Intensified Antituberculosis Therapy in Adults with Tuberculous Meningitis.

BACKGROUND: Tuberculous meningitis is often lethal. Early antituberculosis treatment and adjunctive treatment with glucocorticoids improve survival, but nearly one third of patients with the condition still die. We hypothesized that intensified antituberculosis treatment would enhance the killing of intracerebral Mycobacterium tuberculosis organisms and decrease the rate of death among patients. METHODS: We performed a randomized, double-blind, placebo-controlled trial involving human immunodeficiency virus (HIV)-infected adults and HIV-uninfected adults with a clinical diagnosis of tuberculous meningitis who were admitted to one of two Vietnamese hospitals. We compared a standard, 9-month antituberculosis regimen (which included 10 mg of rifampin per kilogram of body weight per day) with an intensified regimen that included higher-dose rifampin (15 mg per kilogram per day) and levofloxacin (20 mg per kilogram per day) for the first 8 weeks of treatment. The primary outcome was death by 9 months after randomization. RESULTS: A total of 817 patients (349 of whom were HIV-infected) were enrolled; 409 were randomly assigned to receive the standard regimen, and 408 were assigned to receive intensified treatment. During the 9 months of follow-up, 113 patients in the intensified-treatment group and 114 patients in the standard-treatment group died (hazard ratio, 0.94; 95% confidence interval, 0.73 to 1.22; P=0.66). There was no evidence of a significant differential effect of intensified treatment in the overall population or in any of the subgroups, with the possible exception of patients infected with isoniazid-resistant M. tuberculosis. There were also no significant differences in secondary outcomes between the treatment groups. The overall number of adverse events leading to treatment interruption did not differ significantly between the treatment groups (64 events in the standard-treatment group and 95 events in the intensified-treatment group, P=0.08). CONCLUSIONS: Intensified antituberculosis treatment was not associated with a higher rate of survival among patients with tuberculous meningitis than standard treatment. (Funded by the Wellcome Trust and the Li Ka Shing Foundation; Current Controlled Trials number, ISRCTN61649292.).

Epidemiology of isoniazid resistance mutations and their effect on tuberculosis treatment outcomes.

Isoniazid resistance is highly prevalent in Vietnam. We investigated the molecular and epidemiological characteristics and the association with first-line treatment outcomes of the main isoniazid resistance mutations in Mycobacterium tuberculosis in codon 315 of the katG and in the promoter region of the inhA gene. Mycobacterium tuberculosis strains with phenotypic resistance to isoniazid from consecutively diagnosed smear-positive tuberculosis patients in rural Vietnam were subjected to Genotype MTBDRplus testing to identify katG and inhA mutations. Treatment failure and relapse were determined by sputum culture. In total, 227 of 251 isoniazid-resistant strains (90.4%) had detectable mutations: 75.3% in katG codon 315 (katG315) and 28.2% in the inhA promoter region. katG315 mutations were significantly associated with pretreatment resistance to streptomycin, rifampin, and ethambutol but not with the Beijing genotype and predicted both unfavorable treatment outcome (treatment failure or death) and relapse; inhA promoter region mutations were only associated with resistance to streptomycin and relapse. In tuberculosis patients, M. tuberculosis katG315 mutations but not inhA mutations are associated with unfavorable treatment outcome. inhA mutations do, however, increase the risk of relapse, at least with treatment regimens that contain only isoniazid and ethambutol in the continuation phase.

Clustering of Beijing genotype Mycobacterium tuberculosis isolates from the Mekong delta in Vietnam on the basis of variable number of tandem repeat versus restriction fragment length polymorphism typing.

