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Biosensor for Detection of Antibiotic Resistant Staphylococcus Bacteria
Published on: May 8, 2013
Investigation of integron classes 1, 2, and 3 among multi-drug resistant Staphylococcus aureus isolates in Iran: a
Abolfazl Rafati Zomorodi1,2, Mohammad Motamedifar3, Karamatollah Rahmanian4
1Department of Bacteriology and Virology, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran.
Background:
Rising methicillin-resistant Staphylococcus aureus (MRSA) poses a global health threat, contributing to serious infections with high mortality rates. Integrons are recognized as significant genetic elements in disseminating multidrug-resistant (MDR) strains. This study focuses on assessing the prevalence of integron classes 1, 2, and 3 in S. aureus strains from four major cities in Iran.
Methods:
This cross-sectional study analyzed 183 S. aureus isolates from Shiraz, Tehran, Isfahan, and Yazd in Iran. The isolates were identified using specific biochemical and molecullar tests. The Kirby-Bauer disc diffusion method and microbroth dilution method were employed to determine the susceptibility of the isolates to relevant antibiotics and vancomycin, respectively. The macrolide-lincosamide-streptogramin B (MLSB) resistance phenotype was also evaluated using the D-test. All isolates were sought for presence of the intI1, intI2, and intI3 genes.
Results:
Among 183 S. aureus isolates, high resistance rates were noted: 86.3% for erythromycin, 66.1% for ciprofloxacin, and 61.7% for clindamycin, while all isolates were susceptible to linezolid and vancomycin. Of the 183 isolates, 59.6% were identified as MRSA and 78.1% as MDR. According to the D-test results, 112/183 (61.2%), 29/183 (15.8%), 25/183 (13.7%), and 17/183 (9.7%) of S. aureus isolates showed constitutive resistance-MLSB, inducible resistance-MLSB, sensitive, and resistance to macrolide-streptogramin B (MS) phenotypes, respectively. The intI1 gene was found in 14 out of 183 S. aureus isolates (7.6%), while none were positive for the intI2 or intI3 genes. Notably, 11/14 (78.5%) and 13/14 (92.8%) intI1-positive isolates were MRSA and MDR, respectively.
Conclusions:
The distribution of MRSA and MDR S. aureus isolates in Iran seems concerning. Although the prevalence of intI1 was not as high as in prior studies, almost all S. aureus harbored the intI1 gene were MRSA and MDR.
Insights
Methicillin-resistant Staphylococcus aureus (MRSA) and multidrug-resistant (MDR) strains are a growing concern in Iran. While integron class 1 (intI1) prevalence was lower than expected, nearly all intI1-positive strains were MRSA and MDR.
Area of Science:
- Microbiology
- Infectious Diseases
- Genetics
Background:
- Methicillin-resistant Staphylococcus aureus (MRSA) presents a significant global health challenge due to high mortality rates.
- Integrons are key genetic elements facilitating the spread of multidrug-resistant (MDR) strains.
- This study investigated integron classes 1, 2, and 3 in S. aureus from four Iranian cities.
Purpose of the Study:
- To determine the prevalence of integron classes 1, 2, and 3 in Staphylococcus aureus isolates.
- To assess antibiotic resistance patterns, including MRSA and MDR phenotypes, in these isolates.
- To correlate integron presence with MRSA and MDR characteristics.
Main Methods:
- Analysis of 183 S. aureus isolates from Shiraz, Tehran, Isfahan, and Yazd, Iran.
- Identification of isolates using biochemical and molecular tests.
- Antibiotic susceptibility testing (Kirby-Bauer, microbroth dilution) and D-test for MLSB resistance.
- Molecular detection of intI1, intI2, and intI3 genes.
Main Results:
- High resistance rates observed: 86.3% erythromycin, 66.1% ciprofloxacin, 61.7% clindamycin. All isolates were susceptible to linezolid and vancomycin.
- 59.6% of isolates were MRSA and 78.1% were MDR.
- The intI1 gene was detected in 7.6% of isolates; intI2 and intI3 were absent. All intI1-positive isolates (14/183) were MRSA and MDR.
Conclusions:
- The prevalence of MRSA and MDR S. aureus in Iran is a significant concern.
- While intI1 prevalence was lower than in some previous studies, its presence strongly correlated with MRSA and MDR phenotypes.
- Further research is needed to understand the role of integrons in the dissemination of resistance in Iran.
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