Outcomes after Chemotherapy with WHO Category II Regimen in a Population with High Prevalence of Drug Resistant Tuberculosis

Short-course Regimen for Subsequent Treatment of Pulmonary Tuberculosis: A Prospective, Randomized, Controlled Multicenter Clinical Trial in China

PURPOSE

We designed a prospective, multicenter, randomized, controlled study to assess a 5-month regimen compared with the standard regimen on previously treated patients with pulmonary tuberculosis (TB).

METHODS

We enrolled 917 sputum smear-positive patients undergoing additional treatment in 27 major tuberculosis hospitals in China. Patients were randomly assigned to a test group (n = 626)treated with a 5-month regimen of moxifloxacin, pasiniazid, rifabutin, ethambutol, and pyrazinamide or a reference group (n = 291) treated with an 8-month regimen of isoniazid, rifampicin, and streptomycin. All patients with a favorable response were followed up for 5 years after the end of treatment.

FINDINGS

Of the study patients, 61 in the test group and 19 in the reference group had multidrug-resistant (MDR) TB. The treatment success rate in the study group was 74.12%, which was significantly higher than the 67.70% in the reference group (P = 0.04), whereas the treatment success rate of patients with MDR-TB was not significantly different between the test and reference groups (70.5% vs 63.1%, P =0.79). The adverse effects rates in the test and reference groups were 7.4% and 3.1%, respectively (P = .01). The difference in the TB recurrence rates between the group arm (9.6%) and the reference group (21.8%) was statistically significant (P < 0.001).

IMPLICATIONS

The moxifloxacin, pasiniazid, rifabutin, ethambutol, and pyrazinamide test regimen yielded higher success and lower recurrence rates than the currently recommended isoniazid, rifampicin, and streptomycin regimen, but the rate of adverse effects was higher. ClinicalTrials.gov identifier: NCT02331823.

A Multistrain Mathematical Model To Investigate the Role of Pyrazinamide in the Emergence of Extensively Drug-Resistant Tuberculosis

Several infectious diseases of global importance—e.g., HIV infection and tuberculosis (TB)—require prolonged treatment with combination antimicrobial regimens typically involving high-potency core agents coupled with additional companion drugs that protect against the de novo emergence of mutations conferring resistance to the core agents. Often, the most effective (or least toxic) companion agents are reused in sequential (first-line, second-line, etc.) regimens. We used a multistrain model of Mycobacterium tuberculosis transmission in Southeast Asia to investigate how this practice might facilitate the emergence of extensive drug resistance, i.e., resistance to multiple core agents. We calibrated this model to regional TB and drug resistance data using an approximate Bayesian computational approach. We report the proportion of data-consistent simulations in which the prevalence of pre-extensively drug-resistant (pre-XDR) TB—defined as resistance to both first-line and second-line core agents (rifampin and fluoroquinolones)—exceeds predefined acceptability thresholds (1 to 2 cases per 100,000 population by 2035). The use of pyrazinamide (the most effective companion agent) in both first-line and second-line regimens increased the proportion of simulations in which the prevalence exceeded the pre-XDR acceptability threshold by 7-fold compared to a scenario in which patients with pyrazinamide-resistant TB received an alternative drug. Model parameters related to the emergence and transmission of pyrazinamide-resistant TB and resistance amplification were among those that were the most strongly correlated with the projected pre-XDR prevalence, indicating that pyrazinamide resistance acquired during first-line treatment subsequently promotes amplification to pre-XDR TB under pyrazinamide-containing second-line treatment. These findings suggest that the appropriate use of companion drugs may be critical to preventing the emergence of strains resistant to multiple core agents.

Multidrug-Resistant Tuberculosis in Patients for Whom First-Line Treatment Failed, Mongolia, 2010-2011

In Ulaanbaatar, Mongolia, multidrug-resistant tuberculosis (MDR TB) was diagnosed for more than a third of new sputum smear–positive tuberculosis patients for whom treatment had failed. This finding suggests a significant risk for community-acquired MDR TB and a need to make rapid molecular drug susceptibility testing available to more people.

Later emergence of acquired drug resistance and its effect on treatment outcome in patients treated with Standard Short-Course Chemotherapy for tuberculosis

Backgrounds

The failure of current Standard Short-Course Chemotherapy (SCC) in new and previously treated cases with tuberculosis (TB) was mainly due to drug resistance development. But little is known on the characteristics of acquired drug resistant TB during SCC and its correlation with SCC failure. The objective of the study is to explore the traits of acquired drug resistant TB emergence and evaluate their impacts on treatment outcomes.

Methods

A prospective observational study was performed on newly admitted smear positive pulmonary TB (PTB) cases without drug resistance pretreatment treated with SCC under China’s National TB Control Program (NTP) condition from 2008 to 2010. Enrolled cases were followed up through sputum smear, culture and drug susceptibility testing (DST) at the end of 1, 2, and 5 months after treatment initiation. The effect factors of early or late emergence of acquired drug resistant TB , such as acquired drug resistance patterns, the number of acquired resistant drugs and previous treatment history were investigated by multivariate logistic regression; and the impact of acquired drug resistant TB emergence on treatment failure were further evaluated.

