test (TST). DESIGN: HCWs, including medical students, underwent a TST and human immunodeficiency virus (HIV) and IGRA testing at baseline and 12 months, and IGRA at 6 months. The participants kept 12-month TB exposure logs. RESULTS: Among 199 participants (150 [76%] females, median age 31 years [range 20-61]), incident LTBI was documented using IGRA in 25/97 (26%; incident rate 29 cases/100 person-years [py], 95%CI 20-44) and using TST in 25/93 (27%; incident rate 29 cases/100 py, 95%CI 19-42). Agreement between TST and IGRA was poor (44.8%, κ = 0.23). Higher annual exposure to TB cases was reported among persons with LTBI than in those who were persistently IGRA-negative (81 cases, 95%CI 61-102 vs. 50 cases, 95%CI 43-57, P < 0.01). CONCLUSION: The high LTBI incidence and the association of incident LTBI with annual TB caseload among HCWs indicate that more effective TB infection control should be implemented in South African health care facilities.

A pilot evaluation of external quality assessment of GenoType MTBDRplus versions 1 and 2 using dried culture spot material.

Dried culture spots (DCS) of inactivated Mycobacteria strains designed as part of an external quality assessment (EQA) program for the GeneXpert system has applications to other molecular tuberculosis (TB) diagnostic platforms. DCS tested on the GenoType MTBDRplus and Mycobacterium CM assays performed well with MTBDRplus version 2 but require increased bacterial concentration for use with version 1.

Performance monitoring of mycobacterium tuberculosis dried culture spots for use with the GeneXpert system within a national program in South Africa.

The use of dried culture spots (DCSs) has been reported in the verification of GeneXpert instruments as being "fit for purpose" for the South African National implementation program. We investigated and compared the performance of the DCSs for verification across different bulk batches, testing the settings and cadre of staff, and the Xpert MTB/RIF assay version. Four bulk batches (V005 to V008) were used to prepare (i) 619 DCS panels for laboratory testing on G3 or G4 cartridges by a technologist, (ii) 13 DCS panels (batch V005) used for clinic verification on G3 cartridges by a nurse or lay counselor, and (iii) 20 DCS panels (batch V005) used for the verification of 10 GeneXpert 16 module instruments in mobile vehicles on the G3 cartridge performed by a scientist. The stabilities of the DCSs over 6 months at 4°C, room temperature, and 37°C were investigated. The mean cycle threshold (CT) and standard deviation (SD) for probe A were calculated. The proportions of variability in the CT values across bulk batches, assay versions, and settings and cadre of staff were determined using regression analysis. Overall, the DCSs demonstrated SDs of 3.3 (n = 660) for the G3 cartridges and 3.8 (n = 1,888) for the G4 cartridges, with an overall error rate of 1.5% and false rifampin resistance rate of 0.1%. The proportions of variability (R(2)) in the CT values explained by batch were 14%, by setting and cadre of staff, 5.6%, and by assay version, 4.2%. The most stable temperature in a period of up to 6 months was 37°C (SD, 2.7). The DCS is a robust product suitable for storage, transport, and use at room temperature for the verification of the GeneXpert instrument, and the testing can be performed by non-laboratory-trained personnel in nonlaboratory settings.

Performance of the Roche LightCycler real-time PCR assay for diagnosing extrapulmonary tuberculosis.

The Roche LightCycler mycobacterium detection molecular assay for Mycobacterium tuberculosis, M. avium, and M. kansasii, was applied to tissue specimens. It performed well on lymph node and cerebrospinal fluid specimens and less well on lung, liver, and bone marrow core biopsy specimens, but used in conjunction with a clinical suspicion of tuberculosis, it could augment patient management.

Dried culture spots for Xpert MTB/RIF external quality assessment: results of a phase 1 pilot study in South Africa.

Implementation of Xpert MTB/RIF requires quality assessment. A pilot program using dried culture spots (DCSs) of inactivated Mycobacterium tuberculosis is described. Of 274 DCS results received, 2.19% generated errors; the remainder yielded 100% correct Mycobacterium tuberculosis detection. The probe A cycle threshold (C(T)) variability of three DCS batches was ≤ 3.47. The study of longer-term DCS stability is ongoing.