What every neuropathologist needs to know: condensed protocol work-up for clinical dementia syndromes.

Concerns about the costs associated with autopsy assessment of Alzheimer disease and related dementias according to 2012 NIA-AA Guidelines have been expressed since the publication of those guidelines. For this reason, we designed and validated a Condensed Protocol for the neuropathologic diagnoses of Alzheimer disease neuropathologic change, Lewy Body disease neuropathologic change, as well as chronic microvascular lesions, hippocampal sclerosis of aging, and cerebral amyloid angiopathy. In this study, the Condensed Protocol is updated to include frontotemporal lobar degeneration [FTLD] tau (corticobasal degeneration, progressive supranuclear palsy, and Pick disease), FTLD-TDP, and limbic-predominant, age-related TDP-43 encephalopathy. The same 20 brain regions are sampled and processed in 5 tissue cassettes, which reduces reagent costs by approximately 65%. Three board-certified neuropathologists were blinded to the original Northwestern University Alzheimer's Disease Research Center Original Protocol neuropathological diagnoses and all clinical history information. The results yielded near uniform agreement with the original comprehensive Alzheimer's Disease Research Center neuropathologic assessments. Diagnostic sensitivity was not impacted. In summary, our recent results show that our updated Condensed Protocol is also an accurate and less expensive alternative to the comprehensive protocols for the additional neuropathologic diagnoses of FTLD Tau and TDP43 proteinopathies.

A pragmatic stepped-wedge cluster randomized trial to evaluate the effectiveness and cost-effectiveness of active case finding for household contacts within a routine tuberculosis program, San Juan de Lurigancho, Lima, Peru.

BACKGROUND: Active case finding (ACF) in household contacts of tuberculosis (TB) patients is now recommended for National TB Programs (NTP) in low- and middle-income countries. However, evidence supporting these recommendations remains limited. This study evaluates the effectiveness and cost-effectiveness of ACF for household contacts of TB cases in a large TB endemic district of Lima, Peru. METHODS: A pragmatic stepped-wedge cluster randomized controlled trial was conducted in 34 health centers of San Juan de Lurigancho district. Centers were stratified by TB rate and randomly allocated to initiate ACF in groups of eight or nine centers at four-month intervals. In the intervention arm, NTP providers visited households of index patients to screen contacts for active TB. The control arm was routine passive case finding (PCF) of symptomatic TB cases. The primary outcomes were the crude and adjusted active TB case rates among household contacts. Program costs were directly measured, and the cost-effectiveness of the ACF intervention was determined. FINDINGS: 3222 index TB cases and 12,566 household contacts were included in the study. ACF identified more household contact TB cases than PCF, 199.29/10,000 contacts/year vs. 132.13 (incidence rate ratio of 1.51 (95% CI 1.21-1.88)). ACF was associated with an incremental cost-effectiveness ratio of US $16,400 per disability-adjusted life year averted and not cost-effective assuming a willingness-to-pay threshold for Peru of US $6360. CONCLUSION: ACF of TB case household contacts detected significantly more secondary TB cases than PCF alone, but was not cost-effective in this setting. In threshold analyses, ACF becomes cost-effective if associated with case detection rates 2.5 times higher than existing PCF programs.

Prevalence of positive TST among healthcare workers in high-burden TB setting in Peru.

BACKGROUND: Tuberculosis (TB) transmission has long been recognized as an important occupational hazard for healthcare workers (HCWs). HCWs have a 5.8% annual risk of exposure and three times greater risk of developing active TB than the general population. METHODS: We conducted an observational cross-sectional study between September 2014 and March 2015 among HCWs in a high-burden TB setting in Lima to estimate the prevalence of positive Tuberculin Skin Test (TST) and to investigate factors associated with a positive TST. RESULTS: Two hundred forty participants were included in the analysis; TST was administered to 190 (79.2%) while the rest were exempt due to a previous positive TST result, history of TB, or test refusal. A positive TST result was found among 56.2% of participants to whom the TST was applied (95% CI: 49.22-63.55%). When considering those who had a previous positive TST result and those with a history of TB, the prevalence of a positive TST result was 64.3% (95% CI: 57.8-70.3%). No significant differences were observed between clinical/paramedical and administrative staff in the health center. The use of N95 masks during work hours was reported by 142 (69.9%) participants. Prevalence ratios (PR) show that workers with more than 120 months as a HCW were 1.44 times more likely to be TST positive. The multivariate analysis found that HCWs with over 10 years of service were 1.52 times more likely to be TST positive. CONCLUSION: This study supports previous reports that TB infection is an occupational hazard for HCWs. Prevention of TB transmission through control measures, as well as timely diagnosis of LTBI in this particular high-risk group, is critical for individual and public health.

