Bacteriologic evidence of infection caused by coagulase-negative staphylococci in total hip replacement

Coagulase-negative staphylococci are important agents of infected hip arthr oplasties, but sample contamination from the skin flora may confuse the dia gnosis. Recovery of multiple identical strains has been regarded as indicat ion of true infection. We have evaluated 29 total hip replacement operation s with cultures positive for coagulase-negative staphylococci in a prospect ive study, 16 with greater than or equal to 3 isolates available for strain identity analysis. In 26 episodes, greater than or equal to 3 cultures wer e positive for coagulase-negative staphylococci, but only 19 of them had st rong or intermediate clinical evidence of infection. Negative clinical evid ence of infection coincided with the absence of a predominating strain acco rding to plasmid profile analysis. A reliable identity analysis may help to rule out infection when multiple cultures are positive in patients who lac k clinical evidence of infection.