Alfredo Ponce-de-León

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

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

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

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

Association of diabetes and tuberculosis: impact on treatment and post-treatment outcomes

Objective To determine the clinical consequences of pulmonary tuberculosis (TB) among patients with diabetes mellitus (DM). Methods We conducted a prospective study of patients with TB in Southern Mexico. From 1995 to 2010, patients with acid-fast bacilli or Mycobacterium tuberculosis in sputum samples underwent epidemiological, clinical and microbiological evaluation. Annual follow-ups were performed to ascertain treatment outcome, recurrence, relapse and reinfection. Results The prevalence of DM among 1262 patients with pulmonary TB was 29.63% (n=374). Patients with DM and pulmonary TB had more severe clinical manifestations (cavities of any size on the chest x-ray, adjusted OR (aOR) 1.80, 95% CI 1.35 to 2.41), delayed sputum conversion (aOR 1.51, 95% CI 1.09 to 2.10), a higher probability of treatment failure (aOR 2.93, 95% CI 1.18 to 7.23), recurrence (adjusted HR (aHR) 1.76, 95% CI 1.11 to 2.79) and relapse (aHR 1.83, 95% CI 1.04 to 3.23). Most of the second episodes among patients with DM were caused by bacteria with the same genotype but, in 5/26 instances (19.23%), reinfection with a different strain occurred. Conclusions Given the growing epidemic of DM worldwide, it is necessary to add DM prevention and control strategies to TB control programmes and vice versa and to evaluate their effectiveness. The concurrence of both diseases potentially carries a risk of global spreading, with serious implications for TB control and the achievement of the United Nations Millennium Development Goals.

Gender differentials of pulmonary tuberculosis transmission and reactivation in an endemic area

Background: In most low income countries there are twice as many cases of tuberculosis (TB) reported among men than among women, a difference commonly attributed to biological and epidemiological characteristics as well as socioeconomic and cultural barriers in access to health care. The World Health Organization has encouraged gender specific comparisons in TB rates to determine whether women with TB are less likely than men with TB to be diagnosed, reported, and treated. A study was undertaken to identify gender based differences in patients with pulmonary TB and to use this information to improve TB control efforts. Methods: Individuals with a cough for more than 2 weeks in southern Mexico were screened from March 1995 to April 2003. Clinical and mycobacteriological information (isolation, identification, drug susceptibility testing and IS6110 based genotyping, and spoligotyping) was collected from those with bacteriologically confirmed pulmonary TB. Patients were treated in accordance with official norms and followed to ascertain treatment outcome, retreatment, and vital status. Results: 623 patients with pulmonary TB were enrolled. The male:female incidence rate ratio for overall, reactivated, and recently transmitted disease was 1.58 (95% CI 1.34 to 1.86), 1.64 (95% CI 1.36 to 1.98), and 1.41 (95% CI 1.01 to 1.96), respectively. Men were more likely than women to default from treatment (adjusted OR 3.30, 95% CI 1.46 to 7.43), to be retreated (hazard ratio (HR) 3.15, 95% CI 1.38 to 7.22), and to die from TB (HR 2.23, 95% CI 1.25 to 3.99). Conclusions: Higher rates of transmitted and reactivated disease and poorer treatment outcomes among men are indicators of gender differentials in the diagnosis and treatment of pulmonary TB, and suggest specific strategies in endemic settings.