Response of Leptomeningeal Metastases in EGFR-Mutated Non-Small-Cell Lung Cancer to Afatinib in the Absence of Radiotherapy.

Palliative radiotherapy is currently the medical standard of care for non-small-cell lung cancer (NSCLC) patients with symptomatic CNS and leptomeningeal disease. We report the case of a 62-year-old male patient with EGFR mutation (del19+) NSLC with symptomatic lymph node, bone, CNS, and leptomeningeal metastases. Taking into account on one hand the response to tyrosine kinase inhibitors (TKIs) and on the other hand the short- to medium-term side effects of radiotherapy and the lack of timely availability in our healthcare system, the patient was treated with afatinib (40 mg daily) and exhibited a rapid response with improvement of neurological symptoms. The patient presented partial response of extracranial, CNS, and leptomeningeal lesions at 3, 6, and 12 months of treatment, currently completing 16 months of progression-free survival despite presenting mild dermatological and gastrointestinal toxicities. Afatinib is an effective and safe option in patients with NSLC EGFR mutation del19+ with CNS and leptomeningeal compromise avoiding or delaying radiotherapy and its side effects, especially in countries where there is a lack of access to this kind of therapy.

Design and use of mouse control DNA for DNA biomarker extraction and PCR detection from urine: Application for transrenal Mycobacterium tuberculosis DNA detection.

Urine samples are increasingly used for diagnosing infections including Escherichia coli, Ebola virus, and Zika virus. However, extraction and concentration of nucleic acid biomarkers from urine is necessary for many molecular detection strategies such as polymerase chain reaction (PCR). Since urine samples typically have large volumes with dilute biomarker concentrations making them prone to false negatives, another impediment for urine-based diagnostics is the establishment of appropriate controls particularly to rule out false negatives. In this study, a mouse glyceraldehyde 3-phosphate dehydrogenase (GAPDH) DNA target was added to retrospectively collected urine samples from tuberculosis (TB)-infected and TB-uninfected patients to indicate extraction of intact DNA and removal of PCR inhibitors from urine samples. We tested this design on surrogate urine samples, retrospective 1milliliter (mL) urine samples from patients in Lima, Peru and retrospective 5mL urine samples from patients in Cape Town, South Africa. Extraction/PCR control DNA was detectable in 97% of clinical samples with no statistically significant differences among groups. Despite the inclusion of this control, there was no difference in the amount of TB IS6110 Tr-DNA detected between TB-infected and TB-uninfected groups except for samples from known HIV-infected patients. We found an increase in TB IS6110 Tr-DNA between TB/HIV co-infected patients compared to TB-uninfected/HIV-infected patients (N=18, p=0.037). The inclusion of an extraction/PCR control DNA to indicate successful DNA extraction and removal of PCR inhibitors should be easily adaptable as a sample preparation control for other acellular sample types.

Feasibility and Operational Performance of Tuberculosis Detection by Loop-Mediated Isothermal Amplification Platform in Decentralized Settings: Results from a Multicenter Study.

Currently available nucleic acid amplification platforms for tuberculosis (TB) detection are not designed to be simple or inexpensive enough to implement in decentralized settings in countries with a high burden of disease. The loop-mediated isothermal amplification platform (LAMP) may change this. We conducted a study in adults with symptoms suggestive of TB in India, Uganda, and Peru to establish the feasibility of using TB-LAMP (Eiken Chemical Co.) in microscopy laboratories compared with using smear microscopy against a reference standard of solid and liquid cultures. Operational characteristics were evaluated as well. A total of 1,777 participants met the eligibility criteria and were included for analysis. Overall, TB-LAMP sensitivities among culture-positive samples were 97.2% (243/250; 95% confidence interval [CI], 94.3% to 98.2%) and 62.0% (88/142; 95% CI, 53.5% to 70.0%) for smear-positive and smear-negative TB, respectively, but varied widely by country and operator. Specificities ranged from 94.5% (446/472; 95% CI, 92.0% to 96.4%) to 98.0% (350/357; 95% CI, 96.0% to 99.2%) by country. A root cause analysis identified high temperatures, high humidity, and/or low reaction volumes as possible causes for false-positive results, as they may result in nonspecific amplification. The study was repeated in India with training focused on vulnerable steps and an updated protocol; 580 participants were included for analysis. Specificity in the repeat trial was 96.6% (515/533; 95% CI, 94.7% to 97.9%). To achieve acceptable performance of LAMP at the microscopy center level, significant training and infrastructure requirements are necessary.

