Cost-effectiveness of QuantiFERON-TB Gold In-Tube versus tuberculin skin test for diagnosis and treatment of Latent Tuberculosis Infection in primary health care workers in Brazil.

OBJECTIVES: The goal of this study was to perform a cost-effectiveness analysis from the public health system perspective, comparing five strategies for Latent Tuberculosis Infection (LTBI) diagnosis in primary health care workers in Brazil. DESIGN: Analytical model for decision making, characterized by cost-effectiveness analysis. SETTING: Primary Care Level, considering primary health care workers in Brazil. PARTICIPANTS: An analytical model for decision making, characterized by a tree of probabilities of events, was developed considering a hypothetical cohort of 10,000 primary health care workers, using the software TreeAge Pro™ 2013 to simulate the clinical and economic impacts of new diagnostic technology (QuantiFERON®-TB Gold in-Tube) versus the traditional tuberculin skin test. METHODS: This model simulated five diagnostic strategies for LTBI in primary health care workers (HCW) in Brazil: tuberculin skin testing using ≥5 mm cut-off, tuberculin skin testing ≥10 mm cut-off, QuantiFERON®-TB Gold in-Tube, tuberculin skin testing using ≥5 mm cut-off confirmed by QuantiFERON®-TB Gold In-Tube if TST positive, tuberculin skin testing using ≥10 mm cut-off confirmed by QuantiFERON®-TB Gold In-Tube if TST positive. PRIMARY AND SECONDARY OUTCOME MEASURES: The outcome measures are the number of individuals correctly classified by the test and the number of Tuberculosis cases avoided. RESULTS: The most cost-effective strategy was the tuberculin skin test considering ≥10mm cut-off. The isolated use of the QuantiFERON®-TB Gold In-Tube revealed the strategy of lower efficiency with incremental cost-effectiveness ratio (ICER) of US$ 146.05 for each HCW correctly classified by the test. CONCLUSIONS: The tuberculin skin test using ≥10 mm cut-off was the most cost-effective strategy in the diagnosis of Latent Tuberculosis Infection in primary health care works in Brazil.

Risk factors associated with cluster size of Mycobacterium tuberculosis (Mtb) of different RFLP lineages in Brazil.

BACKGROUND: Tuberculosis (TB) transmission is influenced by patient-related risk, environment and bacteriological factors. We determined the risk factors associated with cluster size of IS6110 RFLP based genotypes of Mycobacterium tuberculosis (Mtb) isolates from Vitoria, Espirito Santo, Brazil. METHODS: Cross-sectional study of new TB cases identified in the metropolitan area of Vitoria, Brazil between 2000 and 2010. Mtb isolates were genotyped by the IS6110 RFLP, spoligotyping and RDRio. The isolates were classified according to genotype cluster sizes by three genotyping methods and associated patient epidemiologic characteristics. Regression Model was performed to identify factors associated with cluster size. RESULTS: Among 959 Mtb isolates, 461 (48%) cases had an isolate that belonged to an RFLP cluster, and six clusters with ten or more isolates were identified. Of the isolates spoligotyped, 448 (52%) were classified as LAM and 412 (48%) as non-LAM. Our regression model found that 6-9 isolates/RFLP cluster were more likely belong to the LAM family, having the RDRio genotype and to be smear-positive (adjusted OR = 1.17, 95% CI 1.08-1.26; adjusted OR = 1.25, 95% CI 1.14-1.37; crude OR = 2.68, 95% IC 1.13-6.34; respectively) and living in a Serra city neighborhood decrease the risk of being in the 6-9 isolates/RFLP cluster (adjusted OR = 0.29, 95% CI, 0.10-0.84), than in the others groups. Individuals aged 21 to 30, 31 to 40 and > 50 years were less likely of belonging the 2-5 isolates/RFLP cluster than unique patterns compared to individuals < 20 years of age (adjusted OR = 0.49, 95% CI 0.28-0.85, OR = 0.43 95% CI 0.24-0.77and OR = 0. 49, 95% CI 0.26-0.91), respectively. The extrapulmonary disease was less likely to occur in those infected with strains in the 2-5 isolates/cluster group (adjustment OR = 0.45, 95% CI 0.24-0.85) than unique patterns. CONCLUSIONS: We found that a large proportion of new TB infections in Vitoria is caused by prevalent Mtb genotypes belonging to the LAM family and RDRio genotypes. Such information demonstrates that some genotypes are more likely to cause recent transmission. Targeting interventions such as screening in specific areas and social risk groups, should be a priority for reducing transmission.

