Efficacy and tolerability of prolonged linezolid therapy in the treatment of orthopedic implant infections

Uncommon Septic Arthritis of the Hip Joint in an Immunocompetent Adult Patient Due to Bacillus pumilus and Paenibacillus barengoltzii Managed with Long-Term Treatment with Linezolid: A Case Report and Short Literature Review

The Bacillus and Paenibacillus genera are diverse soil-related bacterial pathogens. In this case report, we describe, to our knowledge, the first report of septic arthritis in a native hip joint in an immunocompetent adult patient caused by Bacillus pumilus and Paenibacillus barengoltzii. We describe the case of a 39-year-old Caucasian male patient who sought medical advice for chronic pain on the mobilization of the right hip, decreased range of motion, and physical asthenia. The patient underwent a surgical intervention (core decompression) for a right osteonecrosis of the femoral head, with a slightly favorable postoperative evolution after surgery for one month. Surgical treatment was planned on the basis of clinical and paraclinical investigations and the joint damage. The hip was explored using an anterior approach under spinal anesthesia and standard antibiotic prophylaxis. After resection of the femoral head, meticulous debridement of all inflammatory tissues was performed, and a preformed temporary spacer was inserted into the femoral canal. Bacteriological laboratory studies identified Bacillus pumilus and Paenibacillus barengoltzii via matrix-assisted laser desorption-ionization time-of-flight mass spectrometry analysis. The patient initially received nine days of empirical therapy with intravenous antibiotics (linezolid and meropenem). After the bacterial strains were identified, the patient received organism-specific antibiotic therapy with the same antibiotics and dose for eight days until discharge. After discharge, the patient was referred to another hospital, where he continued treatment with linezolid for seven weeks and, after that, four weeks of oral therapy with cotrimoxazole and rifampicin. During this period, no severe or potentially life-threatening adverse events were recorded during long-term treatment with linezolid or with the two oral antibiotics. In conclusion, our findings suggest that long-term treatment with linezolid may be a viable option for the management of bone and joint infections caused by Bacillus pumilus and Paenibacillus barengoltzii.

Two-Stage Revision Arthroplasty for Resistant Gram-Positive Periprosthetic Joint Infections Using an Oral Linezolid-Based Antibiotic Regime

BACKGROUND

Increasing antibiotic resistance has been reported as an issue in the systemic treatment of periprosthetic joint infection (PJI). Linezolid offers the advantages of high oral bioavailability and little resistance; however, efficacy in the treatment of PJI varies considerably, and studies reporting consistent surgical treatment are scarce.

METHODS

This is a retrospective, single-center analysis of two-stage revisions performed between 2008 and 2017. We identified 111 patients who met the inclusion criteria. Oral linezolid was given for 28 days following 14 days of intravenous tailored antibiotics in resistant gram-positive PJI. A total of 64% of the patients had methicillin-resistant coagulase-negative staphylococci. The median follow-up was 43 (interquartile range (IQR) 30-57) months.

RESULTS

22% (24/111) of the patients underwent surgery for subsequent infection. The 5-year infection-free survival probability was 77% (95% confidence interval (CI) 69-85). A total of 5% of the patients (6/111) had the same organism at the time of reinfection. The patients with infections caused by other organisms than Coagulase-negative staphylococci tended to have a worse reinfection-free survivorship at five years (70% vs. 81%, p = 0.09). Furthermore, the patients with obesity tended to have reduced reinfection-free survivorship at five years (69% vs. 84%, p = 0.08). Overall, 5% (6/111) of the patients had blood count abnormalities with no treatment discontinuations.

CONCLUSION

Two-stage revision arthroplasty with systemic oral linezolid treatment for resistant gram-positive PJI results in an infection control of 77% at the mid-term.

Pharmacokinetic and pharmacodynamic simulation for the quantitative risk assessment of linezolid-associated thrombocytopenia

WHAT IS KNOWN AND OBJECTIVE

Linezolid (LZD) may cause thrombocytopenia, which can result in discontinuation of treatment. In this study, the blood LZD trough concentration was estimated based on population pharmacokinetic (PK) parameters derived from two previously published models in the Japanese population to determine the rate of achieving the target trough value when the risk of thrombocytopenia is low and to clarify its relationship with the onset of thrombocytopenia.

