Molecular Typing Of Mycobacterium Tuberculosis Research Articles

Molecular Typing of Mycobacterium Tuberculosis Isolated from Iranian Patients Using Highly Abundant Polymorphic GC-Rich-Repetitive Sequence

Molecular Typing of Mycobacterium Tuberculosis Isolated from Iranian Patients Using Highly Abundant Polymorphic GC-Rich-Repetitive Sequence

Molecular characterization of Mycobacterium tuberculosis isolates from Tanga, Tanzania: First insight of MIRU-VNTR and microarray-based spoligotyping in a high burden country

Molecular typing of Mycobacterium tuberculosis(MTB) has greatly enhanced the understanding of the population structure of MTB isolates and epidemiology of tuberculosis (TB). To characterize prevalent genotypes of MTB, microarrays‑based spoligotyping and mycobacterial interspersed repetitive unit‑variable number of tandem repeats (MIRU‑VNTR) were applied on 80 isolates collected from primary health care facilities in Tanga, North‑eastern Tanzania. A total of 18 distinct spoligotypes were identified. The lineages by order of their predominance were EAI and CAS families (26.25%, 21 isolates each), LAM family and T super‑family (10%, 8 isolates each), MANU family (3.75%, 3 isolates), Beijing family (2.5%, 2 isolates) and S family (1.25%, 1 isolate). Overall, sixteen (20%) strains could not be allocated to any lineage according to the SITVIT_WEB database. The allelic diversity (h) for specific MIRU‑VNTR loci showed a considerable variation ranging from 0.826 of VNTR locus 3192 to 0.141 of VNTR locus 2059. The allelic diversity for 11 loci (VNTR 3192, 2996, 2165, 960, 4052, 424, 4156, 2531, 1644, 802 and 3690) exceeded 0.6, indicating highly discriminatory power. Seven loci (VNTR 2163b, 2401, 1955, 577, 4348, 2687 and 580) showed moderate discrimination (0.3 ≤ h ≥ 0.6), and three loci (VNTR3007, 154 and 2059) were less polymorphic. The present study suggests that the TB cases in Tanga might be caused by a diverse array of MTB strain families that may be indicative of a cosmopolitan population with frequent migration and travel. Microarray‑based spoligotyping and MIRU‑VNTR could be reliable tools in detecting different MTB genotypes in high burden settings.

Molecular typing of Mycobacterium tuberculosis isolated from adult patients with tubercular spondylitis

Tuberculosis (TB) is endemic in Taiwan and usually affects the lung, spinal TB accounting for 1-3% of all TB infections. The manifestations of spinal TB are different from those of pulmonary TB. The purpose of this study was to define the epidemiological molecular types of mycobacterial strains causing spinal TB. We retrospectively reviewed the medical charts of adult patients diagnosed with spinal TB from January 1998 to December 2007. Patients with positive culture results and/or pathological findings characteristic of TB were enrolled in this study. Spoligotyping was performed to type the Mycobacterium tuberculosis isolates. A total of 38 patients with spinal TB were identified. Their mean age was 68 years, and their median duration of symptoms was 60 days (range 3-720 days). The lumbar and thoracic spine accounted for 76% of the sites involved. Thirteen specimens (from seven male and six female patients) were available for typing. Spoligotyping of these 13 specimens revealed three Beijing (23%) and 10 non-Beijing types (77%). The non-Beijing types included two EAI2 Manilla (15%), two H3 (15%), two unclassified (15%), and one each of BOVIS1, U, T2, and orphan type. No significant predominant strain was found in this study, and no drug-resistant Beijing strains were identified. TB spondylitis was found to occur in older patients. Spoligotyping results showed that most of the TB spondylitis cases were caused by non-Beijing type Mycobacterium tuberculosis.

