Prosthetic joint infections remain a major complication of arthroplasty. At present, local and international guidelines recommend cefazolin as a surgical antibiotic prophylaxis at the time of arthroplasty. This retrospective cohort study conducted across 10 hospitals over a 3-year period (January 2006 to December 2008) investigated the epidemiology and microbiological etiology of prosthetic joint infections. There were 163 cases of prosthetic joint infection identified. From a review of the microbiological culture results, methicillin-resistant Staphylococcus aureus (MRSA) and coagulase-negative staphylococci were isolated in 45% of infections. In addition, polymicrobial infections, particularly those involving Gram-negative bacilli and enterococcal species, were common (36%). The majority (88%) of patients received cefazolin as an antibiotic prophylaxis at the time of arthroplasty. In 63% of patients in this cohort, the microorganisms subsequently obtained were not susceptible to the antibiotic prophylaxis administered. The results of this study highlight the importance of ongoing reviews of the local ecology of prosthetic joint infection, demonstrating that the spectrum of pathogens involved is broad. The results should inform empirical antibiotic therapy. This report also provokes discussion about infection control strategies, including changing surgical antibiotic prophylaxis to a combination of glycopeptide and cefazolin, to reduce the incidence of infections due to methicillin-resistant staphylococci.

Despite known low sensitivity, culture of periprosthetic tissue specimens on agars and in broths is routine. Culture of periprosthetic tissue samples in blood culture bottles (BCBs) is potentially more convenient, but it has been evaluated in a limited way and has not been widely adopted. The aim of this study was to compare the sensitivity and specificity of inoculation of periprosthetic tissue specimens into blood culture bottles with standard agar and thioglycolate broth culture, applying Bayesian latent class modeling (LCM) in addition to applying the Infectious Diseases Society of America (IDSA) criteria for prosthetic joint infection. This prospective cohort study was conducted over a 9-month period (August 2013 to April 2014) at the Mayo Clinic, Rochester, MN, and included all consecutive patients undergoing revision arthroplasty. Overall, 369 subjects were studied; 117 (32%) met IDSA criteria for prosthetic joint infection, and 82% had late chronic infection. Applying LCM, inoculation of tissues into BCBs was associated with a 47% improvement in sensitivity compared to the sensitivity of conventional agar and broth cultures (92.1 versus 62.6%, respectively); this magnitude of change was similar when IDSA criteria were applied (60.7 versus 44.4%, respectively; P = 0.003). The time to microorganism detection was shorter with BCBs than with standard media ( P < 0.0001), with aerobic and anaerobic BCBs yielding positive results within a median of 21 and 23 h, respectively. Results of our study demonstrate that the semiautomated method of periprosthetic tissue culture in blood culture bottles is more sensitive than and as specific as agar and thioglycolate broth cultures and yields results faster. IMPORTANCE Prosthetic joint infections are a devastating complication of arthroplasty surgery. Despite this, current microbiological techniques to detect and diagnose infections are imperfect. This study examined a new approach to diagnosing infections, through the inoculation of tissue samples from around the prosthetic joint into blood culture bottles. This study demonstrated that, compared to current laboratory practices, this new technique increased the detection of infection. These findings are important for patient care to allow timely and accurate diagnosis of infection.

Prosthetic joint surgery has led to improvement in symptoms of osteoarthritis and patient's quality of life. The popularity of this surgery continues to increase worldwide, including in Australia [ 1 x 1 Australian Orthopaedic Association. National bone and joint registry annual report 2011. Adelaide 2011. Google Scholar See all References 1 ]. Data from epidemiological studies estimate that the number of knee and hip arthroplasties will increase to 4.5 million procedures per year by 2030 in the United States of America [ 2 x 2 Kurtz, S, Ong, K, Lau, E, Mowat, F, Halpern, M et al. Projections of primary and revision hip and knee arthroplasty in the United States from 2005 to 2030. J Bone Joint Surg Am. 2007; 89: 780–785 Crossref | PubMed | Scopus (3058) | Google Scholar See all References 2 ]. Infective complications of the prosthesis occur in 1–3% of patients undergoing hip and knee arthroplasty; however, they can have catastrophic consequences and often result in patient morbidity and significant cost to the public healthcare system [ 3 x 3 Zimmerli, W, Trampuz, A, Ochsner, PE et al. Prosthetic-joint infections. N Engl J Med. 2004; 351: 1645–1654 Crossref | PubMed | Scopus (627) | Google Scholar See all References 3 ]. In addition to the direct complications of infection, the need for treatment with antibiotics contributes to emerging antimicrobial resistance [ 4 x 4 Ridgeway, S, Wilson, J, Charlet, A, Kafatos, G, Pearson, A, Coello, R et al. Infection of the surgical site after arthroplasty of the hip. J Bone Joint Surg Br. 2005; 87: 844–850 Crossref | PubMed | Scopus (252) | Google Scholar See all References 4 ]. Superficial wound complications, such as surgical site infection (SSI) and prolonged wound discharge, have been consistently implicated in the development of prosthetic joint infection and may increase the risk of subsequent deep infection by up to 35-fold [ 5 x 5 Berbari, EF, Hanssen, AD, Duffy, MC et al. Risk factors for prosthetic joint infection: case-control study. Clin Infect Dis. 1998; 27: 1247–1254 Crossref | PubMed | Scopus (497) | Google Scholar See all References , 6 x 6 Saleh, K, Olson, M, Resig, S et al. Predictors of wound infection in hip and knee joint replacement: results from a 20 year surveillance program. J Orthop Res. 2002; 20: 506–515 Crossref | PubMed | Scopus (210) | Google Scholar See all References ]. While there are a number of epidemiological studies examining risk factors for deep prosthetic infections in hip and knee arthroplasty, risk factors for superficial wound complications are not as well established.

Information is required about treatment outcomes of Gram-negative prosthetic joint infections treated with prosthesis retention and surgical debridement, especially where biofilm-active antibiotics such as fluoroquinolones are used. The outcome of 17 consecutive patients with an early Gram-negative prosthetic joint infection who had been treated with prosthesis retention and surgical debridement was analysed. Enterobacteriaceae were isolated in 16 patients and infections were mixed with other organisms in 13 (76%) patients. The median joint age was 17 days and the median duration of symptoms before debridement was 7 days. All patients initially received intravenous β-lactam antibiotic therapy and 14 patients were then treated with oral ciprofloxacin. Treatment failure occurred in two patients over a median period of follow-up of 28 months. In only one patient was a relapsed Gram-negative infection responsible for the failure and this patient had not been treated with ciprofloxacin. The 2-year survival rate free of treatment failure was 94% (95% CI, 63–99%). Prosthesis retention with surgical debridement, in combination with antibiotic regimens including ciprofloxacin, was effective and should be considered for patients with early Gram-negative prosthetic joint infection.

Vancomycin-resistant enterococci (VRE) are common causes of bloodstream infections (BSIs) with high morbidity and mortality rates. They are pathogens of global concern with a limited treatment pipeline.