Characterization of Staphylococcus aureus small colony variant strains isolated from Italian patients attending a regional cystic fibrosis care centre

Patrizia Morelli, Alessandra De Alessandri, Graziana Manno, Anna Marchese, Roberto Bandettini, Marta Bassi, Raffaele Lobello, Laura Minicucci

Research output: Contribution to journalArticlepeer-review

Abstract

Small colony variant (SCV) Staphylococcus aureus are a subpopulation of auxotroph, slow-growing strains causing persisting and relapsing infections in cystic fibrosis (CF) patients. Twenty-eight SCV and 29 normal S. aureus strains were isolated from 42 out of 222 Italian CF patients. The isolates were characterized for: susceptibility to antibiotics, methicillin-resistance (MR), Panton Valentine leukocidin, auxotrophy, hypermutability and biofilm formation. Clonal identity of SCV and normal strains was determined by pulsed-field gel electrophoresis. We found that 27 out of 28 SCVs were thymidine-dependent. Furthermore, in contrast to normal phenotype, SCVs were characterized by antibiotic resistance. We also found that 39.3% SCV vs 20.7% normal strains were strong mutators. Moreover, SCVs showed a higher capability to form biofilm compared to normal strains (100% vs 59%). Importantly, we found evidence of clonal spread of SCV strain among CF patients. Using molecular typing, we found that five patients shared the same type A and five out of seven MR-SCV belonged to the same clone (Clone C). The particular virulence and spreading ability of MR-SCV observed highlights the importance of accurate identification and susceptibility testing of these strains. It is important to adopt the optimal approach to treat patients and to prevent cross-infection in CF centres.

Original languageEnglish
Pages (from-to)235-243
Number of pages9
JournalNew Microbiologica
Volume38
Issue number2
Publication statusPublished - Apr 1 2015

Keywords

  • Antibiotic resistance
  • Biofilm
  • Cystic fibrosis
  • Hypermutability
  • Small colony variants
  • Staphylococcus aureus

ASJC Scopus subject areas

  • Microbiology (medical)
  • Medicine(all)

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