Neel R. Gandhi

Extensively drug-resistant tuberculosis as a cause of death in patients co-infected with tuberculosis and HIV in a rural area of South Africa

BACKGROUND The epidemics of HIV-1 and tuberculosis in South Africa are closely related. High mortality rates in co-infected patients have improved with antiretroviral therapy, but drug-resistant tuberculosis has emerged as a major cause of death. We assessed the prevalence and consequences of multidrug-resistant (MDR) and extensively drug-resistant (XDR) tuberculosis in a rural area in KwaZulu Natal, South Africa. METHODS We undertook enhanced surveillance for drug-resistant tuberculosis with sputum culture and drug susceptibility testing in patients with known or suspected tuberculosis. Genotyping was done for isolates resistant to first-line and second-line drugs. RESULTS From January, 2005, to March, 2006, sputum was obtained from 1539 patients. We detected MDR tuberculosis in 221 patients, of whom 53 had XDR tuberculosis. Prevalence among 475 patients with culture-confirmed tuberculosis was 39% (185 patients) for MDR and 6% (30) for XDR tuberculosis. Only 55% (26 of 47) of patients with XDR tuberculosis had never been previously treated for tuberculosis; 67% (28 of 42) had a recent hospital admission. All 44 patients with XDR tuberculosis who were tested for HIV were co-infected. 52 of 53 patients with XDR tuberculosis died, with median survival of 16 days from time of diagnosis (IQR 6-37) among the 42 patients with confirmed dates of death. Genotyping of isolates showed that 39 of 46 (85%, 95% CI 74-95) patients with XDR tuberculosis had similar strains. CONCLUSIONS MDR tuberculosis is more prevalent than previously realised in this setting. XDR tuberculosis has been transmitted to HIV co-infected patients and is associated with high mortality. These observations warrant urgent intervention and threaten the success of treatment programmes for tuberculosis and HIV.

Multidrug-resistant and extensively drug-resistant tuberculosis: a threat to global control of tuberculosis

Although progress has been made to reduce global incidence of drug-susceptible tuberculosis, the emergence of multidrug-resistant (MDR) and extensively drug-resistant (XDR) tuberculosis during the past decade threatens to undermine these advances. However, countries are responding far too slowly. Of the estimated 440,000 cases of MDR tuberculosis that occurred in 2008, only 7% were identified and reported to WHO. Of these cases, only a fifth were treated according to WHO standards. Although treatment of MDR and XDR tuberculosis is possible with currently available diagnostic techniques and drugs, the treatment course is substantially more costly and laborious than for drug-susceptible tuberculosis, with higher rates of treatment failure and mortality. Nonetheless, a few countries provide examples of how existing technologies can be used to reverse the epidemic of MDR tuberculosis within a decade. Major improvements in laboratory capacity, infection control, performance of tuberculosis control programmes, and treatment regimens for both drug-susceptible and drug-resistant disease will be needed, together with a massive scale-up in diagnosis and treatment of MDR and XDR tuberculosis to prevent drug-resistant strains from becoming the dominant form of tuberculosis. New diagnostic tests and drugs are likely to become available during the next few years and should accelerate control of MDR and XDR tuberculosis. Equally important, especially in the highest-burden countries of India, China, and Russia, will be a commitment to tuberculosis control including improvements in national policies and health systems that remove financial barriers to treatment, encourage rational drug use, and create the infrastructure necessary to manage MDR tuberculosis on a national scale.

Multidrug Resistant Pulmonary Tuberculosis Treatment Regimens and Patient Outcomes: An Individual Patient Data Meta-analysis of 9,153 Patients

Dick Menzies and colleagues report findings from a collaborative, individual patient-level meta-analysis of treatment outcomes among patients with multidrug-resistant tuberculosis.

