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Identification of ica-dependent biofilm production by Staphylococcus aureus clinical isolates and antibiofilm effects of ascorbic acid against biofilm production
  1. Sahra Kırmusaoğlu,
  2. Havva Kaşıkçı
  1. Molecular Biology and Genetics, Haliç University, Istanbul, Sütlüce-Beyoğlu, Turkey
  1. Correspondence to Assist.Prof.Dr. Sahra Kırmusaoğlu, Molecular Biology and Genetics, Haliç University, Istanbul, Sütlüce-Beyoğlu 34394, Turkey; kirmusaoglu_sahra{at}


Aims Staphylococcus aureus (S. aureus) is a life-threatening pathogen with high morbidity and mortality rates which causes nosocomial and community-acquired infections. Biofilm, considered to be a common virulence factor for pathogens, plays a significant role in recurrent and untreatable infections. Biofilm formation of S. aureus is mediated by synthesis of either poly-N-acetylglucosamine in an ica-dependent manner or surface proteins in an ica-independent manner. In some cases treatment is impossible and recurrent. In this study, ica-dependent biofilm-producing S. aureus isolates were detected and the anti-biofilm effect of ascorbic acid against biofilm formation of isolates was investigated.

Methods A total of 21 methicillin-sensitive S. aureus (MSSA) clinical isolates stored in our bacterial stock were used to detect ica-dependent biofilm-producing MSSA isolates. The anti-biofilm study was undertaken with three ica-dependent biofilm-producing isolates (MSSA2–4) and ATCC 29213 (MSSA1). Biofilms and the anti-biofilm effect of ascorbic acid were detected using the microtitre plate (MtP) method. 16S-rRNA, nuc, icaA and icaD genes and expression levels of icaA and icaD of isolates were detected by RT-PCR.

Results The minimum inhibitory concentrations (MICs) of ascorbic acid prevented biofilm formation of MSSA1 and MSSA3. Also, 1/2 MIC of ascorbic acid prevented biofilm formation of MSSA3. It was observed that biofilm formation decreased with increased concentration. There was no significant increase in ica gene expression of MSSA1 and MSSA2. Expression of icaA and icaD of MSSA3 decreased 13% and 38%, respectively. Expression of icaA in MSSA4 decreased 12%.

Conclusion The results of our study show that ascorbic acid can be used as an anti-biofilm agent to prevent biofilm formation of S. aureus and thus biofilm-related infections.

  • antioxidants
  • cell adhesion molecules
  • clinical infectious diseases
  • microbiology
  • staphylococci

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  • Handling editor Tony Mazzulli.

  • Contributors SK: design of the scientific work, obtaining data, analysis and evaluation and experimental work in the laboratory. HK: obtaining data, experimental work in the laboratory.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Patient consent for publication Not required.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data availability statement All data relevant to the study are included in the article or uploaded as supplementary information. All free text downloaded will be published.