METHODS

This study included adult patients hospitalized at Shimane University Hospital, who received LZD treatment for at least 4 days from January 2010 to December 2017. Patients whose platelet count fell below 70% before LZD administration were categorized as the thrombocytopenic group. Patient PK parameters were calculated based on the population PK models described by Matsumoto et al. and Sasaki et al., and these parameters were designated A and B, respectively. Based on these parameters, the rate of achieving an LZD trough concentration of less than 8 μg/ml, which is the safety target achievement rate, was calculated using a random simulation for each patient. We further analysed the association between the incidence of thrombocytopenia and patient factors, including safety target achievement rate, through univariate, multivariate, and receiver operating characteristic (ROC) analyses.

RESULTS AND DISCUSSION

Patients (n = 77) aged 72 ± 11 years and weighing 56.7 ± 10.9 kg, with a creatinine clearance (CL_cr ) of 60.5 ± 47.2 ml/min and a cirrhosis prevalence of 9.1%, were analysed. All patients received LZD at a dose of 600 mg twice daily for a total of 10.9 ± 8.9 days. Univariate analyses revealed significant differences (p < 0.05) in the duration of LZD therapy, serum creatinine, creatinine clearance, LZD clearance, and the safety target achievement rate for parameters A and B between the thrombocytopenic and non-thrombocytopenic groups. A multivariate analysis of these factors stratified with the cutoff values obtained by ROC analysis revealed that the duration of LZD therapy and the safety target achievement rates for parameters A and B were significant factors (odds ratios for duration of LZD therapy: 7.436 [95% confidence interval (CI): 1.918-28.831] and 4.712 [95% CI: 1.567-14.163]; odds ratio for safety target achievement rate: 0.060 [95% CI: 0.016-0.232] and 0.167 [95% CI: 0.056-0.498] for parameters A and B, respectively). When the safety target achievement rates for patients treated with LZD were compared between the thrombocytopenic and non-thrombocytopenic groups, the safety target achievement rate was higher in the non-thrombocytopenic group in both the patients treated with LZD for less than 10 days and those for 10 days or more. Therefore, the safety target achievement rate estimated by the PK/PD simulation may represent to be an important index for risk assessment of LZD-induced thrombocytopenia.

WHAT IS NEW AND CONCLUSION

The risk of LZD-induced thrombocytopenia, which increased with the duration of LZD therapy, may be predicted using the safety target achievement rate obtained by the blood concentration simulation.

A Review of Population Pharmacokinetic Analyses of Linezolid

In recent years, many studies on population pharmacokinetics of linezolid have been conducted. This comprehensive review aimed to summarize population pharmacokinetic models of linezolid, by focusing on dosage optimization to maximize the probability of attaining a certain pharmacokinetic-pharmacodynamic parameter in special populations. We searched the PubMed and EMBASE databases for population pharmacokinetic analyses of linezolid using a parametric non-linear mixed-effect approach, including both observational and prospective trials. Of the 32 studies, 26 were performed in adults, four in children, and one in both adults and children. High between-subject variability was determined in the majority of the models, which was in line with the variability of linezolid concentrations previously detected in observational studies. Some studies found that patients with renal impairment, hepatic failure, advanced age, or low body weight had higher exposure and adverse reactions rates. In contrast, lower concentrations and therapeutic failure were associated with obese patients, young patients, and patients who had undergone renal replacement techniques. In critically ill patients, the inter-individual and intra-individual variability was even greater, suggesting that this population is at an even higher risk of underexposure and overexposure. Therapeutic drug monitoring may be warranted in a large proportion of patients given that the Monte Carlo simulations demonstrated that the one-size-fits-all labeled dosing of 600 mg every 12 h could lead to toxicity or therapeutic failure for high values of the minimum inhibitory concentration of the target pathogen. Further research on covariates, including renal function, hepatic function, and drug–drug interactions related to P-glycoprotein could help to explain variability and improve linezolid dosing regimens.

