Renata Lyrio Peres

Cavitary Disease and Quantitative Sputum Bacillary Load in Cases of Pulmonary Tuberculosis

ABSTRACT We examined sputum bacterial loads in adults with newly diagnosed tuberculosis using quantitative culture and time-until-positive (DTP) culture in BACTEC 460. Patients with cavitary disease had higher CFU levels than those without cavities and shorter DTPs. Within radiographic strata of moderately and far advanced tuberculosis, higher CFU counts were associated with cavitary disease.

Whole Blood Bactericidal Activity during Treatment of Pulmonary Tuberculosis

The timely evaluation of new drugs that can be used to shorten tuberculosis (TB) treatment will require surrogate markers for relapse. This study examined bactericidal activity against intracellular Mycobacterium tuberculosis in whole blood culture (whole blood bactericidal activity; WBA) during TB treatment. In the absence of chemotherapy, immune mechanisms in patient blood resulted in bacteriostasis, whereas administration of oral chemotherapy resulted in bacillary killing. Total WBA per dose was greater during the intensive phase of treatment than during the continuation phase (mean, -2.32 vs. -1.67 log(10) cfu-days, respectively; P<.001). Cumulative WBA throughout treatment was greater in subjects whose sputum cultures converted to negative by the eighth week of treatment than in those for whom conversion was delayed (mean, -365 vs. -250 log(10) cfu-days; P=.04) and correlated with the rate of decrease of sputum colony-forming unit counts during the first 4 weeks of treatment (P=.018), both of which are indicative of prognosis. These findings indicate that measurement of WBA may have a role in assessing the sterilizing activity of new anti-TB drugs.

Smoking and 2-month culture conversion during anti-tuberculosis treatment.

OBJECTIVE To investigate risk factors for delayed sputum culture conversion to negative during anti-tuberculosis treatment, with an emphasis on smoking. DESIGN Nested case-control study of adults with non-cavitary, culture-confirmed pulmonary tuberculosis (TB) participating in an anti-tuberculosis treatment trial in Brazil. A case of delayed culture conversion was a patient who remained culture-positive after 2 months of treatment. Odds ratios with 95% confidence intervals were calculated. RESULTS Fifty-three cases and 240 control patients were analyzed. Smokers had three-fold greater odds of remaining culture-positive after 2 months of treatment (P = 0.007) than non-smokers, while smokers and ex-smokers who smoked >20 cigarettes a day had two-fold greater odds of remaining culture-positive after 2 months of treatment (P = 0.045). CONCLUSION Cigarette smoking adversely affects culture conversion during anti-tuberculosis treatment. Support for smoking cessation should be considered to improve outcomes in TB control programs.

Xpert MTB/RIF Ultra for detection of Mycobacterium tuberculosis and rifampicin resistance: a prospective multicentre diagnostic accuracy study

Summary Background The Xpert MTB/RIF assay is an automated molecular test that has improved the detection of tuberculosis and rifampicin resistance, but its sensitivity is inadequate in patients with paucibacillary disease or HIV. Xpert MTB/RIF Ultra (Xpert Ultra) was developed to overcome this limitation. We compared the diagnostic performance of Xpert Ultra with that of Xpert for detection of tuberculosis and rifampicin resistance. Methods In this prospective, multicentre, diagnostic accuracy study, we recruited adults with pulmonary tuberculosis symptoms presenting at primary health-care centres and hospitals in eight countries (South Africa, Uganda, Kenya, India, China, Georgia, Belarus, and Brazil). Participants were allocated to the case detection group if no drugs had been taken for tuberculosis in the past 6 months or to the multidrug-resistance risk group if drugs for tuberculosis had been taken in the past 6 months, but drug resistance was suspected. Demographic information, medical history, chest imaging results, and HIV test results were recorded at enrolment, and each participant gave at least three sputum specimen on 2 separate days. Xpert and Xpert Ultra diagnostic performance in the same sputum specimen was compared with culture tests and drug susceptibility testing as reference standards. The primary objectives were to estimate and compare the sensitivity of Xpert Ultra test with that of Xpert for detection of smear-negative tuberculosis and rifampicin resistance and to estimate and compare Xpert Ultra and Xpert specificities for detection of rifampicin resistance. Study participants in the case detection group were included in all analyses, whereas participants in the multidrug-resistance risk group were only included in analyses of rifampicin-resistance detection. Findings Between Feb 18, and Dec 24, 2016, we enrolled 2368 participants for sputum sampling. 248 participants were excluded from the analysis, and 1753 participants were distributed to the case detection group (n=1439) and the multidrug-resistance risk group (n=314). Sensitivities of Xpert Ultra and Xpert were 63% and 46%, respectively, for the 137 participants with smear-negative and culture-positive sputum (difference of 17%, 95% CI 10 to 24); 90% and 77%, respectively, for the 115 HIV-positive participants with culture-positive sputum (13%, 6·4 to 21); and 88% and 83%, respectively, across all 462 participants with culture-positive sputum (5·4%, 3·3 to 8·0). Specificities of Xpert Ultra and Xpert for case detection were 96% and 98% (−2·7%, −3·9 to −1·7) overall, and 93% and 98% for patients with a history of tuberculosis. Xpert Ultra and Xpert performed similarly in detecting rifampicin resistance. Interpretation For tuberculosis case detection, sensitivity of Xpert Ultra was superior to that of Xpert in patients with paucibacillary disease and in patients with HIV. However, this increase in sensitivity came at the expense of a decrease in specificity. Funding Government of Netherlands, Government of Australia, Bill & Melinda Gates Foundation, Government of the UK, and the National Institute of Allergy and Infectious Diseases.

