Prosthetic joint infections are difficult to treat due to bacterial biofilm. Our group has developed a linezolid elution system by human cancellous bone delivering high concentrations the first 48 hours (Giannitsioti et al. 53rd ICAAC, 2013: A-1050). We tested the activity of this system to inhibit growth of one ica expressing isolate of Staphylococcus epidermidis (MRSE).

At a first step, sterile mesh cylinders containing bone particles of the femoral head of healthy volunteers (MCB) were impregnated into 3mg/ml linezolid for 1, 24 and 48 hours. Then log-phase inocula of 103, 105 and 107cfu/ml were exposed to MCB at 370C for 8 days with regular readings of bacterial growth. MCB were transferred into fresh Muller-Hinton Broth (MHB) every 24h to avoid material corrosion. At a second step, to simulate the ability of the system against biofilm-coated MCB, MCB without linezolid were incubated with 103 and 105 cfu/ml for 1 and 24h. MCB were daily transferred into fresh MHB containing 100μg/ml on day 1, 15 μg/ml on day 2, 3 μg/ml on day 3 and 0.5 μg/ml on day 4.

24h linezolid impregnated MCB achieved rapid bacterial killing of the 105 cfu/ml bacterial suspension followed by re-growth (Figure, n= 5). Similar results were observed for 1h and 48h impregnation and for both tested inocula. When biofilm-coated MCB generated by 24h exposure to 105 cfu/ml were exposed to linezolid, rapid bacterial killing was achieved followed by re-growth.

Linezolid local elution may inhibit biofilm-producing MRSE only when locally eluted concentrations exceed 10μg/ml.

To compare usual practices against published guidelines of Perioperative Antimicrobial Prophylaxis (AP), which is an established method to reduce the risk of postoperative infection in TJR.

We prospectively evaluated AP in 616 patients, who underwent TJR of the hip and the knee in an ongoing cohort study. Teicoplanin was administered once perioperatively (10mg/kg iv) in one group A (n=278), while in the other group B (n=338) AP was administered according to the usual practice (various antibiotic combinations, including hemisynthetic penicillins/penicillinase inhibitors, cephalosporins, aminoglycosides and quinolones for 2–10 days). An evaluation form and personal examination were used for data collection and monitoring. Patients were followed up for 2 years minimum.

The two groups did not statistically differ (p> 0.05) regarding overall postoperative infections. Superficial soft tissue infection developed in 9/616 pts. 1/278 in group A (0.4%) vs 8/338 in group B (2.4%) (p< 0.05). Deep SSI was rarely seen, 4/616 pts (0.6%). 2/278 in group A (0.7%) vs 2/338 in group B (0.6%) (p=NS). Mean duration of AP was significant higher in group B [6(IQR: 5–8.25)], p< 0.001 Mann-Whitney test. Only in group B, MRSA-MRCNS postoperative infections did appear. The duration (days) of glycopeptide antibiotic usage, therapeutic (group B) or prophylactic (group A), was comparable in both groups (p> 0.05).

Glycopeptide antibiotic prophylaxis for TJR leads to less postoperative infections compared to other antibiotic prophylaxis, but similar duration of overall glycopeptide usage (prophylactic and therapeutic) in both groups.

Background: Perioperative Antimicrobial Prophylaxis (AP) is an established method to reduce the risk of intraoperative infection in TJR. Usual practices are not always compatible with published guidelines leading to excess morbidity, antibiotic overuse and emergence of resistance.

Methods: We prospectively evaluated AP in 616 patients, who underwent TJR of the hip and the knee in an ongoing cohort study. Teicoplanin was administered once perioperatively (10mg/kg iv) in one group A (n=278), while in the other group B (n=338) AP was administered according to the usual practice (various antibiotic combinations, including hemisynthetic penicillins/penicillinase inhibitors, cephalosporins, aminoglycosides and quinolones for 2–10 days). An evaluation form and personal examination were used for data collection and monitoring. Patients were followed up for 2 years minimum.

