Multicenter evaluation of TB-SPRINT 59-Plex Beamedex®: accuracy and cost analysis.

BACKGROUND: Molecular tests can allow the rapid detection of tuberculosis (TB) and multidrug-resistant TB (MDR-TB). TB-SPRINT 59-Plex Beamedex® is a microbead-based assay developed for the simultaneous spoligotyping and detection of MDR-TB. The accuracy and cost evaluation of new assays and technologies are of great importance for their routine use in clinics and in research laboratories. The aim of this study was to evaluate the performance of TB-SPRINT at three laboratory research centers in Brazil and calculate its mean cost (MC) and activity-based costing (ABC). METHODS: TB-SPRINT data were compared with the phenotypic and genotypic profiles obtained using Bactec™ MGIT™ 960 system and Genotype® MTBDRplus, respectively. RESULTS: Compared with MGIT, the accuracies of TB-SPRINT for the detection of rifampicin and isoniazid resistance ranged from 81 to 92% and 91.3 to 93.9%, respectively. Compared with MTBDRplus, the accuracies of TB-SPRINT for rifampicin and isoniazid were 99 and 94.2%, respectively. Moreover, the MC and ABC of TB-SPRINT were USD 127.78 and USD 109.94, respectively. CONCLUSION: TB-SPRINT showed good results for isoniazid and rifampicin resistance detection, but still needs improvement to achieve In Vitro Diagnostics standards.

Frequency of the Mycobacterium tuberculosis RDRio genotype and its association with multidrug-resistant tuberculosis.

BACKGROUND: In recent decades, Mycobacterium tuberculosis with the RDRio genotype, frequently isolated from tuberculosis patients in Rio de Janeiro, has become part of the Latin American - Mediterranean (LAM) family and has been associated with multidrug-resistant tuberculosis (MDR-TB). The aim of this study was to investigate the frequency of M. tuberculosis RDRio in the state of Minas Gerais, Brazil, and its relationship with MDR-TB. METHODS: For convenience, 172 susceptible and 63 MDR M. tuberculosis isolates were taken from pulmonary samples from patients diagnosed between January 2007 and December 2011. The DNA extracted from these isolates was analyzed by spoligotyping, PCR-RFLP to characterize fbpC103/Ag85C103, multiplex PCR to detect RDRio and RD174, and MIRU-VNTR 24 loci. RESULTS: Among the 235 isolates, the RDRio pattern was identified in 122 (51.9%) isolates (IC 0.45-0.58), with 100 (42.5%) wild-type and 13 (5.5%) mixed pattern isolates, whereas RD174 was identified in 93 of the 122 RDRio positive samples (76.3%). The LAM family and the LAM9 lineage were the most frequently identified among the isolates in this study. Among the 63 MDR isolates, 41 (65.1%) were RDRio and 28 (44.4%) RD174. CONCLUSION: The association of both deletions with MDR proved to be statistically significant, corroborating the few reports that have associated RDRio with MDR.

Evaluation of the Mean Cost and Activity Based Cost in the Diagnosis of Pulmonary Tuberculosis in the Laboratory Routine of a High-Complexity Hospital in Brazil.

At a global level, with the increase in healthcare costs, there is a need to assess the economic impact of the incorporation of new technologies in different health disorders in different countries. There is scarce information regarding costs incurred with the use of current or new diagnostic tests for tuberculosis or from the vantage point of their incorporation within the healthcare systems of high-burden countries. The present study aimed to assess the mean cost and the activity based cost of the laboratory diagnosis for tuberculosis by means of conventional techniques and from the Detect TB®LabTest molecular test kit in a general high-complexity hospital of the public health system in Brazil. Cost analysis was performed by means of primary data, collected in the Mycobacteria and Molecular Biology Laboratory in 2013. The mean cost and activity based cost were, respectively, U$10.06/U$5.61 for centrifuged bacilloscopy by Ziehl Neelsen (ZN) and Auramine (AU); U$7.42/U$4.15 for direct bacilloscopy by ZN; U$27.38/U$16.50 for culture in a Loweinstein-Jensen solid medium; and U$115.74/U$73.46 for the Detect TB®LabTest Kit. The calculation of the ABC should be used in making decisions by administrators to be the best method of assessing the costs of conventional techniques and molecular method for providing the real value of the tests. So it is need to calculate the ABC, and not of the mean cost, in various scenarios before incorporating new technologies in health institutions.

