Mycobacterium tuberculosis Beijing Genotype in Western Iran: Distribution and Drug Resistance DC05-DC07
Dr. Parviz Mohajeri,
Department of Microbiology, School of Medicine, Kermanshah University of Medical Sciences, Kermanshah, Iran.
Introduction: Mycobacterium tuberculosis Beijing genotype is gaining importance all over the world because this genotype is highly prevalent in several areas and is also frequently associated with drug resistance.
Aim: To identify and determine the frequency of Beijing genotype and mix infection with Beijing and non-Beijing in west of Iran and analyse the association between Beijing genotype and drug resistance.
Materials and Methods: This cross-sectional study was conducted on 146 Tuberculosis (TB) samples collected at the TB reference laboratory in Kermanshah west of Iran from January 2014 to February 2015, Mycobacterium tuberculosis isolates from sputum samples, detected by microcopy, biochemical tests and solid culture were included and then the confirmed samples with Cepheid Xpert MTB/RIF assay were subjected to drug susceptibility tests for rifampicin, isoniazid, ethambutol using proportional method. The prevalence rate of Beijing and non-Beijing genotype was determined by Multiplex- Polymerase Chain Reaction (PCR).
Result: A total of 15/146 (10%) isolates were diagnosed as Beijing genotypes and the remaining 131/146(90%) isolates were non-Beijing genotypes by Multiplex PCR method. Among the 15 Beijing cases, 14 samples have shown mix infection indicating the presence of both Beijing and non-Beijing strains in samples. Three isolates from all cases were drug resistant. Interestingly all drug resistance isolates were from Beijing genotype which shows strong association between drug resistance and Beijing genotype. Also this genotype was more prevalent in younger age-group people (p=0.035).
Conclusion: Frequency of Beijing genotype in west of Iran is more than other sites of Iran but less than Asia. According to our result, mix infections with Beijing and non-Beijing, had the most prevalence therefore we should be concerned more about mix infections. Multiplex-PCR method is feasible, trustworthy and can distinguish mix infections. It is suggested to perform spoligotyping in addition to multiplex PCR method to discriminate mix infections.