Characterization of rpoB mutations in rifampin-resistant isolates of mycobacterium tuberculosis cultured from the Iranian patients

In this project we investigated the frequency of mutations within the rifampin resistance-determining region [RRDR] of rpoB gene to determine whether this region is useful for molecular detection of rifampin resistant isolates of Mycobacterium tuberculosis from Iranian patients. A set of 25 rifampin resistant and 5 randomly chosen fully susceptible M. tuberculosis complex strains obtained from sputum samples of individual patients were investigated. The M. tuberculosis H37RvT and CDC 1551 standard strains were used as controls. Using the specific primers, the entire RRDR of rpoB gene of selected samples was amplified and sequenced directly. Genetic alterations in the RRDR were present among 96.0% of isolates. The majority of rifampin resistant isolates [72.0%] showed missense mutations in the core region of rpoB that led to substitutions of amino acids at Ser-531 [60.0%], His-526 [16.0%] or Asp-516 [8.0%]. While the codon 531 has been the most common site of nucleotide substitutions worldwide, the frequencies of mutations at the codons 526 and 516 among the Iranian isolates were different from other geographical regions. Mutation at codon 533 was found at higher frequency [8%] comparing to the report from other countries. The high rate of mutations within the RRDR of the rpoB gene suggests that targeted screening of the RRDR may be feasible for the determination of rifampin resistance in clinical isolates of Mycobacterium tuberculosis from Iran

[A survey of detecting Chlamydia pneumoniae DNA with the aid of PCR in human coronary arteries and ascending aorta at postmortem and in alive patients]

Atherosclerosis is an important agent of mortality and morbidily among humans. Knowledge of the causative and precipitating factors of atherosclerosis is therefore highly important. Among the factors, infections have been cited among which Chlamydia pneumoniae. Accordingly we performed a systemic dissection of the 3 coronary arteries and ascending aorta in 49 postmortem subjects who underwent operation and 5 atherosclerotic plaques in alive subjects and studied the relationship in individual persons between the presence of Chlamydia pneumoniae DNA and the number of major risk factors. Other major risk factors comprising age, sex, blood pressure, diabetes mellitus, smoking, hypercholestrolemia and history of deaths due to heart ailment in families were also studied. From each vessels, two sections were obtained, one determining pathological grading of atherosclerosis [study classification], and other determining the prevalence of Chlamydia pneumonia DNA by polymerase chain Reaction [PCR] method. PCR was performed in Pasteur Institute. C.Pneumoniae was detected by PCR in 14 [25.9%] out of 54 subjects. 19 segments of vessels were positive for C. Pneumoniae out of which 16 segments [84.2%] had atherosclerosis and an equal or more than 3 in pathologic gradings. In the C. Pneumoniae positive patients, in comparison of the two groups comprising of patients with one or more risk factors, no statistically significant difference was seen [P>0.05]. This study opens up the path for management strategies in eradicating C. Pneumoniae, and decreasing morbidity, mortality secondary to atherosclerosis