Experimental foreign-body associated infections

The problem of implant-associated infection has been an increasing concern since foreign materials were used in surgery. Several animal models have been developed to study different aspects of such infections. The tissue-cage model is especially suitable to analyse the role of antimicrobial agents in device-related infections. This model perfectly simulates the human situation in the sense that no spontaneous healing occurs, and short-term therapy with most antibiotics does not result in the complete elimination of the implant-associated bacteria. Quinolones have been increasingly used in the treatment of device-related bone and joint infections. We therefore studied the role of quinolones against Staphylococcus aureus infection in the foreign-body model. Ln additions, we analysed the effect of rifampin-quinolone combinations. Ciprofloxacin and fleroxacin completely failed to eradicate infections with six clinical isolates of S. aureus. In contrast rifampin alone or in combination was highly efficacious in eliminating tissue-cage associated S. aureus infections. The most important difference between these two types of antibiotics was the complete inability of quinolones to kill stationary-phase staphylococci, whereas rifampin had a good bactericidal activity not only against growing, but also against stationary-phase S. aureus. In conclusion, the experimental data favour the use of rifampin-quinolone combinations in the treatment of implant-associated infections due to S. aureus.