TITLE: Clinical and Molecular Characterization of Mycobacterium tuberculosis Strains Isolated from Patients in Duhok Province, Iraqi Kurdistan

AUTHOR:  Muayad Aghali Merza, M.B.Ch.B., M.Sc.(Clinical Microbiology)

ISSN:

AWARDING BODY: The University of Duhok

CURRENT INSTITUTION: College of Medicine, The University of Duhok

DATE AWARDED: 2011

Full Text Link: [PLEASE CLICK TO VIEW THE FULL TEXT OF MY M.Sc.]

SUPERVISOR:  Associate Professor Dr. Parissa Farnia (Medical Microbiology, MRC, NRITLD, SBUMS, Tehran, Iran), Assistant Professor Dr. Baheej Y. Mohammad (Internal Medicine, College of Medicine, University of Duhok), and Assistant Professor Dr. Ahmad M. Salih (Molecular Microbiology, College of Medicine, University of Duhok)

SPONSOR: The University of Duhok

QUALIFICATION NAME: Doctor of Philosophy in Clinical Microbiology (Infectious Diseases)

QUALIFICATION LEVEL: PhD

LANGUAGE OF THE THESIS: English

REPOSITORY LINK:  Forthcoming

Citation to this work:

Merza, M.A. (2011). Clinical and Molecular Characterization of Mycobacterium tuberculosis Strains Isolated from Patients in Duhok Province. Iraqi Kurdistan. PhD Thesis. The University of Duhok

Recently, tuberculosis (TB) has been intensely studied because of its resurgence and the emergence of drug-resistance, particularly multidrug resistant TB (MDR-TB). Hence, molecular epidemiological studies have been used to characterize the main causative agent, Mycobacterium tuberculosis (M.tuberculosis) isolates, in order to better understand the origin and propagation of the disease and for effective control and prevention of TB. The objectives of this study were to determine drug resistance pattern in new and previously treated TB patients by both phenotypic and genotypic drug susceptibility testing (DST), to assess function of TB control programme, to underline certain risk factors associated with MDR-TB, and to characterize susceptible and drug resistant strains by molecular fingerprinting methods. All smear positive pulmonary specimens were collected between June 2008 and June 2009 at the national tuberculosis control programme of Dohuk province, Iraq. All conventional and molecular investigations were performed at My cobacteriology Research Center, National Research Institute of Tuberculosis and Lung Diseases, Shahid Beheshti University of Medical Sciences, Tehran, Iran. The DST to the first line anti-TB drugs was performed on Löwenstein-Jensen medium according to the proportion method. Multiplex PCR for detection of isoniazid and rifampicin was performed. IS6110RFLP, spoligotyping and MIRU-VNTR techniques were performed to detect circulating strains of M. tuberculosis isolates from patients in Duhok province. 

M. tuberculosis strains were isolated from 53 patients out of 86 patients with pulmonary TB in Duhok province. Thirty-eight patients (71.7%) were new cases and 15 (28.3%) were previously treated. By conventional DST, out of the 38 new cases, 4 patients (10.5%) had strains resistant to one or more of the first line drugs, whereas 8 (53.3%) among the 15 previously treated patients had resistant strains. IVTen patients (18.9%) had MDR-TB. Three MDR-TB cases (7.9%) were seen among new cases and as much as 7 (46.7%) among previously treated patients. Whereas, by multiplex PCR, there were 44 (83.0%) susceptible, 6 (11.3%) MDR-TB and 3 (5.7%) mono resistance strains. Spoligotyping of M. tuberculosis isolates showed T family (30%) as the predominant genotype. By using the 3 molecular techniques, there were 4 spoligotyping clusters. Complete concordance with RFLPwas observed in one cluster of spoligotyping, but no concordance with MIRU-VNTR profile.

The drug-resistance rate of pulmonary TB, especially MDR-TB, was thus far higher among the previously treated patients than among the new ones. The many drug resistant strains in absence of evidence of recent transmission in combination with the many previously treated cases highlight the need for an improved control programme, coupled with improving case detection rate and early diagnosis of MDR-TB. The study furthermore supports the fact that rifampicin resistance can be used as surrogate marker for detection of MDR-TB in settings with low resources. Molecular fingerprinting methods are vital for differentiating are activation of latent infection from a recent transmission; however, it should be coupled with clinical epidemiological investigation. The low clustering rate in this study suggests that either reactivation of latent infections may be the main driving force for the endemic situation of the disease in Duhok; or it may indicate that big circle of TB transmission is missed in the community, which means effective control measures have not been achieved yet in Duhok. Furthermore, this study highlights the risk of transmission of MDR-TB strains other than Beijing lineage, which might contribute to the global drug resistant TB epidemic.

Hepatitis B Virus (HBV), Chronic Infection, Antiviral Therapy, Immunopathogenesis, Viral Replication

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