Results

Among 1671 enrolled new and previously treated cases with SCC, 62 (3.7 %) acquired different patterns of drug resistant TB at early period within 2 months or later around 3–5 months of treatment. Previously treated cases were more likely to develop acquired multi-drug resistant TB (MDR-TB) (OR, 3.8; 95 %CI, 1.4–10.4; P = 0.015). Additionally, acquired MDR-TB cases were more likely to emerge at later period around 3-5 months after treatment starting than that of non-MDR-TB mainly appeared within 2 months (OR, 8.3; 95 %CI, 1.7–39.9; P = 0.008). Treatment failure was associated with late acquired drug resistant TB emergence (OR, 25.7; 95 %CI, 4.3–153.4; P < 0.001) with the reference of early acquired drug resistant TB emergence.

Conclusions

This study demonstrates that later development of acquired drug resistant TB during SCC is liable to suffer treatment failure and acquired MDR-TB pattern may be one of the possible causes.

Electronic supplementary material

The online version of this article (doi:10.1186/s12890-016-0187-3) contains supplementary material, which is available to authorized users.

Risk Factors for Acquired Rifamycin and Isoniazid Resistance: A Systematic Review and Meta-Analysis

BACKGROUND

Studies looking at acquired drug resistance (ADR) are diverse with respect to geographical distribution, HIV co-infection rates, retreatment status and programmatic factors such as regimens administered and directly observed therapy. Our objective was to examine and consolidate evidence from clinical studies of the multifactorial aetiology of acquired rifamycin and/or isoniazid resistance within the scope of a single systematic review. This is important to inform policy and identify key areas for further studies.

METHODS

Case-control and cohort studies and randomised controlled trials that reported ADR as an outcome during antitubercular treatment regimens including a rifamycin and examined the association of at least 1 risk factor were included. Post hoc, we carried out random effects Mantel-Haenszel weighted meta-analyses of the impact of 2 key risk factors 1) HIV and 2) baseline drug resistance on the binary outcome of ADR. Heterogeneity was assessed used I2 statistic. As a secondary outcome, we calculated median cumulative incidence of ADR, weighted by the sample size of the studies.

RESULTS

Meta-analysis of 15 studies showed increased risk of ADR with baseline mono- or polyresistance (RR 4.85 95% CI 3.26 to 7.23, heterogeneity I2 58%, 95% CI 26 to 76%). Meta-analysis of 8 studies showed that HIV co-infection was associated with increased risk of ADR (RR 3.02, 95% CI 1.28 to 7.11); there was considerable heterogeneity amongst these studies (I2 81%, 95% CI 64 to 90%). Non-adherence, extrapulmonary/disseminated disease and advanced immunosuppression in HIV co-infection were other risk factors noted. The weighted median cumulative incidence of acquired multi drug resistance calculated in 24 studies (assuming whole cohort as denominator, regardless of follow up DST) was 0.1% (5th to 95th percentile 0.07 to 3.2%).

CONCLUSION

Baseline drug resistance and HIV co-infection were significant risk factors for ADR. There was a trend of positive association with non-adherence which is likely to contribute to the outcome of ADR. The multifactorial aetiology of ADR in a programmatic setting should be further evaluated via appropriately designed studies.

Acquisition of second-line drug resistance and extensive drug resistance during recent transmission of Mycobacterium tuberculosis in rural China

Multidrug-resistant tuberculosis (MDR-TB) is prevalent in countries with a high TB burden, like China. As little is known about the emergence and spread of second-line drug (SLD) -resistant TB, we investigate the emergence and transmission of SLD-resistant Mycobacterium tuberculosis in rural China. In a multi-centre population-based study, we described the bacterial population structure and the transmission characteristics of SLD-resistant TB using Spoligotyping in combination with genotyping based on 24-locus MIRU-VNTR (mycobacterial interspersed repetitive unit-variable-number tandem repeat) plus four highly variable loci for the Beijing family, in four rural Chinese regions with diverse geographic and socio-demographic characteristics. Transmission networks among genotypically clustered patients were constructed using social network analysis. Of 1332 M. tuberculosis patient isolates recovered, the Beijing family represented 74.8% of all isolates and an association with MDR and simultaneous resistance between first-line drugs and SLDs. The genotyping analysis revealed that 189 isolates shared MIRU-VNTR patterns in 78 clusters with clustering rate and recent transmission rate of 14.2% and 8.3%, respectively. Fifty-three SLD-resistant isolates were observed in 31 clusters, 30 of which contained the strains with different drug susceptibility profiles and genetic mutations. In conjunction with molecular data, socio-network analysis indicated a key role of Central Township in the transmission across a highly interconnected network where SLD resistance accumulation occurred during transmission. SLD-resistant M. tuberculosis has been spreading in rural China with Beijing family being the dominant strains. Primary transmission of SLD-resistant strains in the population highlights the importance of routine drug susceptibility testing and effective anti-tuberculosis regimens for drug-resistant TB.