BACKGROUND: In comparison to restriction fragment length polymorphism (RFLP) typing, variable number of tandem repeat (VNTR) typing is easier to perform, faster and yields results in a simple, numerical format. Therefore, this technique has gained recognition as the new international gold standard in typing of Mycobacterium tuberculosis. However, some reports indicated that VNTR typing may be less suitable for Beijing genotype isolates. We therefore compared the performance of internationally standardized RFLP and 24 loci VNTR typing to discriminate among 100 Beijing genotype isolates from the Southern Vietnam. METHODS: Hundred Beijing genotype strains defined by spoligotyping were randomly selected and typed by RFLP and VNTR typing. The discriminatory power of VNTR and RFLP typing was compared using the Bionumerics software. RESULTS: Among 95 Beijing strains available for analysis, 14 clusters were identified comprising 34 strains and 61 unique profiles in 24 loci VNTR typing ((Hunter Gaston Discrimination Index (HGDI = 0.994)). 13 clusters containing 31 strains and 64 unique patterns in RFLP typing (HGDI = 0.994) were found. Nine RFLP clusters were subdivided by VNTR typing and 12 VNTR clusters were split by RFLP. Five isolates (5%) revealing double alleles or no signal in two or more loci in VNTR typing could not be analyzed. CONCLUSIONS: Overall, 24 loci VNTR typing and RFLP typing had similar high-level of discrimination among 95 Beijing strains from Southern Vietnam. However, loci VNTR 154, VNTR 2461 and VNTR 3171 had hardly added any value to the level of discrimination.

Tuberculosis relapse in Vietnam is significantly associated with Mycobacterium tuberculosis Beijing genotype infections.

BACKGROUND: In Vietnam, the Mycobacterium tuberculosis Beijing genotype is associated with multi-drug resistance and is emerging. A possible explanation for this genotype's success is an increased rate of relapse. METHODS: In a prospective cohort study, isolates from patients with smear-positive tuberculosis were subjected to drug susceptibility testing and to spoligotyping and variable number of tandem repeats typing before treatment and after recurrence of tuberculosis. RESULTS: Among 1068 patients who were actively followed up over 18 months for recurrence, 23 relapse cases occurred (1.39 cases/100 person-years). After adjustment for genotype, tuberculosis treatment history, and drug resistance, relapse was significantly associated with the Beijing genotype (adjusted hazard ratio [aHR], 5.48; 95% confidence interval [CI], 2.06-14.55) and isoniazid resistance (aHR, 5.91; 95% CI, 2.16-16.16). CONCLUSIONS: The strongly increased relapse rate in tuberculosis cases caused by Beijing strains probably contributes to the successful spread of this genotype in Vietnam and elsewhere.

Increased transmission of Mycobacterium tuberculosis Beijing genotype strains associated with resistance to streptomycin: a population-based study.

BACKGROUND: Studies have shown that the Mycobacterium tuberculosis Beijing genotype is an emerging pathogen that is frequently associated with drug resistance. This suggests that drug resistant Beijing strains have a relatively high transmission fitness compared to other drug-resistant strains. METHODS AND FINDINGS: We studied the relative transmission fitness of the Beijing genotype in relation to anti-tuberculosis drug resistance in a population-based study of smear-positive tuberculosis patients prospectively recruited and studied over a 4-year period in rural Vietnam. Transmission fitness was analyzed by clustering of cases on basis of three DNA typing methods. Of 2531 included patients, 2207 (87%) were eligible for analysis of whom 936 (42%) were in a DNA fingerprint cluster. The clustering rate varied by genotype with 292/786 (37%) for the Beijing genotype, 527/802 (67%) for the East-African Indian (EAI) genotype, and 117/619 (19%) for other genotypes. Clustering was associated with the EAI compared to the Beijing genotype (adjusted odds ratio (OR(adj)) 3.4: 95% CI 2.8-4.4). Patients infected with streptomycin-resistant strains were less frequently clustered than patients infected with streptomycin-susceptible strains when these were of the EAI genotype (OR(adj) 0.6, 95% CI 0.4-0.9), while this pattern was reversed for strains of the Beijing genotype (OR(adj) 1.3, 95% CI 1.0-1.8, p for difference 0.002). The strong association between Beijing and MDR-TB (OR(adj) 7.2; 95% CI 4.2-12.3) existed only if streptomycin resistance was present. CONCLUSIONS: Beijing genotype strains showed less overall transmissibility than EAI strains, but when comparisons were made within genotypes, Beijing strains showed increased transmission fitness when streptomycin-resistant, while the reverse was observed for EAI strains. The association between MDR-TB and Beijing genotype in this population was strongly dependent on resistance to streptomycin. Streptomycin resistance may provide Beijing strains with a fitness advantage over other genotypes and predispose to multidrug resistance in patients infected with Beijing strains.