Evaluation of six different DNA extraction methods for detection of Mycobacterium tuberculosis by means of PCR-IS6110: preliminary study.

BACKGROUND: Developments in molecular detection and strain differentiation of members of Mycobacterium tuberculosis complex have proved to be useful. The DNA extraction method influences the amplification efficiency, causing interference on the sensitivity and respective inhibitors. The aim of this study was to standardize a simple and fast DNA extraction method, providing DNA amplification by IS6110-PCR effectively free from undue interferences. FINDINGS: The efficiency of the six different protocols tested in M. tuberculosis cultures has varied from 75% to 92.5%. This preliminary study evaluating the IS6110 PCR sensitivity and specificity was developed in DNA extracted from microscope slides, and achieved 100% of efficiency. CONCLUSIONS: DNA extraction by Chelex + NP-40 method from both, cultures of M. tuberculosis and smear slides, resulted in good quantity of interference free DNA, especially in samples with low concentrations of genetic material; therefore, such technique may be used for the molecular diagnosis of tuberculosis.

Utilization of bacteriological culture for increased diagnostic performance at a tuberculosis reference center hospital.

The purpose of this study was to assess the increase in positive results of bacteriological diagnostic tests for tuberculosis with the utilization of culture at a referral hospital for tuberculosis (TB). A retrospective analysis was conducted based on the positive bacteriological results obtained at the Júlia Kubistchek Hospital. The number of bacteriological diagnoses was increased by 24.6 % with the utilization of culture of sputum samples and by 56.1% of bronchoalveolar lavage samples. With regard to pleural fluid, all six positive cultures were negative for bacilloscopy. Mycobacterium tuberculosis was isolated in 59.6 % of positive cultures. Since mycobacterial culture was not undertaken for all clinical samples, this procedure is an important laboratory routine at the Júlia Kubistchek Hospital in order to learn the real TB prevalence.

Positive tuberculin test and risk of infection by Mycobacterium tuberculosis in a tuberculosis clinic settled in an upright building, in Minas Gerais, Brazil / Reactividad a tuberculina en trabajadores de la salud de un centro de referencia de tuberculosis

Background: Occupational Tuberculosis (TB) can lead to work absenteeism and a negative professional impact. Knowing the reactivity of the tuberculin test and the risk of M. tuberculosis infection among healthcare professionals is essential for the revision and reinforcement of control measures against TB transmission. Aim: To assess the reactivity of tuberculin test and risk of M. tuberculosis infection among healthcare professionals working in an upright building, in which a TB Reference Clinic is placed. Subjects and Methods: A tuberculosis Skin Test (TST) was done to 251 staff members of a TB clinic that did not have a previous history or suspicion of TB and that did not have a previous TST done. Among subjects with absence of reaction, repeated tests were carried out to assess booster reaction. Results: Fifty one percent of studied subjects (129) had a positive tuberculin test. The booster phenomenon was evidenced in 35.7% (68/190). The seroconversion among non-reactive subjects, subjected to a new TST after one year, was 5.1%. The infection risk was 1.4. Conclusions: This study indicates an important occupational risk of infection in healthcare settings exposed to high TB incidence, and should be used to better allocate resources for infection control.