Molecular typing of Mycobacterium tuberculosis circulated in Moscow, Russian Federation

The present study investigates epidemiological diversity and multidrug resistance spreading among Mycobacterium tuberculosis strains circulating in Moscow, Russian Federation. Among 115 M. tuberculosis strains selected randomly from the sputum of epidemiologically unrelated tuberculosis (TB) patients, multidrug-resistant (MDR) strains predominated. Mutations in the RRDR of the rpoB gene were detected in 64 (83.1%) of 77 rifampicin (RIF)-resistant strains. The Ser531→Leu substitution was prevalent among them (76.5%). Aberrations in the Ser315 codon of katG and/or in the inhA promoter region were found in 79 (84.0%) of 94 isoniazid (INH)-resistant strains. Strains belonging to the Beijing family prevailed. Seventy-one different patterns were identified using the 24-VNTR loci typing scheme. Three main 24-loci VNTR clusters included 34 strains which belonged to the Beijing family. The spoligotyping and 24-loci VNTR typing combination demonstrated maximal discriminatory power. Among the Beijing strains, the MDR phenotype was revealed more frequently than among the others. High genetic heterogeneity of the studied population was shown by the assessment of VNTR loci variability in the analyzed group and in the strains from other parts of Russia. Comparison of the 24-VNTR locus typing and spoligotyping data with revealed resistance-associated mutation allows us to make a suggestion that the active transmission of MDR strains and the independent appearance of drug resistance during chemotherapy occurred in the studied population simultaneously.

Tuberculosis in hospital department health care workers

IntroductionTuberculosis (TB) is considered an occupational disease in health care workers (HCW) and its transmission in health care facilities is an important concern. Some hospital departments are at higher risk of infection. ObjectiveTo describe TB cases detected after TB screening in HCW from a hospital department (Ear, Nose and Throat – ENT) who had had contact with active TB cases. Material and methodsAll HCW (73) from Hospital São João's ENT Unit who had been in contact with two in-patients with active TB underwent TB screening. Those who had symptoms underwent chest X-ray and mycobacteriological sputum exam. ResultsOf 73 HCW who underwent TB screening, TB diagnosis was established in 9 (8 female; median age: 30 years; 1 doctor, 6 nurses, 2 nursing auxiliaries). Pulmonary TB was found in 8 and extra- -pulmonary TB in 1. Microbiology diagnosis was obtained in 7 cases by sputum smear, n=2; culture exam in bronchial lavage, n=4 and histological exam of pleural tissue, n=1. In 4 cases, Mycobacterium tuberculosis genomic DNA was extracted from cultures and molecular typing was done. All cases had identical MIRU types, which allowed identification of the epidemiological link. ConclusionNosocomial TB is prominent and efforts should be made to implement successful infection control measures in health care facilities and an effective TB screening program in HCW. Molecular typing of Mycobacterium tuberculosis facilitates cluster identification.

Tuberculose em profissionais de saúde de um serviço hospitalar

Introduction: Tuberculosis (TB) is considered an occupational disease in health care workers (HCW) and its transmission in health care facilities is an important concern. Some hospital departments are at higher risk of infection.Objective: To describe TB cases detected after TB screening in HCW from a hospital department (Ear, Nose and Throat – ENT) who had had contact with active TB cases.Material and methods: All HCW (73) from Hospital São João’s ENT Unit who had been in contact with two in-patients with active TB underwent TB screening. Those who had symptoms underwent chest X-ray and mycobacteriological sputum exam.Results: Of 73 HCW who underwent TB screening, TB diagnosis was established in 9 (8 female; median age: 30 years; 1 doctor, 6 nurses, 2 nursing auxiliaries). Pulmonary TB was found in 8 and extra-pulmonary TB in 1. Microbiology diagnosis was obtained in 7 cases by sputum smear, n=2; culture exam in bronchial lavage, n=4 and histological exam of pleural tissue, n=1. In 4 cases, Mycobacterium tuberculosis genomic DNA was extracted from cultures and molecular typing was done. All cases had identical MIRU types, which allowed identification of the epidemiological link.Conclusion: Nosocomial TB is prominent and efforts should be made to implement successful infection control measures in health care facilities and an effective TB screening program in HCW. Molecular typing of Mycobacterium tuberculosis facilitates cluster identification.Rev Port Pneumol 2007; XIII (6): 789-799

Molecular epidemiology of tuberculosis in London 1995–7 showing low rate of active transmission

Background: Tuberculosis notification rates for London have risen dramatically in recent years. Molecular typing of Mycobacterium tuberculosis has contributed to our understanding of the epidemiology of tuberculosis throughout the world....

