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Updated: Jul 2, 2025
Biosensor for Detection of Antibiotic Resistant Staphylococcus Bacteria
Published on: May 8, 2013
Bacterial Adaptive Memory in Methicillin-Resistant Staphylococcus aureus from Endotracheal Tubes
Laia Fernández-Barat1,2, Ruben López-Aladid1,2, Nil Vázquez1,2
1Centro de Investigación Biomedica En Red-Enfermedades Respiratorias (CibeRes, CB06/06/0028) and Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), 08036 Barcelona, Spain.
Objectives:
To evaluate the expression dynamics of biofilm genes in methicillin-resistant Staphylococcus aureus (MRSA) retrieved from endotracheal tubes (ETT) and to determine how gene regulation is attenuated in vitro where host-environmental factors are no longer present.
Methods:
Biofilm was grown (24 h) in tryptic broth soy plus 0.25% glucose for a clinical MRSA isolate in planktonic state and after sessile growth named ETT-MRSA (S2, S3, S4, S5, S6, S7). Gene expression of five biofilm-related genes (icaC, clfB, ebps, fnbB, and RNA III) was assessed consecutively from day 1 to day 4 after ETT growth through real-time PCR. 16S rRNA was used as a control.
Results:
The MRSA isolates retrieved from ETT were capable of producing biofilms dependent on ica. The gene expression dynamics of ETT-MRSA changed progressively compared to planktonic MRSA gene expression under both ambient air (p < 0.001) and ambient air with 5% CO2 (p < 0.001). Dynamic assessment of icaC expression in both atmospheric conditions showed progressive downregulation in vitro compared to in vivo ETT biofilms. The expression patterns of clfB and ebps genes were similar to icaC. In contrast, the expression of the RNA III gene showed progressive upregulation from day 1 to day 4 (p < 0.001).
Conclusions:
MRSA loses its biofilm gene expression in vitro, by adaptive features across multiple generations, as evidenced by the progressive downregulation of icaC and upregulation of RNA III. These findings underscore the significance of host-environment dependence in regulating bacterial biofilm genes, highlighting its importance in diagnostics. Bacterial strains lose their host-specific characteristics as they are cultured in vitro.
Insights
Methicillin-resistant Staphylococcus aureus (MRSA) loses biofilm gene expression in vitro. Host-environment factors are crucial for regulating bacterial biofilm genes, impacting diagnostics.
Area of Science:
- Microbiology
- Bacterial Pathogenesis
- Gene Expression Analysis
Background:
- Methicillin-resistant Staphylococcus aureus (MRSA) is a significant pathogen, often associated with device-related infections.
- Biofilm formation by MRSA contributes to persistent infections and antibiotic resistance.
- Endotracheal tubes (ETTs) provide a surface for MRSA biofilm development in ventilated patients.
Purpose of the Study:
- To investigate the expression dynamics of key biofilm genes in MRSA isolated from ETTs.
- To determine how MRSA biofilm gene regulation changes in an in vitro environment compared to in vivo conditions.
- To understand the role of host-environmental factors in MRSA biofilm gene expression.
Main Methods:
- MRSA strains were cultured in vitro to form biofilms (ETT-MRSA).
- Gene expression of biofilm-related genes (icaC, clfB, ebps, fnbB, RNA III) was quantified using real-time PCR from day 1 to day 4.
- Gene expression was compared between planktonic MRSA and in vitro grown ETT-MRSA under different atmospheric conditions.
Main Results:
- MRSA isolates from ETTs demonstrated ica-dependent biofilm production.
- ETT-MRSA showed altered gene expression compared to planktonic MRSA in both ambient air and 5% CO2.
- icaC, clfB, and ebps gene expression progressively downregulated in vitro, while RNA III progressively upregulated.
Conclusions:
- MRSA exhibits adaptive changes leading to reduced biofilm gene expression in vitro.
- The study highlights the critical role of host-environment interactions in regulating MRSA biofilm formation.
- Bacterial strains may lose specific host-associated characteristics upon in vitro culturing, impacting diagnostic interpretations.