Prevalence of tuberculosis and treatment outcome among university students in Northwest Ethiopia: a retrospective study

BACKGROUND

Universities tend to be highly congregate settings, both in the classroom and in residences, and thus provide special opportunities for large number of persons to be exposed to a person with tuberculosis (TB). Despite the high prevalence of TB in Ethiopia, the TB prevalence and the treatment outcome among students have never been studied. Therefore, this study was aimed at determining the prevalence and treatment outcome of TB among students at University of Gondar from January 2007 to December 2011.

METHODS

Data on age, sex, TB type, category, and treatment outcome of students with TB was collected from medical records of University of Gondar Hospital, TB Directly Observed Treatment Short Course (DOTS) clinic. All TB cases diagnosed with smear, culture, and/or radiography were included in the study.

RESULTS

During the five year study period in the university, there were an average of 36 students with TB per year out of a mean of 10,036 enrolled students. Smear positive pulmonary TB, smear negative pulmonary TB, and extra pulmonary TB, respectively, were observed in 46 (25.4%), 81 (44.8%) and 54 (29.8%) of the cases. The prevalence of all forms of TB per 100,000 populations in the University ranged from 297.6 in 2009 to 404 in 2011, respectively. The prevalence of TB in the Social Sciences and Humanities Faculty was higher than the one observed in the Medical College. The overall treatment outcome was classified as cured in 36 (19.9%), completed in 91 (50.3%), defaulted in 9 (5%), failed in 3 (1.7%), died in 1 (0.6%), and transferred out in 41 (22.7%) of the cases. Treatment success rate (TSR) among students in University was generally low ranging from 58.1% in 2009 to 82.9% in 2011 with a mean TSR of 70.2%.

CONCLUSION

The prevalence of TB is higher in comparison to the national figure among students in University of Gondar. Active surveillance systems could be important to get a clear picture of the TB situation in such settings. Assessing the factors associated with the high prevalence to gear the TB control strategy could also be essential.

Novel drugs against tuberculosis: a clinician's perspective

The United Nations Millennium Development Goal of reversing the global spread of tuberculosis by 2015 has been offset by the rampant re-emergence of drug-resistant tuberculosis, in particular fluoroquinolone-resistant multidrug-resistant and extensively drug-resistant tuberculosis. After decades of quiescence in the development of antituberculosis medications, bedaquiline and delamanid have been conditionally approved for the treatment of drug-resistant tuberculosis, while several other novel compounds (AZD5847, PA-824, SQ109 and sutezolid) have been evaluated in phase II clinical trials. Before novel drugs can find their place in the battle against drug-resistant tuberculosis, linezolid has been compassionately used with success in the treatment of fluoroquinolone-resistant multidrug-resistant tuberculosis. This review largely discusses six novel drugs that have been evaluated in phase II and III clinical trials, with focus on the clinical evidence for efficacy and safety, potential drug interactions, and prospect for using multiple novel drugs in new regimens.

Drug resistance of Mycobacterium tuberculosis in Malawi: a cross-sectional survey

Objective

To document the prevalence of multidrug resistance among people newly diagnosed with – and those retreated for – tuberculosis in Malawi.

Methods

We conducted a nationally representative survey of people with sputum-smear-positive tuberculosis between 2010 and 2011. For all consenting participants, we collected demographic and clinical data, two sputum samples and tested for human immunodeficiency virus (HIV).The samples underwent resistance testing at the Central Reference Laboratory in Lilongwe, Malawi. All Mycobacterium tuberculosis isolates found to be multidrug-resistant were retested for resistance to first-line drugs – and tested for resistance to second-line drugs – at a Supranational Tuberculosis Reference Laboratory in South Africa.

Findings

Overall, M. tuberculosis was isolated from 1777 (83.8%) of the 2120 smear-positive tuberculosis patients. Multidrug resistance was identified in five (0.4%) of 1196 isolates from new cases and 28 (4.8%) of 581 isolates from people undergoing retreatment. Of the 31 isolates from retreatment cases who had previously failed treatment, nine (29.0%) showed multidrug resistance. Although resistance to second-line drugs was found, no cases of extensive drug-resistant tuberculosis were detected. HIV testing of people from whom M. tuberculosis isolates were obtained showed that 577 (48.2%) of people newly diagnosed and 386 (66.4%) of people undergoing retreatment were positive.

Conclusion

The prevalence of multidrug resistance among people with smear-positive tuberculosis was low for sub-Saharan Africa – probably reflecting the strength of Malawi’s tuberculosis control programme. The relatively high prevalence of such resistance observed among those with previous treatment failure may highlight a need for a change in the national policy for retreating this subgroup of people with tuberculosis.