Strains of Mycobacterium tuberculosis transmitting infection in Brazilian households and those associated with community transmission of tuberculosis.

Molecular epidemiologic studies have shown that the dynamics of tuberculosis transmission varies geographically. We sought to determine which strains of Mycobacterium tuberculosis (MTB) were infecting household contacts (HHC), and which were causing clusters of tuberculosis (TB) disease in Vitoria-ES, Brazil. A total of 741 households contacts (445 TST +) and 139 index cases were characterized according to the proportion of contacts in each household that had a tuberculin skin test positive: low (LT) (≤40% TST+), high (HT) (≥70% TST+) and (40-70% TST+) intermediate (IT) transmission. IS6110-RFLP and spoligotyping analysis were performed only 139 MTB isolates from index cases and 841 community isolates. Clustering occurred in 45% of the entire study population. There was no statistically significant association between MTB household transmission category and clustering. Within the household study population, the proportion of clusters in HT and LT groups was similar (31% and 36%, respectively; p = 0.82). Among index cases isolates associated with households demonstrating TST conversion, the frequency of unique pattern genotypes was higher for index cases of the LT compared to HT households (p = 0.03). We concluded that clusters and lineages associated with MTB infection in HT households had no proclivity for increased transmission of TB in the community.

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.

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.

[Access to the diagnosis of tuberculosis in health services in the municipality of Vitoria, state of Espírito Santo, Brazil]. / Acesso ao diagnóstico da tuberculose em serviços de saúde do município de Vitória, ES, Brasil.

This study sought to assess the accessibility to the diagnosis of tuberculosis in health services in Victoria, state of Espírito Santo. It featured a cross-sectional study conducted in 2009 of patients with tuberculosis using the Primary Care Assessment Tool and statistical analysis with the Chi-square test (p <0,05). In relation to initial access to care, it was seen that the health service of first access most sought was Primary Care (37.6%), with most diagnoses occurring in the Tuberculosis Control Program Reference Units (61.3%). There was evidence of association between first health service accessed and the factors of time delay in: obtaining consultation at the first health service sought (p = 0.0182); diagnosis made by the first health service sought (p = 0.0001); request for sputum exam (p = 0,0003); request for X-ray exams (p = 0.0159); referral for X-rays at another institution (p = 0.0001); diagnosis by the same health service (p = 0.0001); exams conducted by the same health service that initially diagnosed tuberculosis (p = 0.0018); and proximity to the home (p = 0.0001). Therefore, the identification of important gaps in accessibility to diagnosis of tuberculosis seems to be related to the operational difficulties of organization of health care.

Acesso ao diagnóstico da tuberculose em serviços de saúde do município de Vitória, ES, Brasil / Access to the diagnosis of tuberculosis in health services in the municipality of Vitoria, state of Espírito Santo, Brazil

Objetivou-se avaliar a acessibilidade ao diagnóstico da tuberculose nos serviços de saúde em Vitória (ES). Estudo transversal realizado em 2009 com doentes de tuberculose, utilizando o instrumento Primary Care Assessment Tool. Análise estatística com Teste Qui-quadrado (p < 0,05). Em relação à porta de entrada, notou-se que o serviço de saúde mais procurado foi Atenção Básica (37,6%); a maioria dos diagnósticos ocorreu nas Unidades de Referência do Programa de Controle da Tuberculose (61,3%). Houve evidência de associação entre primeiro serviço de saúde procurado e fatores tempo de demora na obtenção de consulta neste (p = 0,0182), hipótese diagnóstica feita pelo primeiro serviço de saúde procurado (p = 0,0001), solicitação exame de escarro (p = 0,0003), solicitação exame de Raios-X (p = 0,0159), encaminhamento para Raios-X em outro serviço (p = 0,0001), diagnóstico pelo mesmo serviço de saúde (p = 0,0001), exames realizados no próprio serviço de saúde que diagnosticou tuberculose (p = 0,0018), proximidade do domicílio (p = 0,0001). Portanto, a identificação de lacunas importantes na acessibilidade ao diagnóstico de tuberculose parece estar relacionada às dificuldades operacionais de organização da atenção à saúde.

