Mycobacteriosis and Tuberculosis: Laboratory Diagnosis (original) (raw)
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A Review on Laboratory Diagnosis of Mycobacterium tuberculosis
Asian Journal of Research in Infectious Diseases
Tuberculosis remains the major public health concern worldwide responsible for about 1.6 million deaths and 0.3 million co-infected with Human immunodeficiency virus (HIV) annually. Mycobacterium is the causative agent of tuberculosis infection and is transmitted principally through air when an infected person coughs, talks, sneezes etc. This infection can be diagnosed using different Microbiological, Molecular and Immunological techniques including, sputum smear microscopy, sputum culture, nucleic-acid amplification test (NAAT), genotyping assay, tuberculin skin test (TST), interferon-gamma release assay (IGRAs) etc. These techniques vary in sensitivity and specificity as well as the ease with which they are carried out. World Health Organisation (WHO) encourages the use of techniques that are sensitive, patient-friendly, and those which produce accurate results in any clinical setting world-wide. Hence, this review highlights smear microscopy and incorporation of more rapid and se...
Description and evaluation of mycobacterium tuberculosis diagnosis
Early diagnosis of tuberculosis (TB) and initiating optimal treatment would not only enable a cure of an individual patient but will also curb the transmission of infection and disease to others in the community. Of the several distinct components of TB control programmes, case-finding remains the cornerstone for effective control. However, there are no definite guidelines available as on date as how to use optimally the number of diagnostic tests ranging from simple AFB microscopy to complex molecular biological techniques which have become available over a period; to establish or rule out diagnosis of tuberculosis in a given patient. Therefore, there is need for description and evaluation of the existing important techniques available for the diagnosis of TB and drug susceptibility testing and their advantages and limitations which will help in the development of appropriate TB diagnostic guidelines for the implementation of TB control strategies.
Current Trends In The Laboratory Diagnosis Of Tuberculosis
Benin Journal of Postgraduate Medicine, 2009
Mycobacterium tuberculosis (M. tuberculosis) causes tuberculosis and is a very important pathogen of humans. Tuberculosis kills more people than ever, with the increasing number of HIV-infected individuals 1. The fact sheet of global tuberculosis is stunning with one third of the world's population currently infected and new infections occur every second, resulting in new tuberculosis infection in 1% of the world population annually 2. It is projected that newly acquired infections between 2002 and 2010 would be 1 billion persons, of these, 150 million will get sick and 36 million will die of tuberculosis 2. In Sub-Sahara African countries, the incidence of tuberculosis has doubled since the early 1980s 3. Mycobacterium tuberculosis is related and associated with other species of mycobacteria, referred to as the Mycobacteria Tuberculosis Complex (MTB complex). MTB complex includes; M. bovis, (including the vaccination strain BCG) M. tuberculosis, M. africanum, M. microti, and M. canettii 4 .These grouping is based on several parameters which include the analysis of antigenic extracts, target epitopes for monoclonal antibodies and antigenic and DNA relatedness 5 .
Introduction: We aimed to examine clinical specimens of Mycobacterium tuberculosis complex (MTC) strains and to identify the methods used to isolate MTC. In addition, we aimed to classify nontuberculous mycobacteria (NTM) strains and to analyze their hsp65 fragments. Materials and methods: Polymerase chain reaction (PCR) was performed to amplify the hsp65 gene. PCR products were digested with the enzymes and agarose gel electrophoresis was performed for restriction fragment length polymorphism (RFLP) analysis. Results: Based on MGIT 960 automated system analysis, 221 samples belonging to 81 patients were found positive and, of these patients, 71 (87.7%) were identified as MTC positive. The hsp65 gene was amplified in 10 (12.3%) samples that were identified as positive by MGIT 960 automated system but were not defined as MTC in the identification study. The following were identified upon analysis of the bands after RFLP: four M. intracellulare, and M. gordonae I, M. gordonae I/M. xenopi, M. peregrinum, M. peregrinum/M. scrofulaceum, M. szulgai/Mycobacterium spp. and Mycobacterium spp. Conclusion: The identification of atypical mycobacteria should be enlightening for the distribution rates in public and defining appropriate drug regimens. Therefore, a molecular approach is of fundamental importance for the correct diagnosis of these infections due to atypical mycobacteria which may be easily misinterpreted.
2013
This research compares the microscopic observation of drug susceptibility tests with traditional methods for identifying Mycobacterium Tuberculosis . Methods: This study analyzed 100 sputum samples from two patient groups: one group was categorized as having been exposed to tuberculosis and the other group was categorized as having a high risk of TB. This study performed Sputum-smears, Lowenstein-Jensen cultures, as well as the MODS method, and the proportion method. Results: Out of 100 samples studied, 22 cases were sputum-smear positive. 22 cases were found positive to Lowenstein-Jensen, and 23 positive cases were found to MODS. Both sensitivity and specificity for MODS were 100% (P < 0.05). Lowenstein-Jensen had a sensitivity of 100% and a specificity of 98.7% (P <0.05). The average time for positive results using MODS was 7.04 days, while LJ took 34.18 days (P < 0.05). Of the 22 Sputum samples taken in order to determine the pattern of resistance, MODS and the proportio...
