Setting KwaZulu-Natal, South Africa a predominantly rural province with high burdens of TB, MDR-TB and HIV infection. Objective To determine the most effective model of care by comparing MDR-TB treatment outcomes at community-based sites with traditional care at a central, specialised hospital. Design A non-randomised observational prospective cohort study comparing community-based and centralised care. Patients at community-based sites were closer to home, had easier access to care and home-based care was available from treatment initiation. Results Four community-based sites treated 736 patients, while 813 were treated at the centralised hospital (a total of 1549 patients). Overall, 75% were HIV co-infected (community: 76% vs. hospitalised: 73%, p=0.45) and 86% received antiretroviral therapy (community: 91% vs. hospitalised: 82%, p=0.22). In multivariate analysis MDR-TB patients were more likely to have a successful treatment outcome if they were treated at a community-based site (adjusted OR=1.43, p=0.01). However, there was heterogeneity in outcomes at the four community-based sites, with Site 1 demonstrating that home-based care was associated with increased treatment success of 72% compared with success of between 52 - 60% at the other three sites. Conclusion Community-based care for patients with MDR-TB was more effective than care in a central, specialised hospital. Home-based care further increased treatment success.

A postmortem study by Ted Cohen and colleagues reveals a huge toll of tuberculosis among patients dying in hospitals in KwaZulu-Natal, South Africa.

We performed spoligotyping and 24-locus mycobacterial interspersed repetitive-unit-variable-number tandem-repeat (MIRU-VNTR) typing on M. tuberculosis culture-positive biopsy specimens collected from adults dying in a hospital in KwaZulu-Natal. Of 56 culture-positive samples genotyped, we detected mixed strains in five (9%) and clonal heterogeneity in an additional four (7%).The application of molecular approaches for detecting variation among Mycobacterium tuberculosis isolates has generated new appreciation for the diversity present within this relatively genetically conserved bacterial species (4, 17). Genotyping methods, such as insertion sequence typing (IS6110), spacer oligonucleotide typing (spoligotyping), and mycobacterial interspersed repetitive-unit-variable-number tandem-repeat (MIRU-VNTR) typing, have been used to identify transmission chains (1,10,18,26), to classify strains into families and lineages (2,5,9,18,27,29), to identify episodes of exogenous reinfection (3,20,25,31), and, most recently, to detect the presence of within-host genetic heterogeneity (11,19,24,33).Genetic heterogeneity of M. tuberculosis within a host may arise by one of two mechanisms: (i) within-host diversification following a single infection event or (ii) reinfection resulting in a mixed infection with more than one strain (12, 16). The clinical consequences of within-host diversity are most obvious when manifesting as subpopulations of bacteria with resistance to tuberculosis (TB) antibiotics, either reflecting acquired drug resistance (mechanism 1) or transmitted drug resistance (mechanism 2). Furthermore, because individuals can be simultaneously infected by strains with different phenotypic characteristics (e.g., growth rates, drug resistance), the withinhost competition between strains may influence the clinical outcomes for coinfected patients (30) and may affect the population dynamics of the pathogen in the community (6,8).While within-host M. tuberculosis genetic diversity has been documented in many settings, systematic efforts to measure the prevalence of these complex infections have rarely been attempted. In this study, we report the results of a genotyping analysis on isolates collected from young adults dying in a hospital in KwaZulu-Natal, South Africa.We conducted limited autopsies on adults aged 20 to 45 years who died after admission to Edendale Hospital in KwaZulu-Natal, South Africa, between October 2008 and August 2009. The incidence of tuberculosis in KwaZulu-Natal is 1,094 cases/100,000 persons per year, and the HIV prevalence among women in antenatal clinical settings is 39% (14, 21). Our primary aim was to investigate the burden of tuberculosis as a contributing cause of death in this highly vulnerable community. Of the 240 decedents enrolled in the study, 94% were HIV seropositive. Fifty-eight percent of those on treatment for tuberculosis at the time of death were still infected with viable M. tuberculosis, while 42% of those not receiving treatment for TB also had positive M. tuberculosis cul...