Orthopaedic Implant-Associated Staphylococcal Infections: A Critical Reappraisal of Unmet Clinical Needs Associated with the Implementation of the Best Antibiotic Choice

Infections associated with orthopaedic implants represent a major health concern characterized by a remarkable incidence of morbidity and mortality. The wide variety of clinical scenarios encountered in the heterogeneous world of infections associated with orthopaedic implants makes the implementation of an optimal and standardized antimicrobial treatment challenging. Antibiotic bone penetration, anti-biofilm activity, long-term safety, and drug choice/dosage regimens favouring outpatient management (i.e., long-acting or oral agents) play a major role in regards to the chronic evolution of these infections. The aim of this multidisciplinary opinion article is to summarize evidence supporting the use of the different anti-staphylococcal agents in terms of microbiological and pharmacological optimization according to bone penetration, anti-biofilm activity, long-term safety, and feasibility for outpatient regimens, and to provide a useful guide for clinicians in the management of patients affected by staphylococcal infections associated with orthopaedic implants Novel long-acting lipoglycopeptides, and particularly dalbavancin, alone or in combination with rifampicin, could represent the best antibiotic choice according to real-world evidence and pharmacokinetic/pharmacodynamic properties. The implementation of a multidisciplinary taskforce and close cooperation between microbiologists and clinicians is crucial for providing the best care in this scenario.

Tolerance of Prolonged Oral Tedizolid for Prosthetic Joint Infections: Results of a Multicentre Prospective Study

Objectives: Data on clinical and biological tolerance of tedizolid (TZD) prolonged therapy are lacking. Methods: We conducted a prospective multicentre study including patients with prosthetic joint infections (PJIs) who were treated for at least 6 weeks but not more than 12 weeks. Results: Thirty-three adult patients of mean age 73.3 ± 10.5 years, with PJI including hip (n = 19), knee (n = 13) and shoulder (n = 1) were included. All patients were operated, with retention of the infected implants and one/two stage-replacements in 11 (33.3%) and 17/5 (51.5%/15.2%), respectively. Staphylococci and enterococci were the most prevalent bacteria identified. The mean duration of TZD therapy was 8.0 ± 3.27 weeks (6–12). TZD was associated with another antibiotic in 18 patients (54.5%), including rifampicin in 16 cases (48.5). Six patients (18.2%) had to stop TZD therapy prematurely because of intolerance which was potentially attributable to TZD (n = 2), early failure of PJI treatment (n = 2) or severe anaemia due to bleeding (n = 2). Regarding compliance with TZD therapy, no cases of two or more omissions of medication intake were recorded during the whole TZD treatment duration. Conclusions: These results suggest good compliance and a favourable safety profile of TZD, providing evidence of the potential benefit of the use of this agent for the antibiotic treatment of PJIs.

Proactive therapeutic drug monitoring (TDM) may be helpful in managing long-term treatment with linezolid safely: findings from a monocentric, prospective, open-label, interventional study

BACKGROUND

Thrombocytopenia may be a dose-dependent adverse effect of linezolid therapy.

OBJECTIVES

To assess whether proactive therapeutic drug monitoring (TDM) could be helpful in preventing and/or in recovering from the occurrence of linezolid-induced thrombocytopenia during long-term treatment.

METHODS

This was a monocentric, prospective, open-label, interventional study conducted between June 2015 and December 2017 among adult patients receiving >10 days of linezolid therapy and undergoing proactive TDM (desired trough level 2-8 mg/L) and platelet count assessment at day 3-5 and then once weekly up to the end of treatment.

RESULTS

Sixty-one patients were included. Twenty-eight (45.9%) always had desired trough level (group A) and 33 (54.1%) experienced linezolid overexposure (group B) [29/33 transiently (subgroup B1) and 4/33 persistently (subgroup B2)]. No patient experienced linezolid underexposure. Median duration of treatment for the different groups ranged between 19 and 54 days. Thrombocytopenia occurred overall in 14.8% of cases (9/61). The incidence rate of thrombocytopenia was significantly lower (P=0.012) in both group A (10.7%; 3/28) and subgroup B1 (10.3%; 3/29) than in subgroup B2 (75.0%; 3/4). Thrombocytopenic patients belonging to both group A and group B1 recovered from thrombocytopenia without the need for discontinuing therapy. Multivariate linear regression analysis revealed that thrombocytopenia was independently associated with baseline platelet count and with median linezolid trough concentrations.

CONCLUSIONS

Proactive TDM of linezolid may be beneficial either in preventing or in recovering from dose-dependent thrombocytopenia, even when treatment lasts for more than 28 days. Larger prospective studies are warranted to confirm our findings.

Linezolid as salvage therapy for central nervous system infections due to methicillin-resistant Staphylococcus aureus at two medical centers in Taiwan

BACKGROUND

Methicillin-resistant Staphylococcus aureus (MRSA)-associated central nervous system infections are potentially devastating. Linezolid has good penetration into cerebrospinal fluid and brain tissue. In clinical practice, linezolid may be used to treat central nervous system infections caused by MRSA resulting from glycopeptide intolerance or treatment failure. However, the clinical experience of linezolid in treating MRSA related central nervous system infections is scarce.

