مقالات پذیرفته شده در هشتمین کنگره بین المللی زیست پزشکی
Antibacterial effect of vancomycin/ceftriaxone on the expression level of mecA gene in methicillin-resistant Staphylococcus aureus
Antibacterial effect of vancomycin/ceftriaxone on the expression level of mecA gene in methicillin-resistant Staphylococcus aureus
Alireza Khodavandi,1Shiva RezaeiKhah,2Fahimeh Alizadeh,3,*Fatemeh Kafaei,4
1. Department of Microbiology, Gachsaran Branch, Islamic Azad University, Gachsaran, Iran 2. Department of Microbiology, Gachsaran Branch, Islamic Azad University, Gachsaran, Iran 3. Department of Microbiology, Gachsaran Branch, Islamic Azad University, Gachsaran, Iran 4. Department of Microbiology, Gachsaran Branch, Islamic Azad University, Gachsaran, Iran
Introduction: Introduction: Methicillin- resistant Staphylococcus aureus (MRSA) is a significant cause of hospital-acquired infections. Vancomycin is often used to treat MRSA bacteremia despite a high incidence of microbiological failure. Unfortunately, the number of resistances to vancomycin has been steadily rising. It is reported that appropriate β-lactams such as ceftriaxone in combination with vancomycin demonstrated synergistic activity against MRSA. In this study, we aimed to evaluate the antimicrobial effect of combined vancomycin/ceftriaxone on the expression level of mecA gene in MRSA isolates from patients in Gachsaran Shahid Rajaie Hospital.
Methods: Methods: Firstly, nasal swabs were obtained from 120 immunocompromised patients such as diabetes, cancers and pregnant and cultured on differential and selective media to isolate Staphylococcus aureus, which was confirmed by standard biochemical tests. Then bacterial suspensions were cultured on Muller-Hinton Agar containing NaCl and Oxacillin for detection of MRSA isolates. Subsequently, antibacterial susceptibility of vancomycin and ceftriaxone against all MRSA isolates was performed via disc diffusion agar and followed by CLSI recommend microdilution broth test for determination of MICs and then, FIC index is calculated for combination therapy. Eventually, the expression level of Mec A gene in MRSA treated with vancomycin/ceftriaxone was evaluated using quantitative real time RT-PCR.
Results: Results: Out of 120 clinical samples from immunocompromised patients, 28 isolates of MRSA (23.3%) were identified. Findings indicated the relative resistance of all MRSA isolates to vancomycin (25%) and ceftriaxone (28.5%) antibiotics. The overall MIC for MRSA isolates with vancomycin was ranged from 0.0625 to 2 μg/ml while, for ceftriaxone was ranged from 0.0625 to 4 μg/ml. FIC index of combination therapy of vancomycin/ceftriaxone showed synergistic activity (82.1%) in all MRSA isolates and ranged from 0.37 to 0.45. Eventually, the expression level of mecA gene showed a significant reduction (2-3.5 fold) in all MRSA isolates after treatment with combined vancomycin/ceftriaxone.
Conclusion: Conclusion: The combination between vancomycin and ceftriaxone could be a potential agent against MRSA that can serve as possible model for new antibacterial drug. Combination therapy may reduce the risk of relapse, but additional high-quality studies are needed.