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Strong biofilm production but not adhesion virulence factors can discriminate between invasive and commensal

Mohamed A Mekni1, Ons Bouchami, Wafa Achour

  • 1Service des laboratoires, Centre National de Greffe de Moelle osseuse (C.N.G.M.O.), Tunis, Tunisia. mekni1983@gmail.com

APMIS : Acta Pathologica, Microbiologica, Et Immunologica Scandinavica
|July 12, 2012
PubMed

Insights

Staphylococcus epidermidis strains from invasive infections show higher antimicrobial resistance and biofilm production compared to commensal strains. Strong biofilm formation is more prevalent in catheter-related infections, indicating its significance in diagnosing these infections.

Area of Science:

  • Medical Microbiology
  • Infectious Diseases
  • Hospital Epidemiology

Background:

  • Staphylococcus epidermidis is a primary cause of hospital-acquired infections, particularly in immunocompromised patients with medical devices.
  • The bacterium originates from skin flora, which can be altered by the hospital environment, influencing its pathogenic potential.
  • Understanding the differences between S. epidermidis from various clinical sources is crucial for infection control and treatment.

Purpose of the Study:

  • To compare antimicrobial resistance and virulence factors of S. epidermidis isolates from catheter-related infections (CRI), non-catheter related bacteremia (NCRB), and commensal sources.
  • To investigate the association between biofilm formation, specific genes, and the clinical origin of S. epidermidis strains.
  • To determine the clinical significance of strong biofilm production in identifying S. epidermidis as an etiological agent of CRI.

Main Methods:

  • Analysis of S. epidermidis isolates from CRI (n=47), NCRB (n=25), and commensal (n=25) sources.
  • Investigation of antimicrobial resistance profiles and the presence of virulence-associated genes (icaABC, aap, atlE, bhp, fbe, embp, IS256).
  • Assessment of polysaccharide intercellular adhesin synthesis and biofilm formation capacity.
  • Clonal relationship determination using pulsed field gel electrophoresis.

Main Results:

  • Genes like bhp, atlE, fbe, embp, and aap were commonly found across all isolate types.
  • Resistance to multiple antibiotics, presence of ica genes, IS256, and biofilm production were significantly higher in invasive strains (CRI and NCRB) than commensal strains.
  • Strong biofilm production was significantly more frequent in CRI strains compared to NCRB strains.

Conclusions:

  • Invasive S. epidermidis strains exhibit increased antimicrobial resistance and biofilm-forming capabilities compared to commensal strains.
  • The presence of specific virulence genes and resistance markers differentiates invasive from commensal isolates.
  • Detecting strong biofilm production in S. epidermidis from blood cultures is a significant indicator for diagnosing catheter-related infections.

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