High incidence of tuberculosis, low sensitivity of current diagnostic scheme and prolonged culture positivity in four colombian prisons. A cohort study

OBJECTIVE

To determine the incidence of pulmonary tuberculosis (TB) in inmates, factors associated with TB, and the time to sputum smear and culture conversion during TB treatment.

METHODS

Prospective cohort study. All prisoners with respiratory symptoms (RS) of any duration were evaluated. After participants signed consent forms, we collected three spontaneous sputum samples on consecutive days. We performed auramine-rhodamine staining, culturing with the thin-layer agar method, Löwestein-Jensen medium and MGIT, susceptibility testing for first-line drugs; and HIV testing. TB cases were followed, and the times to smear and culture conversion to negative were evaluated.

RESULTS

Of 9,507 prisoners held in four prisons between April/30/2010 and April/30/2012, among them 4,463 were screened, 1,305 were evaluated for TB because of the lower RS of any duration, and 72 were diagnosed with TB. The annual incidence was 505 cases/100,000 prisoners. Among TB cases, the median age was 30 years, 25% had <15 days of cough, 12.5% had a history of prior TB, and 40.3% had prior contact with a TB case. TB-HIV coinfection was diagnosed in three cases. History of prior TB, contact with a TB case, and being underweight were risk factors associated with TB. Overweight was a protective factor. Almost a quarter of TB cases were detected only by culture; three cases were isoniazid resistant, and two resistant to streptomycin. The median times to culture conversion was 59 days, and smear conversion was 33.

CONCLUSIONS

The TB incidence in prisons is 20 times higher than in the general Colombian population. TB should be considered in inmates with lower RS of any duration. Our data demonstrate that patients receiving adequate anti-TB treatment remain infectious for prolonged periods. These findings suggest that current recommendations regarding isolation of prisoners with TB should be reconsidered, and suggest the need for mycobacterial cultures during follow-up.

A registry-based cohort study of pulmonary tuberculosis treatment outcomes in Istanbul, Turkey

The aim of this study is to evaluate the treatment outcomes and identify factors associated with adverse tuberculosis treatment outcomes for bacteriologically confirmed pulmonary tuberculosis. Treatment outcomes of pulmonary tuberculosis were evaluated retrospectively among 11,186 smear- and/or culture-positive patients treated between 2006 and 2009 in Istanbul, Turkey. Adverse treatment outcomes were identified in 1,010 (9.0%) patients including death (1.8%), treatment default (6.1%), and treatment failure (1.1%). Factors associated with adverse treatment outcomes included being born abroad (odds ratios [OR], 5.38; 95% confidence intervals [CI], 3.67-7.91), history of tuberculosis treatment (OR, 3.77; 95% CI, 3.26-4.36), age > 65 years (OR, 2.79; 95% CI, 2.21-3.53), and male gender (OR, 1.91; 95% CI, 1.59-2.27). Death was most strongly associated with age > 65 years (OR, 45.1; 95% CI, 27.0-75.6), followed by treatment default with history of interrupted treatment (OR, 11.6; 95% CI, 8.94-15.1), and treatment failure with prior history of treatment failure (OR, 17.1; 95% CI, 6.97-41.6). Multidrug resistance was strongly associated with adverse treatment outcomes (OR, 10.8; 95% CI, 8.02-14.6). Age > 65 years, male sex, being born abroad, and history of treatment failure were found to be risk factors for adverse treatment outcomes. Hence, patients with any of these characteristics should be carefully monitored and treated aggressively.

Management of difficult multidrug-resistant tuberculosis and extensively drug-resistant tuberculosis: update 2012

Multidrug-resistant (MDR) tuberculosis (TB) denotes bacillary resistance to at least isoniazid and rifampicin. Extensively drug-resistant (XDR) TB is MDR-TB with additional bacillary resistance to any fluoroquinolone and at least one second-line injectable drugs. Rooted in inadequate TB treatment and compounded by a vicious circle of diagnostic delay and improper treatment, MDR-TB/XDR-TB has become a global epidemic that is fuelled by poverty, human immunodeficiency virus (HIV) and neglect of airborne infection control. The majority of MDR-TB cases in some settings with high prevalence of MDR-TB are due to transmission of drug-resistant bacillary strains to previously untreated patients. Global efforts in controlling MDR-TB/XDR-TB can no longer focus solely on high-risk patients. It is difficult and costly to treat MDR-TB/XDR-TB. Without timely implementation of preventive and management strategies, difficult MDR-TB/XDR-TB can cripple global TB control efforts. Preventive strategies include prompt diagnosis with adequate TB treatment using the directly observed therapy, short-course (DOTS) strategy and drug-resistance programmes, airborne infection control, preventive treatment of TB/HIV, and optimal use of antiretroviral therapy. Management strategies for established cases of difficult MDR-TB/XDR-TB rely on harnessing existing drugs (notably newer generation fluoroquinolones, high-dose isoniazid, linezolid and pyrazinamide with in vitro activity) in the best combinations and dosing schedules, together with adjunctive surgery in carefully selected cases. Immunotherapy may also have a role in the future. New diagnostics, drugs and vaccines are required to meet the challenge, but science alone is insufficient. Difficult MDR-TB/XDR-TB cannot be tackled without achieving high cure rates with quality DOTS and beyond, and concurrently addressing poverty and HIV.