Antecedentes: La tuberculosis ocupacional causa ausentismo laboral. Conocer la reactividad tuberculínica de los trabajadores de la salud ayuda a mejorar las medidas de control para evitar la infección laboral con M. tuberculosis. Objetivo: Estudiar la reactividad tuberculínica de un grupo de trabajadores de la salud de un centro de referencia de tuberculosis que está ubicado en una edificación vertical. Material y Métodos: Se realizó una prueba de tuberculina a 251 empleados de una clínica de tuberculosis, que no tenían antecedentes o sospecha de tuberculosis y quienes no habían sido sometidos previamente a la prueba. Aquellos sujetos que no respondieron a tuberculina fueron sometidos a una nueva prueba para evaluar la reacción de refuerzo. Resultados: El 51% de los sujetos estudiados tuvieron una reacción tuber-culínica positiva. El fenómeno de refuerzo se observó en 69 de 190 sujetos (35,7%). La tasa de seroconversión en aquellos sujetos con una tuberculina negativa en que se repitió la prueba la cabo de un año, fue de 5,1%. Conclusiones: En este grupo de trabajadores de la salud expuestos a M. tuberculosis, hay una alta tasa de reactividad negativa a tuberculina.

Positive tuberculin test and risk of infection by Mycobacterium tuberculosis in a tuberculosis clinic settled in an upright building, in Minas Gerais, Brazil.

BACKGROUND: Occupational Tuberculosis (TB) can lead to work absenteeism and a negative professional impact. Knowing the reactivity of the tuberculin test and the risk of M. tuberculosis infection among healthcare professionals is essential for the revision and reinforcement of control measures against TB transmission. AIM: To assess the reactivity of tuberculin test and risk of M. tuberculosis infection among healthcare professionals working in an upright building, in which a TB Reference Clinic is placed. SUBJECTS AND METHODS: A tuberculosis Skin Test (TST) was done to 251 staff members of a TB clinic that did not have a previous history or suspicion of TB and that did not have a previous TST done. Among subjects with absence of reaction, repeated tests were carried out to assess booster reaction. RESULTS: Fifty one percent of studied subjects (129) had a positive tuberculin test. The booster phenomenon was evidenced in 35.7% (68/190). The seroconversion among non-reactive subjects, subjected to a new TST after one year, was 5.1%. The infection risk was 1.4. CONCLUSIONS: This study indicates an important occupational risk of infection in healthcare settings exposed to high TB incidence, and should be used to better allocate resources for infection control.

RDRio Mycobacterium tuberculosis infection is associated with a higher frequency of cavitary pulmonary disease.

Molecular genotyping has shown Mycobacterium tuberculosis lineages to be geographically restricted and associated with distinct ethnic populations. Whether tuberculosis (TB) caused by some M. tuberculosis lineages can present with a differential clinical spectrum is controversial because of very limited clinical data. We recently reported on the discovery of RD(Rio) M. tuberculosis, a Latin American-Mediterranean sublineage that is the predominant cause of TB in Rio de Janeiro, Brazil. To investigate the clinical attributes of TB caused by RD(Rio) strains, we studied a cohort of TB cases from Belo Horizonte, Brazil, in which clinical information recorded on a standardized questionnaire was collected at the time of microbiological testing. These patients were referred for culture and drug susceptibility testing because of the clinical suspicion of "complicated" TB, as demonstrated by high rates of multidrug resistance (12%) and cavitary TB (80%). We performed spoligotyping and RD(Rio) genotyping on the M. tuberculosis strains and analyzed the clinical data from these patients. RD(Rio) M. tuberculosis accounted for 37% of the total TB burden. Multivariate analysis found a significant association between TB caused by RD(Rio) strains and pulmonary cavitation and residence in Belo Horizonte. Since cavitary TB is associated with higher sputum bacillary load, our findings support the hypothesis that RD(Rio) M. tuberculosis is associated with a more "severe" disease as a strategy to increase transmission. Future studies are needed to confirm these observations and to better define the contribution of RD(Rio) M. tuberculosis to the global TB epidemic.