Implementation of a stepped-wedge cluster randomized design in routine public health practice: design and application for a tuberculosis (TB) household contact study in a high burden area of Lima, Peru.

BACKGROUND: We designed a pragmatic stepped-wedge cluster randomized controlled trial in order to evaluate provider-initiated evaluation of household contacts (HCs) of smear positive tuberculosis (TB) cases within a routine TB program in Lima, Peru. METHODS/DESIGN: National TB program (NTP) officers of San Juan de Lurigancho District (Lima, Peru) and university-based researchers jointly designed a pragmatic stepped-wedge cluster randomized trial design in order to evaluate a planned active case finding (ACF) program for all HCs of smear-positive TB cases in 34 district healthcare centres. Randomization of time to intervention initiation was stratified by health centre TB case rate. The ACF intervention included provider-initiated home visits of all new sputum smear positive TB patients in order to evaluate household contacts for active TB. Active TB was diagnosed using symptom screening, sputum screening, chest x-ray and clinical evaluation. Once initiated, ACF was provided by NTP staff and integrated into the routine DOTS TB program activities. DISCUSSION: This study protocol describes the pragmatic stepped-wedge cluster randomized trial of active household contact evaluations within an NTP. The stepped-wedge design met overlapping needs of local TB programmers and researchers to adequately evaluate the large-scale roll out of a new control program in a TB endemic setting. Multiple planning meetings were required to develop the necessary networks and in order to understand the operations, needs and goals of the NTP staff and researchers collaborating on this project. The advantages and challenges of using this study design in practice and within existing routine TB programs in a middle-income country context are discussed. TRIAL REGISTRATION: ClinicalTrials.gov NCT02174380. Registered 24 Jun 2014.

Public transportation and tuberculosis transmission in a high incidence setting.

BACKGROUND: Tuberculosis (TB) transmission may occur with exposure to an infectious contact often in the setting of household environments, but extra-domiciliary transmission also may happen. We evaluated if using buses and/or minibuses as public transportation was associated with acquiring TB in a high incidence urban district in Lima, Peru. METHODS: Newly diagnosed TB cases with no history of previous treatment and community controls were recruited from August to December 2008 for a case-control study. Crude and adjusted odd ratios (OR) and 95% confidence intervals (CI) were calculated using logistic regression to study the association between bus/minibus use and TB risk. RESULTS: One hundred forty TB cases and 80 controls were included. The overall use of buses/minibuses was 44.9%; 53.3% (72/135) among cases and 30.4% (24/79) among controls [OR: 3.50, (95% CI: 1.60-7.64)]. In the TB group, 25.7% (36/140) of subjects reported having had a recent household TB contact, and 13% (18/139) reported having had a workplace TB contact; corresponding figures for controls were 3.8% (3/80) and 4.1% (3/73), respectively[OR: 8.88 (95% CI: 2.64-29.92), and OR: 3.89 (95% CI: 1.10-13.70)]. In multivariate analyses, age, household income, household contact and using buses/minibuses to commute to work were independently associated with TB [OR for bus/minibus use: 11.8 (95% CI: 1.45-96.07)]. CONCLUSIONS: Bus/minibus use to commute to work is associated with TB risk in this high-incidence, urban population in Lima, Peru. Measures should be implemented to prevent TB transmission through this exposure.

Resistencia a drogas de segunda línea en cepas peruanas de Mycobacterium tuberculosis multidrogorresistentes / Resistance to second-line anti-tuberculosis drugs among peruvian multidrug resistant Mycobacterium tuberculosis strains

