This is the largest series of PJI by S. aureus managed with DAIR reported to date. The success rate was 55%. The use of rifampin may have contributed to homogenizing MSSA and MRSA prognoses, although the specific rifampin combinations may have had different efficacies.

It is important to know the spectrum of the microbial aetiology of prosthetic joint infections (PJIs) to guide empiric treatment and establish antimicrobial prophylaxis in joint replacements. There are no available data based on large contemporary patient cohorts. We sought to characterize the causative pathogens of PJIs and to evaluate trends in the microbial aetiology. We hypothesized that the frequency of antimicrobial-resistant organisms in PJIs has increased in the recent years. We performed a cohort study in 19 hospitals in Spain, from 2003 to 2012. For each 2-year period (2003-2004 to 2011-2012), the incidence of microorganisms causing PJIs and multidrug-resistant bacteria was assessed. Temporal trends over the study period were evaluated. We included 2524 consecutive adult patients with a diagnosis of PJI. A microbiological diagnosis was obtained for 2288 cases (90.6%). Staphylococci were the most common cause of infection (1492, 65.2%). However, a statistically significant rising linear trend was observed for the proportion of infections caused by Gram-negative bacilli, mainly due to the increase in the last 2-year period (25% in 2003-2004, 33.3% in 2011-2012; p 0.024 for trend). No particular species contributed disproportionally to this overall increase. The percentage of multidrug-resistant bacteria PJIs increased from 9.3% in 2003-2004 to 15.8% in 2011-2012 (p 0.008), mainly because of the significant rise in multidrug-resistant Gram-negative bacilli (from 5.3% in 2003-2004 to 8.2% in 2011-2012; p 0.032). The observed trends have important implications for the management of PJIs and prophylaxis in joint replacements.

We sought to characterize the causative pathogens of surgical site infections (SSIs) following primary total joint arthroplasties and to evaluate trends in the microbial etiology. We analyzed the etiology of SSIs following 2,632 total hip arthroplasty and knee arthroplasty procedures performed at our institution from 2004 through 2010. We calculated the annual proportion of SSIs accounted for each of the most common organisms and evaluated trends using the x 2 test for trend. SSIs were identified in 111 procedures (4.2%). The annual incidence of SSIs did not change significantly during the study period. Staphylococci were the most common cause of infection (59.6%) and most of infections were monomicrobial (82.8%). From 2004 to 2010, the annual proportion of infections due to gram-negative bacilli (GNB) increased from 21.4% to 66.7% (p ¼ 0.085 for trend). This increase was accompanied by a decline in the proportion of SSIs from coagulase-negative staphylococci (p ¼ 0.003). Additionally, we found an increase in the percentage of polymicrobial infections (from 7.1% in 2004 to 41.7% in 2010, p ¼ 0.014). Multivariate analysis corroborated these trends. Our study reports an emergence of GNB as a cause of SSIs after primary total joint arthroplaties and an increase of polymicrobial infections.