Anthony P. Moll

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.

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.

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.

Successful integration of tuberculosis and HIV treatment in rural South Africa: the Sizonq'oba study.

Background:Tuberculosis (TB) is the leading cause of death among HIV-infected patients worldwide. In KwaZulu-Natal, South Africa, 80% of TB patients are HIV coinfected, with high treatment default and mortality rates. Integrating TB and HIV care may be an effective strategy for improving outcomes for both diseases. Methods:Prospective operational research study treating TB/HIV-coinfected patients in rural KwaZulu-Natal with once-daily antiretroviral (ARV) therapy concurrently with TB therapy by home-based, modified directly observed therapy. Patients were followed for 12 months after ARV initiation. Results:Of 119 TB/HIV-coinfected patients enrolled, 67 (56%) were female, mean age was 34.0 years, and median CD4 count was 78.5 cells per cubic millimeter. After 12 months on ARVs, mean CD4 count increase was 211 cells per cubic millimeter, and 88% had an undetectable viral load; 84% completed TB treatment. Thirteen patients (11%) died; 10 (77%) with multidrug-resistant or extensively drug-resistant TB. There were few severe adverse events or immune reconstitution events. Adherence was high with 93% of study visits attended and 99% of ARV doses taken. Conclusions:Integration of TB and HIV treatment in a rural setting using concurrent home-based therapy resulted in excellent adherence and TB and HIV outcomes. This model may result in successful management of both diseases in other rural resource-poor settings.

Nosocomial Transmission of Extensively Drug-Resistant Tuberculosis in a Rural Hospital in South Africa

BACKGROUND Extensively drug-resistant tuberculosis (XDR-tuberculosis) is a global public health threat, but few data exist elucidating factors driving this epidemic. The initial XDR-tuberculosis report from South Africa suggested transmission is an important factor, but detailed epidemiologic and molecular analyses were not available for further characterization. METHODS We performed a retrospective, observational study among XDR-tuberculosis patients to identify hospital-associated epidemiologic links. We used spoligotyping, IS6110-based restriction fragment-length polymorphism analysis, and sequencing of resistance-determining regions to identify clusters. Social network analysis was used to construct transmission networks among genotypically clustered patients. RESULTS Among 148 XDR-tuberculosis patients, 98% were infected with human immunodeficiency virus (HIV), and 59% had smear-positive tuberculosis. Nearly all (93%) were hospitalized while infectious with XDR-tuberculosis (median duration, 15 days; interquartile range: 10-25 days). Genotyping identified a predominant cluster comprising 96% of isolates. Epidemiologic links were identified for 82% of patients; social network analysis demonstrated multiple generations of transmission across a highly interconnected network. CONCLUSIONS The XDR-tuberculosis epidemic in Tugela Ferry, South Africa, has been highly clonal. However, the epidemic is not the result of a point-source outbreak; rather, a high degree of interconnectedness allowed multiple generations of nosocomial transmission. Similar to the outbreaks of multidrug-resistant tuberculosis in the 1990s, poor infection control, delayed diagnosis, and a high HIV prevalence facilitated transmission. Important lessons from those outbreaks must be applied to stem further expansion of this epidemic.

Averting epidemics of extensively drug-resistant tuberculosis

Extensively drug-resistant tuberculosis (XDR TB) has been detected in most provinces of South Africa, particularly in the KwaZulu-Natal province where several hundred cases have been reported since 2004. We analyzed the transmission dynamics of XDR TB in the region using mathematical models, and observed that nosocomial transmission clusters of XDR TB may emerge into community-based epidemics under the public health conditions of many South African communities. The effective reproductive number of XDR TB in KwaZulu-Natal may be around 2. Intensified community-based case finding and therapy appears critical to curtailing transmission. In the setting of delayed disease presentation and high system demand, improved diagnostic approaches may need to be employed in community-based programs rather than exclusively at tertiary hospitals. Using branching process mathematics, we observed that early, community-based drug-susceptibility testing and effective XDR therapy could help curtail ongoing transmission and reduce the probability of XDR TB epidemics in neighboring territories.

Increasing Drug Resistance in Extensively Drug-Resistant Tuberculosis, South Africa

We expanded second-line tuberculosis (TB) drug susceptibility testing for extensively drug-resistant Mycobacterium tuberculosis isolates from South Africa. Of 19 patients with extensively drug-resistant TB identified during February 2008–April 2009, 13 (68%) had isolates resistant to all 8 drugs tested. This resistance leaves no effective treatment with available drugs in South Africa.

