Treatment approaches to prosthetic joint infections: results of an Emerging Infections Network survey

Variation in North American Infectious Disease Specialists' Practice Regarding Oral and Suppressive Antibiotics for Adult Osteoarticular Infections: Results of an Emerging Infections Network (EIN) Survey

Background

Osteoarticular infections (OAIs) are commonly treated with prolonged intravenous (IV) antimicrobials. The Oral versus Intravenous Antibiotics for Bone and Joint Infection (OVIVA) trial demonstrated that oral (PO) antibiotics are noninferior to IV antibiotics in the treatment of OAIs. We surveyed infectious disease (ID) physicians about their use of PO antibiotics in the treatment of OAIs.

Methods

An Emerging Infection Network survey with 9 questions regarding antibiotic prescribing for the treatment of OAIs was sent to 1475 North American ID physicians. The questions were mostly multiple choice and focused on the use of definitive oral antibiotic therapy (defined as oral switch within 2 weeks of starting antibiotics) and chronic suppressive antibiotic therapy (SAT).

Results

Of the 413 physicians who reported treating OAIs, 91% used oral antibiotics at least sometimes and 31% used them as definitive therapy, most often for diabetic foot osteomyelitis and native joint septic arthritis. The oral antibiotics most frequently used for OAIs included trimethoprim-sulfamethoxazole, doxycycline/minocycline, and linezolid for Staphylococcus aureus, amoxicillin/cefadroxil/cephalexin for streptococci, and fluoroquinolones for gram-negative organisms. The most common rationales for not transitioning to oral antibiotics included nonsusceptible pathogens, comorbidities preventing therapeutic drug levels, and concerns about adherence. SAT use was variable but employed by a majority in most cases of periprosthetic joint infection managed with debridement and implant retention.

Conclusions

North American ID physicians utilize oral antibiotics and SAT for the management of OAIs, although significant practice variation exists. Respondents voiced a need for updated guidelines.

Mapping Bacterial Biofilm on Features of Orthopedic Implants In Vitro

Implant-associated infection is a major complication of orthopedic surgery. One of the most common organisms identified in periprosthetic joint infections is Staphylococcus aureus, a biofilm-forming pathogen. Orthopedic implants are composed of a variety of materials, such as titanium, polyethylene and stainless steel, which are at risk for colonization by bacterial biofilms. Little is known about how larger surface features of orthopedic hardware (such as ridges, holes, edges, etc.) influence biofilm formation and attachment. To study how biofilms might form on actual components, we submerged multiple orthopedic implants of various shapes, sizes, roughness and material type in brain heart infusion broth inoculated with Staphylococcus aureus SAP231, a bioluminescent USA300 strain. Implants were incubated for 72 h with daily media exchanges. After incubation, implants were imaged using an in vitro imaging system (IVIS) and the metabolic signal produced by biofilms was quantified by image analysis. Scanning electron microscopy was then used to image different areas of the implants to complement the IVIS imaging. Rough surfaces had the greatest luminescence compared to edges or smooth surfaces on a single implant and across all implants when the images were merged. The luminescence of edges was also significantly greater than smooth surfaces. These data suggest implant roughness, as well as large-scale surface features, may be at greater risk of biofilm colonization.

Oral versus intravenous antibiotics for bone and joint infections: the OVIVA non-inferiority RCT

BACKGROUND

Management of bone and joint infection commonly includes 4-6 weeks of intravenous (IV) antibiotics, but there is little evidence to suggest that oral (PO) therapy results in worse outcomes.

OBJECTIVE

To determine whether or not PO antibiotics are non-inferior to IV antibiotics in treating bone and joint infection.

DESIGN

Parallel-group, randomised (1 : 1), open-label, non-inferiority trial. The non-inferiority margin was 7.5%.

SETTING

Twenty-six NHS hospitals.

PARTICIPANTS

Adults with a clinical diagnosis of bone, joint or orthopaedic metalware-associated infection who would ordinarily receive at least 6 weeks of antibiotics, and who had received ≤ 7 days of IV therapy from definitive surgery (or start of planned curative treatment in patients managed non-operatively).

INTERVENTIONS

Participants were centrally computer-randomised to PO or IV antibiotics to complete the first 6 weeks of therapy. Follow-on PO therapy was permitted in either arm.

MAIN OUTCOME MEASURE

The primary outcome was the proportion of participants experiencing treatment failure within 1 year. An associated cost-effectiveness evaluation assessed health resource use and quality-of-life data.

