Evaluation of modified petroff’s method and manual MGIT culture system to facilitate detection of acid-fast bacilli in smear-negative presumptive cases of pulmonary tuberculosis (original) (raw)
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2009
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Sensitivity and specificity of direct and concentrated AFB smear microscopy has been investigated by PCR analysis and culture methods to determine a rapid and cheap detection of pulmonary tuberculosis. In this study 305 patients were selected and 915 specimens were collected from suspected and hospital admitted patients. Patients were taken from Dhaka Central Jail Hospital and National TB Hospital, Dhaka, Bangladesh. All samples were smeared and Ziehl-Neelsen method and Lowenstein-Jensen (L-J) method were applied. PCR analysis and culture method was used to confirm the detection. Isolated DNA was used in PCR analysis. In this detection study PCR based IS6110 analysis was developed to identify the pulmonary tuberculosis rapidly and cheaply. A total of 915 samples were prepared for analysis and found 70.47% and 82.85% sensitivity in direct and concentrated smears respectively. Both type of smears (direct and concentrated) showed 100% sensitivity and specificity in culture and PCR IS61...
Comparison of Acid Fast Bacilli Smear and Culture for the Diagnosis of Extra-Pulmonary Tuberculosis
Journal of Nepal Medical Association
The study was conducted with the objectives to compare the Acid Fast Bacilli (AFB) staining and Culture for the diagnosis of extra-pulmonary tuberculosis and to find out the burden of extra-pulmonary tuberculosis from the different site of the body in suspected TB patients. The standard Ziehl-Neelsen Technique was done for AFB staining and culture was done in Ogawa Medium. Of the 292 extra-pulmonary samples examined by AFB smear only 2(0.7%) were positive and of the 1058 extra-pulmonary samples cultured 20 (1.9%) were positive. The isolation rate for extra-pulmonary samples was three fold higher in culture in comparison to AFB Smear. The confirmation rate of extra-pulmonary tuberculosis was approximately 1/ 8th of the pulmonary tuberculosis by conventional bacteriological diagnostic methods. Of the extra-pulmonary tuberculosis renal, endometrial or pelvic and cold abscess were common in this study. M.tuberculosis was also isolated from peritoneal fluid, pericardial fluid, Synovial f...
Biomedicine, 2022
Introduction and Aim: Tuberculosis (TB) remains a major public health concern with its high incidence and mortality. In developing countries, smear microscopy continues to be the primary diagnostic tool for the diagnosis of TB. Sputum samples processing under resource-limited settings could be hazardous, which urges safe and efficient smear microscopy techniques. This study aimed to evaluate the efficacy of two different pot methods: Phenol ammonium sulfate (PhAS) auramine O and PhAS basic fuchsin in comparison to the conventional Auramine O method. Materials and Methods: A prospective cross-sectional study was conducted at the Department of Microbiology with 74 sputum samples. All sputum samples were processed using the Auramine O method PhAS auramine O and PhAS basic fuchsin staining methods. Microsoft Office Excel (Microsoft, Redmond, WA, USA) was used to maintain and analyze all the data. Results: A total of 8 (10.7%) samples were positive for AFB and 67 (89.3%) samples were negative, according to routine auramine O method and pot methods. Pot methods showed a 100% sensitivity and specificity compared to the conventional Auramine O method. In terms of sputum smear grading, the direct smear using auramine O showed better results compared to pot methods. Conclusion: Pot methods like PhAS basic fuchsin and PhAS auramine O are efficient to detect AFB in sputum smears by reducing the risk of laboratory-acquired infections.
IP Innovative Publication Pvt. Ltd., 2018
Introduction: Tuberculosis (TB) is still a leading cause of death in many parts of the world. Adept techniques of rapid detection, isolation, identification and susceptibility testing of Mycobacterium tuberculosis (M.tb) are essential for management. Our aim was to compare the sensitivity and rapidity of smear microscopy, concentration method, rapid slide culture, Lowenstein - Jensen (LJ) culture and MGIT semiautomated culture methods in detection of Mycobacterium tuberculosis among smear negative pulmonary TB and extra pulmonary TB cases and to detect the drug resistance pattern to first line drugs among M.tb isolates. Materials and Methods: A prospective study was conducted for one year between January 2016 to January 2017 in the Department of Microbiology at a tertiary care hospital. Sputum smear negative pulmonary and extra pulmonary specimens were subjected to direct microscopy by Zeihl-Neelsen and fluorescent staining. Culture was done by Rapid slide culture, Lowenstein-Jensen media (LJ media) and BACTEC MGIT system. Positive isolates were confirmed by appropriate biochemical reactions and rapid immunochromatographic test. Drug susceptibility testing was done for first line drugs. Results: The sensitivity of direct microscopy was 3% and after concentration it was 4%. Overall culture positivity was 12%. Detection rate by LJ method, rapid slide culture method and MGIT methods was 6%, 4% and 12% respectively. The mean detection time was 22.5 days by MGIT and 31.5 days by conventional LJ method. Conclusion: This study highlights the importance of culturing suspected smear negative pulmonary and extra pulmonary Tuberculosis cases prior to empirical therapy. Newer automated culture methods aid in earlier detection of cases. Keywords: Extrapulmonary tuberculosis, MGIT, Mycobacterium tuberculosis, Smear negative tuberculosis.
