Spectrum of pathogens in surgical site infections at a Swiss university hospital.

Background: The type of surgical antimicrobial prophylaxis (SAP) is determined by the spectrum and antimicrobial resistance of pathogens causing surgical site infections (SSI). The aim of this study was to define the microbiological features of SSI in general surgery patients at Basel University Hospital in order to validate our current strategy of single-shot SAP with 1.5 g cefuroxime (plus 500 mg metronidazole in colorectal surgery).

Methods: A prospective observational cohort of consecutive vascular, visceral and trauma procedures was analysed to evaluate the incidence of SSI. Surgical wounds and resulting infections were assessed to centres for disease control standards. Microbiological evaluation was performed by microscopic direct preparation, cultures and testing for antibiotic resistance.

Results: A total of 293 instances of SSI were detected in this cohort of 6283 surgical procedures (4.7%). Microbiological species were identified in 129 of 293 SSI (44%). Staphylococcus aureus (29.5%) was the most common pathogen causing SSI in trauma and vascular surgery, whereas Escherichia coli (20.9%) was more frequently responsible for SSI in visceral surgery. Importantly, not a single case of SSI was caused by antimicrobial-resistant pathogens in this series.

Conclusions: The spectrum of pathogens causing SSI identified and the very low incidence of antimicrobial resistance at Basel University Hospital validate the continuous use of single-shot single-drug SAP with cefuroxime (plus metronidazole in colorectal surgery).