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Biosensor for Detection of Antibiotic Resistant Staphylococcus Bacteria
Published on: May 8, 2013
Molecular Investigation and Virulence Determination of Methicillin and Vancomycin Resistant Clinical Staphylococcus
N Eslamnezhad1, F Ghandehari1, M Mirzaee2
1Department of Microbiology, Falavarjan Branch, Islamic Azad University, Isfahan, Iran.
Abstract:
Staphylococcus aureus is an opportunistic pathogen that provides conditions for host invasion due to various virulence factors and plays a role in causing various infections. The pathogenicity of these bacteria may vary depending on the host's susceptibility. This study investigates the sensitivity of S. aureus strains isolated from clinical samples to methicillin and vancomycin, and it evaluates the presence of resistance, virulence and toxin-producing genes, and their expression level in the methicillin-resistant S. aureus (MRSA), vancomycin-resistant S. aureus (VRSA), and vancomycin-intermediate S. aureus (VISA) isolates. A cross-sectional study was conducted, encompassing 502 S. aureus isolates obtained from diverse infections over the course of a year. The methicillin and vancomycin sensitivities of the isolates were ascertained by disk diffusion and microdilution broth methods, respectively. The presence of genes associated with resistance, adhesion, and toxin production was subsequently investigated through the implementation of multiplex polymerase chain reaction (PCR) methodology. The expression levels of virulence and resistance genes were detected in resistant and sensitive isolates using real-time quantitative PCR (qPCR). Among the 502 S. aureus isolates, 168 (33.6%) were identified as MRSA. Furthermore, a total of six isolates (1.2%) were identified as VRSA, and two isolates (0.4%) were identified as VISA. The distribution of virulence and resistance-related genes varied among the isolates. The results of the gene expression study demonstrated that the expression levels of the majority of the studied genes were significantly higher in resistant isolates (MRSA and VRSA) compared to sensitive isolates. It is imperative to acknowledge that VRSA and MRSA are regarded as grave hazards to human health. The present study underscores the necessity for enhanced sanitary measures to more effectively control this hospital pathogen, particularly in light of the presence and expression of genes encoding virulence factors in S. aureus isolates.
Insights
Methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant S. aureus (VRSA) pose significant health risks. This study found higher virulence and resistance gene expression in these resistant strains, highlighting the need for improved sanitation to control this pathogen.
Area of Science:
- Clinical Microbiology
- Infectious Diseases
- Molecular Biology
Background:
- Staphylococcus aureus is an opportunistic pathogen causing diverse infections.
- Pathogenicity varies with host susceptibility and bacterial virulence factors.
- Antibiotic resistance, particularly to methicillin and vancomycin, is a growing concern.
Purpose of the Study:
- To investigate antibiotic sensitivity of S. aureus clinical isolates to methicillin and vancomycin.
- To evaluate the presence and expression of resistance, virulence, and toxin genes in resistant S. aureus strains.
- To assess the public health threat posed by methicillin-resistant S. aureus (MRSA), vancomycin-resistant S. aureus (VRSA), and vancomycin-intermediate S. aureus (VISA).
Main Methods:
- Cross-sectional study of 502 S. aureus isolates from clinical samples.
- Antibiotic sensitivity testing using disk diffusion and microdilution broth methods.
- Multiplex PCR for detecting resistance, adhesion, and toxin genes.
- Real-time quantitative PCR (qPCR) for gene expression analysis.
Main Results:
- 33.6% of isolates were MRSA (168/502).
- 1.2% were VRSA (6/502) and 0.4% were VISA (2/502).
- Virulence and resistance gene distribution varied among isolates.
- Resistant isolates (MRSA, VRSA) showed significantly higher expression of most studied genes compared to sensitive isolates.
Conclusions:
- MRSA and VRSA represent significant threats to human health.
- Elevated gene expression of virulence and resistance factors in resistant strains contributes to pathogenicity.
- Enhanced sanitary measures are crucial for controlling this hospital pathogen.
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