Results: The two groups did not statistically differ (p> 0.05) regarding overall postoperative infections. Superficial soft tissue infection developed in 9/616 pts. 1/278 in group A (0.4%) vs 8/338 in group B(2.4%) (p< 0.05). Deep SSI was rarely seen, 4/616 pts (0.6%). 2/278 in group A (0.7%) vs 2/338 in group B (0.6%) (p=NS). Mean duration of AP was significant higher in group B [6(IQR:5–8.25)], p< 0.001 Mann-Whitney test. Only in group B, MRSA-MRCNS postoperative infections did appear. The duration (days) of glycopeptide antibiotic usage, prophylactic (group A) or therapeutic (group B), was comparable in both groups (p> 0.05).

Conclusions: Glycopeptide antibiotic prophylaxis for TJR leads to less postoperative infections compared to other antibiotic prophylaxis, but similar duration of overall glycopeptide usage (prophylactic or therapeutic) in both groups.

The objective of the present study is to analyse the clinical, microbiological, and therapeutic features of patients with infective spondylodiscitis (ISD), who were followed up in our Outpatient Bone Infection Clinic.

We retrospectively studied the epidemiological and clinical characteristics of all patients diagnosed with ISD from January 1998 to December 2006. Data were extracted from an electronic data base registry and patients’ files.

Sixty patients either with spontaneous (n= 42, 70%) or postoperative (n= 18, 30%) ISD were evaluated. Population mean age was 56 years, 33 (55%) were male and 27 (45%) were female. The infection was localised in the lumbar (78%), thoracic (18%) or cervical (4%) spine. Predominate symptoms were pain (87%) and fever (50%). Fistula was observed exclusively in postoperative ISD (45%). In spontaneous ISD, the major causes were Brucella spp (33%), gram positive cocci (12%), gram negative bacteria (14%), Mycobacterium tuberculosis (7%), while in 33% of cases no pathogen was detected. In postoperative episodes of ISD the major causes were gram positive cocci (45%), gram negative bacteria (30%) and polymicrobial infection was documented in 22% of cases while in 25% of cases no pathogen was detected. Based on clinical, laboratory and imaging (especially MRI) data, treatment was individualised. Most patients (88%) received a combined antimicrobial treatment. Patients with spontaneous pyogenic/brucellosis or tuberculous/post-operative ISD received treatment for a median duration of 8/12/10 months and the response rate was 84%/81%/55.5%, respectively. Surgery was necessary in 40% of postoperative ISD cases for healing, while only one spontaneous case required a surgical intervention.

ISD is more frequently localised at the lumbar level. Long term combination antimicrobial treatment may be essential. Surgery may be required in iatrogenic cases in the presence of foreign bodies.

Aims: The effectiveness of the local treatment of experimental osteomyelitis by MRSA with a mixture of calcium phosphate bone cement and 3% teicoplanin into the femur of rabbits.

Methods: Thirty-six male rabbits with chronic (3 weeks) MRSA (Methicillin Resistant Staph. aureus) osteomyelitis of the right femur (Model of Norden CW) were treated with a new local Teicoplanin delivery system prepared by a mixture of calcium phosphate cement plus 3% teicoplanin. Osteomyelitis was introduced by inoculating 107 cfu/ml of the MRSA strain in a 2mm hole of the bone medula, placement of a needle serving as a foreign body and subsequent closure with a sterile bone wax. The follow-up of the infection was performed by clinical, microbiological, x-rays and histological findings. On the third week all animals were reoperated and the needle was removed followed by implantation of the above mixture. One control and five treated animals were sacrificed each week thereafter until the sixth week.

Results: Cultures of the treated animals were positive during the first week but turned negative after the second week, while throughout the same period cultures from the controls remain positive. Clinical and histologic studies were in accordance.

Conclusions: The above mixture could be approved as a supplementary method in the treatment of bone infections. It can be used by replacing the gentamycin polymethylmethacrylate beads whose use demands reoperation to be removed. Finally it offers the possibility to contribute to the filling of the bone gaps as it can be replaced by host bone.