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Updated: Oct 7, 2025
A Fluorescence-based Method to Study Bacterial Gene Regulation in Infected Tissues
Published on: February 19, 2019
Investigation of Virulence Genes of Staphylococcus aureus Isolated from Sterile Body Fluid Samples and Their
Tao Lin1, Qianhui Li1, Defu Jin1
1Department of Medical Laboratory, The Affiliated Huaian No. 1 People's Hospital of Nanjing Medical University, Huanghe West Road 1, Huai'an, Jiangsu 223300, China.
Abstract:
Staphylococcus aureus is the major pathogen causing nosocomial human infections and produces a variety of virulence factors that contribute to its ability to colonize and cause diseases. This study was conducted to investigate the virulence genes in S. aureus isolated from sterile body fluid samples and their correlation with clinical symptoms and outcomes. The VITEK 2® Compact system was used to perform biochemical identification and antimicrobial susceptibility tests on 33 S. aureus isolates. Virulence genes were amplified using multiplex PCR. The virulence gene patterns were analyzed by systematic cluster analysis. The frequency of methicillin-resistant S. aureus was 45.45%, and 17 virulence genes were identified. Genes encoding hemolysins showed high frequencies. The frequencies of hla, hlb, hld, and hlgB were 93.94% and that of the luk-F/S-PV was 21.21%. Except for the frequency of splB (51.52%), the remaining genes encoding invasive proteases showed frequencies greater than 81.82%. Among the patients, 100.00% had undergone invasive medical procedures and 24.00% had been treated with more than three types of antibiotic drugs. Invasive medical procedures are the main causes of infection. Resistance to antibiotic drugs and the status of carrying virulence genes were highly related to clinical symptoms and outcomes.
Insights
Staphylococcus aureus infections are linked to invasive procedures. Virulence genes, particularly hemolysin genes, are common and correlate with clinical outcomes in patients with S. aureus bloodstream infections.
Area of Science:
- Clinical microbiology
- Infectious diseases
- Molecular epidemiology
Background:
- Staphylococcus aureus is a significant cause of hospital-acquired infections.
- Virulence factors are crucial for S. aureus colonization and pathogenesis.
- Understanding virulence gene profiles aids in predicting infection severity.
Purpose of the Study:
- To investigate virulence genes in S. aureus from sterile body fluids.
- To correlate gene patterns with clinical symptoms and patient outcomes.
- To assess the prevalence of methicillin-resistant S. aureus (MRSA).
Main Methods:
- Biochemical identification and antimicrobial susceptibility testing using VITEK 2® Compact system.
- Multiplex PCR for virulence gene amplification.
- Systematic cluster analysis of virulence gene patterns.
Main Results:
- 45.45% of S. aureus isolates were MRSA.
- 17 virulence genes were identified, with high frequencies of hemolysin genes (hla, hlb, hld, hlgB: 93.94%).
- Genes for invasive proteases were present in >81.82% of isolates.
Conclusions:
- Invasive medical procedures are a primary driver of S. aureus infections.
- Antibiotic resistance and virulence gene carriage are strongly associated with clinical presentation and outcomes.
- Targeting virulence factors may offer novel therapeutic strategies.
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