Aim

Gram negative bacteria (GNB) are emerging pathogens in chronic post-traumatic osteomyelitis. However, data on multi-drug (MDR) and extensively drug resistant (XDR) GNB are sparse.

Aim

Data on Prosthetic joint infection (PJI) caused by multi-drug resistant (MDR) or XDR (extensively drug resistant) Gram negative bacteria (GNB) are limited. Treatment options are also restricted. We conducted a multi-national, multi-center assessment of clinical data and factors of outcome for these infections.

Acute postoperative periprosthetic joint infection (PJI) is a serious complication after any hemiarthroplasty (HHA) implanted due to a proximal hip fracture. The growing number of chronic institutionalized geriatric patients (CIGP) colonized with multi-drug resistant bacteria (e.g.: MRSA), not covered by usual antibiotic prophylaxis, has been identified as a risk factor for PJI after HHA. We therefore sought to compare the HHA infection characteristics between non-institutionalized patients (NIP) with proximal hip fractures and CIGP. We investigate (1) the rate of compliance with a new proposed protocol, (2) the acute infection rate, 3) the microbiologic characteristics of the infection, and 4) the success of the new protocol.

We gathered clinical, operative and infection data on all patients who underwent HHA due to a proximal femoral fracture in our center, during a 3-year period. We focus in the cases of acute postoperative infection (Zimmerli´s criteria). The new proposed antibiotic prophylaxis is cefazolin except in CIGP in which co-trimoxazole is used.

During the study period a total of 385 HHA in 385 patients were performed. In all cases the HHA was performed after a proximal femoral fracture. Overall, 109 patients (28,2%) were CIGP. We found an acute postoperative PJI in 21 out 385 HHA procedures, that is, a global acute infection rate of 5.43%. Ten out 109 (9.17%) CIGP patients resulted infected compared to 11 out 278 (3.9%) non-institutionalized patients (p: 0.049). One or more causative microorganisms were identified in 20/21 (95%) of PJI. Globally the Gram-Negative bacilli group accounted for the majority of the infections (60%). Staphylococus aureus was isolated in 3 cases (8.6%) with only a single MRSA infection. The percentage of polymicrobial infections was 47% (10 out of 21). Co-trimoxazole was used in the prophylaxis in 80.1% of the CIGP. In the infected cases a non-effective drug against the microorganism was used in the prophylaxis in 17 (81%) of the acute infected HHA.

We confirm that institutionalized patients are more prone to acute infections after a HHA. Our current strategy of antibiotic prophylaxis has showed to be effective in preventing MRSA PJI in CIGP. However, we found an increased rate of infection due to gram-negative bacilli non-covered by the current antibiotic prophylaxis. According our data an extended antibiotic prophylaxis on gram-negative drug will be proposed to be implemented in CIGP scheduled to a HHA because a proximal femoral fracture.

This study evaluates the long-term survival of spinal implants after surgical site infection (SSI) and the risk factors associated with treatment failure.

A Kaplan-Meier survival analysis was carried out on 43 patients who had undergone a posterior spinal fusion with instrumentation between January 2006 and December 2008, and who consecutively developed an acute deep surgical site infection. All were appropriately treated by surgical debridement with a tailored antibiotic program based on culture results for a minimum of eight weeks.

A ‘terminal event’ or failure of treatment was defined as implant removal or death related to the SSI. The mean follow-up was 26 months (1.03 to 50.9). A total of ten patients (23.3%) had a terminal event. The rate of survival after the first debridement was 90.7% (95% confidence interval (CI) 82.95 to 98.24) at six months, 85.4% (95% CI 74.64 to 96.18) at one year, and 73.2% (95% CI 58.70 to 87.78) at two, three and four years. Four of nine patients required re-instrumentation after implant removal, and two of the four had a recurrent infection at the surgical site. There was one recurrence after implant removal without re-instrumentation.

Multivariate analysis revealed a significant risk of treatment failure in patients who developed sepsis (hazard ratio (HR) 12.5 (95% confidence interval (CI) 2.6 to 59.9); p < 0.001) or who had > three fused segments (HR 4.5 (95% CI 1.25 to 24.05); p = 0.03). Implant survival is seriously compromised even after properly treated surgical site infection, but progressively decreases over the first 24 months.

Cite this article: Bone Joint J 2013;95-B:1121–6.

