Empirical antibiotic therapy in prosthetic joint infections.

When dealing with prosthetic joint infections (PJI) there is often the need to start antibiotic therapy without having identified the underlying pathogen. Under these circumstances there is no consensus regarding which antibiotic to use. We aimed to produce local recommendations for empirical antibiotic treatment of PJI by describing the microbiological spectrum involved and respective antibiotic susceptibility profile. We examined the records of 75 consecutive patients that underwent surgery for prosthetic joint infection from July 2001 to December 2008. There were 49 women and 26 men with an average age of 63 years. Ninety culture results were available from 41 hips and 34 knee replacements. Staphylococcus sp. was present in most infections (72.8%) regardless of surgical site or classification. The prevalence of methicillin-resistance among staphylococci was 64.2% with no relevant difference between sub-groups. Vancomycin is 100% effective against most commonly isolated Gram positives. Gram negative pathogens were present in about 15% of all cases, especially in haematogenous and chronic infections. Carbapenems and aminoglycosides are the most effective antibiotics against these pathogens. Our results suggest that in acute post-operative infections, treatment should start with vancomycin. In chronic and haematogeneous infections, vancomycin in combination with carbapenems appears to be an effective regimen. Treatment should be adjusted as soon as preliminary or definitive microbiology results are available.