Novel rat model of methicillin-resistant Staphylococcus aureus-infected silicone breast implants: a study of biofilm pathogenesis.
BACKGROUND
Clinical infection of breast implants occurs in 7 to 24 percent of breast reconstructions. It may persist over time in the form of biofilm without overt manifestation and is extremely difficult to eradicate. The authors' aim was to establish a novel model for biofilm infection of silicone breast implants in rats.


METHODS
Fifty-six rats underwent implantation of miniature silicone breast implants and/or methicillin-resistant Staphylococcus aureus (MRSA) bacteria. Group A received implants covered with MRSA biofilm. Group B received implants and free planktonic MRSA. Group C received free planktonic MRSA without implants. A control group received sterile implants without MRSA. Each group was divided to receive either saline or vancomycin injections between days 4 and 11. Clinical evaluation, bacterial counts, and scanning electron microscopy were performed.


RESULTS
The mortality rate in group B (implants infected with free planktonic MRSA) was significantly higher than that in all other groups [37 percent versus groups A and D (0 percent) and group C (7 percent)]. Treatment with vancomycin lowered temperature in groups B and C (p < 0.05) and improved wound healing in group B (p < 0.01). Vancomycin treatment reduced wound bacterial counts in free planktonic MRSA groups B and C but had no significant effect on biofilm MRSA-infected group A.


CONCLUSIONS
The model successfully induced persistent breast implant infection. Free planktonic MRSA produced in situ biofilm on silicone implants. Biofilm infection has milder manifestations than free planktonic MRSA infection, which has higher rates of systemic infections and death when compared with either isolated biofilm infection or free planktonic MRSA infection without implant. Vancomycin has limited effect against mature biofilm.
Tel Aviv, Israel From the Department of Plastic and Reconstructive Surgery and the Laboratory for Epidemiology and Antibiotic Research, Tel Aviv Sourasky Medical Center, Affiliated with Tel Aviv Sackler Medical School, Tel Aviv University.
Ehud
E
Arad
Shiri
S
Navon-Venezia
Eyal
E
Gur
Boris
B
Kuzmenko
Rivka
R
Glick
Daphna
D
Frenkiel-Krispin
Eyal
E
Kramer
Yehuda
Y
Carmeli
Yoav
Y
Barnea
D000818:Animals; D018441:Biofilms; D018427:Breast Implants / Q000009:adverse effects*; D004195:Disease Models, Animal; D005260:Female; D055624:Methicillin-Resistant Staphylococcus aureus / Q000502:physiology*; D016459:Prosthesis-Related Infections / Q000209:etiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D020034:Silicone Gels; D013203:Staphylococcal Infections / Q000209:etiology*
D020034:Silicone Gels