Extrapulmonary Tuberculosis: Mycobacterium tuberculosis Strains and Host Risk Factors in a Large Urban Setting in Brazil

Background Factors related to the development of extrapulmonary forms of tuberculosis (EPTB) are still poorly understood, particularly in high-endemic countries like Brazil. The objective of the paper is to determine host and Mycobacterium tuberculosis (MTB) strain-related factors associated with the development of EPTB in Espírito Santo state, Brazil. Methods and Findings We conducted a retrospective laboratory-based surveillance study of new tuberculosis (TB) cases diagnosed in Espírito Santo state, Brazil between 1998 and 2007. We genotyped 612 isolates of MTB from 606 TB patients using spoligotyping and IS6110-restriction fragment length polymorphism (RFLP) typing and compared sociodemographic and clinical characteristics of patients with pulmonary TB (PTB) and EPTB. Among 606 patients, 464 (77%) had PTB, 79 (13%) had EPTB, 51 (8%) had both, and 12 (2%) had miliary TB. The IS6110 RFLP analysis demonstrated that 250 (41%) isolates belonged to clustered RFLP patterns, 27 (11%) of which were from EPTB. We identified 73 clusters including 35 (48%) composed of 2 isolates each. By spoligotyping, 506 (83%) MTB isolates fell into known patterns and 106 (17%) fell into patterns with no family assignment; 297 (48%) isolates belonged to the Latin-American Mediterranean family. Higher school level (4-7 years OR: 0.16 95% CI 0.34-0.73 and > 8 years of education, OR 0.06 95% CI 0.009-0.50) white ethnicity (OR: 2.54 95% CI 1.03-6.25) and HIV infection (OR: 16.83 95% CI 5.23-54.18) were associated with EPTB. No specific strain lineage or percentage of clustering was associated with EPTB. Conclusions These results demonstrate that risk factors for EPTB are related more to host than to MTB strain lineage characteristics.

Genotypic and Spatial Analysis of Mycobacterium tuberculosis Transmission in a High-Incidence Urban Setting

BACKGROUND Genotyping Mycobacterium tuberculosis isolates allows study of dynamics of tuberculosis transmission, while geoprocessing allows spatial analysis of clinical and epidemiological data. Here, genotyping data and spatial analysis were combined to characterize tuberculosis transmission in Vitória, Brazil, to identify distinct neighborhoods and risk factors associated with recent tuberculosis transmission. METHODS From 2003 to 2007, 503 isolates were genotyped by IS6110 restriction fragment length polymorphism (RFLP) and spoligotyping. The analysis included kernel density estimation, K-function analysis, and a t test distance analysis. Mycobacterium tuberculosis isolates belonging to identical RFLP patterns (clusters) were considered to represent recent tuberculosis infection (cases). RESULTS Of 503 genotyped isolates, 242 (48%) were categorized into 70 distinct clusters belonging to 12 RFLP families. The proportion of recent transmission was 34.2%. Kernel density maps indicated 3 areas of intense concentration of cases. K-function analysis of the largest RFLP clusters and families showed they co-localized in space. The distance analysis confirmed these results and demonstrated that unique strain patterns (controls) randomly distributed in space. A logit model identified young age, positive smear test, and lower Index of Quality of Urban Municipality as risk factors for recent transmission. The predicted probabilities for each neighborhood were mapped and identified neighborhoods with high risk for recent transmission. CONCLUSIONS Spatial and genotypic clustering of M. tuberculosis isolates revealed ongoing active transmission of tuberculosis caused by a small subset of strains in specific neighborhoods of the city. Such information provides an opportunity to target tuberculosis transmission control, such as through rigorous and more focused contact investigation programs.