Mixed tuberculosis infections in rural South Vietnam.

Tuberculosis patients may be infected with or have disease caused by more than one Mycobacterium tuberculosis strain, usually referred to as "mixed infections." These have mainly been observed in settings with a very high tuberculosis incidence and/or high HIV prevalence. We assessed the rate of mixed infections in a population-based study in rural Vietnam, where the prevalences of both HIV and tuberculosis are substantially lower than those in previous studies looking at mixed infections. In total, 1,248 M. tuberculosis isolates from the same number of patients were subjected to IS6110 restriction fragment length polymorphism (RFLP) typing, spoligotyping, and variable-number-tandem-repeat (VNTR) typing. We compared mixed infections identified by the presence of (i) discrepant RFLP and spoligotype patterns in isolates from the same patient and (ii) double alleles at ≥ 2 loci by VNTR typing and assessed epidemiological characteristics of these infections. RFLP/spoligotyping and VNTR typing identified 39 (3.1%) and 60 (4.8%) mixed infections, respectively (Cohen's kappa statistic, 0.57). The number of loci with double alleles in the VNTR pattern was strongly associated with the proportion of isolates with mixed infections according to RFLP/spoligotyping (P < 0.001). Mixed infections occurred more frequently in newly treated than in previously treated patients, were significantly associated with minor X-ray abnormalities, and were almost significantly associated with lower sputum smear grades. Although the infection pressure in our study area is lower than that in previously studied populations, mixed M. tuberculosis infections do occur in rural South Vietnam in at least 3.1% of cases.

Nontuberculous mycobacterial disease in patients with HIV in Southeast Asia.

RATIONALE: Although nontuberculous mycobacteria (NTM) are widely documented as a cause of illness among HIV-infected people in the developed world, studies describing the prevalence of NTM disease among HIV-infected people in most resource-limited settings are rare. OBJECTIVES: To evaluate the prevalence of mycobacterial disease in HIV-infected patients in Southeast Asia. METHODS: We enrolled people with HIV from three countries in Southeast Asia and collected pulmonary and extrapulmonary specimens to evaluate the prevalence of mycobacterial disease. We adapted American Thoracic Society/Infectious Disease Society of America guidelines to classify patients into NTM pulmonary disease, NTM pulmonary disease suspects, NTM disseminated disease, and no NTM categories. MEASUREMENTS AND MAIN RESULTS: In Cambodia, where solid media alone was used, NTM was rare. Of 1,060 patients enrolled in Thailand and Vietnam, where liquid culture was performed, 124 (12%) had tuberculosis and 218 (21%) had NTM. Of 218 patients with NTM, 66 (30%) were classified as NTM pulmonary disease suspects, 9 (4%) with NTM pulmonary disease, and 10 (5%) with NTM disseminated disease. The prevalence of NTM disease was 2% (19 of 1,060). Of 51 patients receiving antiretroviral therapy (ART), none had NTM disease compared with 19 (2%) of 1,009 not receiving ART. CONCLUSIONS: Although people with HIV frequently have sputum cultures positive for NTM, few meet a strict case definition for NTM disease. Consistent with previous studies, ART was associated with lower odds of having NTM disease. Further studies of NTM in HIV-infected individuals in tuberculosis-endemic countries are needed to develop and validate case definitions.

The Mycobacterium tuberculosis Beijing genotype does not affect tuberculosis treatment failure in Vietnam.

