New insights in Staphylococcus pseudintermedius pathogenicity: Antibiotic-resistant biofilm formation by a human wound-associated strain

Arianna Pompilio, Serena De Nicola, Valentina Crocetta, Simone Guarnieri, Vincenzo Savini, Edoardo Carretto, Giovanni Di Bonaventura

Research output: Contribution to journalArticle

Abstract

Background: Staphylococcus pseudintermedius is an opportunistic pathogen recognized as the leading cause of skin, ear, and post-operative bacterial infections in dogs and cats. Zoonotic infections have also recently been reported causing endocarditis, infection of surgical wounds, rhinosinusitis, and catheter-related bacteremia. The aim of the present study is to evaluate, for the first time, the pathogenic potential of S. pseudintermedius isolated from a human infection. To this end, strain DSM 25713, which was recently isolated from a wound of a leukemic patient who underwent a bone marrow transplantation, was investigated for biofilm formation and antibiotic-resistance under conditions relevant for wound infection. Results: The effect of pH (5.5, 7.1, and 8.7) and the presence of serum (diluted at 1:2, 1:10, and 1:100) on biofilm formation was assessed through a crystal violet assay. The presence of serum significantly reduced the ability to form biofilm, regardless of the pH value tested. In vitro activity of eight antibiotics against biofilm formation and mature 48 h-old biofilms was comparatively assessed by crystal violet assay and viable cell count, respectively. Antibiotics at sub-inhibitory concentrations reduced biofilm formation in a dose-dependent manner, although cefoxitin was the most active, causing a significant reduction already at 1/8xMIC. Rifampicin showed the highest activity against preformed biofilms (MBEC90: 2xMIC). None of the antibiotics completely eradicated the preformed biofilms, regardless of tested concentrations. Confocal and electron microscopy analyses of mature biofilm revealed a complex "mushroom-like" architecture consisting of microcolonies embedded in a fibrillar extracellular matrix. Conclusions: For the first time, our results show that human wound-associated S. pseudintermedius is able to form inherently antibiotic-resistant biofilms, suggestive of its pathogenic potential, and consistent with recent reports of zoonotic infections.

Original languageEnglish
Article number109
JournalBMC Microbiology
Volume15
Issue number1
DOIs
Publication statusPublished - May 21 2015

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Biofilms
Staphylococcus
Virulence
Anti-Bacterial Agents
Wounds and Injuries
Gentian Violet
Zoonoses
Surgical Wound Infection
Cefoxitin
Agaricales
Wound Infection
Rifampin
Microbial Drug Resistance
Bacteremia
Endocarditis
Serum
Bone Marrow Transplantation
Bacterial Infections
Confocal Microscopy
Extracellular Matrix

Keywords

  • Antibiotic-resistance
  • Biofilm formation
  • Staphylococcus pseudintermedius
  • Wound infection
  • zoonotic infection

ASJC Scopus subject areas

  • Microbiology
  • Microbiology (medical)

Cite this

New insights in Staphylococcus pseudintermedius pathogenicity : Antibiotic-resistant biofilm formation by a human wound-associated strain. / Pompilio, Arianna; De Nicola, Serena; Crocetta, Valentina; Guarnieri, Simone; Savini, Vincenzo; Carretto, Edoardo; Di Bonaventura, Giovanni.

In: BMC Microbiology, Vol. 15, No. 1, 109, 21.05.2015.

Research output: Contribution to journalArticle

Pompilio, Arianna ; De Nicola, Serena ; Crocetta, Valentina ; Guarnieri, Simone ; Savini, Vincenzo ; Carretto, Edoardo ; Di Bonaventura, Giovanni. / New insights in Staphylococcus pseudintermedius pathogenicity : Antibiotic-resistant biofilm formation by a human wound-associated strain. In: BMC Microbiology. 2015 ; Vol. 15, No. 1.
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AU - Guarnieri, Simone

AU - Savini, Vincenzo

AU - Carretto, Edoardo

AU - Di Bonaventura, Giovanni

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