Cost analysis of smear microscopy and the Xpert assay for tuberculosis diagnosis: average turnaround time

Abstract INTRODUCTION: Rapid and accurate tuberculosis detection is critical for improving patient diagnosis and decreasing tuberculosis transmission. Molecular assays can significantly increase laboratory costs; therefore, the average time and economic impact should be evaluated before implementing a new technology. The aim of this study was to evaluate the cost and average turnaround time of smear microscopy and Xpert assay at a university hospital. METHODS: The turnaround time and cost of the laboratory diagnosis of tuberculosis were calculated based on the mean cost and activity based costing (ABC). RESULTS: The average turnaround time for smear microscopy was 16.6 hours while that for Xpert was 24.1 hours. The Xpert had a mean cost of USD 17.37 with an ABC of USD 10.86, while smear microscopy had a mean cost of USD 13.31 with an ABC of USD 6.01. The sensitivity of smear microscopy was 42.9% and its specificity was 99.1%, while the Xpert assay had a sensitivity of 100% and a specificity of 96.7%. CONCLUSIONS: The Xpert assay has high accuracy; however, the turnaround time and cost of smear microscopy were lower than those of Xpert.

Genotype®MTBDRplus and Xpert®MTB/RIF in the diagnosis of tuberculosis and resistant tuberculosis: cost analysis in a tertiary referral hospital

Abstract INTRODUCTION: The present study sought to assess the mean and activity based cost (ABC) of the laboratory diagnosis for tuberculosis through the application of conventional and molecular techniques-Xpert®MTB/RIF and Genotype®MTBDRplus-in a tertiary referral hospital in Brazil. METHODS: The mean cost and ABC formed the basis for the cost analysis of the TB laboratory diagnosis. RESULTS: The mean cost and ABC were US$ 4.00 and US$ 3.24, respectively, for a bacilloscopy; US$ 6.73 and US$ 5.27 for a Lowenstein-Jensen (LJ) culture; US$ 105.42 and US$ 76.56 for a drug sensitivity test (DST)-proportions method (PM) in LJ; US$ 148.45 and US$ 136.80 for a DST-BACTECTM MGITTM 960 system; US$ 11.53 and US$ 9.89 for an Xpert®MTB/RIF; and US$ 84.21 and US$ 48.38 for a Genotype®MTBDRplus. CONCLUSIONS: The mean cost and ABC proved to be good decision-making parameters in the diagnosis of TB and MDR-TB. The effective implementation of algorithms will depend on the conditions at each location.

Standardization of in-house polymerase chain reaction for the identification of Mycobacterium tuberculosis at the reference tropical disease hospital in the State of Goiás, Brazil

This study compares smear, growth in Lowenstein-Jensen medium, and in-house polymerase chain reaction (PCR) techniques for the detection of Mycobacterium tuberculosis. A total of 72 specimens from 72 patients with clinical symptoms of tuberculosis, including 70 sputum and two bronchial aspirate samples, were tested in parallel by smear, culture, and in-house PCR techniques. From these, 48 (66.6 percent) were negative by the 3 methods, 2 (2.8 percent) were smear positive and negative by culture and in-house PCR, 11 (15.3 percent) were both smear and culture negative, and in-house PCR positive, 7 (9.7 percent) were positive by the 3 methods, 2 (2.8 percent) were positive by smear and culture, and negative by PCR, 2 (2.8 percent) were positive by culture and PCR, but smear negative. After the resolution of discrepancies in PCR results, the sensitivity and specificity for in-house PCR technique to M. tuberculosis relative to the culture, were 81.8 percent and 81.9 percent, respectively. These results confirm that this method, in-house PCR, may be a sensitive and specific technique for M. tuberculosis detection, occurring in both positive and negative smear and negative cultures.

Identificaçäo e teste de susceptibilidade a drogas de cepas de Mycobacterium tuberculosis isoladas de pacientes provenientes de Hospital Público de Referência, Goiânia/GO / Identification and drug susceptibility test of Mycobacterium tuberculosis strains isolated from patients at the Public Reference Hospital, Goiânia, Goiás

Com o intuito de identificar e verificar a sensibilidade de cepas de Mycobacterium tuberculosis isoladas de 206 amostras clínicas obtidas de formas pulmonares e extrapulmonares, provenientes de 144 pacientes externos e internos do Hospital de Doenças Tropicais do Estado de Goiás, foi realizado baciloscopia pela técnica de coloraçäo de Ziehl-Neelsen e a cultura em Lowenstein-Jensen e sistema bifásico. A identificaçäo foi realizada através de provas de crescimento na presença de inibidores, produçäo de pigmentos, tempo de crescimento e provas bioquímicas, conjuntamente com a determinaçäo da susceptibilidade às drogas antimicobacterianas. Foram isoladas micobactérias em 13 (6,3 porcento) amostras, sendo 12 (92,3 porcento) identificadas como M. tuberculosis e uma (7,7 porcento) do complexo M. avium (MAC). Das amostras isoladas, 12 apresentaram sensibilidade a isoniazida, etambutol, rifampicina, estreptomicina, pirazinamida, etionamida e somente uma amostra, apresentou resistência à isoniazida, rifampicina, pirazinamida e etionamida