RESULTS

Out of 1054 participants (527 in each arm), end-point data were available for 1015 (96.30%) participants. Treatment failure was identified in 141 out of 1015 (13.89%) participants: 74 out of 506 (14.62%) and 67 out of 509 (13.16%) of those participants randomised to IV and PO therapy, respectively. In the intention-to-treat analysis, using multiple imputation to include all participants, the imputed risk difference between PO and IV therapy for definitive treatment failure was -1.38% (90% confidence interval -4.94% to 2.19%), thus meeting the non-inferiority criterion. A complete-case analysis, a per-protocol analysis and sensitivity analyses for missing data each confirmed this result. With the exception of IV catheter complications [49/523 (9.37%) in the IV arm vs. 5/523 (0.96%) in the PO arm)], there was no significant difference between the two arms in the incidence of serious adverse events. PO therapy was highly cost-effective, yielding a saving of £2740 per patient without any significant difference in quality-adjusted life-years between the two arms of the trial.

LIMITATIONS

The OVIVA (Oral Versus IntraVenous Antibiotics) trial was an open-label trial, but bias was limited by assessing all potential end points by a blinded adjudication committee. The population was heterogenous, which facilitated generalisability but limited the statistical power of subgroup analyses. Participants were only followed up for 1 year so differences in late recurrence cannot be excluded.

CONCLUSIONS

PO antibiotic therapy is non-inferior to IV therapy when used during the first 6 weeks in the treatment for bone and joint infection, as assessed by definitive treatment failure within 1 year of randomisation. These findings challenge the current standard of care and provide an opportunity to realise significant benefits for patients, antimicrobial stewardship and the health economy.

FUTURE WORK

Further work is required to define the optimal total duration of therapy for bone and joint infection in the context of specific surgical interventions. Currently, wide variation in clinical practice suggests significant redundancy that likely contributes to the excess and unnecessary use of antibiotics.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN91566927.

FUNDING

This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 23, No. 38. See the NIHR Journals Library website for further project information.

Clinical Outcome of Massive Endoprostheses Used for Managing Periprosthetic Joint Infections of the Hip and Knee

BACKGROUND

Endoprosthetic replacement (EPR) is an option for management of massive bone loss resulting from infection around failed lower limb implants. The aim of this study is to determine the mid-term outcome of EPRs performed in the treatment of periprosthetic joint infection (PJI) and infected failed osteosyntheses around the hip and knee joint and identify factors that influence it.

METHODS

We retrospectively reviewed all hip and knee EPRs performed between 2007 and 2014 for the management of chronic infection following complex arthroplasty or fracture fixation. Data recorded included indication for EPR, number of previous surgeries, comorbidities, and organism identified. Outcome measures included PJI eradication rate, complications, implant survival, mortality, and functional outcome (Oxford Hip or Knee Score).

RESULTS

Sixty-nine EPRs (29 knees and 40 hips) were performed with a mean age of 68 years (43-92). Polymicrobial growth was detected in 36% of cases, followed by coagulase-negative staphylococci (28%) and Staphylococcus aureus (10%). Recurrence of infection occurred in 19 patients (28%): 5 were treated with irrigation and debridement, 5 with revision, 1 with above-knee amputation, and 8 remain on long-term antibiotics. PJI eradication was achieved in 50 patients (72%); the chance of PJI eradication was greater in hips (83%) than in knees (59%) (P = .038). The 5-year implant survivorship was 81% (95% confidence interval 74-88). The mean Oxford Hip Score and Oxford Knee Score were 22 (4-39) and 21 (6-43), respectively.

CONCLUSION

This study supports the use of EPRs for eradication of PJI in complex, multiply revised cases. We describe PJI eradication rate of 72% with acceptable functional outcome.

Antibiotic treatment of biofilm infections

Bacterial biofilms are associated with a wide range of infections, from those related to exogenous devices, such as catheters or prosthetic joints, to chronic tissue infections such as those occurring in the lungs of cystic fibrosis patients. Biofilms are recalcitrant to antibiotic treatment due to multiple tolerance mechanisms (phenotypic resistance). This causes persistence of biofilm infections in spite of antibiotic exposure which predisposes to antibiotic resistance development (genetic resistance). Understanding the interplay between phenotypic and genetic resistance mechanisms acting on biofilms, as well as appreciating the diversity of environmental conditions of biofilm infections which influence the effect of antibiotics are required in order to optimize the antibiotic treatment of biofilm infections. Here, we review the current knowledge on phenotypic and genetic resistance in biofilms and describe the potential strategies for the antibiotic treatment of biofilm infections. Of note is the optimization of PK/PD parameters in biofilms, high-dose topical treatments, combined and sequential/alternate therapies or the use antibiotic adjuvants.

Oral versus intravenous antibiotic treatment for bone and joint infections (OVIVA): study protocol for a randomised controlled trial

Background

Bone and joint infection in adults arises most commonly as a complication of joint replacement surgery, fracture fixation and diabetic foot infection. The associated morbidity can be devastating to patients and costs the National Health Service an estimated £20,000 to £40,000 per patient.

