Rapid Diagnosis of Pulmonary and Extrapulmonary Tuberculosis in HIV-Infected Patients. Comparison of LED Fluorescent Microscopy and the GeneXpert MTB/RIF Assay in a District Hospital in India (original) (raw)
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Tuberculosis …, 2012
HIV-related tuberculosis is difficult to diagnose and is associated with high morbidity and mortality. Recently, the World Health Organization has endorsed the GeneXpert MTB/RIF (Xpert) assay for the diagnosis of pulmonary tuberculosis in HIV-infected patients from developing countries, but information about the use of Xpert for the diagnosis of extrapulmonary tuberculosis is scarce. In this study, we compared the performance of light-emitting diode (LED) auramine fluorescent microscopy and the Xpert assay for the diagnosis of tuberculosis in HIV infected patients in a district hospital of India. Although at higher cost, Xpert outperformed LED fluorescent microscopy in all type of specimens, especially in cerebrospinal fluid where the number of positive results was increased 11 times. Pleural fluid, ascitic fluid, pus, and stool specimens also yielded positive results with the Xpert assay. When collecting two additional early-morning sputum samples, the increase of the number of positive results with the Xpert assay was lower than previously reported for HIV infected patients. Rifampicin resistance was observed in 2.2% of the cases. The results of this study show that the Xpert assay can dramatically improve the rapid diagnosis of tuberculous meningitis and other types of extrapulmonary tuberculosis of HIV infected patients.
A51. DIAGNOSIS OF LATENT AND ACTIVE TUBERCULOSIS, 2010
Introduction: Light-emitting diode fluorescence microscopy (LED-FM) has been endorsed by the World Health Organization (WHO) for tuberculosis diagnosis, but its accuracy in HIV-infected patients remains controversial, and only some few studies have explored procedural factors that may affect its performance. Objective: To evaluate the performance of LED-FM for tuberculosis diagnosis in patients with and without HIV infection using a newer, less expensive LED lamp. Materials and methods: We compared the performance of LED-FM and Ziehl-Neelsen (ZN) microscopy on respiratory specimen smears from tuberculosis (TB) suspects and patients on treatment examined by different technicians blinded for HIV-status and for the result of the comparative test. We analyzed the effect of concentrating specimens prior to microscopy using different examination schemes and user-appraisal of the LED device. Results: Of the 6,968 diagnostic specimens collected, 869 (12.5%) had positive Mycobacterium tuberculosis cultures. LED-FM was 11.4% more sensitive than ZN (p<0.01). Among HIV-positive TB patients, sensitivity differences between LED-FM and ZN (20.6%) doubled the figure obtained in HIVnegative patients or in those with unknown HIV status (9.3%). After stratifying by direct and concentrated slides, the superiority of LED-FM remained. High specificity values were obtained both with LED-FM (99.9%) and ZN (99.9%).The second reading of a sample of slides showed a significantly higher positive detection yield using 200x magnification (49.4 %) than 400x magnification (33.8%) (p<0.05). The LEDdevice had a very good acceptance among the technicians. Conclusion: LED-FM better performance compared with ZN in HIV-infected patients and user-appraisal support the rapid roll-out of LED-FM. Screening at 200x magnification was essential to achieve LED-FM increased sensitivity.
BMC Infectious Diseases
Background: The relatively simple and cheaper light-emitting diode fluorescent microscopy (LED-FM) was recommended by the World Health Organization (WHO) to replace the conventional tuberculosis (TB) microscopy in both high-and low-volume laboratories. More recently the WHO also endorsed one more technique, Xpert MTB/RIF® assay (Xpert), for improved TB diagnosis particularly among human immunodeficiency virus (HIV)-infected cases. However, the relative performance of both of these tools differs from setting to setting in reference to the conventional TB diagnostics. This study thus aimed to evaluate these tools for TB detection in individuals visiting Ambo Hospital, west-central Ethiopia. Methods: Cross-sectional early-morning sputum samples were collected from presumptive TB patients between January and August 2015. Socio-demographic data were captured using a structured questionnaire. Clinical information was gathered from patients' medical records. The sputum samples were diagnosed using LED-FM, Xpert, concentrated Ziehl-Neelsen (cZN) staining and Lowenstein-Jensen (LJ) culture as the gold standard. Drug sensitivity test (DST) was also conducted. Results: Out of 362 sputum samples collected and processed, 36(9.9%) were positive by LED-FM, 42(11.6%) by cZN and 50(13.8%) by Xpert. But, only 340 samples could be declared culture positive or negative for mycobacteria. Of these 340, eight were non-tubercle mycobacteria (NTM). Out of the remaining 332 samples, 45(13.6%) had culture-confirmed TB with 11(24.4%) being HIV co-infected. LED-FM, Xpert and culture detected 54.5% (6/11), 90.9% (10/11) and 100% (11/11) mycobacteria in HIV-positive individuals and 81.3% (26/32), 73.7% (28/38), 78. 8% (26/33) and 73.2% (30/41), in HIV negatives respectively. Two samples were rifampicin resistant by both Xpert and DST. The overall sensitivity, specificity, positive and negative predictive values of LED-FM and Xpert were 77.8, 100, 100 and 96; and 93.3, 98, 97.5 and 98.9% respectively. Conclusion: The data demonstrated the high diagnostic yield of Xpert. LED-FM sensitivity is higher compared to results quoted by recent systematic reviews although it appears to be lower than what was cited in the WHO policy statement (83.6%) during the recommendation of the technology. The high specificity of LED-FM in the study area is encouraging and is expected to boost its reliability and uptake.
