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Interactions of vancomycin resistant enterococci with biomaterial surfaces
S H Su1, J W Eaton, R A Venezia
1Department of Pediatrics, Baylor College of Medicine, Houston, Texas 77030, USA.
Abstract:
Enterococci are a frequent cause of nosocomial infections and are often found adherent to indwelling catheters. Concern about such device associated infections has increased with the appearance of vancomycin resistant (VR) enterococci. However, the possible influence of vancomycin resistance in the pathogenesis of biomaterial centered infection has not yet been assessed. Using polyethylene terephthalate (PET) disks as model surfaces, the authors evaluated possible differences in the adherence and persistence of vancomycin sensitive (VS) and VR strains of Enterococcus faecium and Enterococcus faecalis on biomaterial surfaces in vitro and in vivo. The results indicate that: 1) as expected, the clearance of free VR and VS organisms after intraperitoneal injection into normal mice is equally efficient. 2) In vitro, VR bacteria are roughly twice as adherent to plasma coated PET surfaces as are VS organisms. 3) However, in vivo persistence of VS organisms preadherent to biomaterial implants is 5- to 10-fold better than that of preadherent VR organisms. The authors now believe that a discrete change in bacterial cell wall composition between VR and VS enterococci may contribute to the substantial differences in bacterial adhesion and survival of adherent organisms.
Insights
Vancomycin-resistant enterococci adhere better to biomaterials in vitro. However, vancomycin-sensitive strains persist longer in vivo, suggesting cell wall changes influence device-associated infections.
Area of Science:
- Microbiology
- Infectious Diseases
- Biomaterials Science
Background:
- Enterococci are a common cause of hospital-acquired infections, often linked to indwelling medical devices.
- The rise of vancomycin-resistant (VR) enterococci raises concerns about device-associated infections, but the impact of resistance on pathogenesis is unclear.
Purpose of the Study:
- To investigate the influence of vancomycin resistance on the adherence and persistence of Enterococcus faecium and Enterococcus faecalis on biomaterial surfaces.
- To compare vancomycin-sensitive (VS) and VR enterococci in vitro and in vivo models of biomaterial-centered infection.
Main Methods:
- Utilized polyethylene terephthalate (PET) disks as model biomaterial surfaces.
- Assessed bacterial adherence and persistence in vitro using plasma-coated PET disks.
- Evaluated bacterial clearance and persistence in vivo following intraperitoneal injection in mice with biomaterial implants.
Main Results:
- In vitro, VR enterococci demonstrated approximately twice the adherence to plasma-coated PET surfaces compared to VS strains.
- In vivo, clearance of free-circulating VR and VS enterococci was similar in mice.
- However, VS enterococci pre-adherent to biomaterial implants exhibited 5- to 10-fold greater persistence in vivo than pre-adherent VR strains.
Conclusions:
- Bacterial cell wall composition differences between VR and VS enterococci may significantly impact bacterial adhesion and survival on biomaterials.
- These findings highlight a complex relationship between vancomycin resistance, bacterial adherence, and in vivo persistence in the context of device-associated infections.