[The current pathogen spectrum--what are we fighting against?].

Surgical site infections are mainly caused by bacteria from the patients' skin or gut flora representing endogenous infections. In orthopedic and trauma surgery the skin commensals dominate and as a consequence Gram-positive bacteria are the main pathogens, particularly S. aureus. Additionally and especially in the case of foreign body infections, less virulent pathogens, e.g. coagulase-negative staphylococci play an important role. Due to newer microbiological techniques in detecting pathogens the spectrum of causative organisms is steadily increasing. As known for other nosocomial infections the relevance of multidrug resistant bacteria in surgical site infections is growing and the key player is methicillin-resistant S. aureus (MRSA); however vancomycin-resistant enterococci (VRE), extended spectrum betalactamases and/or carbapenemases producing enterobacteria and recently even panresistant Acinetobacter baumannii isolates have to be considered.