METHODS

From 2006 to 2016, patients aged ≥20 years who had central nervous system infections caused by MRSA treated with linezolid for more than 24 hours were retrospectively included from two medical centers. The demographic details, treatment response, side effects, and relapse of infection were reviewed.

RESULTS

Sixty-six patients with proven CNS infection caused by MRSA were treated with linezolid. The mean age was 53.3 years. The diagnoses in this cohort consisted of brain abscesses (n = 19, 28.8%), spinal epidural abscess (n = 18, 27.3%), meningitis only (n = 12, 18.2%), meningitis with brain epidural abscess (n = 9, 13.6%), and spine device-related infection (n = 5, 7.6%). The main reasons to prescribe linezolid were glycopeptide treatment failure (51.5%) and glycopeptide allergy (48.5%). Ninety-one percent of patients were treated with linezolid for more than 14 days. The in-hospital mortality rate was 13.6%. The relapse rate after treatment was 16.7%. Drug-related adverse events (mainly cytopenia) were observed in 27.3% of patients, but none of the adverse events was fatal.

CONCLUSIONS

In our retrospective study, linezolid demonstrated promising effect as a salvage therapy for central nervous system infection caused by MRSA, whether due to drug allergy or glycopeptide treatment failure.

Clinical use of linezolid in periprosthetic joint infections - a systematic review

Introduction: The most common causative organism in periprosthetic joint infections (PJIs) is Gram-positive bacteria that are increasingly drug resistant. In these cases the use of linezolid may be warranted. However, there are conflicting reports regarding its role in antibiotic treatment of PJIs. The aim of this review is to gather and analyze clinical results and treatment details on linezolid in patients with PJIs. Methods: In August 2019, a comprehensive literature search using MEDLINE (Pubmed and Ovid) and Cochrane Library was performed. A total of 504 records were screened, and a total of 16 studies including 372 patients treated with linezolid for a PJI were included in this review based on the PRISMA criteria and after quality analysis using the MINOR score and Newcastle–Ottawa scale, as well as assessing level of evidence. Pooling analysis as well as descriptive analysis was performed. Results: Based on the results from the studies included, infection control was achieved in 80 % (range 30 %–100 %) of patients after a mean follow-up period of 25 (range 2–66) months. The mean duration of treatment was 58 d intravenous and orally at a median dose of 600 mg bis in die (b.i.d.) (range 400–900 b.i.d.). A combination therapy with rifampicin was used in 53 % of patients. MRSA (methicillin-resistant Staphylococcus aureus) infections were present in 29 % and resistant CoNS (coagulase-negative Staphylococcus) in 46 %. Adverse effects occurred in 33 % of cases, mostly anemia, thrombocytopenia and gastrointestinal complaints leading to treatment discontinuation in 9 %. However, great heterogeneity was found with respect to surgical treatment, diagnosis of infection and indication for linezolid. Discussion: Linezolid is an appropriate option for treatment of resistant Gram-positive organisms in PJIs. Most commonly 600 mg b.i.d. is used, and a combination with rifampicin appears feasible although one must consider individual increases in doses in these cases. However, adverse effects are common and there are limited data for long-term use and optimal antibiotic combinations or individual doses.

Linezolid in the treatment of periprosthetic joint infection caused by coagulase-negative staphylococci

Background: Periprosthetic joint infection (PJI) caused by coagulase-negative staphylococci (CoNS) is increasingly common and is sometimes treated with off-label use of linezolid. Methods: We conducted a retrospective study of patients with PJI caused by CoNS treated with surgical intervention and orally administrated linezolid during the period 1995-2014 (n = 28). Clinical outcomes and adverse events related to linezolid administration were evaluated. Mean time to follow-up was 4.3 years (range: 0.2-12). Results: Twenty-two of 28 patients were infection-free at follow-up. No CoNS strain was resistant to vancomycin, but 16 of 28 were resistant to rifampicin, 23 of 28 to clindamycin and 20 of 27 to quinolones. The mean duration of linezolid treatment was 4.2 weeks (range: 1-12). Eleven of 28 patients had an adverse event related to the antimicrobial treatment, and four had to discontinue linezolid, but all adverse events were reversible within 2 months after discontinuation. Conclusions: Oral linezolid administration combined with adequate surgical treatment may be useful for the treatment of PJIs caused by CoNS.