HIV Coinfection in Multidrug- and Extensively Drug-Resistant Tuberculosis Results in High Early Mortality

RATIONALE The multidrug-resistant (MDR) and extensively drug-resistant (XDR) tuberculosis (TB) epidemics are rapidly expanding in South Africa. Our initial report of HIV-associated XDR TB in South Africa revealed rapid and near complete mortality. Lower mortality has been described in the literature, but few of these patients have been HIV coinfected. OBJECTIVES To characterize mortality from MDR and XDR TB in a setting with high HIV-coinfection rates. METHODS We conducted a retrospective observational study among 654 MDR and XDR TB cases diagnosed in Tugela Ferry, South Africa, from 2005 to 2007. Demographics and HIV status were abstracted from available medical records. MEASUREMENTS AND MAIN RESULTS Survival was determined from the date of sputum collection until October 2008 and correlated with year of diagnosis and drug-susceptibility test results. From 2005 to 2007, 272 MDR TB and 382 XDR TB cases were diagnosed; HIV-coinfection rates were 90 and 98%, respectively. One-year mortality was 71% for MDR and 83% for XDR TB patients; 40% of MDR TB and 51% of XDR TB cases died within 30 days of sputum collection. One-year mortality among both MDR and XDR TB patients improved from 2005 to 2007; however, the majority of deaths still occurred within the first 30 days. One-year and 30-day mortality rates were worse with greater degree of drug resistance (P < 0.001). CONCLUSIONS Mortality from MDR and XDR TB in this high HIV-prevalence region is extraordinarily high, particularly within the first 30 days. Efforts to reduce mortality must focus on earlier diagnosis and early initiation of second-line TB and antiretroviral therapy.

Resistance to fluoroquinolones and second-line injectable drugs: impact on multidrug-resistant TB outcomes

A meta-analysis for response to treatment was undertaken using individual data of multidrug-resistant tuberculosis (MDR-TB) (resistance to isoniazid and rifampicin) patients from 26 centres. The analysis assessed the impact of additional resistance to fluoroquinolones and/or second-line injectable drugs on treatment outcome. Compared with treatment failure, relapse and death, treatment success was higher in MDR-TB patients infected with strains without additional resistance (n=4763; 64%, 95% CI 57–72%) or with resistance to second-line injectable drugs only (n=1130; 56%, 95% CI 45–66%), than in those having resistance to fluoroquinolones alone (n=426; 48%, 95% CI 36–60%) or to fluoroquinolones plus second-line injectable drugs (extensively drug resistant (XDR)-TB) (n=405; 40%, 95% CI 27–53%). In XDR-TB patients, treatment success was highest if at least six drugs were used in the intensive phase (adjusted OR 4.9, 95% CI 1.4–16.6; reference fewer than three drugs) and four in the continuation phase (OR 6.1, 95% CI 1.4–26.3). The odds of success in XDR-TB patients was maximised when the intensive phase reached 6.6–9.0 months duration and the total duration of treatment 20.1–25.0 months. In XDR-TB patients, regimens containing more drugs than those recommended in MDR-TB but given for a similar duration were associated with the highest odds of success. All data were from observational studies and methodologies varied between centres, therefore, the bias may be substantial. Better quality evidence is needed to optimise regimens.

Prevention of nosocomial transmission of extensively drug-resistant tuberculosis in rural South African district hospitals: an epidemiological modelling study

BACKGROUND Extensively drug-resistant (XDR) tuberculosis has spread among hospitalised patients in South Africa, but the epidemic-level effect of hospital-based infection control strategies remains unknown. We modelled the plausible effect of rapidly available infection control strategies on the overall course of the XDR tuberculosis epidemic in a rural area of South Africa. METHODS We investigated the effect of administrative, environmental, and personal infection control measures on the epidemic trajectory of XDR tuberculosis in the rural community of Tugela Ferry. Assessments were done with a mathematical model incorporating over 2 years of longitudinal inpatient and community-based data. The model simulated inpatient airborne tuberculosis transmission, community tuberculosis transmission, and the effect of HIV and antiretroviral therapy. FINDINGS If no new interventions are introduced, about 1300 cases of XDR tuberculosis are predicted to occur in the area of Tugela Ferry by the end of 2012, more than half of which are likely to be nosocomially transmitted. Mask use alone would avert fewer than 10% of cases in the overall epidemic, but could prevent a large proportion of cases of XDR tuberculosis in hospital staff. The combination of mask use with reduced hospitalisation time and a shift to outpatient therapy could prevent nearly a third of XDR tuberculosis cases. Supplementing this approach with improved ventilation, rapid drug resistance testing, HIV treatment, and tuberculosis isolation facilities could avert 48% of XDR tuberculosis cases (range 34-50%) by the end of 2012. However, involuntary detention could result in an unexpected rise in incidence due to restricted isolation capacity. INTERPRETATION A synergistic combination of available nosocomial infection control strategies could prevent nearly half of XDR tuberculosis cases, even in a resource-limited setting. XDR tuberculosis transmission will probably continue in the community, indicating the need to develop and implement parallel community-based programmes.