This study sought to assess the accessibility to the diagnosis of tuberculosis in health services in Victoria, state of Espírito Santo. It featured a cross-sectional study conducted in 2009 of patients with tuberculosis using the Primary Care Assessment Tool and statistical analysis with the Chi-square test (p <0,05). In relation to initial access to care, it was seen that the health service of first access most sought was Primary Care (37.6%), with most diagnoses occurring in the Tuberculosis Control Program Reference Units (61.3%). There was evidence of association between first health service accessed and the factors of time delay in: obtaining consultation at the first health service sought (p = 0.0182); diagnosis made by the first health service sought (p = 0.0001); request for sputum exam (p = 0,0003); request for X-ray exams (p = 0.0159); referral for X-rays at another institution (p = 0.0001); diagnosis by the same health service (p = 0.0001); exams conducted by the same health service that initially diagnosed tuberculosis (p = 0.0018); and proximity to the home (p = 0.0001). Therefore, the identification of important gaps in accessibility to diagnosis of tuberculosis seems to be related to the operational difficulties of organization of health care.

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.

Mycobacterium tuberculosis DNA fingerprint clusters and its relationship with RD(Rio) genotype in Brazil.

Mycobacterium tuberculosis (Mtb) strains designated as RD(Rio) are responsible for a large cluster of new cases of tuberculosis (TB) in Rio de Janeiro. They were previously shown to be associated with severe manifestations of TB. Here, we used three genotyping methods (IS6110 RFLP, spoligotyping, and multiplex PCR) to characterize RD(Rio) and non-RD(Rio) strains from the metropolitan area of Vitória, State of Espirito Santo in southeast Brazil to determine strain diversity and transmission patterns. Strains with identical IS6110 RFLP patterns were considered to belong to a cluster indicative of recent transmission. Between 2000 and 2010, we identified 5470 new TB patients and genotyped 981 Mtb strains. Of these, 376 (38%) were RD(Rio). By RFLP, 180 (48%) of 376 RD(Rio) strains and 235 (40%) of 593 non-RD(Rio) strains belonged to RFLP cluster pattern groups (p = 0.023). Simpson's diversity index based on RFLP patterns was 0.96 for RD(Rio) and 0.98 for non-RD(Rio) strains. Thus, although RD(Rio) strains appear to be comprised of a fewer number of RFLP genotypes, they represent a heterogeneous group. While TB cases caused by RD(Rio) appear more likely to be due to recent transmission than cases caused by non-RD(Rio) strains, the difference is small. These observations suggest that factors other than inherent biological characteristic of RD(Rio) lineages are more important in determining recent transmission, and that public health measures to interrupt new transmissions need to be emphasized for TB control in Vitória.

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.

Guided sputum sample collection and culture contamination rates in the diagnosis of pulmonary TB / Associação entre coleta de escarro guiada e taxas de contaminação de culturas para o diagnóstico de TB pulmonar

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.

Realizou-se um estudo comparativo para avaliar a contaminação em culturas de amostras matinais de escarro coletadas em domicílio sob condições recomendadas atualmente e amostras coletadas sob supervisão após orientação e educação dos pacientes. Os grupos de coleta domiciliar e supervisionada produziram 43 e 76 amostras, respectivamente. A taxa de contaminação foi aproximadamente 3 vezes maior nas amostras coletadas em domicílio do que naquelas coletadas sob supervisão (37% vs.13%; p < 0,05; OR = 0,25). As simples medidas educacionais e de higiene descritas podem reduzir a taxa de contaminação de amostras de escarro coletadas para culturas diagnósticas.

Use of in-house PCR for identification of Mycobacterium tuberculosis in BACTEC broth cultures of respiratory specimens.

We evaluated the ability of a PCR assay to identify Mycobacterium tuberculosis complex (MTBC) from positive BACTEC 12B broth cultures. A total of 107 sputum samples were processed and inoculated into Ogawa slants and BACTEC 12B vials. At a growth index (GI) > or=30, 1.0 ml of the 12B broth was removed, stored, and assayed with PCR. Molecular results were compared to those obtained by phenotypic identification methods, including the BACTEC NAP method. The average times required to perform PCR and NAP were compared. Of the 107 broth cultures evaluated, 90 were NAP positive, while 91 were PCR positive for MTBC. Of particular interest were three contaminated BACTEC 12B broth cultures yielding microorganisms other than acid-fast bacilli growth with a MTBC that were successfully identified by PCR, resulting in a mean time of 14 days to identify MTBC before NAP identification. These results suggest that PCR could be used as an alternative to the NAP test for the rapid identification of MTBC in BACTEC 12B cultures, particularly in those that contained both MTBC and nontuberculous mycobacteria.

