Open Access Publications

Open Access HIV & TB PublicationsThe Victor Daitz Information Gateway provides financial support to HIV and TB researchers at the University of KwaZulu-Natal wishing to publish papers in Open Access journals. The list of Open Access articles below are papers published with the support of the Victor Daitz Information Gateway.

  • Chinta KC, Saini V, Glasgow JN, Mazorodze JH, Rahman MA, Reddy D, Lancaster JR Jr, Steyn AJ

    Nitric Oxide, Vol 59, Issue , 07/2016

    Mycobacterium tuberculosis (Mtb) is a facultative intracellular pathogen and the second largest contributor to global mortality caused by an infectious agent after HIV. In infected host cells, Mtb is faced with a harsh intracellular environment including hypoxia and the release of nitric oxide (NO) and carbon monoxide (CO) by immune cells. Hypoxia, NO and CO induce a state of in vitro dormancy where Mtb senses these gases via the DosS and DosT heme sensor kinase proteins, which in turn induce a set of ∼47 genes, known as the Mtb Dos dormancy regulon. On the contrary, both iNOS and HO-1, which produce NO and CO, respectively, have been shown to be important against mycobacterial disease progression. In this review, we discuss the impact of O2, NO and CO on Mtb physiology and in host responses to Mtb infection as well as the potential role of another major endogenous gas, hydrogen sulfide (H2S), in Mtb pathogenesis.

  • Cohen KA, El-Hay T, Wyres KL, Weissbrod O, Munsamy V, Yanover C, Aharonov R, Shaham O, Conway TC, Goldschmidt Y, Bishai WR, Pym AS

    EBioMedicine, Vol 9, Issue , 07/2016

    Mycobacterium tuberculosis (M. tuberculosis) is considered innately resistant to β-lactam antibiotics. However, there is evidence that susceptibility to β-lactam antibiotics in combination with β–lactamase inhibitors is variable among clinical isolates, and these may present therapeutic options for drug-resistant cases. Here we report our investigation of susceptibility to β-lactam/β–lactamase inhibitor combinations among clinical isolates of M. tuberculosis, and the use of comparative genomics to understand the observed heterogeneity in susceptibility. Eighty-nine South African clinical isolates of varying first and second-line drug susceptibility patterns and two reference strains of M. tuberculosis underwent minimum inhibitory concentration (MIC) determination to two β-lactams: amoxicillin and meropenem, both alone and in combination with clavulanate, a β–lactamase inhibitor. 41/91 (45%) of tested isolates were found to be hypersusceptible to amoxicillin/clavulanate relative to reference strains, including 14/24 (58%) of multiple drug-resistant (MDR) and 22/38 (58%) of extensively drug-resistant (XDR) isolates. Genome-wide polymorphisms identified using whole-genome sequencing were used in a phylogenetically-aware linear mixed model to identify polymorphisms associated with amoxicillin/clavulanate susceptibility. Susceptibility to amoxicillin/clavulanate was over-represented among isolates within a specific clade (LAM4), in particular among XDR strains. Twelve sets of polymorphisms were identified as putative markers of amoxicillin/clavulanate susceptibility, five of which were confined solely to LAM4. Within the LAM4 clade, ‘paradoxical hypersusceptibility’ to amoxicillin/clavulanate has evolved in parallel to first and second-line drug resistance. Given the high prevalence of LAM4 among XDR TB in South Africa, our data support an expanded role for β-lactam/β-lactamase inhibitor combinations for treatment of drug-resistant M. tuberculosis.

  • Dirk A Lamprecht, Peter M Finin, Mohammed A Rahman, Bridgette M Cumming, Shannon L Russell, Surendranadha R Jonnala, John H Adamson, Adrie JC Steyn

    Nature Communications, Vol 7, Issue , 08/2016

    The Mycobacterium tuberculosis (Mtb) electron transport chain (ETC) has received significant attention as a drug target, however its vulnerability may be affected by its flexibility in response to disruption. Here we determine the effect of the ETC inhibitors bedaquiline, Q203 and clofazimine on the Mtb ETC, and the value of the ETC as a drug target, by measuring Mtb’s respiration using extracellular flux technology. We find that Mtb’s ETC rapidly reroutes around inhibition by these drugs and increases total respiration to maintain ATP levels. Rerouting is possible because Mtb rapidly switches between terminal oxidases, and, unlike eukaryotes, is not susceptible to back pressure. Increased ETC activity potentiates clofazimine’s production of reactive oxygen species, causing rapid killing in vitro and in a macrophage model. Our results indicate that combination therapy targeting the ETC can be exploited to enhance killing of Mtb.

  • Mashamba-Thompson TP, Drain PK, Sartorius B

    BMJ Open, Vol 6, Issue 6, 06/2016

    Poor healthcare access is a major barrier to receiving antenatal care and a cause of high maternal mortality in South Africa (SA). ‘Point-of-care’ (POC) diagnostics is a powerful emerging healthcare approach to improve healthcare access. This study focuses on evaluating the accessibility and utility of POC diagnostics for maternal health in rural SA primary healthcare (PHC) clinics in order to generate a model framework of implementation of POC diagnostics in rural South African clinics.

    We will use several research methods, including a systematic review, quasi-experiments, survey, key informant interviews and audits. We will conduct a systematic review and experimental study to determine the impact of POC diagnostics on maternal health. We will perform a cross-sectional case study of 100 randomly selected rural primary healthcare clinics in KwaZulu-Natal to measure the context and patterns of POC diagnostics access and usage by maternal health providers and patients. We will conduct interviews with relevant key stakeholders to determine the reasons for POC deficiencies regarding accessibility and utility of HIV-related POC diagnostics for maternal health. We will also conduct a vertical audit to investigate all the quality aspects of POC diagnostic services including diagnostic accuracy in a select number of clinics. On the basis of information gathered, we will propose a model framework for improved implementation of POC diagnostics in rural South African public healthcare clinics. Statistical (Stata-13) and thematic (NVIVO) data analysis will be used in this study.

  • Coutsoudis A, Daniels B, Moodley-Govender E, Ngomane N, Zako L, Spooner E, Kiepiela P, Reddy S, Kuhn L, Ramjee G

    BMJ Open, Vol 6, Issue 7, 07/2016

    No randomised controlled trial (RCT) has examined the efficacy of cotrimoxazole (CTX) prophylaxis in HIV-exposed uninfected (HEU) infants during the breastfeeding period, in this new era of effective prevention of mother-to-child transmission (PMTCT) prophylaxis. The efficacy of CTX prophylaxis has presently been demonstrated only in HIV-infected children. The absence of proven benefits in HEU breastfed infants associated with infectious diseases justifies an RCT as proposed. Herewith lies the rationale for conducting the proposed study.

    A partially blinded RCT is proposed to evaluate the efficacy of CTX prophylaxis administered from 6 weeks of age to HEU infants receiving a PMTCT regimen. A non-inferiority design will be used, randomising 1298 infants to receive CTX or not to receive CTX. Participants will be reviewed at the following time points: 6 weeks (enrolment and randomisation), 10 weeks, 14 weeks, 4 months and monthly thereafter until 12 months of age. They will be evaluated for anthropometric growth, interval illness, CTX adherence, signs and symptoms of study drug toxicity, concomitant medication use, breastfeeding status and HIV infection status. The study will compare the incidence of grade 3 and grade 4 common childhood illnesses (focusing on pneumonia and diarrhoea) and all-cause mortality until 12 months of age. In a subset of participants, we will compare grade 3 and grade 4 haemoglobin and alanine aminotransferase results as well as investigate gut integrity.