James C. M. Brust

Transmission of Extensively Drug-Resistant Tuberculosis in South Africa.

BACKGROUND Drug‐resistant tuberculosis threatens recent gains in the treatment of tuberculosis and human immunodeficiency virus (HIV) infection worldwide. A widespread epidemic of extensively drug‐resistant (XDR) tuberculosis is occurring in South Africa, where cases have increased substantially since 2002. The factors driving this rapid increase have not been fully elucidated, but such knowledge is needed to guide public health interventions. METHODS We conducted a prospective study involving 404 participants in KwaZulu‐Natal Province, South Africa, with a diagnosis of XDR tuberculosis between 2011 and 2014. Interviews and medical‐record reviews were used to elicit information on the participants’ history of tuberculosis and HIV infection, hospitalizations, and social networks. Mycobacterium tuberculosis isolates underwent insertion sequence (IS)6110 restriction‐fragment–length polymorphism analysis, targeted gene sequencing, and whole‐genome sequencing. We used clinical and genotypic case definitions to calculate the proportion of cases of XDR tuberculosis that were due to inadequate treatment of multidrug‐resistant (MDR) tuberculosis (i.e., acquired resistance) versus those that were due to transmission (i.e., transmitted resistance). We used social‐network analysis to identify community and hospital locations of transmission. RESULTS Of the 404 participants, 311 (77%) had HIV infection; the median CD4+ count was 340 cells per cubic millimeter (interquartile range, 117 to 431). A total of 280 participants (69%) had never received treatment for MDR tuberculosis. Genotypic analysis in 386 participants revealed that 323 (84%) belonged to 1 of 31 clusters. Clusters ranged from 2 to 14 participants, except for 1 large cluster of 212 participants (55%) with a LAM4/KZN strain. Person‐to‐person or hospital‐based epidemiologic links were identified in 123 of 404 participants (30%). CONCLUSIONS The majority of cases of XDR tuberculosis in KwaZulu‐Natal, South Africa, an area with a high tuberculosis burden, were probably due to transmission rather than to inadequate treatment of MDR tuberculosis. These data suggest that control of the epidemic of drug‐resistant tuberculosis requires an increased focus on interrupting transmission. (Funded by the National Institute of Allergy and Infectious Diseases and others.)

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.

Culture conversion among HIV co-infected multidrug-resistant tuberculosis patients in Tugela Ferry, South Africa.

Background Little is known about the time to sputum culture conversion in MDR-TB patients co-infected with HIV, although such patients have, historically, had poor outcomes. We describe culture conversion rates among MDR-TB patients with and without HIV-co-infection in a TB-endemic, high-HIV prevalent, resource-limited setting. Methods Patients with culture-proven MDR-TB were treated with a standardized second-line regimen. Sputum cultures were taken monthly and conversion was defined as two negative cultures taken at least one month apart. Time-to-conversion was measured from the day of initiation of MDR-TB therapy. Subjects with HIV received antiretroviral therapy (ART) regardless of CD4 count. Results Among 45 MDR-TB patients, 36 (80%) were HIV-co-infected. Overall, 40 (89%) of the 45 patients culture-converted within the first six months and there was no difference in the proportion who converted based on HIV status. Median time-to-conversion was 62 days (IQR 48-111). Among the five patients who did not culture convert, three died, one was transferred to another facility, and one refused further treatment before completing 6 months of therapy. Thus, no patients remained persistently culture-positive at 6 months of therapy. Conclusions With concurrent second-line TB and ART medications, MDR-TB/HIV co-infected patients can achieve culture conversion rates and times similar to those reported from HIV-negative patients worldwide. Future studies are needed to examine whether similar cure rates are achieved at the end of MDR-TB treatment and to determine the optimal use and timing of ART in the setting of MDR-TB treatment.