Current standard of care in most UK centres includes a prolonged course (4–6 weeks) of intravenous antibiotics supported, if available, by an outpatient parenteral antibiotic therapy service. Intravenous therapy carries with it substantial risks and inconvenience to patients, and the antibiotic-related costs are approximately ten times that of oral therapy. Despite this, there is no evidence to suggest that oral therapy results in inferior outcomes.

We hypothesise that, by selecting oral agents with high bioavailability, good tissue penetration and activity against the known or likely pathogens, key outcomes in patients managed primarily with oral therapy are non-inferior to those in patients treated by intravenous therapy.

Methods

The OVIVA trial is a parallel group, randomised (1:1), un-blinded, non-inferiority trial conducted in thirty hospitals across the UK. Eligible participants are adults (>18 years) with a clinical syndrome consistent with a bone, joint or metalware-associated infection who have received ≤7 days of intravenous antibiotic therapy from the date of definitive surgery (or the start of planned curative therapy in patients treated without surgical intervention). Participants are randomised to receive either oral or intravenous antibiotics, selected by a specialist infection physician, for the first 6 weeks of therapy. The primary outcome measure is definite treatment failure within one year of randomisation, as assessed by a blinded endpoint committee, according to pre-defined microbiological, histological and clinical criteria. Enrolling 1,050 subjects will provide 90 % power to demonstrate non-inferiority, defined as less than 7.5 % absolute increase in treatment failure rate in patients randomised to oral therapy as compared to intravenous therapy (one-sided alpha of 0.05).

Discussion

If our results demonstrate non-inferiority of orally administered antibiotic therapy, this trial is likely to facilitate a dramatically improved patient experience and alleviate a substantial financial burden on healthcare services.

Trial registration

ISRCTN91566927 - 14/02/2013

Electronic supplementary material

The online version of this article (doi:10.1186/s13063-015-1098-y) contains supplementary material, which is available to authorized users.

Current management of prosthetic joint infections in adults: results of an Emerging Infections Network survey

There is a dearth of guidance on the management of prosthetic joint infections (PJIs), in particular because of the lack of high-quality evidence for optimal antibiotics. Thus, we designed a nine-question survey of current practices and preferences among members of the Emerging Infections Network, a CDC-sponsored network of infectious diseases physicians, which was distributed in May 2012. In total, 556 (47.2%) of 1178 network members responded. As first-line antibiotic choice for MSSA PJI, 59% of responders indicated oxacillin/nafcillin, 33% cefazolin and 7% ceftriaxone; the commonest alternative was cefazolin (46%). For MRSA PJI, 90% preferred vancomycin, 7% daptomycin and 0.8% ceftaroline; the commonest alternative was daptomycin (65%). Antibiotic selection for coagulase-negative staphylococci varied depending on methicillin susceptibility. For staphylococcal PJIs with retained hardware, most providers would add rifampicin. Propionibacterium is usually treated with vancomycin (40%), penicillin (23%) or ceftriaxone (17%). Most responders thought 10-19% of all PJIs were culture-negative. Culture-negative PJIs of the lower extremities are usually treated with a vancomycin/fluoroquinolone combination, and culture-negative shoulder PJIs with vancomycin/ceftriaxone. The most cited criteria for selecting antibiotics were ease of administration and the safety profile. A treatment duration of 6-8 weeks is preferred (by 77% of responders) and is mostly guided by clinical response and inflammatory markers. Ninety-nine percent of responders recommend oral antibiotic suppression (for varying durations) in patients with retained hardware. In conclusion, there is considerable variation in treatment of PJIs both with identified pathogens and those with negative cultures. Future studies should aim to identify optimum treatment strategies.

Silver nanoparticles-modified films versus biomedical device-associated infections

A serious issue related to biomedical devices (BDs) is that of bacterial infections. BDs colonized by bacteria may cause infection or mortality. To prevent such infections, an effective strategy is to develop novel BDs with antibacterial abilities via various surface modification processes. Thus, plenty of silver nanoparticles (Ag NPs)-modified films were brought forward to because of their potential applications in improving the antibacterial properties of BDs. This article reviews the difficulties in diagnosing and treating biomedical device-associated infections as well as the state of arts in fabricating the Ag NPs-modified films for antibacterial applications. In addition, the nanoeffect of silver particles and the cytotoxicity of Ag NPs are also discussed. It is clear that safe and durable Ag NPs-modified films are more desirable for the BDs prone to bacteria. To further extend the investigations on controlling the toxicity path of Ag NPs to both bacteria and mammalian cells, developing novel green fabrication processes with more 'cleaner' (without accompaniment of ligands or reduction agents) Ag NPs should be the first mission for the material scientists to complete.