Aims

Currently, the most common approach for the management of a chronic PJI is a Two-Stage Replacement; because of success rates exceeding 90% when using an antibiotic impregnated cement spacer. Reliable information regarding the etiologic microorganism and its sensitivities is essential to select the antimicrobial therapy that should be used locally in the bone cement spacer during the first stage surgery as well as to select the appropriate microbiological systemic agent. Diagnostic algorithms focus to the importance of joint aspiration cultures although in the modern literature, preoperative joint aspiration has a broad range of values of sensitivity and the proportion of “dry-aspirations” is not well assessed. This low sensitivity of aspiration fluid samples in chronic-PJI is partly attributable to the fact that the majority of the microorganisms in these infections grow in biofilms attached to the implant. We have developed this biopsy technique in an effort to improve the identification rates of the causative organism.

Successful treatment of prosthetic joint infections (PJIs) requires surgical intervention and prolonged antimicrobial therapy (AT), although the most suitable management has not been clearly defined yet. The aim of the study is to review our experience in the management of AHPJIs.

From 01/01/2004 to 31/12/2006 all patients with PJIs were prospectively evaluated in 8 Spanish hospitals by the REIPI. We focused here on AHPJIs. Diagnostic of infection was based on clinical-microbiological evidence.

Forty-nine patients, 30 (61.2%) women, median age: 75.35 years (range: 31–92), were diagnosed of AHPJIs: 22 (44.8%) hips, 26 (53%) knees and 1 (2%) elbow implants. Following total joint replacement our patients had a median infection-free period of 4.9 years (range 0.3 to 18.7). The comorbidities were: 9 (18.3%) rheumatoid arthritis, 7 (14.3%) diabetes, and 6 (12.2%) chronic renal failure. Clinical features were acute in all cases: pain 100%, inflammatory signs 75.5%, and fever 70%. In 27 (55%) of the cases a distant previous infection caused by the same microorganism could be identified. The etiology was: S. aureus 18 (36.7%), streptococcal infections 13 (26.5%), coagulase-negative staphylococci 2 (4%), gram-negative bacilli 11 (22.4%), anaerobes 2 (4%), and mixed infections in 3 (6.1%) cases. Thirty (61.1%) patients underwent early drainage/debridement with retention of the implant, 11 (22.4%) two-stage replacement, 6 (12.5%) arthrodesis, 1 (2.1%) resection arthroplasty, and 1 unknown. Patients were treated with specific AT (median duration of 10.6 weeks) according to the isolated microorganism. At 1 year follow-up 25 (51%) were cured, 7 (14.3%) relapsed after a conservative approach (3 required an arthrodesis and 1 a two-stage replacement), 5 (10.2 %) died and 5 (10.2%) had a re-infection; in 7 the evolution was unknown.

AHPJs can be successfully treated in most cases with surgical debridement plus an antibiotic course. If a relapse is observed, removal of the prostheses could be necessary.

Although linezolid has been used in the therapy of osteoarticular infections (OI), there is little information about its effectiveness and safety in prolonged therapy for OI.

Therefore the aim of our study was to assess the effectiveness and tolerability in OI and retrospectively evaluate multi-resistant gram-positive OI treated with linezolid 600 mg bid orally.

Between January 2003 and January 2007, 20 patients (10 men, mean age: 65 years) with 23 episodes of OI (19 of them associated with implants including 16 prosthetic joints) were treated with linezolid. In all but one episode, vitamin B6 was administered. Five were diabetic and 1 had renal insufficiency. All but two cases had infections due to multi-resistant coagulase-negative staphylococci. The median duration of therapy was 12.3 weeks (range 4–36 weeks). In 9 episodes the implant was removed. At the end of the therapy, response was observed in 22/23 (95.6%) of the episodes, and at the follow-up 10 relapses occurred (median duration: 1 month) resulting in an overall successful rate of cure of 12/23 (52.2%). The cure rate in episodes with and without implant removal was 6/9 (66.7%) and 3/10 (30%), respectively, while in the cases without implant 3/4 (75%). Adverse events that required drug discontinuation were observed in 10 (43.5%) episodes: anemia in 6/10 (60%), gastrointestinal in 6/10 (60%), lactic acidosis in two, teeth pigmentation in two and optic neuritis in one. Risk factors associated with secondary effects were: older age, diabetes mellitus and renal insufficiency. One patient developed anemia after one month; linezolid was stopped and restarted with vitamin B6 and no anemia was observed after 9 months of therapy.

Linezolid may be useful in multi-resistant gram-positive OI, especially when the implant is removed. However, with prolonged therapy, side effects are common, thus close monitoring for severe complications is needed.