Guided sputum sample collection and culture contamination rates in the diagnosis of pulmonary TB

A comparative study to evaluate contamination in cultures of morning sputum samples, comparing those collected at home under currently recommended conditions and those collected under supervision after patient orientation and education. The home and supervised collection groups produced 43 and 76 sputum samples, respectively. The contamination rate was nearly 3-times higher among samples collected at home than among those collected under supervision (37% vs. 13%, p < 0.05; OR = 0.25). The simple educational and hygiene measures described can decrease the contamination rate among sputum samples collected for diagnostic culture.

Comparison of Interferon-γ Release Assay to Two Cut-Off Points of Tuberculin Skin Test to Detect Latent Mycobacterium tuberculosis Infection in Primary Health Care Workers

Background An interferon-γ release assay, QuantiFERON-TB (QFT) test, has been introduced an alternative test for the diagnosis of latent Mycobacterium tuberculosis infection (LTBI). Here, we compared the performance of QFT with tuberculin skin test (TST) measured at two different cut-off points among primary health care work (HCW) in Brazil. Methods A cross-sectional study was carried out among HCWs in four Brazilian cities with a known history of high incidence of TB. Results of the QFT were compared to TST results based on both ≥5 mm and ≥10 mm as cut-off points. Results We enrolled 632 HCWs. When the cut-off value of ≥10 mm was used, agreement between QFT and TST was 69% (k = 0.31), and when the cut-off of ≥5 mm was chosen, the agreement was 57% (k = 0.22). We investigated possible factors of discordance of TST vs QFT. Compared to the TST−/QFT− group, risk factors for discordance in the TST+/QFT− group with TST cut-off of ≥5 mm included age between 41–45 years [OR = 2.70; CI 95%: 1.32–5.51] and 46–64 years [OR = 2.04; CI 95%: 1.05–3.93], BCG scar [OR = 2.72; CI 95%: 1.40–5.25], and having worked only in primary health care [OR = 2.30; CI 95%: 1.09–4.86]. On the other hand, for the cut-off of ≥10 mm, BCG scar [OR = 2.26; CI 95%: 1.03–4.91], being a household contact of a TB patient [OR = 1.72; CI 95%: 1.01–2.92] and having had a previous TST [OR = 1.66; CI 95%: 1.05–2.62], were significantly associated with the TST+/QFT− group. No statistically significant associations were found among the TST−/QFT+ discordant group with either TST cut-off value. Conclusions Although we identified BCG vaccination to contribute to the discordance at both TST cut-off measures, the current Brazilian recommendation for the initiation of LTBI treatment, based on information gathered from medical history, TST, chest radiograph and physical examination, should not be changed.

Evaluation of a commercial test based on ligase chain reaction for direct detection of Mycobacterium tuberculosis in respiratory specimens

A ligase chain reaction DNA amplification method for direct detection of Mycobacterium tuberculosis (Abbott LCx MTB) in respiratory specimens was evaluated. Results from LCx MTB Assay were compared with those from acid fast bacilli smear, culture, and final clinical diagnosis for each patient. A total of 297 respiratory specimens (sputum and bronchial lavage) from 193 patients were tested. The sensitivity, specificity, positive predictive value and negative predictive value of LC vs culture were 92.7%, 93%, 67.8% and 98.7%, respectively. When compared to the clinical final diagnosis, the sensitivity, specificity, PPV and NPV for LCx were 88.9%, 96.8%, 86.5% and 97.4%, respectively. The sensitivity of LCx MTB assay was 75% for smear-negative, culture positive samples. The results indicate that LCx MTB assay is a rapid, simple and valuable technique as a complementary tool for the diagnosis of tuberculosis.

Contribution of the Ogawa-Kudoh swab culture method to the diagnosis of pulmonary tuberculosis in Brazil.

OBJECTIVE To analyse the contribution of the Ogawa-Kudoh (O-K) swab culture method to the diagnosis of pulmonary tuberculosis (PTB) in four different regions of Brazil. DESIGN This study was carried out in two phases. Phase 1 was designed to compare the direct swab culture method (O-K) with the culture concentrated method (N-acetyl-L-cysteine-sodium hydroxide [NALC-NaOH]); for this purpose, 569 sputum samples were cultured by both methods. Phase 2 was carried out to assess the contribution of the O-K method to the diagnosis of PTB in four different regions in Brazil, based on the evaluation of 19,163 sputum samples. RESULTS In the first phase of the study, O-K culture had a sensitivity of 94.8% and specificity of 99.8% in cases confirmed by NALC-NaOH/Löwenstein-Jensen (LJ) culture. In the second phase of the study, the overall contribution of O-K culture compared to acid-fast bacilli (AFB) examination (AFB-/culture+) to the diagnosis of PTB was 29.8%. CONCLUSION O-K culture contributes significantly to the diagnosis of smear-negative PTB. Importantly, this method allows the recovery of clinical isolates in areas where use of the standard culture centrifuge is impossible, indicating that the O-K swab culture method should become a standard method for TB diagnosis in these regions.