Setting In KwaZulu-Natal, South Africa, a TB and HIV endemic setting, prolonged hospitalisation for the treatment of the growing number of MDR-TB patients is not possible or effective. Objective We compared early treatment outcomes in patients with MDR-TB, with and without HIV co infection, at a central, urban, referral hospital with four decentralised rural sites. Design This is an operational, prospective cohort study of patients between 1 July 2008 to 30 November 2009, where culture conversion, time-to-culture-conversion, survival and predictors of these outcomes were analysed. Results Of the 860 patients with MDR-TB, 419 were at the decentralised sites and 441 at the central hospital. Overall, 71% were HIV co-infected. In the 17 month study period, there was a higher proportion of culture conversion at the decentralised sites compared with the centralised hospital (54% vs. 24%; P<0.001; Odds Ratio 3.76, 95% CI 2.81 – 5.03). The median time to treatment initiation was significantly shorter at the decentralised sites compared with the centralised hospital (72 vs 93 days; p<0.001). There was no significant difference in survival following treatment initiation. Conclusion This study shows that early treatment outcomes suggest that decentralised care for MDR-TB patients is superior to that in a centralised setting.

The retrovirus forms its envelope by budding at the plasma membrane (PM). This process is primarily driven by its cytoplasmic core-precursor protein, Gag, as shown by the efficient formation of virus-like Gag particles in the absence of its envelope protein, Env. Most interestingly, several studies have demonstrated incorporation of various PM proteins into retrovirus, but the underlying mechanism of this phenomenon has remained elusive. We have purified Moloney murine leukemia virus Gag particles by sedimentation in an iodixanol gradient and donor PMs by flotation in a sucrose gradient and compared their protein compositions at equal lipid basis. We found that most PM proteins are present at similar density in both membranes. The inclusion of PM proteins was unaffected by incorporation of Env protein into the envelope of the Gag particles and whether these were produced at high or low level in the cells. These findings indicate that most PM proteins become incorporated into the retrovirus envelope without significant sorting. This feature of retrovirus assembly should be considered when studying retrovirus functions and developing retrovirus vectors.A ccording to a prevailing model, virus-specific membrane proteins are incorporated into the viral envelope by means of specific interactions with the viral core, whereas host membrane proteins, lacking possibilities to undergo such interactions, will be excluded (1). Although, experimental results support the validity of this model for some viruses-e.g., the alphaviruses (2)-it is not applicable to others-e.g., the retroviruses. In particular, several studies with HIV-1 suggest that many plasma membrane (PM) proteins of the host become incorporated into the viral envelope. These proteins include cell adhesion molecules such as CD44, LFA-1, and ICAM-1 and the antigen presenters . Similarly, studies with several different retroviruses show that they can be pseudotyped with envelope proteins of nonrelated viruses if the latter are expressed at the PM of the host cell (reviewed in refs. 4 and 5). These phenomenon may be related to the fact that retrovirus budding is not, like that of alphavirus, dependent on core-envelope protein (Env) interactions but depend on interactions of core proteins alone (reviewed in ref. 5). Thus, expression of the gag gene-i.e., the gene encoding the internal core protein (the Gag precursor)-in the absence of other viral genes results in formation of retrovirus-like Gag particles (reviewed in ref. 6). This Env-independent budding might favor host protein incorporation into the retrovirus envelope. However, the exact mechanism for the incorporation is still unclear. In particular, it is not known whether only certain or most PM proteins are incorporated into the retrovirus envelope and whether that incorporation occurs passively. To characterize this process it is necessary to compare the densities of PM proteins in the donor PM of the host cell and in the envelope of the retrovirus. Here we present such a study with Moloney murine leukemia ...

The p21 membrane protein of vaccinia virus (VV), encoded by the A17L gene, has been reported to localize on the inner of the two membranes of the intracellular mature virus (IMV). It has also been shown that p21 acts as a membrane anchor for the externally located fusion protein p14 (A27L gene). Since p14 is located on the surface of IMVs, it is hard to envision that p21 should be located only on the inner membrane. Our results from (i) immunoelectron microscopy, (ii) biotinylation, and (iii) protease treatment of purified IMVs showed that the N-terminus of p21 is exposed on the surface of virus particles, while the C-terminus is embedded in the membrane. Mono-specific antibodies to the N-terminus of p21 neutralize infection of VV while antibodies to the C-terminal domain do not. We suggest that p21 molecules are located both in the inner and in the outer membrane of IMV.