BACKGROUND: Studies have suggested that the Mycobacterium tuberculosis Beijing genotype causes more severe clinical disease and higher treatment failure rates with standard regimens, possibly in association with an increased risk of acquiring drug resistance. We studied the effect of genotype on treatment failure in a rural area in Vietnam where multidrug resistance is strongly associated with the Beijing genotype. METHODS: In a population-based prospective cohort study, patients with smear-positive tuberculosis were tested before and after treatment by spoligotyping and drug susceptibility analysis. Reinfections were excluded by DNA fingerprinting. The outcome was treatment failure based on culture. RESULTS: Of 1106 patients eligible for analysis, 33 experienced treatment failure (3.0%; 95% confidence interval [CI], 2.1%-4.1%). The proportion of failure was 5.3% (95% CI, 0.3%-7.9%) among 380 patients with Beijing genotype infections. Multidrug-resistant tuberculosis strongly predicted failure (odds ratio [OR], 114; 95% CI, 30-430). After adjusting for multidrug-resistant tuberculosis, treatment failure was not associated with the Beijing genotype (adjusted OR, 0.7; 95% CI, 0.3-2.0). Amplification of drug resistance occurred in 3 patients (0.3%; 95% CI, 0.1%-0.7%) and was associated with multidrug resistance at baseline (P = .004) but not with the Beijing genotype. No multidrug resistance was created. CONCLUSION: The Beijing genotype was not associated with treatment failure in Vietnam; apparent associations were explained by the strong association of this genotype with multidrug resistance. Amplification of resistance in this patient population was rare.

Bloodstream infections among HIV-infected outpatients, Southeast Asia.

Bloodstream infections (BSIs) are a major cause of illness in HIV-infected persons. To evaluate prevalence of and risk factors for BSIs in 2,009 HIV-infected outpatients in Cambodia, Thailand, and Vietnam, we performed a single Myco/F Lytic blood culture. Fifty-eight (2.9%) had a clinically significant BSI (i.e., a blood culture positive for an organism known to be a pathogen). Mycobacterium tuberculosis accounted for 31 (54%) of all BSIs, followed by fungi (13 [22%]) and bacteria (9 [16%]). Of patients for whom data were recorded about antiretroviral therapy, 0 of 119 who had received antiretroviral therapy for ≥14 days had a BSI, compared with 3% of 1,801 patients who had not. In multivariate analysis, factors consistently associated with BSI were fever, low CD4+ T-lymphocyte count, abnormalities on chest radiograph, and signs or symptoms of abdominal illness. For HIV-infected outpatients with these risk factors, clinicians should place their highest priority on diagnosing tuberculosis.

Validation of the GenoType MTBDRplus assay for diagnosis of multidrug resistant tuberculosis in South Vietnam.

BACKGROUND: To control multidrug resistant tuberculosis (MDR-TB), the drug susceptibility profile is needed to guide therapy. Classical drug susceptibility testing (DST) may take up to 2 to 4 months. The GenoType MTBDRplus test is a commercially available line-probe assay that rapidly detects Mycobacterium tuberculosis (MTB) complex, as well as the most common mutations associated with rifampin and isoniazid resistance.We assessed sensitivity and specificity of the assay by using a geographically representative set of MTB isolates from the South of Vietnam. METHODS: We re-cultured 111 MTB isolates that were MDR, rifampin-resistant or pan-susceptible according to conventional DST and tested these with the GenoType MTBDRplus test. RESULTS: By conventional DST, 55 strains were classified as MDR-TB, four strains were rifampicin mono-resistant and 52 strains were susceptible to all first-line drugs. The sensitivity of the GenoType MTBDRplus was 93.1% for rifampicin, 92.6% for isoniazid and 88.9% for the combination of both; its specificity was 100%. The positive predictive value of the GenoType MTBDRplus test for MDR-TB was 100% and the negative predictive value 90.3%. CONCLUSIONS: We found a high specificity and positive predictive value of the GenoType MTBDRplus test for MDR-TB which merits its use in the MDR-TB treatment program in Vietnam.

A common human TLR1 polymorphism regulates the innate immune response to lipopeptides.