Drug resistance beyond extensively drug-resistant tuberculosis: individual patient data meta-analysis

The broadest pattern of tuberculosis drug resistance for which a consensus definition exists is extensively drug-resistant tuberculosis (XDR-TB). It is not known if additional drug resistance portends worsened patient outcomes. This study compares treatment outcomes of XDR-TB patients with and without additional resistance to explore the need for a new definition. Individual patient data on XDR-TB outcomes were included in a meta-analysis comparing outcomes between XDR-alone and three non-mutually exclusive XDR-TB patient groups: XDR plus resistance to all the second-line injectables (sli) capreomycin and kanamycin/amikacin (XDR+2sli); XDR plus resistance to second-line injectables and to ≥1 Group 4 drug, i.e. : ethionamide/prothionamide, cycloserine/terizidone or PAS (XDR+sliG4); and XDR+sliG4 plus resistance to ethambutol and/or pyrazinamide (XDR+sliG4EZ). Of 405 XDR-TB cases, 301 were XDR-alone; 68 XDR+2sli; 48 XDR+sliG4; and 42 XDR+sliG4EZ. In multivariate analysis, the odds of cure were significantly lower in XDR+2sli (adjusted Odds Ratio (aOR): 0.4; 95% Confidence Interval: 0.2–0.8) compared to XDR-alone, while odds of failure+death were higher in all XDR patients with additional resistance (aOR range: 2.6–2.8). Patients with additional resistance beyond XDR-TB showed poorer outcomes. Limitations in availability, accuracy and reproducibility of current DST methods preclude the adoption of a useful definition beyond the one currently used for XDR-TB.The broadest pattern of tuberculosis (TB) drug resistance for which a consensus definition exists is extensively drug-resistant (XDR)-TB. It is not known if additional drug resistance portends worsened patient outcomes. This study compares treatment outcomes of XDR-TB patients with and without additional resistance in order to explore the need for a new definition. Individual patient data on XDR-TB outcomes were included in a meta-analysis comparing outcomes between XDR alone and three nonmutually exclusive XDR-TB patient groups: XDR plus resistance to all the second-line injectables (sli) and capreomycin and kanamycin/amikacin (XDR+2sli) XDR plus resistance to second-line injectables and to more than one group 4 drug, i.e. ethionamide/protionamide, cycloserine/terizidone or para-aminosalicylic acid (XDR+sliG4) and XDR+sliG4 plus resistance to ethambutol and/or pyrazinamide (XDR+sliG4EZ). Of 405 XDR-TB cases, 301 were XDR alone, 68 XDR+2sli, 48 XDR+sliG4 and 42 XDR+sliG4EZ. In multivariate analysis, the odds of cure were significantly lower in XDR+2sli (adjusted OR 0.4, 95% CI 0.2–0.8) compared to XDR alone, while odds of failure and death were higher in all XDR patients with additional resistance (adjusted OR 2.6–2.8). Patients with additional resistance beyond XDR-TB showed poorer outcomes. Limitations in availability, accuracy and reproducibility of current drug susceptibility testing methods preclude the adoption of a useful definition beyond the one currently used for XDR-TB.

Development and verification of a "virtual" cohort using the National VA Health Information System.