Objetivos. Determinar los perfiles de resistencia de las quinolonas; ciprofloxacina (Cpx), ofloxacina (Ofx), gatifloxacina (Gfx) y moxifloxacina (Mfx), y de los inyectables; kanamicina (Km), amikacina (Am) y capreomicina (Cm) en cepas multidrogorresistente (MDR). Se buscó la presencia de mutaciones en los genes rrs,tlyA y gyrA/B, y su posible asociación con la resistencia a inyectables y quinolonas. Materiales y métodos. En este estudio piloto descriptivo se seleccionaron cepas MDR aisladas durante junio a diciembre de 2004, que fueron criopreservadas en el banco de muestras del Instituto de Medicina Tropical ôAlexander von Humboldtõ en Lima, Perú. Se determinó la concentración mínima inhibitoria (CMI) para Cpx, Ofx, Gfx, Mfx, Km, Am y Cm. Se investigó las mutaciones presentes en los genes rrs, tlyA y gyrA/B a través de un PCR convencional y posterior secuenciamiento de los productos obtenidos. Resultados. Cuatro de los once aislados presentaron resistencia contra los inyectables y en todas se observó una alta CMI; >120 ug/mL para Km y >160 ug/mL para Am y Cm. Solo dos aislados presentaron resistencia a Ofx con un CMI = 4 ug/mL. Los resultados de secuenciamiento sugirieron que la mutación A1401T en rrs podría ser la causa molecular de resistencia a los inyectables; mientras que en este estudio no se halló ninguna mutación en tlyA ni en gyrA/B asociada a resistencia. Conclusiones. Este estudio sugiere una posible asociación entre la mutación en A1401G y la resistencia a los antibióticos inyectables.

Objectives. To determine the drug resistance profiles for quinolones: ciprofloxacin (CFX), ofloxacin (OFX), moxifloxacin (MFX), and gatifloxacin (GFX); and for injectables: kanamycin (KAN), amikacin (AMK), and capreomycin (CAP) in multidrug resistant (MDR) strains. We also investigated the correlation between mutations in rrs, tlyA and gyrA/B genes, and the in vitro resistance to the second-line anti-tuberculosis drugs. Materials and methods. In this pilot study we selected MDR clinical isolates collected from June-December 2004 in the Tropical Medicine Institute ôAlexander von Humboldtõ (Lima, Peru). The Minimum Inhibitory Concentration (MIC) of CFX, OFX, MFX, GFX, KAN, AMK and CAP for 14 clinical isolates were determined and the sequences of rrs, tlyA and gyrA/B genes were analyzed by conventional PCR followed by sequencing. Results. We obtained valid results for 11 samples. Four isolates were resistant to injectable drugs, and in all the cases the MICs were; >120 ug/mL for KAN and >160 ug/mL for AMK and CAP. Only 2 isolates were resistant to OFX with MIC = 4 ug/mL. Sequencing results suggested that the mutation A1401T in rrs gene could be the molecular cause of the resistance to injectable drugs. In this study we did not find any mutation in tlyA and gyrA/B associated to resistance. Conclusions. Our study suggests a possible association between the mutation A1401T in rrs and resistance to injectable drugs. However further studies should be done to confirm this hypothesis in Peru.

[Resistance to second-line anti-tuberculosis drugs among peruvian multidrug resistant Mycobacterium tuberculosis strains]. / Resistencia a drogas de segunda línea en cepas peruanas de Mycobacterium tuberculosis multidrogorresistentes.

OBJECTIVES: To determine the drug resistance profiles for quinolones: ciprofloxacin (CFX), ofloxacin (OFX), moxifloxacin (MFX), and gatifloxacin (GFX); and for injectables: kanamycin (KAN), amikacin (AMK), and capreomycin (CAP) in multidrug resistant (MDR) strains. We also investigated the correlation between mutations in rrs, tlyA and gyrA/B genes, and the in vitro resistance to the second-line anti-tuberculosis drugs. MATERIALS AND METHODS: In this pilot study we selected MDR clinical isolates collected from June-December 2004 in the Tropical Medicine Institute "Alexander von Humboldt" (Lima, Perú). The Minimum Inhibitory Concentration (MIC) of CFX, OFX, MFX, GFX, KAN, AMK and CAP for 14 clinical isolates were determined and the sequences of rrs, tlyA and gyrA/B genes were analyzed by conventional PCR followed by sequencing. RESULTS: We obtained valid results for 11 samples. Four isolates were resistant to injectable drugs, and in all the cases the MICs were; >120 µg/mL for KAN and >160 µg/mL for AMK and CAP. Only 2 isolates were resistant to OFX with MIC = 4 µg/mL. Sequencing results suggested that the mutation A1401T in rrs gene could be the molecular cause of the resistance to injectable drugs. In this study we did not find any mutation in tlyA and gyrA/B associated to resistance. CONCLUSIONS: Our study suggests a possible association between the mutation A1401T in rrs and resistance to injectable drugs. However further studies should be done to confirm this hypothesis in Perú.