Clinical data and molecular analysis of Mycobacterium tuberculosis isolates from drug-resistant tuberculosis patients in Goiás, Brazil

Drug resistance is one of the major concerns regarding tuberculosis (TB) infection worldwide because it hampers control of the disease. Understanding the underlying mechanisms responsible for drug resistance development is of the highest importance. To investigate clinical data from drug-resistant TB patients at the Tropical Diseases Hospital, Goiás (GO), Brazil and to evaluate the molecular basis of rifampin (R) and isoniazid (H) resistance in Mycobacterium tuberculosis. Drug susceptibility testing was performed on 124 isolates from 100 patients and 24 isolates displayed resistance to R and/or H. Molecular analysis of drug resistance was performed by partial sequencing of the rpoB and katGgenes and analysis of the inhA promoter region. Similarity analysis of isolates was performed by 15 loci mycobacterial interspersed repetitive unit-variable number tandem repeat (MIRU-VNTR) typing. The molecular basis of drug resistance among the 24 isolates from 16 patients was confirmed in 18 isolates. Different susceptibility profiles among the isolates from the same individual were observed in five patients; using MIRU-VNTR, we have shown that those isolates were not genetically identical, with differences in one to three loci within the 15 analysed loci. Drug-resistant TB in GO is caused by M. tuberculosis strains with mutations in previously described sites of known genes and some patients harbour a mixed phenotype infection as a consequence of a single infective event; however, further and broader investigations are needed to support our findings.

Relatively low primary drug resistant tuberculosis in southwestern Ethiopia

Background

The prevalence of drug resistant tuberculosis (TB) in Ethiopia in general, and Jimma area in particular, is not well documented. We conducted a study at Jimma University specialized hospital in southwest Ethiopia among new cases of smear positive TB patients to determine the pattern of resistance to first-line drugs.

Methods

A health institution based cross sectional study was conducted from November 2010 to September 2011. Any newly diagnosed smear positive TB patient 18 years and above was included in the study. Demographic and related data were collected by trained personnel using a pretested structured questionnaire. Mycobacterial drug susceptibility testing (DST) to the first line drugs isoniazid (INH), rifampicin (RIF), ethambutol (EMB) and streptomycin (STM) was performed on cultures using the indirect proportion method. M. tuberculosis complex (MTBC) was identified with the Capilia TB-Neo test.

Results

136 patients were enrolled in the study. Resistance to at least one drug was identified in 18.4%. The highest prevalence of resistance to any drug was identified against INH (13.2%) followed by STM (8.1%). There was no statistically significant difference in the proportion of any resistance by sex, age, HIV status and history of being imprisoned. The highest mono resistance was observed against INH (7.4%). Mono resistance to streptomycin was associated with HIV infection (crude OR 15.63, 95%CI: 1.31, 187). Multidrug-resistance TB (MDR-TB) was observed in two patients (1.5%).

Conclusion

Resistance to at least one drug was 18.4% (INH-13.2% and STM-8.1%). STM resistance was associated with HIV positivity. There was relatively low prevalence of MDR-TB yet INH resistance was common around Jimma. The capacity of laboratories for TB culture and DST should be strengthened, in order to correctly manage TB patients and avoid amplification of drug resistance.

Early results of systematic drug susceptibility testing in pulmonary tuberculosis retreatment cases in Cameroon

Background

The number of pulmonary tuberculosis (PTB) patients reported with resistance to first-line anti-tuberculosis drugs after a standardized retreatment regimen in Cameroon is increasing. Hence, the National Tuberculosis Control Program (NTP) implemented, in one of the ten Regions of the country, a pilot programme aimed at performing routine drug susceptibility testing (DST) for previously treated PTB cases. The objectives of the programme were to evaluate the feasibility of monitoring drug resistance among retreatment cases under programme conditions and to measure the presence and magnitude of anti-TB drug resistance in order to inform NTP policies.

Findings

This retrospective cohort study was conducted in the Littoral Region of Cameroon in 2009. It included all sputum smear positive (SM+) PTB cases registered for retreatment. TB cases were identified and classified according to World Health Organization (WHO) recommendations for national TB programs. Bacterial susceptibility testing to first-line anti-TB drugs was performed using standard culture methods. In 2009, 5,668 TB cases were reported in the Littoral Region, of which 438 (7.7%) were SM + PTB retreatment cases. DST results were available for 216 (49.4%) patients. Twenty six patients (12%) harbored multi-drug resistant (MDR) strains. Positive treatment outcome rates were particularly low in retreatment patients with MDR-TB (46.2%; 95% CI: 27.1-66.3). Thirteen MDR-TB patients were treated using a standardized MDR treatment regimen. Delivery of laboratory results took on average 17 (12-26) weeks.