Nested Polymerase Chain Reaction for Mycobacterium tuberculosis DNA Detection in Aqueous and Vitreous of Patients with Uveitis

BACKGROUND Tuberculosis may be a lethal disease. Its ocular manifestations are commonly associated with severe difficulties in diagnosis and therapy; furthermore, it may cause blindness. DNA amplification methods may allow early detection of small amounts of Mycobacterium tuberculosis DNA to afford the possibility of prompt diagnosis. We evaluated a nested polymerase chain reaction (nPCR) assay for detection of Mycobacterium tuberculosis DNA in aqueous and vitreous. METHODS In a case-control study, 22 cases of diagnosed TB uveitis (three HIV-infected patients) and 38 controls (18 HIV-infected patients) with other types of uveitis (syphilis, nine; cytomegalovirus, seven; toxoplasmosis, five; herpes simplex, one; autoimmune vasculitis, eight; Vogt-Koyanagi-Harada, four; pars planitis, one; serpinginous choroiditis, one; Wegener granulomatosis, one; and Fuchs iridocyclitis, one studied). Samples from aqueous or vitreous were cultured and analyzed by nPCR for presence of M. tuberculosis nucleic acids. We used two sets of primers corresponding to IS6110 region coding for 219 bp and 123 bp DNA sequences. RESULTS Results were confirmed by Southern blot. All samples were tested by PCR simultaneously for Herpes simplex I, Herpes zoster, cytomegalovirus (CMV) and Toxoplasma gondii. nPCR was positive in 17 cases (77.2%) and only in three controls (8.8%) p = 0.022. All cultures were negative. Southern blot confirmed all positive nPCR tests. According to our definition of cases, there were five false negative results: two in patients with pulmonary tuberculosis; two in patients with tuberculous lymphadenitis, and one with positive skin test and hematuria. There were three cases considered false positives for nPCR: one with autoimmune vasculitis, and two with toxoplasmic uveitis. CONCLUSIONS nPCR for TB in ocular fluids was positive in the majority of cases of ocular TB. This method is useful in early confirmation of ocular tuberculosis.

Rapid Detection of Rifampin Resistance in Mycobacterium tuberculosis Isolates from India and Mexico by a Molecular Beacon Assay

ABSTRACT We assessed the performance of a rapid, single-well, real-time PCR assay for the detection of rifampin-resistant Mycobacterium tuberculosis by using clinical isolates from north India and Mexico, regions with a high incidence of tuberculosis. The assay uses five differently colored molecular beacons to determine if a short region of the M. tuberculosis rpoB gene contains mutations that predict rifampin resistance in most isolates. Until now, the assay had not been sufficiently tested on samples from countries with a high incidence of tuberculosis. In the present study, the assay detected mutations in 16 out of 16 rifampin-resistant isolates from north India (100%) and in 55 of 64 rifampin-resistant isolates from Mexico (86%) compared to results with standard susceptibility testing. The assay did not detect mutations (a finding predictive of rifampin susceptibility) in 37 out of 37 rifampin-susceptible isolates from India (100%) and 125 out of 126 rifampin-susceptible isolates from Mexico (99%). DNA sequencing revealed that none of the nine rifampin-resistant isolates from Mexico, which were misidentified as rifampin susceptible by the molecular beacon assay, contained a mutation in the region targeted by the molecular beacons. The one rifampin-susceptible isolate from Mexico that appeared to be rifampin resistant by the molecular beacon assay contained an S531W mutation, which is usually associated with rifampin resistance. Of the rifampin-resistant isolates that were correctly identified in the molecular beacon assay, one contained a novel L530A mutation and another contained a novel deletion between codons 511 and 514. Overall, the molecular beacon assay appears to have sufficient sensitivity (89%) and specificity (99%) for use in countries with a high prevalence of tuberculosis.

Virulence, immunopathology and transmissibility of selected strains of Mycobacterium tuberculosis in a murine model