The Malaysian journal of pathology, 2009
A prospective study was conducted on 510 respiratory specimens for the presence of M. tuberculosis detected by direct acid-fast bacilli (AFB) smear examination, culture in the Manual Mycobacteria Growth Indicator Tube (BBL MGIT, Becton-Dickinson) and culture on Lowenstein-Jensen (LJ) medium. From positive BBL MGIT tubes, Ziehl-Neelsen and Gram stains were performed and subcultures were put up on LJ medium. A total of 101 (19.8%) specimens were positive by the BBL MGIT, 60 (11.8%) by primary LJ medium culture, 31 (6.1%) by direct smear examination and 29 (5.7%) by all three methods. Using primary LJ culture as the gold standard, the sensitivity and specificity of the BBL MGIT were 90% and 89.6% respectively but the sensitivity of AFB smear microscopy was only 48.3%. About half (51.1%) of the BBL MGIT false positives were due to contamination by non-AFB bacteria. The remaining false positives comprised specimens that were AFB microscopy positive but LJ culture negative. Of the AFB iso...
Indian Journal of Medical Microbiology, 2005
Purpose: To evaluate the performance of 65 kDa antigen based PCR assay in clinical samples obtained from pulmonary and extrapulmonary cases of tuberculosis. Methods: One hundred and fifty six samples were processed for detection of Mycobacterium tuberculosis by ZN smear examination, LJ medium culture, BACTEC radiometric culture and PCR tests. Results: A significant difference was seen in the sensitivities of different tests, the figures being 74.4% for PCR test, 33.79% for ZN smear examination, 48.9% for LJ culture and 55.8% for BACTEC culture (P<0.05). However, there was no significant difference (P>0.05) as far as specificity of different tests was concerned. PCR test sensitivity in pulmonary and extrapulmonary clinical samples were 72.7% and 75.9% respectively and found to be significantly higher (P<0.05) when compared with those of other tests. The mean detection time for M.tuberculosis was 24.03 days by LJ medium culture, 12.89 days by BACTEC culture and less than one day by PCR test. Conclusions: PCR is a rapid and sensitive method for the early diagnosis of pulmonary and extrapulmonary tuberculosis.
Microbiological diagnosis of tuberculosis: a comparison of old and new methods
Journal of chemotherapy (Florence, Italy), 1998
The aim of our study was to evaluate the diagnostic value of various methods widely used in microbiological diagnosis of tuberculosis: direct smear examination for acid-fast bacilli, cultural identification in Lowestein-Jensen (L-J) medium, the radiometric BACTEC 460 system, and Polymerase Chain Reaction (PCR). Three hundred and ninety-three clinical samples of sputum (375), gastric aspirate (3), pleural fluid (12) and urine (3) were taken from 125 patients hospitalized at our Institute for suspected pulmonary tuberculosis, between January 1995 and June 1997. On completion of diagnosis, 35 were found to be affected by active tuberculosis (30 pulmonary, 4 pleural and 1 urinary) and 90 by other non-tubercular diseases (pneumonia, lung cancer, non-tubercular pleural effusion, etc.). In our study, direct smear examination for acid-smear bacilli gave diagnostic value results of 88% and positive predictive value of 91.67%. Cultural identification in L-J and BACTEC 460 TB radiometric syste...
Background: Tuberculosis remains a major public health threat in Nepal and one of the leading causes of death from communicable diseases among adults. The majority of tuberculosis is pulmonary tuberculosis infecting lungs and sputum examination is important for this as it is the major way of transmission of disease. The diagnostic procedures rely on simple and inexpensive methods mostly of microscopy and culture examination. Therefore the evaluation of these diagnostic approaches has great importance. Objectives: To evaluate and compare the efficacy of Ziehl-Neelsen staining, Auramine O staining and culture of sputum samples for the diagnosis of pulmonary tuberculosis. Materials and methods: Total 299 sputum samples (170 samples from 78 Group I suspected cases with no treatment; 42 samples from 22 Group II DOTS follow-up cases; and 87 samples from 87 Group III MDR follow-up cases) were subjected to direct smear preparation each for ZN and AO staining for 1000x light microscopy and 400x fluorescent microscopy examination respectively and the remaining sample were further processed with NALC-NaOH method for culture on modified Lowenstein-Jensen Media for detection of Mycobacterium tuberculosis. Positive smears were graded according to IUATLD/WHO guideline. Result: Out of total 299 sputum samples of all types of cases, 19.06%, 29.1% and 24.41% were found pulmonary tuberculosis positive by ZN, AO and culture respectively. The case detection rates for suspected patients with no treatment were 20%, 25.88% & 28.24%; for DOTS follow-up patients were 30.95%, 57.14% & 19.05%; and for MDR follow-up patients were 11.49%, 21.84% & 19.54% for ZN, AO and culture respectively. The difference in their case detection rates was statistically significant (p < 0.01). No AO negative result with ZN positive samples was found. More number of paucibacillary cases was detected by AO method than ZN. There were 25 cultural contaminated samples. Removing contaminated cultural samples and taking culture as gold standard, the sensitivity and specificity of direct microscopic examination were found to be 60.03% and 98.51% for ZN method; and 83.56% and 94.53% for fluorescent AO method respectively. The percentage of false negative by AO staining was only 16.44% which was in sharp contrast to that of ZN (39.73%). Conclusion: This comparative study proves that AO staining (Fluorescent microscopy) is superior to ZN staining (Light microscopy) in several aspects as efficacy, sensitivity, false negativity. Thus the AO staining aided with culture can prove to be important tool for the effective and reliable diagnosis and screening of pulmonary tuberculosis. Keywords: Mycobacterium tuberculosis, suspected case, follow-up case, MDR, sputum sample