Conclusions

WHO-recommended routine DST in retreatment patients seems feasible in Cameroon. However, coverage needs to be improved through better management. Moreover, diagnostic delay should be shortened by introducing more rapid diagnostic tools. The high risk of MDR in standard regimen failure cases virtually rules out the standard retreatment regimen for such patients without prior DST.

Detecting drug-resistant tuberculosis: the importance of rapid testing

Despite numerous intervention strategies, including the direct observed short-course treatment strategy and improved diagnostic methods, the incidence of multidrug-resistant and extensively drug-resistant tuberculosis (TB) continues to rise globally. Many treatment policies are based on the model that acquisition of drug resistance in already infected individuals drives the drug-resistant TB epidemic, hence the focus on drug-resistance testing of retreatment cases. However, molecular epidemiology and mathematical modeling suggest that the majority of multidrug-resistant TB cases are due to ongoing transmission of multidrug-resistant strains. This is most likely the result of diagnostic delay, thereby emphasizing the need for rapid diagnostics and comprehensive contact tracing, as well as active case finding. Current diagnosis of TB in low-income, high-burden regions relies on smear microscopy and clinical signs and symptoms. However, this smear-centered approach has many pitfalls, including low sensitivity in HIV patients and children, the inability of smear to reveal drug-resistance patterns, and the need for sampling on consecutive days. In order to address these limitations, efforts have been made to expand access to Mycobacterium tuberculosis culture and drug susceptibility testing. However, the slow growth rate of the causative agent, M. tuberculosis, contributes to significant diagnostic delay. Molecular-based diagnostic methods, targeting mutations that are known to confirm drug resistance, are capable of significantly reducing diagnostic delay. Two such methods, the line-probe assay and the real-time PCR-based Xpert® MTB/RIF assay, have been described. The latter test shows particular promise for smear-negative and extrapulmonary specimens. This may prove especially useful in settings where co-infection rates with HIV are high. However, since most research focuses on the performance of both of these assays, further investigations need to be done regarding the impact of the routine implementation of these assays on TB control programs and the cost effectiveness thereof.

Use of a molecular diagnostic test in AFB smear positive tuberculosis suspects greatly reduces time to detection of multidrug resistant tuberculosis

Background

The WHO has recommended the implementation of rapid diagnostic tests to detect and help combat M/XDR tuberculosis (TB). There are limited data on the performance and impact of these tests in field settings.

Methods

The performance of the commercially available Genotype MTBDRplus molecular assay was compared to conventional methods including AFB smear, culture and drug susceptibility testing (DST) using both an absolute concentration method on Löwenstein-Jensen media and broth-based method using the MGIT 960 system. Sputum specimens were obtained from TB suspects in the country of Georgia who received care through the National TB Program.

Results

Among 500 AFB smear-positive sputum specimens, 458 (91.6%) had both a positive sputum culture for Mycobacterium tuberculosis and a valid MTBDRplus assay result. The MTBDRplus assay detected isoniazid (INH) resistance directly from the sputum specimen in 159 (89.8%) of 177 specimens and MDR-TB in 109 (95.6%) of 114 specimens compared to conventional methods. There was high agreement between the MTBDRplus assay and conventional DST results in detecting MDR-TB (kappa = 0.95, p<0.01). The most prevalent INH resistance mutation was S315T (78%) in the katG codon and the most common rifampicin resistance mutation was S531L (68%) in the rpoB codon. Among 13 specimens from TB suspects with negative sputum cultures, 7 had a positive MTBDRplus assay (3 with MDR-TB). The time to detection of MDR-TB was significantly less using the MTBDRplus assay (4.2 days) compared to the use of standard phenotypic tests (67.3 days with solid media and 21.6 days with broth-based media).

Conclusions

Compared to conventional methods, the MTBDRplus assay had high accuracy and significantly reduced time to detection of MDR-TB in an area with high MDR-TB prevalence. The use of rapid molecular diagnostic tests for TB and drug resistance should increase the proportion of patients promptly placed on appropriate therapy.

Screening and rapid molecular diagnosis of tuberculosis in prisons in Russia and Eastern Europe: a cost-effectiveness analysis

BACKGROUND

Prisons of the former Soviet Union (FSU) have high rates of multidrug-resistant tuberculosis (MDR-TB) and are thought to drive general population tuberculosis (TB) epidemics. Effective prison case detection, though employing more expensive technologies, may reduce long-term treatment costs and slow MDR-TB transmission.