After encounter with Mycobacterium tuberculosis, a series of non‐uniform immune responses are triggered that define the course of the infection. Eight M. tuberculosis strains were selected from a prospective population‐based study of pulmonary tuberculosis patients (1995–2003) based on relevant clinical/epidemiological patterns and tested in a well‐characterized BALB/c mouse model of progressive pulmonary tuberculosis. In addition, a new mouse model of transmissibility consisting of prolonged cohousing (up to 60 days) of infected and naïve animals was tested. Four phenotypes were defined based on strain virulence (mouse survival, lung bacillary load and tissue damage), immunology response (cytokine expression determined by real‐time polymerase chain reaction) and transmissibility (lung bacillary loads and cutaneous delayed‐type hypersensitivity in naïve animals).We identified four clearly defined strain phenotypes: (1) hypervirulent strain with non‐protective immune response and highly transmissible; (2) virulent strain, associated with high expression of proinflammatory cytokines (tumour necrosis factor and interferon) and very low anti‐inflammatory cytokine expression (interleukins 4 and 10), which induced accelerated death by immunopathology; (3) strain inducing efficient protective immunity with lower virulence, and (4) strain demonstrating strong and early macrophage activation (innate immunity) with delayed participation of acquired immunity (interferon expression). We were able to correlate virulent and transmissible phenotypes in the mouse model and markers of community transmission such as tuberculin reactivity among contacts, rapid progression to disease and cluster status. However, we were not able to find correlation with the other two phenotypes. Our new transmission model supported the hypothesis that among these strains increased virulence was linked to increased transmission.

Tuberculosis-Related Deaths within a Well-Functioning DOTS Control Program

To describe the molecular epidemiology of tuberculosis (TB)-related deaths in a well-managed program in a low-HIV area, we analyzed data from a cohort of 454 pulmonary TB patients recruited between March 1995 and October 2000 in southern Mexico. Patients who were sputum acid-fast bacillus smear positive underwent clinical and mycobacteriologic evaluation (isolation, identification, drug-susceptibility testing, and IS6110-based genotyping and spoligotyping) and received treatment from the local directly observed treatment strategy (DOTS) program. After an average of 2.3 years of follow-up, death was higher for clustered cases (28.6 vs. 7%, p=0.01). Cox analysis revealed that TB-related mortality hazard ratios included treatment default (8.9), multidrug resistance (5.7), recently transmitted TB (4.1), weight loss (3.9), and having less than 6 years of formal education (2). In this community, TB is associated with high mortality rates.

Tuberculosis in ageing: high rates, complex diagnosis and poor clinical outcomes

BACKGROUND worldwide, the frequency of tuberculosis among older people almost triples that observed among young adults. OBJECTIVE to describe clinical and epidemiological consequences of pulmonary tuberculosis among older people. METHODS we screened persons with a cough lasting more than 2 weeks in Southern Mexico from March 1995 to February 2007. We collected clinical and mycobacteriological information (isolation, identification, drug-susceptibility testing and IS6110-based genotyping and spoligotyping) from individuals with bacteriologically confirmed pulmonary tuberculosis. Patients were treated in accordance with official norms and followed to ascertain treatment outcomes, retreatment, and vital status. RESULTS eight hundred ninety-three tuberculosis patients were older than 15 years of age; of these, 147 (16.5%) were 65 years of age or older. Individuals ≥ 65 years had significantly higher rates of recently transmitted and reactivated tuberculosis. Older age was associated with treatment failure (OR=5.37; 95% CI: 1.06-27.23; P=0.042), and death due to tuberculosis (HR=3.52; 95% CI: 1.78-6.96; P<0.001) adjusting for sociodemographic and clinical variables. CONCLUSIONS community-dwelling older individuals participate in chains of transmission indicating that tuberculosis is not solely due to the reactivation of latent disease. Untimely and difficult diagnosis and a higher risk of poor outcomes even after treatment completion emphasise the need for specific strategies for this vulnerable group.