Journal of Clinical Microbiology, 2002
The performance of the Amplified Mycobacterium Tuberculosis Direct (AMTD) test (Gen-Probe Inc., San Diego, Calif.) was assessed in a large tertiary care mycobacteriology laboratory. Both acid-fast smear-positive and smear-negative respiratory and nonrespiratory clinical specimens were analyzed. From February 1998 to 4 October 2001, AMTD assays were performed on 391 respiratory specimens and 164 nonrespiratory specimens. The AMTD assay was compared to the "gold standard" of combined culture and clinical diagnosis. The overall sensitivity for all specimens, including those for which no smear result was available, was 91.2%. The overall sensitivities of the assay, including acid-fast smear-positive and -negative specimens, were 97.8 and 77.3% for respiratory and nonrespiratory specimens, respectively. The corresponding specificities for respiratory and nonrespiratory specimens were 99.1 and 98.5%, respectively. The overall specificity for all specimens was 98.9%. Positive and negative predictive values were 93.9 and 99.7% and 91.7 and 96.4% for respiratory and nonrespiratory specimens, respectively. The time saved by using the AMTD test for making a diagnosis of tuberculosis instead of using culture was 8.99 days. Inhibitors to the AMTD assay were found in 3.1% of respiratory specimens and 3.1% of nonrespiratory specimens. The assay, used in a general mycobacteriology laboratory setting, represents an important advance in improving the speed and accuracy of diagnosis in the management of patients with tuberculosis.
Journal of Microbiology and Infectious Diseases, 2011
The aim of the present study was to evaluate the efficacy (recovery rate, time to detection and Drug Susceptibility Tests-DST-of Mycobacteria-only B460) of new colorimetric medium, Dio-TK and to compare it with routinely used conventional media, Lowenstein Jensen (LJ) and Bactec 460 TB culture system. Materials and methods: Totally 901 clinic specimens were investigated for assignment of tuberculosis by Ehrlich-Ziehl-Nielsen smear strain method, Lowenstein-Jensen, BACTEC 460TB and Dio-TK medium culture systems. Results: Nineteen of 901 clinic specimens (2.1%) were positive by any of these methods. 17 (89.5%) of these specimens positive found by smear strain method, 17 (89.5%) by Lowenstein-Jensen, 19 (100%) by BACTEC 460TB and 14 (73.7%) by Dio-TK medium. NAP and Niacin identification tests were applied to Mycobacterium strains. 12 (63.1%) of 19 isolates were identified as M.tuberculosis complex and 7 (36.9%) were identified as Mycobacterium other than tuberculosis (MOTT) bacilli. 10 (83.3%) of 12 M.tuberculosis complex strains were not resistant to any major drug. But one of 2 isolate was resistant to streptomycin and the other one isolate was resistant to both streptomycin and isoniazid. Conclusion: Our data suggest that some advantages (such as an early detection and differentiation mycobacterium growth from contamination) of the Dio-TK CS over other mycobacterial culture systems make it a practical and rapid system for daily use, and a suitable alternative to other currently available solid media, such as LJ, for detection time of mycobacteria and DST.
Microevolution of Mycobacterium tuberculosis in a Tuberculosis Patient
Journal of clinical …, 2010
Five Mycobacterium tuberculosis isolates were obtained from three body sites from a Dutch patient. The isolates displayed a single genotype by 24-locus MIRU-VNTR typing (except for a single locus not amplified from one isolate) but were differentiated by small variations in IS6110 fingerprints, spoligotypes, 6 hypervariable MIRU-VNTR loci, and/or DiversiLab profiles, revealing patterns of microevolution in a clonal infection. CASE REPORT A 56-year-old woman born in the Netherlands, a low-tuberculosis (TB)-incidence country, presented with diffuse nodular abnormalities on her chest X-ray. She had no history of TB. The tuberculin skin test result was 0 mm. Bronchoscopy was performed, and sarcoidosis was diagnosed. Treatment of sarcoidosis was started and was given for a year and a half. Five years later, she returned with an inflammatory finger. Under suspicion of relapse of her sarcoidosis, treatment with prednisone was started. At the start of treatment with prednisone, a urine sample (23 May 1986) was collected. Due to deterioration of the patient's condition, 2 months later, 2 more urine samples were collected on the same day (30 July 1986). The following day, samples from sputum (31 July 1986) and pus from her finger (31 July 1986) were also collected. The isolates were cultured on Lowenstein-Jensen medium after routine decontamination with 4% Na-OH. Cultures of the sputum, urine, and pus were all positive for Mycobacterium tuberculosis. At that time, antituberculosis treatment with isoniazide (INH), rifampin, and pyrazinamide was started, after a 4-month period of prednisone treatment. All five isolates were sensitive to INH (MIC, 0.2 g/ml), ethambutol (MIC, 4 g/ml), and rifampin (MIC, 0.5 g/ml); the result for susceptibility to pyrazi