Toll-like receptors (TLR) are critical mediators of the immune response to pathogens and human polymorphisms in this gene family regulate inflammatory pathways and are associated with susceptibility to infection. Lipopeptides are present in a wide variety of microbes and stimulate immune responses through TLR1/2 or TLR2/6 heterodimers. It is not currently known whether polymorphisms in TLR1 regulate the innate immune response. We stimulated human whole blood with triacylated lipopeptide, a ligand for TLR1/2 heterodimers, and found substantial inter-individual variation in the immune response. We sequenced the coding region of TLR1 and found a non-synonymous polymorphism, I602S (base pair T1805G), that regulated signalling. In comparison to TLR1_602S, the 602I variant mediated substantially greater basal and lipopeptide-induced NF-kappaB signalling in transfected HEK293 cells. These signalling differences among TLR1 variants were also found with stimulation by extracts of Mycobacterium tuberculosis. Furthermore, individuals with the 602II genotype produced substantially more IL-6 than those with the 602SS variant in a lipopeptide-stimulated whole-blood cytokine assay. Together, these observations demonstrate that variation in the inflammatory response to bacterial lipopeptides is regulated by a common TLR1 transmembrane domain polymorphism that could potentially impact the innate immune response and clinical susceptibility to a wide spectrum of pathogens.

Antituberculosis drug resistance in the south of Vietnam: prevalence and trends.

BACKGROUND: There is limited evidence that the DOTS (directly observed therapy, short course) strategy for tuberculosis (TB) control can contain the emergence and spread of drug resistance in the absence of second-line treatment. We compared drug-resistance levels between 1996 and 2001 in the south of Vietnam, an area with a well-functioning DOTS program. METHODS: Sputum specimens were collected from consecutively diagnosed patients with smear-positive TB at 40 randomly selected public TB clinics. Mycobacterium tuberculosis isolates were tested for susceptibility to first-line drugs. RESULTS: Among 888 new patients in 2001, resistance to any drug was observed in 238 (26.3%), resistance to isoniazid was observed in 154 (16.6%), resistance to rifampin was observed in 22 (2.0%), resistance to ethambutol was observed in 12 (1.1%), resistance to streptomycin was observed in 173 (19.4%), and resistance to both isoniazid and rifampicin (multidrug resistance [MDR]) was observed in 20 (1.8% [95% confidence interval, 1.0%-3.3%]). Among 136 previously treated patients in 2001, any resistance was observed in 89 (62.9%), and MDR was observed in 35 (23.2%). The prevalence of any drug resistance and of streptomycin resistance among new patients had decreased significantly (P<.01) since 1996; there was no increase in the prevalence of MDR. CONCLUSION: The prevalence of drug resistance decreased despite high initial levels of resistance to isoniazid and streptomycin and despite the absence of second-line treatment. Therefore, a DOTS program can contain drug-resistant TB in this setting.

Public-private mix for DOTS implementation: what makes it work?

OBJECTIVE: To compare processes and outcomes of four public-private mix (PPM) projects on DOTS implementation for tuberculosis (TB) control in New Delhi, India; Ho Chi Minh City, Viet Nam; Nairobi, Kenya; and Pune, India. METHODS: Cross-project analysis of secondary data from separate project evaluations was used. Differences among PPM project sites in impact on TB control (change in case detection, treatment outcomes and equity in access) were correlated with differences in chosen intervention strategies and structural conditions. FINDINGS: The analysis suggests that an effective intervention package should include the following provider-side components: (1) orienting private providers (PPs) and the staff of the national TB programme (NTP); (2) improving the referral and information system through simple practical tools; (3) the NTP adequately supervising and monitoring PPs; and (4) the NTP providing free anti-TB drugs to patients treated in the private sector. CONCLUSION: Getting such an intervention package to work requires that the NTP be strongly committed to supporting, supervising and evaluating PPM projects. Further, using a local nongovernmental organization or a medical association as an intermediary may facilitate collaboration. Investing time and effort to ensure that sufficient dialogue takes place among all stakeholders is important to help build trust and achieve a high level of agreement.

Steep increase in HIV prevalence among tuberculosis patients in Ho Chi Minh City.

In Vietnam the spread of HIV infection is thought to be limited. In 12 urban districts of Ho Chi Minh City representative samples of tuberculosis patients have undergone HIV testing since 1995. HIV prevalence increased steeply from 0.5% in 1995 to 4% in 2000, with a doubling time of approximately 21 months. This study highlights the need to intensify HIV/AIDS prevention and control in Vietnam.