Bangladesh Medical Research Council Bulletin, 2011
Background: Tuberculosis remains world`s leading cause of death from a single infectious agent. Fluorescence microscopy offers well-described benefits, comparing with brightfield microscopy, for the evaluation sputum smear samples for tuberculosis. We evaluated the diagnostic performance of fluorescence microscopy, using novel Light Emitting Diode (LED) technology as an alternative to the conventional fluorescence microscopy by Auramine stain as well as brightfield microscopy by Ziehl-Neelsen (ZN) stain. Objectives: The objective of the study was to see the usefulness of LED fluorescent microscopy in the diagnosis of pulmonary tuberculosis. Methods: This is a prospective study consisted of 150 sputum samples from the patients of NIDCH, Mohakhali. All samples were stained by auramine and ZN stain at BSMMU and culture was done in Lowenstein-Jensen (L-J) media as gold standard at NTRL, Mohakhali. Results: In this study total 66(44%) out of 150 sputum specimens were positive for Mycobacterium Tuberculosis by culture. Sensitivity and specificity documented for the different modalities were 95.38% and 94.11%, respectively, for the LED assessment; 68.18% and 90.47%, respectively, for the CFM assessment; and 56.06% and 97.61%, respectively, for brightfield microscopy by ZN stain. The difference in their case detection rate was statistically significant (χ 2 =119.38, p<0.001). Conclusion: Fluorescence Microscopy (FM) is more sensitive than ZN for diagnosis of pulmonary tuberculosis. However, since FM is more sensitive and rapid, using this method (LED) in clinical laboratories with large specimen numbers is recommended.
PLoS ONE, 2013
Background: Fluorescence microscopy (FM) has not been implemented widely in TB endemic settings and little evaluation has been done in HIV-infected patients. We evaluated diagnostic performance, time and costs of FM with light-emitting diodes technology (LED-FM), compared with conventional (Zieh-Neelsen) microscopy in a hospital in Indonesia which acts as referral centre for HIV-infected patients. Method: We included pulmonary tuberculosis suspects from the outpatient and HIV clinic. Direct and concentrated sputum smears were examined using LED-FM and ZN microscopy by two technicians who were blinded for the HIV-status and the result of the comparative test. Mean reading time per slide was recorded and cost of each slide was calculated. Mycobacteria culture served as the reference standard. Results: Among 404 tuberculosis suspects from the outpatient clinic and 256 from the HIV clinic, mycobacteria culture was positive in 12.6% and 27%, respectively. The optimal sensitivity of LED-FM was achieved by using a threshold of $2 AFB/ length. LED-FM had a higher sensitivity (75.5% vs. 54.9%, P,0.01) but lower specificity (90.0% vs 96.6%, P,0.01) compared to ZN microscopy. HIV was associated with a lower sensitivity but similar specificity. The average reading time using LED-FM was significantly shorter (2.2360.78 vs 5.8261.60 minutes, P,0.01), while costs per slide were similar. Conclusion: High sensitivity of LED-FM combined with shorter reading time of sputum smear slides make this method a potential alternative to ZN microscopy. Additional data on specificity are needed for effective implementation of this technique in high burden TB laboratories.
Performance of light-emitting diode fluorescence microscope for diagnosis of tuberculosis
International Journal of Mycobacteriology, 2013
Background: Fluorescence microscopy (FM) over the years has shown the potential for increasing the performance of microscopy. The present study was aimed to access the performance of the LED microscope for the detection of acid fast bacilli in a tuberculosis (TB) endemic country. Methods: The study was conducted at a National Reference Laboratory (NRL) in New Delhi, India. Sputum samples were collected from suspected TB patients. Each sample was processed with Auramine O and ZN methods. Auramine O stained smears were evaluated using two different excitatory light sources (MVP and LED); and ZN stained smears were examined under light microscope. The mean time required to read the smears with different modalities was recorded. Bacterial cultures provided the reference standard. Results: A total of 200 patients were included in this study. Sensitivity and specificity for the LED assessment, MVP assessment and light microscopy were 83.1% and 82.4%, 78.5% and 87.5% and 81.6% and 83.5%, respectively. Mean reading time was approximately three times faster than ZN microscopy. The mean time to read a negative smear was 2 min with fluorescence microscopy and 5 min with light microscopy with time savings of 60%. Conclusion: Although the use of LED-FM only marginally increased sensitivity, the considerable time saving ability combined with very good acceptance and ease of use makes it a reliable alternative to other conventional methods available.