Use of in-house PCR for identification of Mycobacterium tuberculosis in BACTEC broth cultures of respiratory specimens

We evaluated the ability of a PCR assay to identify Mycobacterium tuberculosis complex (MTBC) from positive BACTEC® 12B broth cultures. A total of 107 sputum samples were processed and inoculated into Ogawa slants and BACTEC® 12B vials. At a growth index (GI) > 30, 1.0 ml of the 12B broth was removed, stored, and assayed with PCR. Molecular results were compared to those obtained by phenotypic identification methods, including the BACTEC® NAP method. The average times required to perform PCR and NAP were compared. Of the 107 broth cultures evaluated, 90 were NAP positive, while 91 were PCR positive for MTBC. Of particular interest were three contaminated BACTEC® 12B broth cultures yielding microorganisms other than acid-fast bacilli growth with a MTBC that were successfully identified by PCR, resulting in a mean time of 14 days to identify MTBC before NAP identification. These results suggest that PCR could be used as an alternative to the NAP test for the rapid identification of MTBC in BACTEC® 12B cultures, particularly in those that contained both MTBC and nontuberculous mycobacteria.

Cavitary disease and quantitative sputum bacillary load in cases of pulmonary tuberculosis.

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.

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

O método de amplificação de DNA baseado na reação em cadeia da ligase (Abbott LCx MTB) foi avaliado para detecção do Mycobacterium tuberculosis em espécimes pulmonares. Os resultados do LCx MTB foram comparados aos resultados de baciloscopia, cultura e diagnóstico clínico para cada paciente. Um total de 297 espécimes (escarro e lavado broncoalveolar) de 189 pacientes foram testadas. Os valores de sensibilidade, especificidade, valor preditivo positivo e valor preditivo negativo do LCX vs cultura foram 92,7%, 93%, 67,8% e 98,7%, respectivamente. Quando comparados ao diagnóstico clínico, os valores de sensibilidade, especificidade, VPP e VPN para o LCx foram 88,9%, 96,8%, 86,5% e 97,4%, respectivamente. A sensibilidade do LCx MTB foi de 75% para as amostras com baciloscopia negativa e cultura positiva. Os resultados indicam que o teste LCx MTB é simples, rápido, eficiente e pode ser utilizado como um recurso complementar para o diagnóstico da tuberculose.

Prevalence and risk behaviors for chlamydial infection in a population-based study of female adolescents in Brazil.

BACKGROUND: Adolescents are vulnerable to sexually transmitted infections (STIs) and unplanned pregnancy. Prevention measures and assistance are of significant public health importance in this population. OBJECTIVE: The objective of this study was to identify demographic, behavioral, and clinical factors for STIs and to determine the prevalence of Chlamydia trachomatis infection (CT) among female adolescents in Vitória, Brazil. METHODS: We performed a cross-sectional study among female adolescents (15-19 years) served by the Health Family Program. Participants were screened for CT and Neisseria gonorrhoeae (GC) using ligase chain reaction applied to urine and answered a face-to-face questionnaire to assess demographic, behavioral, and clinical factors. All participants and their parents signed the informed consent. RESULTS: Four hundred sixty-four young women were sampled. The prevalence of CT was 8.9% (95% confidence interval [CI], 6.5-11.9%) overall. Among sexually active women, CT and gonorrhea prevalence were 12.2 (95% CI, 9.4-17.0%) and 1.9% (95% CI, 1.1-2.7%), respectively. Previously diagnosed STI was reported by 12.8%. Women who reported regular condom use and having condoms at home were significantly less likely to have CT, and having never purchased condoms was significantly associated with a positive CT result. CONCLUSION: A high prevalence of CT was found in this population, and behavioral risk was high despite readily available STI prevention information. Women who reported positive condom use behaviors were less likely to have CT. These results demonstrate the need for ongoing STI prevention activities, including STI screening and continued successful risk reduction activities such as condom use to further decrease CT and other STI among adolescents.

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.