S N Javid, E A Ghaemi, N Amirmozaffari, S Rafiee, A Moradi, T Dadgar,
Volume 3, Issue 1 (Spring - Summer 2009[PERSIAN] 2009)
Abstract
Abstract
Background and objectives: With almost nine million new cases each
year, tuberculosis is still one of the most Life-threatening diseases in the
World. Distribution of drug resistant strains of M.tuberculosis has a lot of
importance. This research was carried out to determine the frequency of drug
resistance of M. tuberculosis in strains isolated in Golestan province.
Material and Methods: In this cross -sectional study, 104 isolate of
M.tuberculosis which isolated from patients referred to Gorgan tuberculosis
Health Center, in 2008 were studied. DNA was extracted by Boiling Method.
By using PCR method, we determine the M.tubeculosis strain and resistance
to Rifampin (Using IS6110 and Gene rpoB primers) and resistance to
Isoniazid (Using InhA and KatG primers). As a Gold Standandard,
“Proportional method” was performed for 45 Samples.
Results: 87 strains were identified as M.tuberculosis. 6.9% of them were
resistant to Isoniazid, 4.6% to Rifampin and 2.3% to both (MDR).Sensitivity
and Specifity of PCR method in detection of resistant to Isoniazid were
95.3% and 57.1% and for Rifampin were 94.7% and 33.3%.
Conclusion: We found that in our region, the MDR is not very common.
More than 16% of isolated strains from tuberculosis suspected patients were
MOTT, for this reason it is necessary to mention that use biochemical or PCR
method to determine M.tuberculosis is necessary.
Key words: Mycobacterium tuberculosis, MDR, PCR, Proportional method
, Golestan province.
Hadi Koohsari , Ezzat Allah Ghaemi , Nour Amir Mozaffari , Abdolvahab Moradi ,
Volume 10, Issue 1 (Jan,Feb 2016 2016)
Abstract
Abstract
Background and Objective: Agr is the most important regulatory system for the expression of Staphylococcus aureus virulence factors in different conditions. Agr acts as a quorum sensing system in this bacterium which is activated by increased cell concentration during the transition from logarithmic growth phase to stationary phase. Its role is to upregulate the secretory virulence factors such as alpha-hemolysin and inhibit the transcription of surface proteins including protein A-encoding gene. The aim of this study was to assess the relationship between the agr system expression and some virulence factors of Staphylococcus aureus in Brain-heart infusion (BHI) culture medium.
Methods: The expression level of agrA and RNAIII genes from the agr locus along with the expression of hla, spa and mecA genes in BHI broth were assessed in different growth phases using Real time-PCR. Also, gyrB was used as an internal control in this study.
Results: The growth curve of the five tested isolates in BHI broth at 24 hours showed that all the isolates had relatively similar growth patterns. AgrA gene expression in the stationary phase was decreased by 0.89-fold compared with the logarithmic phase. Although the expression of RNAIII gene increased by 3-fold, hla expression decreased by 0.47-fold.
Conclusion: An inactive agr system is observed in the BHI broth medium. BHI broth medium contains high amounts of suitable nutrients for the growth of Staphylococcus aureus, thus the bacteria do not require the activity of the agr system for the regulation of the virulence genes in these conditions.