Knowledge about HIV prevention and transmission among recently diagnosed tuberculosis patients: a cross sectional study.

BACKGROUND: Patients with Tuberculosis (TB) are a vulnerable group for acquiring HIV infection. Therefore, countries with a concentrated HIV epidemic and high prevalence of TB should provide adequate information about HIV prevention to TB patients. METHODS: We conducted a cross-sectional study to evaluate the level of knowledge on HIV prevention and transmission among newly diagnosed TB patients in Lima, Peru. The survey evaluated knowledge about HIV infection and prevention and was administered before HIV counseling and blood sampling for HIV testing were performed. RESULTS: A total of 171 TB patients were enrolled; mean age was 31.1 years, 101 (59%) were male. The overall mean level of knowledge of HIV was 59%; but the specific mean level of knowledge on HIV transmission and prevention was only 33.3% and 41.5%, respectively. Age and level of education correlated with overall level of knowledge in the multivariate model (P-value: 0.02 and <0.001 respectively). CONCLUSIONS: The study shows inadequate levels of knowledge about HIV transmission and prevention among newly-diagnosed TB patients in this setting, and underscores the need for implementing educational interventions in this population.

Association of major depressive episode with negative outcomes of tuberculosis treatment.

BACKGROUND: Pulmonary tuberculosis (TB) persists an important contributor to the burden of diseases in developing countries. TB control success is based on the patient's compliance to the treatment. Depressive disorders have been negatively associated with compliance of therapeutic schemes for chronic diseases. This study aimed to estimate the significance and magnitude of major depressive episode as a hazard factor for negative outcomes (NO), including abandon or death in patients receiving TB treatment. METHODOLOGY/PRINCIPAL FINDINGS: A longitudinal study was conducted to evaluate the association of major depressive episode (MDE), as measured by a 5-item version of the Center for Epidemiological Studies Depression Scale (CES-D) with NO to TB treatment. Patients with confirmed TB were enrolled before the start of TB treatment. Baseline measurements included socio-demographic variables as well as the CES-D, which was also applied every month until the end of the treatment. Death and treatment default were assessed monthly. Survivor function (SF) for NO according to MDE status (CES-D≥6) at baseline (MDEb) was estimated. Cox's Regression was performed for bivariate analyses as well as for the multivariate model. A total of 325 patients accepted to participate in the study, of which 34 where excluded for diagnosis of MDR-TB. NO was observed in 24 patients (8.2%); 109 (37%) presented MDEb. Statistically significant difference was found on the SF of patients with and without MDEb (0.85 vs. 0.96, p-value = 0.002). The hazard ratio for NO, controlled for age, sex, marital status and instruction level was 3.54 (95%CI 1.43-8.75; p-value = 0.006). CONCLUSION: The presence of MDE at baseline is associated to NO of TB treatment. Targeting detection and treatment of MDE may improve TB treatment outcomes.

A diagnostic accuracy study of Xpert®MTB/RIF in HIV-positive patients with high clinical suspicion of pulmonary tuberculosis in Lima, Peru.

BACKGROUND: Diagnosis of pulmonary tuberculosis (TB) among human immunodeficiency virus (HIV) patients remains complex and demands easy to perform and accurate tests. Xpert®MTB/RIF (MTB/RIF) is a molecular TB diagnostic test which is rapid and convenient; the test requires minimal human resources and reports results within two hours. The majority of performance studies of MTB/RIF have been performed in high HIV burden settings, thus TB diagnostic studies among HIV patients in low HIV prevalence settings such as Peru are still needed. METHODOLOGY/PRINCIPAL FINDINGS: From April 2010 to May 2011, HIV-positive patients with high clinical suspicion of TB were enrolled from two tertiary hospitals in Lima, Peru. Detection of TB by MTB/RIF was compared to a composite reference standard Löwenstein-Jensen (LJ) and liquid culture. Detection of rifampicin resistance was compared to the LJ proportion method. We included 131 patients, the median CD4 cell count was 154.5 cells/mm(3) and 45 (34.4%) had TB. For TB detection among HIV patients, sensitivity of MTB/RIF was 97.8% (95% CI 88.4-99.6) (44/45); specificity was 97.7% (95% CI 91.9-99.4) (84/86); the positive predictive value was 95.7% (95% CI 85.5-98.8) (44/46); and the negative predictive value, 98.8% (95% CI 93.6-99.8) (84/85). MTB/RIF detected 13/14 smear-negative TB cases, outperforming smear microscopy [97.8% (44/45) vs. 68.9% (31/45); p = 0.0002]. For rifampicin resistance detection, sensitivity of MTB/RIF was 100% (95% CI 61.0-100.0) (6/6); specificity was 91.0% (95% CI 76.4-96.9) (30/33); the positive predictive value was 66.7% (95% CI 35.4-87.9) (6/9); and the negative predictive value was 100% (95% CI 88.7 -100.0) (30/30). CONCLUSIONS/SIGNIFICANCE: In HIV patients in our population with a high clinical suspicion of TB, MTB/RIF performed well for TB diagnosis and outperformed smear microscopy.

