SNP Scanning in mecA Gene for Methicillin-Resistant Staphylococcus aureus
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Updated: Nov 9, 2025
Multiplex PCR Assay for Typing of Staphylococcal Cassette Chromosome Mec Types I to V in Methicillin-resistant Staphylococcus aureus
Published on: September 5, 2013
Mitra Salehi1, S Abdolhamid Angaji2, Nader Mosavari3
1Department of Microbiology, Islamic Azad University Tehran North Branch, Tehran,Iran.
Background:
Staphylococcus aureus (SA) is known as an important human pathogen, which is responsible for many cases of both hospital and community-acquired infections all over the world. Studying on drug resistance is regarded as an important prevention strategy regarding these types of infections.
Objectives:
The current study is aimed to assess the association between the single-nucleotide polymorphism (SNP) and resistance to antibiotics in the methicillin-resistant Staphylococcus aureus (MRSA) strains as well as the molecular typing of isolates, collected from the clinical samples.
Materials And Methods:
We used the disc-diffusion method to test the isolates antibiotic resistance. In addition, the genotypes of staphylococcal cassette chromosome mec (SCCmec) in the Methicillin-resistant Staphylococcus aureus isolates were determined by multiplex -polymerase chain reaction (PCR). SNP was identified in the mecA gene using sequencing and amplification refractory mutation system-polymerase chain reaction (ARMS-PCR) method.
Results:
The highest resistance was shown against oxacillin, and erythromycin and cephalexin. The most sensitive antibiotic was vancomycin (97%) and resistance to at least three antibiotic classes were identified in all isolates. Eighty six percent of isolates were positive for mecA gene and more than 50% of which were healthcare-acquired methicillin-resistant Staphylococcus aureus (HA-MRSA). Moreover, SCCmec type 3, 1were the predominant strains of the identified MRSA. Also, 23 isolates (23%) were non-typable. By using the ARMS-PCR method, it was found that 10% of the clinical specimens had SNP in the mecA gene.
Conclusion:
According to the Chi-square test (χ2), it reveals that the association between SNP in the mecA gene and oxacillin, cefoxitin, and erythromycin resistance was confirmed among clinical MRSA. Furthermore, there is a 95%probability of association between SNP and resistance to more than three antibiotics in MRSA strains.
Insights
Single-nucleotide polymorphism (SNP) in the mecA gene is linked to antibiotic resistance in methicillin-resistant Staphylococcus aureus (MRSA). This finding aids in understanding and preventing MRSA infections.
Area of Science:
- Microbiology
- Genetics
- Infectious Diseases
Background:
- Staphylococcus aureus (SA) is a major human pathogen causing global infections.
- Understanding SA drug resistance is crucial for infection control.
Purpose of the Study:
- To investigate the association between single-nucleotide polymorphism (SNP) and antibiotic resistance in methicillin-resistant Staphylococcus aureus (MRSA).
- To perform molecular typing of clinical MRSA isolates.
Main Methods:
- Antibiotic resistance was assessed using the disc-diffusion method.
- Staphylococcal cassette chromosome mec (SCCmec) genotypes were determined by multiplex PCR.
- SNP identification in the mecA gene utilized sequencing and ARMS-PCR.
Main Results:
- Highest resistance observed against oxacillin, erythromycin, and cephalexin; vancomycin showed 97% sensitivity.
- All isolates exhibited resistance to at least three antibiotic classes.
- 86% of isolates were mecA-positive, with over 50% identified as healthcare-acquired MRSA (HA-MRSA).
- SCCmec types 3 and 1 were predominant; 23% of isolates were non-typable.
- ARMS-PCR detected SNP in the mecA gene in 10% of clinical specimens.
Conclusions:
- A significant association was confirmed between SNP in the mecA gene and resistance to oxacillin, cefoxitin, and erythromycin in clinical MRSA.
- There is a 95% probability of association between SNP and multi-drug resistance (resistance to >3 antibiotics) in MRSA strains.