Community-based care vs. centralised hospitalisation for MDR-TB patients KwaZulu-Natal, South Africa

SETTING KwaZulu-Natal, South Africa, a predominantly rural province with a high burden of tuberculosis (TB), multidrug-resistant TB (MDR-TB) and human immunodeficiency virus (HIV) infection. OBJECTIVE To determine the most effective care model 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 and 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 (total = 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). On 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, outcomes at the four community-based sites were heterogeneous, with Site 1 demonstrating that home-based care was associated with an increased treatment success of 72% compared with success rates of 52-60% at the other three sites. CONCLUSION Community-based care for MDR-TB patients was more effective than care in a central, specialised hospital. Home-based care further increased treatment success.

Comparing early treatment outcomes of MDR-TB in decentralised and centralised settings in KwaZulu-Natal, South Africa

SETTING In KwaZulu-Natal, South Africa, a setting endemic for tuberculosis (TB) and the human immunodeficiency virus (HIV), prolonged hospitalisation for the treatment of the growing number of multidrug-resistant TB (MDR-TB) patients is neither possible nor effective. OBJECTIVE To compare early treatment outcomes in patients with MDR-TB with and without HIV co-infection at four decentralised rural sites with a central urban referral hospital. DESIGN This is an operational, prospective cohort study of patients between 1 July 2008 and 30 November 2009, where culture conversion, time to culture conversion, survival and predictors of these outcomes were analysed. RESULTS Of 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, OR 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 In this study, early treatment outcomes suggest that decentralised care for MDR-TB patients is superior to that in a centralised setting.

Minimal Diversity of Drug-Resistant Mycobacterium tuberculosis Strains, South Africa

Multidrug- (MDR) and extensively drug-resistant tuberculosis (XDR TB) are commonly associated with Beijing strains. However, in KwaZulu-Natal, South Africa, which has among the highest incidence and mortality for MDR and XDR TB, data suggest that non-Beijing strains are driving the epidemic. We conducted a retrospective study to characterize the strain prevalence among drug-susceptible, MDR, and XDR TB cases and determine associations between strain type and survival. Among 297 isolates from 2005–2006, 49 spoligotype patterns were found. Predominant strains were Beijing (ST1) among drug-susceptible isolates (27%), S/Quebec (ST34) in MDR TB (34%) and LAM4/KZN (ST60) in XDR TB (89%). More than 90% of patients were HIV co-infected. MDR TB and XDR TB were independently associated with mortality, but TB strain type was not. We conclude that, although Beijing strain was common among drug-susceptible TB, other strains predominated among MDR TB and XDR TB cases. Drug-resistance was a stronger predictor of survival than strain type.

Five cases of bacteraemia due to Gordonia species

Gordonia species are aerobic Gram-positive bacilli and a rare cause of human disease. To our knowledge, there are only two cases of human infection with Gordonia sputi reported in the literature. We report five cases of bacteraemia due to Gordonia species at our institution since 2005, including four caused by G. sputi. Three of these cases were likely related to chronic indwelling central venous catheters.

Natural ventilation reduces high TB transmission risk in traditional homes in rural KwaZulu-Natal, South Africa

BackgroundTransmission of drug susceptible and drug resistant TB occurs in health care facilities, and community and households settings, particularly in highly prevalent TB and HIV areas. There is a paucity of data regarding factors that may affect TB transmission risk in household settings. We evaluated air exchange and the impact of natural ventilation on estimated TB transmission risk in traditional Zulu homes in rural South Africa.MethodsWe utilized a carbon dioxide decay technique to measure ventilation in air changes per hour (ACH). We evaluated predominant home types to determine factors affecting ACH and used the Wells-Riley equation to estimate TB transmission risk.ResultsTwo hundred eighteen ventilation measurements were taken in 24 traditional homes. All had low ventilation at baseline when windows were closed (mean ACH = 3, SD = 3.0), with estimated TB transmission risk of 55.4% over a ten hour period of exposure to an infectious TB patient. There was significant improvement with opening windows and door, reaching a mean ACH of 20 (SD = 13.1, p < 0.0001) resulting in significant decrease in estimated TB transmission risk to 9.6% (p < 0.0001). Multivariate analysis identified factors predicting ACH, including ventilation conditions (windows/doors open) and window to volume ratio. Expanding ventilation increased the odds of achieving ≥12 ACH by 60-fold.ConclusionsThere is high estimated risk of TB transmission in traditional homes of infectious TB patients in rural South Africa. Improving natural ventilation may decrease household TB transmission risk and, combined with other strategies, may enhance TB control efforts.