American Journal of Internal Medicine, 2017
Bright field microscopy using Ziehl-Neelsen (ZN) stained smear has been the major diagnostic technique for the diagnosis of pulmonary tuberculosis and treatment initiation in resource limited settings. However, it has its own limitation in terms of its sensitivity. Various reports have shown superior sensitivity of light emitting-diode fluorescent microscopy (LED-FM) and comparable specificity to bright field microscopy. The aim of the study was to compare the results of Auramine O-stained sputum smears by LED-FM against Ziehl-Neelsen stained sputum smears and JD-TB-Antigen test using TB culture as a reference test. A cross-sectional study was conducted in Southern Nations and Nationality People Regions (SNNPR) of Ethiopia from September 2013 to November 2014. A total of 248 sputum samples were collected from different Health Centers and Hospitals of the study area, analyzed by LED-FM and ZN stained bright field microscopy. The sensitivity, specificity, positive and negative predict...
IP innovative publication pvt ltd, 2020
Introduction: Mycobacterium tuberculosis cultures although being the gold standard for diagnosing tuberculosis has its limitations as it is time consuming. Thus newer methods using light-emitting diode fluorescent microscopy (LED-FM) and molecular methods like the GeneXpert MTB/RIF assay are being adopted as a mainstay for diagnosing tuberculosis around the globe. Materials and Methods: This observational descriptive study was carried out for a period of 21 months. Sputum samples from 110 adult subjects with a clinical suspicion of pulmonary tuberculosis (PTB) were stained for LED-FM microscopy and also inoculated into the GeneXpert assay. The positive smears were graded as per the Revised National Tuberculosis Control Programme (RNTCP) guidelines and positive GeneXpert assay results along with Rifampicin resistance were noted and analysed. Results: Out of the 110 samples, (77.2%) were males and (22.7%) females. Of the 110 samples, 75 (68.1%) were positive for Mycobacterium tuberculosis by the GeneXpert assay. In contrast with LED-FM, all 25 smear positive samples were also GeneXpert positive. Additionally, GeneXpert detected 10 smear negative cases. 10 (9%) positive GeneXpert isolates showed resistance to Rifampicin. The overall sensitivity of GeneXpert was greater but its specificity was comparable with LED-FM. Conclusion: The Xpert and LED-FM tests were comparable in specificity, but the GeneXpert assay out did the LED-FM as it was a more sensitive and rapid test for the diagnosis of tuberculosis and additionally detection of Rifampicin resistance. Our study fully agrees that the GeneXpert assay is a step ahead in the early diagnosis of tuberculosis even for smear negative cases of PTB. This assay is also a relatively simple and routine test that staff can perform with minimal training.
PLoS ONE, 2013
Background: The diagnosis of tuberculosis (TB) in resource-limited settings relies on Ziehl-Neelsen (ZN) smear microscopy. LED fluorescence microscopy (LED-FM) has many potential advantages over ZN smear microscopy, but requires evaluation in the field. The aim of this study was to assess the sensitivity/specificity of LED-FM for the diagnosis of pulmonary TB and whether its performance varies with the timing of specimen collection.
BACKGROUND: Sputum microscopy is the only tuberculosis (TB) diagnostic available at peripheral levels of care in resource limited countries. Its sensitivity is low, particularly in high HIV prevalence settings. Fluorescence microscopy (FM) can improve performance of microscopy and with the new light emitting diode (LED) technologies could be appropriate for peripheral settings. The study aimed to compare the performance of LED-FM versus Ziehl-Neelsen (ZN) microscopy and to assess feasibility of LED-FM at a low level of care in a high HIV prevalence country. METHODS: A prospective study was conducted in an urban health clinic in Nairobi, Kenya. Three sputum specimens were collected over 2 days from suspected TB patients. Each sample was processed with Auramine O and ZN methods and a 4(th) specimen was collected for TB culture reference standard. Auramine smears were read using the same microscope, equipped with the FluoLED™ fluorescence illuminator. Inter-reader agreement, reading time and technicians' acceptability assessed feasibility. RESULTS: 497 patients were included and 1394 specimens were collected. The detection yields of LED-FM and ZN microscopy were 20.3% and 20.6% (p = 0.64), respectively. Sensitivity was 73.2% for LED-FM and 72% for ZN microscopy, p = 0.32. It was 96.7% and 95.9% for specificity, p = 0.53. Inter-reader agreement was high (kappa = 0.9). Mean reading time was three times faster than ZN microscopy with very good acceptance by technicians. CONCLUSIONS: Although it did not increase sensitivity, the faster reading time combined with very good acceptance and ease of use supports the introduction of LED-FM at the peripheral laboratory level of high TB and HIV burden countries.