METHODS AND FINDINGS

We developed a dynamic transmission model of TB and drug resistance matched to the epidemiology and costs in FSU prisons. We evaluated eight strategies for TB screening and diagnosis involving, alone or in combination, self-referral, symptom screening, mass miniature radiography (MMR), and sputum PCR with probes for rifampin resistance (Xpert MTB/RIF). Over a 10-y horizon, we projected costs, quality-adjusted life years (QALYs), and TB and MDR-TB prevalence. Using sputum PCR as an annual primary screening tool among the general prison population most effectively reduced overall TB prevalence (from 2.78% to 2.31%) and MDR-TB prevalence (from 0.74% to 0.63%), and cost US$543/QALY for additional QALYs gained compared to MMR screening with sputum PCR reserved for rapid detection of MDR-TB. Adding sputum PCR to the currently used strategy of annual MMR screening was cost-saving over 10 y compared to MMR screening alone, but produced only a modest reduction in MDR-TB prevalence (from 0.74% to 0.69%) and had minimal effect on overall TB prevalence (from 2.78% to 2.74%). Strategies based on symptom screening alone were less effective and more expensive than MMR-based strategies. Study limitations included scarce primary TB time-series data in FSU prisons and uncertainties regarding screening test characteristics.

CONCLUSIONS

In prisons of the FSU, annual screening of the general inmate population with sputum PCR most effectively reduces TB and MDR-TB prevalence, doing so cost-effectively. If this approach is not feasible, the current strategy of annual MMR is both more effective and less expensive than strategies using self-referral or symptom screening alone, and the addition of sputum PCR for rapid MDR-TB detection may be cost-saving over time.

Eliminating the category II retreatment regimen from national tuberculosis programme guidelines: the Georgian experience

PROBLEM

The category II retreatment regimen for management of tuberculosis in previously treated patients was first introduced in the early 1990s. It consists of 8 months of total therapy with the addition of streptomycin to standard first-line medications. A review of 6500 patients on category II therapy in Georgia showed poor outcomes and high rates of streptomycin resistance.

APPROACH

The National Tuberculosis Program used an evidence-based analysis of national data to convince policy-makers that category II therapy should be eliminated from national guidelines in Georgia.

LOCAL SETTING

The World Health Organization tuberculosis case-notification rate in Georgia is 102 per 100,000 population. All patients receive culture and drug susceptibility testing as a standard part of tuberculosis diagnosis. In 2009, routine surveillance found multidrug-resistant tuberculosis in 10.6% of newly diagnosed patients and 32.5% of previously treated cases.

RELEVANT CHANGES

Category II retreatment regimen is no longer used in Georgia. Treatment is guided by results of drug susceptibility testing--using rapid, molecular tests where possible--for all previously treated tuberculosis patients.

LESSONS LEARNT

There was little resistance to policy change because the review was initiated and led by the National Tuberculosis Program. This experience can serve as a successful model for other countries to make informed decisions about the use of category II therapy.

Multidrug resistance after inappropriate tuberculosis treatment: a meta-analysis

We conducted a systematic review and meta-analysis to assess the evidence for the postulation that inappropriate tuberculosis (TB) regimens are a risk for development of multidrug-resistant (MDR)-TB. MEDLINE, EMBASE and other databases were searched for relevant articles in January 2011. Cohort studies including TB patients who received treatment were selected and data on treatment regimen, drug susceptibility testing results and genotyping results before treatment and at failure or relapse were abstracted from the articles. Four studies were included in the systematic review and two were included in the meta-analysis. In these two studies the risk of developing MDR-TB in patients who failed treatment and used an inappropriate treatment regimen was increased 27-fold (RR 26.7, 95% CI 5.0-141.7) when compared with individuals who received an appropriate treatment regimen. This review provides evidence that supports the general opinion that the development of MDR-TB can be caused by inadequate treatment, given the drug susceptibility pattern of the Mycobacterium tuberculosis bacilli. It should be noted that only two studies provided data for the meta-analysis. The information can be used to advocate for adequate treatment for patients based on drug resistance profiles.

How do patients who fail first-line TB treatment but who are not placed on an MDR-TB regimen fare in South India?

Setting

Seven districts in Andhra Pradesh, South India

Objectives

To a) determine treatment outcomes of patients who fail first line anti-TB treatment and are not placed on an multi-drug resistant TB (MDR-TB) regimen, and b) relate the treatment outcomes to culture and drug susceptibility patterns (C&DST).

Design

Retrospective cohort study using routine programme data and Mycobacterium TB Culture C&DST between July 2008 and December 2009.

Results

There were 202 individuals given a re-treatment regimen and included in the study. Overall treatment outcomes were: 68 (34%) with treatment success, 84 (42%) failed, 36 (18%) died, 13 (6.5%) defaulted and 1 transferred out. Treatment success for category I and II failures was low at 37%. In those with positive cultures, 81 had pan-sensitive strains with 31 (38%) showing treatment success, while 61 had drug-resistance strains with 9 (15%) showing treatment success. In 58 patients with negative cultures, 28 (48%) showed treatment success.

Conclusion

Treatment outcomes of patients who fail a first-line anti-TB treatment and who are not placed on an MDR-TB regimen are unacceptably poor. The worst outcomes are seen among category II failures and those with negative cultures or drug-resistance. There are important programmatic implications which need to be addressed.