Risk Factors for Mortality among MDR- and XDR-TB Patients in a High HIV-Prevalence Setting

SETTING Recent studies suggest that the prevalence of drug-resistant tuberculosis (TB) in sub-Saharan Africa may be rising. This is of concern, as human immunodeficiency virus (HIV) co-infection in multidrug-resistant (MDR) and extensively drug-resistant (XDR) TB has been associated with exceedingly high mortality rates. OBJECTIVE To identify risk factors associated with mortality in MDR- and XDR-TB patients co-infected with HIV in South Africa. DESIGN Case-control study of patients who died of all causes within 2 years of diagnosis with MDR- or XDR-TB. RESULTS Among 123 MDR-TB patients, 78 (63%) died following diagnosis. CD4 count ≤ 50 (HR 4.64, P = 0.01) and 51-200 cells/mm(3) (HR 4.17, P = 0.008) were the strongest independent risk factors for mortality. Among 139 XDR-TB patients, 111 (80%) died. CD4 count ≤ 50 cells/mm(3) (HR 4.46, P = 0.01) and resistance to all six drugs tested (HR 2.54, P = 0.04) were the principal risk factors. Use of antiretroviral therapy (ART) was protective (HR 0.34, P = 0.009). CONCLUSIONS Mortality due to MDR- and XDR-TB was associated with greater degree of immunosuppression and drug resistance. Efforts to reduce mortality must focus on preventing the amplification of resistance by strengthening TB treatment programs, as well as reducing the pool of immunosuppressed HIV-infected patients through aggressive HIV testing and ART initiation.

Predictors of multidrug- and extensively drug-resistant tuberculosis in a high HIV prevalence community.

Background Multidrug-resistant (MDR) and extensively drug-resistant (XDR) tuberculosis (TB) have emerged in high-HIV-prevalence settings, which generally lack laboratory infrastructure for diagnosing TB drug resistance. Even where available, inherent delays with current drug-susceptibility testing (DST) methods result in clinical deterioration and ongoing transmission of MDR and XDR-TB. Identifying clinical predictors of drug resistance may aid in risk stratification for earlier treatment and infection control. Methods We performed a retrospective case-control study of patients with MDR (cases), XDR (cases) and drug-susceptible (controls) TB in a high-HIV-prevalence setting in South Africa to identify clinical and demographic risk factors for drug-resistant TB. Controls were selected in a 1∶1∶1 ratio and were not matched. We calculated odds ratios (OR) and performed multivariate logistic regression to identify independent predictors. Results We enrolled 116, 123 and 139 patients with drug-susceptible, MDR, and XDR-TB. More than 85% in all three patient groups were HIV-infected. In multivariate analysis, MDR and XDR-TB were each strongly associated with history of TB treatment failure (adjusted OR 51.7 [CI 6.6-403.7] and 51.5 [CI 6.4–414.0], respectively) and hospitalization more than 14 days (aOR 3.8 [CI 1.1–13.3] and 6.1 [CI 1.8–21.0], respectively). Prior default from TB treatment was not a risk factor for MDR or XDR-TB. HIV was a risk factor for XDR (aOR 8.2, CI 1.3–52.6), but not MDR-TB. Comparing XDR with MDR-TB patients, the only significant risk factor for XDR-TB was HIV infection (aOR 5.3, CI 1.0–27.6). Discussion In this high-HIV-prevalence and drug-resistant TB setting, a history of prolonged hospitalization and previous TB treatment failure were strong risk factors for both MDR and XDR-TB. Given high mortality observed among patients with HIV and drug-resistant TB co-infection, previously treated and hospitalized patients should be considered for empiric second-line TB therapy while awaiting confirmatory DST results in settings with a high-burden of MDR/XDR-TB.

Multidrug-resistant and extensively drug-resistant tuberculosis: consequences for the global HIV community

Purpose of review Physicians, researchers and policy makers must understand the myriad consequences of multidrug and extensively drug-resistant tuberculosis (TB) within the HIV community in order to guide clinical care, research and resource allocation. Recent findings Extensively drug-resistant TB can no longer be considered as occurring in isolated outbreaks as it has been reported in 45 countries from all regions of the world. HIV has been associated as an independent risk factor for infection with drug-resistant TB. HIV patients appear more likely to suffer from primary, transmitted resistance as opposed to developing acquired resistance during the course of treatment for TB. New rapid diagnostics offer promise of providing clinically useful first-line drug susceptibility information but require validation in HIV patients and smear negative individuals. Demonstration projects of community-based treatment of drug-resistant TB and integration of TB and HIV care provide opportunities to decentralize management of drug-resistant TB. Summary Multidrug-resistant and extensively drug-resistant TB disproportionately affect HIV patients and result in increased morbidity and mortality. In this study, we address these challenging issues and offer some short-term and longer term strategies for their alleviation.