Additional evidence to support the phasing-out of treatment category II regimen for pulmonary tuberculosis in Peru.

The effectiveness of the World Health Organization's (WHO) treatment category II regimen for tuberculosis in 124 patients was compared to that of 1147 patients receiving treatment category I in Lima, Peru following WHO's guidelines. Drug susceptibility test was available for 85% of patients. Prevalence of multi drug resistance and streptomycin resistance were 5.1% and 20.7%, respectively. Overall cure rate for regimen II was lower than that of regimen I: 67.8% (95% CI: 58.9-75.6.) vs 77.8% (95% CI: 75.3-80.2), p=0.014. Multi-drug resistance exerted a profound effect on cure rates in both regimens. Our results support the phasing-out of treatment category II regimen in Peru.

High prevalence of primary multidrug resistant tuberculosis in persons with no known risk factors.

INTRODUCTION: In high multidrug resistant (MDR) tuberculosis (TB) prevalence areas, drug susceptibility testing (DST) at diagnosis is recommended for patients with risk factors for MDR. However, this approach might miss a substantial proportion of MDR-TB in the general population. We studied primary MDR in patients considered to be at low risk of MDR-TB in Lima, Peru. METHODS: We enrolled new sputum smear-positive TB patients who did not report any MDR-TB risk factor: known exposure to a TB patient whose treatment failed or who died or who was known to have MDR-TB; immunosuppressive co-morbidities, ex prison inmates; prison and health care workers; and alcohol or drug abuse. A structured questionnaire was applied to all enrolled participants to confirm the absence of these factors and thus minimize underreporting. Sputum from all participants was cultured on Löwenstein-Jensen media and DST for first line drugs was performed using the 7H10 agar method. RESULTS: Of 875 participants with complete data, 23.2% (203) had risk factors for MDR-TB elicited after enrolment. Among the group with no reported risk factors who had a positive culture, we found a 6.3% (95%CI 4.4-8.3) (37/584) rate of MDR-TB. In this group no epidemiological characteristics were associated with MDR-TB. Thus, in this group, multidrug resistance occurred in patients with no identifiable risk factors. CONCLUSIONS: We found a high rate of primary MDR-TB in a general population with no identifiable risk factors for MDR-TB. This suggests that in a high endemic area targeting patients for MDR-TB based on the presence of risk factors is an insufficient intervention.

Rapid diagnosis of tuberculosis with the Xpert MTB/RIF assay in high burden countries: a cost-effectiveness analysis.

BACKGROUND: Xpert MTB/RIF (Xpert) is a promising new rapid diagnostic technology for tuberculosis (TB) that has characteristics that suggest large-scale roll-out. However, because the test is expensive, there are concerns among TB program managers and policy makers regarding its affordability for low- and middle-income settings. METHODS AND FINDINGS: We estimate the impact of the introduction of Xpert on the costs and cost-effectiveness of TB care using decision analytic modelling, comparing the introduction of Xpert to a base case of smear microscopy and clinical diagnosis in India, South Africa, and Uganda. The introduction of Xpert increases TB case finding in all three settings; from 72%-85% to 95%-99% of the cohort of individuals with suspected TB, compared to the base case. Diagnostic costs (including the costs of testing all individuals with suspected TB) also increase: from US$28-US$49 to US$133-US$146 and US$137-US$151 per TB case detected when Xpert is used "in addition to" and "as a replacement of" smear microscopy, respectively. The incremental cost effectiveness ratios (ICERs) for using Xpert "in addition to" smear microscopy, compared to the base case, range from US$41-$110 per disability adjusted life year (DALY) averted. Likewise the ICERS for using Xpert "as a replacement of" smear microscopy range from US$52-$138 per DALY averted. These ICERs are below the World Health Organization (WHO) willingness to pay threshold. CONCLUSIONS: Our results suggest that Xpert is a cost-effective method of TB diagnosis, compared to a base case of smear microscopy and clinical diagnosis of smear-negative TB in low- and middle-income settings where, with its ability to substantially increase case finding, it has important potential for improving TB diagnosis and control. The extent of cost-effectiveness gain to TB programmes from deploying Xpert is primarily dependent on current TB diagnostic practices. Further work is required during scale-up to validate these findings.