Background:The VAs integrated electronic medical record makes it possible to create a “virtual” cohort of veterans with and without HIV infection to monitor trends in utilization, toxicity, and outcomes. Objectives:We sought to develop a virtual cohort of HIV-infected veterans by adapting an existing algorithm, verifying this algorithm against independent clinical data, and finally identifying demographically-similar HIV-uninfected comparators. Research Design:Subjects were identified from VA administrative data in fiscal years 1998–2003 using a modified existing algorithm, then linked with Immunology Case Registry (ICR, the VAs HIV registry) and Pharmacy Benefits Management (centralized database of outpatient prescriptions) to verify accuracy of identification. The algorithm was modified to maximize positive predictive value (PPV) against ICR. Finally, 2 HIV-uninfected comparators were matched to each HIV-infected subject. Results:Using a single HIV code, 30,564 subjects were identified (positive predictive value 69%). Modification to require >1 outpatient or 1 inpatient code improved the positive predictive value to 88%. The lack of confirmatory laboratory and pharmacy data for the majority of subjects with a single outpatient code also supported this change. Of subjects identified with the modified algorithm, 89% had confirmatory evidence. When the modified algorithm was applied to fiscal years 1997–2004, 33,420 HIV-infected subjects were identified. Two HIV-uninfected comparators were matched to each subject for an overall cohort sample of 100,260. Conclusions:In the HAART era, HIV-related codes are sufficient for identifying HIV-infected subjects from administrative data when patients with a single outpatient code are excluded. A large cohort of HIV-infected subjects and matched comparators can be identified from existing VA administrative datasets.

Global control of tuberculosis: from extensively drug-resistant to untreatable tuberculosis

Extensively drug-resistant tuberculosis is a burgeoning global health crisis mainly affecting economically active young adults, and has high mortality irrespective of HIV status. In some countries such as South Africa, drug-resistant tuberculosis represents less than 3% of all cases but consumes more than a third of the total national budget for tuberculosis, which is unsustainable and threatens to destabilise national tuberculosis programmes. However, concern about drug-resistant tuberculosis has been eclipsed by that of totally and extremely drug-resistant tuberculosis--ie, resistance to all or nearly all conventional first-line and second-line antituberculosis drugs. In this Review, we discuss the epidemiology, pathogenesis, diagnosis, management, implications for health-care workers, and ethical and medicolegal aspects of extensively drug-resistant tuberculosis and other resistant strains. Finally, we discuss the emerging problem of functionally untreatable tuberculosis, and the issues and challenges that it poses to public health and clinical practice. The emergence and growth of highly resistant strains of tuberculosis make the development of new drugs and rapid diagnostics for tuberculosis--and increased funding to strengthen global control efforts, research, and advocacy--even more pressing.

Multidrug-Resistant and Extensively Drug-Resistant Tuberculosis: Implications for the HIV Epidemic and Antiretroviral Therapy Rollout in South Africa

Drug-resistant tuberculosis (TB) is emerging as a major clinical and public health challenge in areas of sub-Saharan Africa where there is a high prevalence of human immunodeficiency virus (HIV) infection. TB drug-resistance surveillance in this region has been limited by laboratory capacity and the public health infrastructure; however, with the maturation of the HIV epidemic, the burden of drug-resistant TB is increasing rapidly. The recent discovery of large numbers of cases of multidrug-resistant (MDR) TB and extensively drug-resistant (XDR) TB in South Africa likely represents an unrecognized and evolving epidemic rather than sporadic, localized outbreaks. The combination of a large population of HIV-infected susceptible hosts with poor TB treatment success rates, a lack of airborne infection control, limited drug-resistance testing, and an overburdened MDR-TB treatment program provides ideal conditions for an MDR-TB and XDR-TB epidemic of unparalleled magnitude. In the present article, we review the history of drug-resistant TB in South Africa, describe its interaction with the HIV epidemic and the resultant consequences, and suggest measures necessary for controlling MDR-TB and XDR-TB in this context. A successful response to the emergence of MDR-TB and XDR-TB will necessitate increased resources for and collaboration between TB and HIV programs.