Prosthetic joint infection is one of the most challenging complications of joint alloplasty and the diagnosis remains difficult. The aim of the study was to investigate the bacterial flora in surgical samples from 22 prosthetic patients using a panel of culture-independent molecular methods including broad range 16S rRNA gene PCR, cloning, sequencing, phylogeny, quantitative PCR (qPCR), and fluorescence in situ hybridization (FISH). Concomitant samples were cultured by standard methods. Molecular methods detected presence of bacteria in samples from 12 of 22 patients. Using clone libraries a total of 40 different bacterial species were identified including known pathogens and species not previously described in association with prosthetic joint infections. The predominant species were Propionibacterium acnes and Staphylococcus epidermidis; polymicrobial infections were found in 9 patients. Culture-based methods showed bacterial growth in 8 cases with the predominant species being S. epidermidis. Neither anaerobic bacteria (including P. acnes) nor any of the species not previously described in implant infections were isolated. Additionally, 7 of the 8 culture positive cases were monomicrobial. Overall, the results of culture-based and molecular methods showed concordance in 11 cases (hereof 9 negative by both methods) and discrepancy in 6 cases. In the remaining 5 cases, culture-based methods identified only one species or a group of bacteria (e.g., coagulase negative staphylococci or coryneform rods), while culture-independent molecular methods were able to detect several distinct bacterial species including a species within the group identified by culture. A qPCR assay was developed to assess the abundance of Propionibacterium while S. aureus was quantified by a published S. aureus qPCR assay. These quantifications confirmed the findings from the clone library approach and showed the potential of qPCR for fast detection of bacteria in orthopedic samples. Additionally, both single cells and microcolonies were visualized using FISH and confocal scanning laser microscopy. In conclusion, the molecular methods detected a more diverse bacterial flora in prosthetic joint infections than revealed by standard culture-based methods, and polymicrobial infections were more frequently observed. The pathogenesis of these microorganisms and their role in implant-associated infections needs to be determined

Prosthetic joint infections provide complex management, due to often-difficult diagnosis, need for multiple surgeries and increased technical and financial requirements. “2 in 1” single stage approaches have been advocated due to reduction in risks, costs and complications. This study aimed to investigate the results of single stage revision using metaphyseal sleeves for infected primary Total Knee Replacement (TKR). Prospective data was collected on all patients presenting with an infected primary TKR over an 8-year period (2009–17). All revision procedures were undertaken in a single stage using metaphyseal sleeves. 26 patients were included, 2 of which had previously failed 2 stage revision and 3 failed DAIR procedures. Mean age was 72.5. Mean BMI was 33.4. Median ASA 2. Mean time to revision was 3.5 years range 3 months to 12 years. Six patients had actively discharging sinuses at the time of surgery. Only 4 of the 26 patients had no positive microbiological cultures from deep tissue samples or joint aspirates. Only one patient has a recurrence of infection. This patient did not require further surgery and is treated on long term antibiotic suppression and is systemically well. There were statistically significant improvements in both the pain and function component of AKSS scores. There was no significant improvement in flexion, however mean extension and total range of movement both showed statistically significant improvements. Using Metaphyseal sleeves in single stage revision for infected TKR are safe and lead to an improvement in pain, function and have excellent efficacy for eradication of infection

Background. Previous data from our institution show that more than half of all prosthetic joint infections are due to S. aureus. A significant proportion of these bacteria may have an endogenous source. Detecting and treating asymptomatic S. aureus nasal carriers preoperatively has been shown to reduce the risk of infection. Material and Methods. This is an ongoing prospective study that started in March/2009 and involves primary total knee or hip arthroplasties candidates. So far preoperative nasal swab cultures were performed in 211(61%) out of 347 patients operated until April/2010. Carriers are identified and randomly chosen for preoperative treatment consisting of nasal mupirocin twice a day and daily cloro-hexidine baths in the 5 days that precede surgery. Antibiotic prophylaxis is cefazolin 24hours adding a single vancomycin dose in MRSA carriers. Results. Around 30% (64/211) of patients presented Saureus nasal carriage and 6 of them (9.4%) were methicilin-resistant. Infection rate was lower in the non-carriers: 1.36% (2/147). The group of 33 untreated carriers so far has the higher prevalence of infection (6.06%; Odds ratio=4.677; p=0.098). In the 31 treated carriers there was only one infection to date (3.23%; Odds ratio=2.371; p=0.463). The 136 patients control group in which no preoperative nasal culture was made registered 4 infections (2.94%; Odds ratio=2.197; p=0.356). Five out of the nine infections involved S. aureus. We further isolated 3 S. epidermidis, 1 enterococcus and 2 gram-negatives. Discussion. It seems that two S. aureus infections were due to endogenous contamination as the infecting bacteria possesses the exact same phenotype as the colonizing preoperative one (one untreated and one treated carrier). In other two S. aureus cases the seeding appears exogenous (a preoperative negative culture and a infecting bacteria different than the preoperative screening). One infection was registered in a non-studied patient. Accordingly, exogenous contamination seems responsible for at least 6 out of 9 infections. Conclusion. These preliminary results suggest that S. aureus colonization may be an endogenous risk factor for prosthetic joint infection that can be influenced. However exogenous contamination is still a major risk factor in our institution

Enterococcus faecalis is a rare but recognized cause of prosthetic joint infection. It is notorious for formation of biofilm on prosthetic surfaces. We hypothesized that a ‘serum factor’ was responsible for transformation of E. faecalis from its planktonic form to a biofilm existence upon making contact with prostheses. Using a novel ‘proteomic approach’, we studied the protein expression profiles of this bacterium when grown on an artificial surface in a serum environment against a control. E.faecalis 628 transconjugant formed by conjugation clinical strain (E55) and laboratory strain (JH2-2) was used to inoculate each of rabbit serum (RS) and Brain Heart Infusion (BHI) agar as a control and grown for 24 hours. Proteins were harvested for analysis in fractions including cell surface, membrane and cytosolic proteins. Recovered proteins were separated using 2-dimentional polyacrylamide gel electrophoresis (2D PAGE). Gels were stained and spots of interest harvested. These were analyzed using MALDI mass spectrometry followed by peptide mass fingerprinting using online database searches. Two surface exclusion proteins Sea1 and PrgA were only expressed from the serum culture. These proteins are both encoded by genes very close to the gene for enterococcal aggregation substance PrgB, which plays an integral role in biofilm formation. PrgA and PrgB are both encoded by the prgQ operon and hence expressed simultaneously upon activation of the operon. This tendency for serum only protein expression suggests the possibility of a pheromone-like activator in serum that could be a potential therapeutic target for management of biofilm associated E. faecalis prosthetic infections

Aims

This study describes and compares the operative management and outcomes in a consecutive case series of patients with dislocated hemiarthroplasties of the hip, and compares outcomes with those of patients not sustaining a dislocation.

Objectives

Deep bone and joint infections (DBJI) are directly intertwined with health, demographic change towards an elderly population, and wellbeing.

The elderly human population is more prone to acquire infections, and the consequences such as pain, reduced quality of life, morbidity, absence from work and premature retirement due to disability place significant burdens on already strained healthcare systems and societal budgets.

DBJIs are less responsive to systemic antibiotics because of poor vascular perfusion in necrotic bone, large bone defects and persistent biofilm-based infection. Emerging bacterial resistance poses a major threat and new innovative treatment modalities are urgently needed to curb its current trajectory.

Aims

Hip hemiarthroplasty is a standard treatment for intracapsular proximal femoral fractures in the frail elderly. In this study we have explored the implications of early return to theatre, within 30 days, on patient outcome following hip hemiarthroplasty.