Investigation of QUB11b, QUB4156, QUB26 loci in Mycobacterium Simiae Using the VNTR Method

Mycobacterium simiae has been identified as the most abundant species of slow-growing mycobacterium isolated from clinical specimens in Iran. One of the genetic fingerprinting methods used for this purpose is called Variable number tandem repeat (VNTR). In this study, in addition to the hsp65 PCR-RFLP method, the genetic pattern of Mycobacterium simiae was investigated using QUB11b, QUB4156, QUB26 loci and VNTR method for epidemiological studies. In this study, among 56 samples of atypical pulmonary and extrapulmonary mycobacteria isolated from patients with pulmonary tuberculosis symptoms, using culture on Lowenstein Jensen medium and differential tests including nitrate reduction, catalase activity test, niacin test, growth rate and pigment production and hsp65 PCR-RFLP method, all isolated mycobacterium simiae were identified. Out of 56 isolated non-tuberculous mycobacteria, 41 samples (73.2%) were slow-growing and 15 samples (26.7%) were fast-growing. Among the slow growths, 30 specimens (73.1%) were mycobacterium simiae and among the fast growths, the highest number was related to mycobacterium abscessus(80%). Among 30 mycobacterium simiae samples, (10%) of the samples were sensitive to amikacin and kanamycin and resistant to ciprofloxacin and (6.6%) were resistant to amikacin and kanamycin and sensitive to ciprofloxacin. The QUB11b locus had the highest differentiation power (HGI = 0.7) among the strains of mycobacterium simiae tested and was highly polymorphic.

QUB11b locus in both mycobacterium tuberculosis complex and mycobacterium simiae isolates has the highest discriminative power, 0.6 and 0.7, respectively. This locus can not be used to differentiate the two groups of mycobacterium tuberculosis complex and mycobacterium simiae, but this locus is suitable for differentiating mycobacterium simiae subtypes due to its high discriminative power.