Self-reported risks for multiple-drug resistance among new tuberculosis cases: implications for drug susceptibility screening and treatment.

BACKGROUND: Multiple drug-resistance in new tuberculosis (TB) cases accounts for the majority of all multiple drug-resistant TB (MDR-TB) worldwide. Effective control requires determining which new TB patients should be tested for MDR disease, yet the effectiveness of global screening recommendations of high-risk groups is unknown. METHODS: Sixty MDR-TB cases with no history of previous TB treatment, 80 drug-sensitive TB and 80 community-based controls were recruited in Lima, Peru between August and December, 2008 to investigate whether recommended screening practices identify individuals presenting with MDR-TB. Odd ratios (OR) and 95% confidence intervals (CI) were calculated using logistic regression to study the association of potential risk factors with case/control variables. RESULTS: MDR-TB cases did not differ from drug-sensitive TB and community controls in rates of human immunodeficiency virus infection, reported hospital or prison visits in the 3 years prior to diagnosis. MDR-TB cases were more likely than drug-sensitive TB controls to have had a recent MDR-TB household contact (OR 4.66, (95% CI 1.56-13.87)); however, only 15 cases (28.3%) reported this exposure. In multivariate modeling, recent TB household contact, but not contact with an MDR-TB case, remained predictive of MDR-TB, OR 7.47, (95% CI 1.91-29.3). Living with a partner rather than parents was associated with a lower risk of MDR-TB, OR 0.15, (95% CI 0.04-0.51). CONCLUSION: Targeted drug susceptibility testing (DST) linked to reported MDR-TB contact or other high-risk exposures does not identify the majority of new TB cases with MDR disease in Lima where it is endemic. All new TB cases should be screened with DST to identify MDR patients. These findings are likely applicable to other regions with endemic MDR-TB.

A multisite assessment of the quantitative capabilities of the Xpert MTB/RIF assay.

RATIONALE: The Xpert MTB/RIF is an automated molecular test for Mycobacterium tuberculosis that estimates bacterial burden by measuring the threshold-cycle (Ct) of its M. tuberculosis-specific real-time polymerase chain reaction. Bacterial burden is an important biomarker for disease severity, infection control risk, and response to therapy. OBJECTIVES: Evaluate bacterial load quantitation by Xpert MTB/RIF compared with conventional quantitative methods. METHODS: Xpert MTB/RIF results were compared with smear-microscopy, semiquantiative solid culture, and time-to-detection in liquid culture for 741 patients and 2,008 samples tested in a multisite clinical trial. An internal control real-time polymerase chain reaction was evaluated for its ability to identify inaccurate quantitative Xpert MTB/RIF results. MEASUREMENTS AND MAIN RESULTS: Assays with an internal control Ct greater than 34 were likely to be inaccurately quantitated; this represented 15% of M. tuberculosis-positive tests. Excluding these, decreasing M. tuberculosis Ct was associated with increasing smear microscopy grade for smears of concentrated sputum pellets (r(s) = -0.77) and directly from sputum (r(s) =-0.71). A Ct cutoff of approximately 27.7 best predicted smear-positive status. The association between M. tuberculosis Ct and time-to-detection in liquid culture (r(s) = 0.68) and semiquantitative colony counts (r(s) = -0.56) was weaker than smear. Tests of paired same-patient sputum showed that high viscosity sputum samples contained ×32 more M. tuberculosis than nonviscous samples. Comparisons between the grade of the acid-fast bacilli smear and Xpert MTB/RIF quantitative data across study sites enabled us to identify a site outlier in microscopy. CONCLUSIONS: Xpert MTB/RIF quantitation offers a new, standardized approach to measuring bacterial burden in the sputum of patients with tuberculosis.