Comparison of Sodium Carbonate, Cetyl-Pyridinium Chloride, and Sodium Borate for Preservation of Sputa for Culture of Mycobacterium tuberculosis

Antimicrobial susceptibility testing of Mycobacterium tuberculosis is essential for a successful treatment of patients, mainly those with a previous history of antituberculosis therapy. Susceptibility testing of strains requires their isolation from sputum samples within 24 to 48 h of collection and storage at 2° to 4°C. If the sample is left at room temperature or in refrigeration for longer periods of time, the recovery of M. tuberculosis decreases to 63% and contamination rises to 18% (3). Both problems occur when the laboratory is located far from the patients home, when refrigeration is not available, or when transportation to the laboratory is inadequate, all common situations in developing countries. Despite these problems, no preservatives are presently used to improve the rate of isolation of M. tuberculosis from sputum. In previous studies, sodium carbonate (SC), cetyl-pyridinium chloride (CP), and sodium borate (SB) proved to be good preservatives of this bacterium (1, 5, 6-8). We compared the efficacy of these three compounds in preserving the viability of M. tuberculosis in 58 sputum samples positive for acid-fast bacilli (AFB) from 23 patients with pulmonary tuberculosis who lived in a rural area of Mexico. The study was approved by the Institutional Review Board of our institution. All samples were initially processed in the local laboratory, in Huauchinango Puebla. Each sample was divided into four equal aliquots and placed in a 50-ml conical test tube with one of the following: (i) SC, 75 mg (J. T. Baker, Xalostoc, Mexico); (ii) 5% SB, 800 μl (J. T. Baker); (iii) 1% CP, equal volume (Sigma Aldrich Chemical Co., St. Louis, Mo.); and (iv) no chemical (control). Aliquots were left at room temperature (25 to 35°C) for 5 to 18 days; 8 samples were stored for 5 days, 17 for 6 days, 13 for 7 days, 6 for 8 days, 8 for 9 days, 1 for 15 days, 3 for 16 days, and 2 for 18 days. Aliquots were then sent to our laboratory where they were digested and were decontaminated with 0.5% N-acetyl-cisteine and 2% NaOH (4). Part of the sediment was smeared and was stained first with auramine-rhodamine (AR) (Sigma-Aldrich) and was then stained with Ziehl-Neelsen (ZN) (Sigma-Aldrich) to confirm results. The remaining sediment was resuspended in Na2HPO4-KH2PO4 (0.067 M); 0.5 ml was inoculated in Lowenstein-Jensen (LJ) medium (Becton Dickinson, Mexico City, Mexico) and another 0.5 ml in mycobacterial growth indicator tube (MGIT) medium (Becton Dickinson, Sparks, Md.). The remaining sediment was kept at 4°C for 15 days and was redigested if the first culture became contaminated. LJ was incubated at 37°C in 7.5% CO2 and was examined weekly for 8 weeks. MGIT was incubated in the MGIT 960 instrument (Becton Dickinson). M. tuberculosis was identified in positive cultures by DNA probe (Gene Probe, San Diego, Calif.) (2). AR and ZN stains were AFB positive in 91.4% of smears from samples preserved with SC, 96.6% with SB, and 98.3% of the controls. In contrast, of these samples preserved with CP only, 31% were AR positive and 37.9% were ZN positive. M. tuberculosis was isolated from at least one of the four aliquots in all 58 sputum samples. AFB were cultured in LJ and MGIT from all samples preserved with SC; however, due to contamination with bacteria and fungi, M. tuberculosis was identified in only 86 and 98% of samples, respectively (Table ​(Table1).1). From samples preserved in CP, 98% grew M. tuberculosis when cultured in LJ, and in contrast, only 71% grew M. tuberculosis when cultured in MGIT. The recovery of M. tuberculosis was significantly lower in samples preserved with SB and in controls, mainly due to contamination (Table ​(Table1).1). We observed viability of M. tuberculosis in samples preserved with all compounds for 5 to 18 days. TABLE 1. Comparison of three compounds for recovery of M. tuberculosis from 58 sputum samples Although this study did not include a systematic analysis of the maximum effective storage time of sputum with the different compounds, we can conclude that the recovery and staining of M. tuberculosis were best when sputum was preserved in SC and was cultured in liquid media. Similar yields were obtained when sputum was preserved in CP and cultured in LJ.