BackgroundSouth Africa has a high burden of MDR-TB, and to provide accessible treatment the government has introduced different models of care. We report the most cost-effective model after comparing cost per patient successfully treated across 5 models of care: centralized hospital, district hospitals (2), and community-based care through clinics or mobile injection teams.MethodsIn an observational study five cohorts were followed prospectively. The cost analysis adopted a provider perspective and economic cost per patient successfully treated was calculated based on country protocols and length of treatment per patient per model of care. Logistic regression was used to calculate propensity score weights, to compare pairs of treatment groups, whilst adjusting for baseline imbalances between groups. Propensity score weighted costs and treatment success rates were used in the ICER analysis. Sensitivity analysis focused on varying treatment success and length of hospitalization within each model.ResultsIn 1,038 MDR-TB patients 75% were HIV-infected and 56% were successfully treated. The cost per successfully treated patient was 3 to 4.5 times lower in the community-based models with no hospitalization. Overall, the Mobile model was the most cost-effective.ConclusionReducing the length of hospitalization and following community-based models of care improves the affordability of MDR-TB treatment without compromising its effectiveness.

Standard tuberculosis (TB) treatment includes an initial regimen containing drugs that are both rapidly bactericidal (isoniazid) and sterilizing (rifampin and pyrazinamide), and ethambutol to help prevent the emergence of drug resistance. Antagonism between isoniazid and pyrazinamide has been demonstrated in a TB treatment mouse model. Because isoniazid's bactericidal activity is greatest during the initial two treatment days, we hypothesized that removing isoniazid after the second day would increase the effectiveness of the standard regimen. To test this hypothesis, we developed a mouse model to measure the early bactericidal activity (EBA) of drug regimens designed to analyze the essentiality of both isoniazid and pyrazinamide during the first 14 d of therapy. Our results clearly indicate that discontinuation of isoniazid after the second day of treatment increases the EBA of standard therapy in the mouse model, whereas omitting pyrazinamide during the first 14 d was detrimental. Substitution of moxifloxacin for isoniazid on day 3 did not increase the EBA compared with only removing isoniazid after day 2. Our data show that a mouse model can be used to analyze the EBA of TB drugs, and our findings support pursuing clinical trials to evaluate the possible benefit of removing isoniazid after the first 2 treatment days.chemotherapy | Mycobacterium A lthough tuberculosis (TB) has largely disappeared from many regions of the world, globally this disease is the leading cause of mortality due to bacterial infection, causing nearly 2 million deaths each year (1). The current standard of TB treatment requires daily administration of multiple drugs for at least 6 mo (2). Several unique characteristics of the etiologic agent Mycobacterium tuberculosis may account for this required duration of treatment. M. tuberculosis is a true human pathogen in that treatment of TB is meant to eliminate every tubercle bacillus in the body, in contrast to other opportunistic bacterial pathogens which can also be part of the normal human microbiota. Furthermore, as M. tuberculosis is an extremely slow-growing organism (doubling time of ∼20 h), the sterilization process does not occur rapidly.The standard drug treatment of TB unfolds in two phases (3), an initial phase known as the "bactericidal phase" and a continuation phase known as the "sterilizing phase." The former phase aims at killing the vast majority (99%) of actively metabolizing and replicating bacilli without selecting drug-resistant mutants, whereas the latter phase aims at eliminating the remaining bacilli, referred to as nonreplicating persisters. The key bactericidal TB drug (4, 5) is isoniazid (INH), which is responsible for killing rapidly growing bacilli during the first 2 d of treatment (6). Beyond these 2 d, the remaining persisting bacilli are killed in a process of slow sterilization, dependent on the two sterilizing drugs, rifampin (RIF) and pyrazinamide (PZA). It is on these concepts that the standard 6-mo short-course chemotherapy of TB is based. In M. tubercul...