High Prevalence of inhA Promoter Mutations among Patients with Drug-Resistant Tuberculosis in KwaZulu-Natal, South Africa

Background Drug-resistant tuberculosis (TB) remains extremely difficult to treat because there are often few remaining active medications and limited diagnostic options to detect resistance. Resistance to isoniazid is typically caused by mutations in either katG or the inhA promoter. inhA mutations confer low-level resistance to isoniazid and cross-resistance to ethionamide while katG mutations confer high-level isoniazid resistance and no cross-resistance. Line Probe Assays (LPAs) that detect mutations in katG and inhA are currently performed on all positive TB cultures in KwaZulu-Natal province, South Africa, but the frequency of inhA mutations in drug-resistant TB patients has not been examined. Methods We sought to determine the proportion of patients who could potentially benefit from high-dose isoniazid and who may be resistant to ethionamide. We reviewed 994 LPA (Hain MTBDRplus) results at the TB reference laboratory in KwaZulu-Natal to determine the frequency of mutations in either katG or the inhA promoter. We stratified these results by drug-resistance category (i.e., MDR-TB, pre-XDR-TB, and XDR-TB) as determined by phenotypic drug-susceptibility testing. Results Among MDR- and XDR-TB isolates, the prevalence of inhA mutations without a concurrent katG mutation was 14.8% and 10.3% respectively. The prevalence of inhA mutations with OR without a katG mutation was 30.3% and 82.8%, respectively. Conclusion More than 10% of patients with MDR- and XDR-TB may benefit from high-dose isoniazid. Although ethionamide is empirically included in all MDR- and XDR-TB regimens, nearly a third of MDR-TB patients and a majority of XDR-TB patients likely have resistance to ethionamide. Laboratories performing line probe assays should report specific band patterns so that clinicians may adjust treatment regimens accordingly.

Chest Radiograph Findings and Time to Culture Conversion in Patients with Multidrug-Resistant Tuberculosis and HIV in Tugela Ferry, South Africa

Background The majority of patients with multidrug-resistant tuberculosis (MDR-TB) in South Africa are co-infected with HIV, but the radiographic features of MDR-TB and their relationship with time to sputum culture conversion in the antiretroviral therapy era have not been described. Methods We reviewed baseline chest radiographs for 56 patients with MDR-TB from a rural area of South Africa. We analyzed the association of cavities, consolidation, pleural effusion and hilar lymphadenopathy with time to sputum culture conversion, adjusting for HIV status, baseline sputum smear and CD4 count. Results Of the 56 subjects, 49 (88%) were HIV-positive, with a median CD4 count of 136 cells/mm3 (IQR 65-249). Thirty-two (57%) patients were sputum smear positive. Twenty-two (39%) patients had a cavity and 37 (66%) patients had consolidations. Cavitary disease and consolidations were each associated with longer time to culture conversion on bivariate analysis but not after adjusting for sputum smear status (aORs 1.79 [0.94-3.42] and 1.09 [0.67-1.78], respectively). Positive baseline sputum smear remained independently associated with longer time to conversion (aOR 3.45 [1.39-8.59]). We found no association between pleural effusion or hilar lymphadenopathy and time to conversion. Seventy-nine percent of patients were cured at the end of treatment. Conclusions Despite high rates of HIV co-infection and advanced immunodeficiency, the majority of patients had severe pathology on baseline chest radiograph. Nevertheless, culture conversion rates were high and treatment outcomes were favorable. Cavitation and consolidation do not appear to have an independent association with time to culture conversion beyond that of baseline sputum smear status.