Coagulase-negative staphylococcal bloodstream and prosthetic-device-associated infections: the role of biofilm formation and distribution of adhesin and toxin genes

Nikolaos Giormezis, Fevronia Kolonitsiou, Antigoni Foka, Eleanna Drougka, Apostolos Liakopoulos, Antonia Makri, Anastasios D Papanastasiou, Aliki Vogiatzi, Gabriel Dimitriou, Markos Marangos, Myrto Christofidou, Evangelos D Anastassiou, Efthimia Petinaki, Iris Spiliopoulou*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review


Coagulase-negative staphylococci (CNS), especially Staphylococcus epidermidis and Staphylococcus haemolyticus, have emerged as opportunistic pathogens in immunocompromised patients and those with indwelling medical devices. In this study, CNS recovered from patients with bloodstream infections (BSIs) or prosthetic-device-associated infections (PDAIs) were compared in terms of biofilm formation, antimicrobial resistance, clonal distribution, and carriage of adhesin and toxin genes. A total of 226 CNS isolates (168 S. epidermidis and 58 S. haemolyticus) recovered from hospital inpatients with BSIs (100 isolates) or PDAIs (126 isolates) were tested for biofilm formation, antimicrobial susceptibility, and mecA, ica operon, adhesin (aap, bap, fnbA, atlE, fbe) and toxin (tst, sea, sec) genes. The selected CNS were classified into pulsotypes by PFGE and assigned to sequence types by multilocus sequence typing. In total, 106/226 isolates (46.9%) produced biofilm, whereas 150 (66.4%) carried the ica operon. Most isolates carried mecA and were multidrug resistant (90.7%). CNS recovered from BSIs were significantly more likely to produce biofilm (P=0.003), be resistant to antimicrobials and carry mecA (P<0.001), as compared with isolates derived from PDAIs. CNS from PDAIs were more likely to carry the aap and bap genes (P=0.006 and P=0.045, respectively). No significant differences in the carriage of toxin genes were identified (P>0.05). Although PFGE revealed genetic diversity, especially among S. epidermidis, analysis of representative strains from the main PFGE types by multilocus sequence typing revealed three major clones (ST2, ST5 and ST16). A clonal relationship was found with respect to antimicrobial susceptibility and ica and aap gene carriage, reinforcing the premise of clonal expansion in hospital settings. The results of this study suggest that the pathogenesis of BSIs is associated with biofilm formation and high-level antimicrobial resistance, whereas PDAIs are related to the adhesion capabilities of S. epidermidis and S. haemolyticus strains.

Original languageEnglish
Pages (from-to)1500-1508
Number of pages9
JournalJournal of Medical Microbiology
Issue numberPt 11
Publication statusPublished - Nov 2014
Externally publishedYes


  • Adhesins, Bacterial/genetics
  • Anti-Bacterial Agents/pharmacology
  • Bacteremia/microbiology
  • Bacterial Toxins/genetics
  • Biofilms/growth & development
  • Coagulase/genetics
  • Drug Resistance, Bacterial
  • Gene Expression Regulation, Bacterial
  • Humans
  • Microbial Sensitivity Tests
  • Prosthesis-Related Infections/microbiology
  • Staphylococcal Infections/microbiology
  • Staphylococcus/drug effects


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