Molecular epidemiology of tuberculosis in London 1995–7 showing low rate of active transmission

Background: Tuberculosis notification rates for London have risen dramatically in recent years. Molecular typing of Mycobacterium tuberculosis has contributed to our understanding of the epidemiology of tuberculosis throughout the world....

Prospective use of molecular typing of Mycobacterium tuberculosis by use of restriction fragment-length polymorphism in a public tuberculosis-control program.

We performed a prospective, community-based evaluation of molecular typing of Mycobacterium tuberculosis isolates as a method for tuberculosis (TB) control. We performed restriction fragment-length polymorphism (RFLP) analysis of the insertion sequences IS6110 and pTBN12 for isolates recovered from 61 of 62 patients with culture-positive TB in St. Louis during 12 months. Twenty-four (39%) of the 61 patients were infected with an isolate with an RFLP pattern that was shared with >/=1 other isolate, and 11 (46%) also had epidemiologic links with patients in their cluster of cases. One case each of laboratory cross-contamination and occupational transmission were discovered. The patients in clusters were more likely to be younger, black, United States-born, to have substance abuse problems, and to live in poorer areas. A predictive algorithm for molecular identification of clusters had a sensitivity and a specificity of 75%. This study allowed the TB-control program in St. Louis to be redirected toward the affected subpopulations.

Demonstration of reinfection and reactivation in HIV-negative autopsied cases of secondary tuberculosis: multilesional genotyping of Mycobacterium tuberculosis utilizing IS 6110 and other repetitive element-based DNA fingerprinting

Setting: Secondary tuberculosis may follow reinfection or endogenous reactivation. The design of effective preventive and treatment protocols requires knowledge about the relative importance of these mechanisms in specific communities. Molecular typing of Mycobacterium tuberculosis has permitted linkage of cases and demonstration of patterns of inter- or intrapatient strain diversity correlating with reinfection and reactivation.Objective: The use of DNA fingerprinting to examine intrapatient strain diversity in autopsied, HIV-negative individuals resident in a high incidence community.Design: Autopsy (12 cases) and pneumonectomy (one case) permitted multilesional sampling for bacterial culture and comparative genotyping. Mycobacterium tuberculosis strains were typed using probes directed against IS6110 , the direct repeat sequence (DR) and MTB484(1).Results: In two patients, the demonstration of pulmonary infection by two distinct strains suggested dual infection of these individuals. In one other case, the strain isolated from a Ghon-focus was identical to that obtained from all secondary cavitating lesions, which suggested reactivation of the primary infection. In the remaining cases, all isolates were identical, but primary lesions could not be identified with certainty or were culture negative. One of these cases showed evidence of strain evolution.Conclusions: Multilesional strain genotyping suggested both reinfection and reactivation in a series of HIV-negative autopsied patients with secondary tuberculosis. In most (11/13) cases, the same strain (or clonal variant) was present in all lesions, pulmonary and extrapulmonary.

Principe et intérêt du typage moléculaire appliqué a Mycobacterium tuberculosis

The targets of the main methods for the molecular typing of Mycobacterium tuberculosis are the repeated sequence IS 6110 and the single region DR. The reference method is the RFLP method using IS 6110. Rapid methods requiring less amounts of DNA have been developed. However these methods have been showed to be less discriminant than the reference method. Molecular typing of M. tuberculosis is being used increasingly in epidemiological studies, e.g.nosocomial outbreaks, transmission of tuberculosis in communities, characterization of risk factors for transmission, surveillance of multi-drug resistance, contamination due to fibroscopes, laboratory contamination.