Exploring phenotypic and genotypic diversity among methicillin-resistant, vancomycin-resistant, and sensitive...

Area of Science:

• Microbiology
• Infectious Diseases
• Antimicrobial Resistance

Background:

• Methicillin-Resistant Staphylococcus aureus (MRSA) poses a global health threat due to multidrug-resistant (MDR) strains.
• Vancomycin, a primary MRSA treatment, faces increasing resistance, necessitating comparative studies for antimicrobial stewardship.

Purpose of the Study:

• To investigate the prevalence, antimicrobial resistance, and virulence characteristics of Vancomycin-sensitive S. aureus (VSSA) and Vancomycin-resistant S. aureus (VRSA) within MRSA strains.
• To understand the complex interactions between host factors, sample origin, antimicrobial resistance, biofilm production, and virulence genes.

Main Methods:

• Phenotypic methods including antimicrobial susceptibility testing.
• Genotypic techniques such as molecular typing and virulence gene identification.
• Analysis of clinical samples to determine S. aureus, MRSA, VSSA, and VRSA prevalence.

Main Results:

• MRSA was identified in 27 of 250 clinical samples, with 7 (25.9%) being VRSA and 20 (74.1%) VSSA. All MRSA isolates were MDR.
• VRSA isolates exhibited higher antimicrobial resistance but lower virulence compared to VSSA isolates. Linezolid showed a 3.7% resistance rate.
• High biofilm production (96.3%) and multi-virulence patterns were observed. Complex interactions were found among host factors, resistance, biofilm, and virulence.

Conclusions:

• The study underscores the alarming spread of MRSA and VRSA, characterized by significant resistance and virulence.
• Emergence of vancomycin resistance may alter the relationship between antimicrobial resistance and virulence, impacting pathogenic profiles.
• Findings are expected to inform treatment strategies and public health interventions for MRSA and VRSA infections.