Effectiveness of the standard WHO recommended retreatment regimen (category II) for tuberculosis in Kampala, Uganda: a prospective cohort study

BACKGROUND

Each year, 10%-20% of patients with tuberculosis (TB) in low- and middle-income countries present with previously treated TB and are empirically started on a World Health Organization (WHO)-recommended standardized retreatment regimen. The effectiveness of this retreatment regimen has not been systematically evaluated.

METHODS AND FINDINGS

From July 2003 to January 2007, we enrolled smear-positive, pulmonary TB patients into a prospective cohort to study treatment outcomes and mortality during and after treatment with the standardized retreatment regimen. Median time of follow-up was 21 months (interquartile range 12-33 months). A total of 29/148 (20%) HIV-uninfected and 37/140 (26%) HIV-infected patients had an unsuccessful treatment outcome. In a multiple logistic regression analysis to adjust for confounding, factors associated with an unsuccessful treatment outcome were poor adherence (adjusted odds ratio [aOR] associated with missing half or more of scheduled doses 2.39; 95% confidence interval (CI) 1.10-5.22), HIV infection (2.16; 1.01-4.61), age (aOR for 10-year increase 1.59; 1.13-2.25), and duration of TB symptoms (aOR for 1-month increase 1.12; 1.04-1.20). All patients with multidrug-resistant TB had an unsuccessful treatment outcome. HIV-infected individuals were more likely to die than HIV-uninfected individuals (p<0.0001). Multidrug-resistant TB at enrollment was the only common risk factor for death during follow-up for both HIV-infected (adjusted hazard ratio [aHR] 17.9; 6.0-53.4) and HIV-uninfected (14.7; 4.1-52.2) individuals. Other risk factors for death during follow-up among HIV-infected patients were CD4<50 cells/ml and no antiretroviral treatment (aHR 7.4, compared to patients with CD4≥200; 3.0-18.8) and Karnofsky score <70 (2.1; 1.1-4.1); and among HIV-uninfected patients were poor adherence (missing half or more of doses) (3.5; 1.1-10.6) and duration of TB symptoms (aHR for a 1-month increase 1.9; 1.0-3.5).

CONCLUSIONS

The recommended regimen for retreatment TB in Uganda yields an unacceptable proportion of unsuccessful outcomes. There is a need to evaluate new treatment strategies in these patients.

Xpert(®) MTB/RIF for point-of-care diagnosis of TB in high-HIV burden, resource-limited countries: hype or hope?

Despite the identification of Mycobacterium tuberculosis as the cause of tuberculosis (TB) more than a century ago, diagnosing TB in resource-poor countries remains a challenge, especially in people living with HIV. In the past decade, important research investments have been made towards the development of new diagnostics for TB and the Xpert(®) MTB/RIF assay (Cepheid, CA, USA) has emerged as one of the most promising. In this article, we review the current knowledge on Xpert MTB/RIF, discuss the potential value of Xpert MTB/RIF as a point-of-care diagnostic for drug-sensitive and drug-resistant TB, and outline the potential indications for the assay in resource-limited, high-HIV burden settings. We also discuss key research questions that need to be addressed prior to possible large-scale implementation of the assay.

Tuberculosis incidence in prisons: a systematic review

BACKGROUND

Transmission of tuberculosis (TB) in prisons has been reported worldwide to be much higher than that reported for the corresponding general population.

METHODS AND FINDINGS

A systematic review has been performed to assess the risk of incident latent tuberculosis infection (LTBI) and TB disease in prisons, as compared to the incidence in the corresponding local general population, and to estimate the fraction of TB in the general population attributable (PAF%) to transmission within prisons. Primary peer-reviewed studies have been searched to assess the incidence of LTBI and/or TB within prisons published until June 2010; both inmates and prison staff were considered. Studies, which were independently screened by two reviewers, were eligible for inclusion if they reported the incidence of LTBI and TB disease in prisons. Available data were collected from 23 studies out of 582 potentially relevant unique citations. Five studies from the US and one from Brazil were available to assess the incidence of LTBI in prisons, while 19 studies were available to assess the incidence of TB. The median estimated annual incidence rate ratio (IRR) for LTBI and TB were 26.4 (interquartile range [IQR]: 13.0-61.8) and 23.0 (IQR: 11.7-36.1), respectively. The median estimated fraction (PAF%) of tuberculosis in the general population attributable to the exposure in prisons for TB was 8.5% (IQR: 1.9%-17.9%) and 6.3% (IQR: 2.7%-17.2%) in high- and middle/low-income countries, respectively.

CONCLUSIONS

The very high IRR and the substantial population attributable fraction show that much better TB control in prisons could potentially protect prisoners and staff from within-prison spread of TB and would significantly reduce the national burden of TB. Future studies should measure the impact of the conditions in prisons on TB transmission and assess the population attributable risk of prison-to-community spread. Please see later in the article for the Editors' Summary.