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Published on: September 5, 2013
Analysis of S. Epidermidis icaA and icaD genes by polymerase chain reaction and slime production: a case control
Shusheng Zhou1, Xiaoguang Chao, Mingming Fei
1Department of Critical Care Medicine, Affiliated Provincial Hospital of Anhui Medical University, Hefei, China. az306w@gmail.com
Background:
Staphylococcus epidermidis is a common pathogen in medical device-associated infections and have an ability to form adherent slime. We aimed to study the effects of icaA and icaD genes on the slime formation of Staphylococcus epidermidis associated with catheter-associated infections.
Methods:
S. epidermidis isolates from the central venous catheter blood of patients with catheter-associated infections, and from the nasal vestibules of healthy volunteers, intensive care unit hospital staff, and patients, were collected. Slime phenotype was determined by Congo red agar test. The icaA/D was detected by polymerase chain reaction. Slime was examined using scanning electron microscopy.
Results:
A total of 82 S. epidermidis isolates were collected. We found a statistically significant difference with regards to slime production between the clinical isolates from the catheter blood specimens and those from the nasal vestibules (p<0.05). All S. epidermidis slime positive strains isolated were icaA positive. There was a greater correlation between the presence of both icaA and icaD and the slime production than the single expression of icaA or icaD and the presence of slime in all groups. The co-expression of mecA and icaD was associated with enhanced resistance to antibiotics.
Conclusion:
S. epidermidis bacteria are significant nosocomial pathogens, and icaA/D can clarify the adhesion mechanism in the pathogenesis of infections associated with medical devices. This study result could be useful for the development of rapid diagnosis for slime producing and methicillin resistant S. epidermidis strains.
Insights
The icaA and icaD genes are crucial for Staphylococcus epidermidis slime formation in catheter infections. Understanding these genes aids in diagnosing slime-producing and antibiotic-resistant strains.
Area of Science:
- Microbiology
- Infectious Diseases
- Medical Device Infections
Background:
- Staphylococcus epidermidis is a leading cause of medical device-associated infections.
- This bacterium possesses the ability to form adherent slime, contributing to its pathogenicity.
- The icaA and icaD genes are implicated in the slime formation process.
Purpose of the Study:
- To investigate the role of icaA and icaD genes in Staphylococcus epidermidis slime formation.
- To analyze the association of these genes with catheter-associated infections.
Main Methods:
- Collected S. epidermidis isolates from catheter blood and nasal vestibules.
- Determined slime phenotype using Congo red agar test.
- Detected icaA/D genes via polymerase chain reaction and examined slime with scanning electron microscopy.
Main Results:
- A significant difference in slime production was observed between clinical and nasal isolates (p<0.05).
- All slime-positive strains were icaA positive.
- Co-expression of icaA and icaD showed a stronger correlation with slime production than individual gene expression. Co-expression of mecA and icaD correlated with increased antibiotic resistance.
Conclusions:
- S. epidermidis is a significant nosocomial pathogen.
- The icaA/D genes elucidate the adhesion mechanism in medical device-associated infections.
- Findings can aid in developing rapid diagnostic methods for slime-producing and methicillin-resistant S. epidermidis.