Clinical Pharmacokinetics and Pharmacodynamics of Oxazolidinones

Oxazolidinones are a class of synthetic antimicrobial agents with potent activity against a wide range of multidrug-resistant Gram-positive pathogens including methicillin-resistant Staphylococcus aureus and vancomycin-resistant enterococci. Oxazolidinones exhibit their antibacterial effects by inhibiting protein synthesis acting on the ribosomal 50S subunit of the bacteria and thus preventing formation of a functional 70S initiation complex. Currently, two oxazolidinones have been approved by the US Food and Drug Administration: linezolid and more recently tedizolid. Other oxazolidinones are currently under investigation in clinical trials. These antimicrobial agents exhibit a favourable pharmacokinetic profile with an excellent bioavailability and a good tissue and organ penetration. In-vitro susceptibility studies have shown that oxazolidinones are bacteriostatic against enterococci and staphylococci, and bactericidal for the majority of strains of streptococci. In the context of emergence of resistance to glycopeptides, oxazolidinones have become an effective alternative to vancomycin treatment frequently associated with nephrotoxicity. However, oxazolidinones, and linezolid in particular, are associated with significant adverse events, myelosuppression representing the main unfavourable side effect. More recently, tedizolid has been shown to effectively treat acute bacterial skin and skin structure infections. This newer oxazolidinone offers the advantages of once-daily dosing and a better safety profile in healthy volunteer studies (fewer gastrointestinal and haematological side effects). The potential use of tedizolid for other infections that could require longer therapy warrants further studies for positioning this new oxazolidinone in the available antimicrobial armamentarium. Moreover, other oxazolidinones are currently under active investigation.

Management of periprosthetic infections

Periprosthetic joint infection (PJI) is considered one of the most challenging complications compromising patient health and is considered an economic burden. Despite all strategies PJI prevalence is between 1%-2%. Considerable efforts have been investigated in the past decade to diminish or erradicate PJI prevalence. This article manages the definition of PJI and the new major and minor criteria from Parvizi et al Then a scientific analysis of every minor and major criteria. Multidisciplinary management is reccommended according to guidelines. A numerous of surgical options exist each and everyone with its indications, contraindications and specific antibiotic therapy regimen. Surgical options are: (1) irrigation and cleaning with retention of the prosthesis with a success rate 0%-89%; (2) single-stage revision surgery with a succes rate of > 80%; and (3) two-stage revision surgery (authors preferred method) with a succes rate of 87%. Radical treatment options like arthrodesis and amputation are reserved for specific group of patients, with a succes rate varying from 60%-100%. The future of PJI is focused on improving the diagnostic tools and to combat biofilm. The cornerstone of management consists in a rapid diagnosis and specific therapy. This article presents the most current diagnostic and treatment criteria as well as the different surgical treatment options depending on the type of infection, bacterial virulence and patient comorbidities.

Safety of long-term use of linezolid: results of an open-label study

Objective

The objective of this study was to assess the long-term safety of linezolid in patients with chronic infections requiring treatment for ≥6 weeks. Enhanced monitoring for optic neuropathy was included to characterize the early development of this side effect and to identify ophthalmologic tests that might be valuable in early detection of this event.

Methods

This was a multicenter, open-label, pilot study of patients aged ≥18 years on long-term linezolid therapy. Matched control patients were included for baseline assessment comparison. Patients were assessed at study entry, monthly while on treatment, at the end of treatment, and 30 days following the last dose. Aggregate ocular safety data were reviewed. Response to treatment was reported.

Results

The study was terminated owing to slow enrollment. Twenty-four patients received linezolid; nine patients were included as matched controls. Linezolid was prescribed for a median of 80.5 days (range, 50–254 days). In patients with a reported clinical outcome, the majority were considered improved or cured. Common treatment-related adverse events (AEs) included anemia, peripheral neuropathy, polyneuropathy, vomiting, and asthenia, and were consistent with the known safety profile. Most AEs resolved or stabilized with discontinuation of treatment. Results of ophthalmologic tests in the one case adjudicated as probable linezolid-associated optic neuropathy revealed abnormal color vision, characteristic changes in the optic disk, and central scotomas in each eye.

Conclusion

In our small population, linezolid was generally well tolerated and AEs were consistent with the known safety profile. Extensive ophthalmologic testing of all 24 linezolid-treated patients identified one case adjudicated as probable, linezolid-associated optic neuropathy.

