Detection of pcaA gene in M. tuberculosis strains isolated from clinical specimens

Abstract number: p548

Ramazanzadeh  R.


The aim of this study was to investigate the prevalence of pcaA gene in M. tuberculosis strains isolated and typed by spoligotyping. The associated risk factors among patients with different nationalities residing in Iran were also determined.


The study population involved a total of 439 patients that referred to the NRITLD, the referral tuberculosis centre in Iran; during March 21st, 2003 to March 21st 2004. The isolated Mycobacterium tuberculosis strains have been characterized by performing susceptibility tests against four first-line antituberculosis drugs and were then subjected to spoligotyping characterization. PCR was used for detection of pcaA gene and its nucleotide sequence was also determined.


Spoligotyping of M. tuberculosis strains resulted in 140 different patterns that divided into three evolutionary groups (É, ÉÉ, ÉÉÉ). One hundred twenty-two (87.1%) of these spoligotype isolates were unique and reported for the first time. The remaining18 (12.8%) spoligotype patterns were previously reported from other geographical regions of the world. Interestingly, 6.3% of the strains belonged to the Beijing family. The MDR (multi drug resistance), double and triple resistance were seen in group É of evolutionary scenario. The pcaA gene was detected in M. tuberculosis clinical isolates but not in saprophyte strains such as M. kansasi.


The results showed that multi drug-resistances were more prevalent in bacteria isolated from Afghani TB patients residing in Iran. In addition, spread of M. tuberculosis strains belonging to the Beijing family among Iranian patients has to be considered seriously. This study confirmed the widespread existence of pcaA gene in almost all the clinical isolates. It is also important to undertake studies to identify which factors are the most significant to consider in tuberculosis control program.

Session Details

Date: 01/08/2007
Time: 00:00-00:00
Session name: XXIst ISTH Congress
Location: Oxford, UK
Presentation type:
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