Risk factors associated with high linezolid trough plasma concentrations

AIM

The major concern of linezolid is the adverse events. High linezolid trough serum concentration (Cmin) has been associated with toxicity. The aim of this study was to analyze factors associated with high Cmin.

METHODS

Main clinical characteristics of 104 patients treated with 600 mg/12 hours of linezolid were retrospectively reviewed. Samples were obtained just before the next dose after at least three doses and within the first 8 days of treatment. High Cmin was considered when it was >8 mg/L. Univariate and multivariate analysis were performed.

RESULTS

34.6% patients had a Cmin >8 mg/L, and they were older and had more frequently an estimated glomerular filtration by MDRD <40 mL/min. There were more patients co-treated with rifampin in the group with low Cmin. The only factor independently associated with Cmin >8 was the renal function. Patients with an eGF < 40 mL/min had significantly higher Cmin than those with eGF > 80 mL/min (OR: 4.273) and there was a trend towards a high Cmin in patients with eGF between 40-80 mL/min (OR: 2.109).

CONCLUSIONS

High Cmin were frequent, especially in patients with MDRD <40 mL/min. Therapeutic drug monitoring could be useful to avoid toxicity in patients with renal dysfunction.

Linezolid as an eradication agent against assembled methicillin-resistant Staphylococcus aureus biofilms

Methicillin-resistantStaphylococcus aureus(MRSA) biofilms eradicated by linezolid.

Thrombocytopenia Associated with Linezolid Therapy in Solid Organ Transplant Recipients: A Retrospective Cohort Study

BACKGROUND

Linezolid is associated infrequently with bone marrow suppression in immunocompetent patients, but hematologic complications from linezolid in transplant recipients are understudied. This study evaluated the hematologic safety of linezolid in solid organ transplant recipients.

METHODS

We performed a retrospective study of inpatients at our institution treated with linezolid from June 1, 2009 until June 6, 2012. The solid organ transplant cohort (TP) was compared with the non-transplant cohort (NTP) using parameters related to linezolid safety. Outcomes included incidences of leukopenia or thrombocytopenia at the end of linezolid treatment (EOT), lengths of stay, and blood product requirements.

RESULTS

The TP cohort included 110 patients; the NTP cohort included 583 patients. Baseline parameters were similar between the TP and NTP cohorts. Non-transplant patients were more likely to have methicillin-resistant Staphylococcus aureus (MRSA), whereas TP patients received more doses of linezolid (17.0 vs. 11.3, p<0.001) and were more likely to receive other drugs associated with thrombocytopenia (91.7% vs. 11.3%, p<0.0001). Transplant patients with normal platelet counts at baseline were more likely to have EOT thrombocytopenia (29.3% vs. 10.7%, p=0.005), and multivariable regression analysis confirmed only a beginning platelet count less than 150,000 platelets per micoliter to be significantly different between groups: 43% TP versus 26.9% NTP (p=0.0009) making it the only independent predictor of EOT thrombocytopenia. Finally, TP patients were more likely to require platelet transfusions compared with the NTP cohort.

CONCLUSIONS

Transplant patients who received linezolid had a higher incidence of EOT thrombocytopenia and platelet transfusions, compared with NTP. Transplant patients who are thrombocytopenic at baseline are at the greatest risk. These findings may relate to more frequent use of drugs associated with marrow suppression or greater linezolid exposure in the TP cohort. Clinicians caring for transplant patients should take into account this higher risk of thrombocytopenia and need for platelets when considering use of linezolid in this population.

Clinical experience with linezolid for the treatment of orthopaedic implant infections

Gram-positive cocci are commonly isolated in orthopaedic implant infections and their resistance to β-lactams and fluoroquinolones is increasing. The high oral bioavailability of linezolid makes it an attractive oral alternative to glycopeptides and its use has increased in the last decade. To evaluate experience with linezolid in orthopaedic implant infections a systematic review of the literature available in English was undertaken. Only those articles describing series of ≥10 patients with acute or chronic orthopaedic implant infections treated with linezolid and with a clear definition of diagnosis and outcome were selected. A total of 293 patients (79.9% had prosthetic joint infections) were analysed in the 10 articles included. The overall remission rate with at least 3 months of follow-up was 79.9%, depending on whether the implant was removed or not (94% versus 69.9%). The addition of rifampicin was described in only two articles and no significant difference was observed. Adverse events were frequent during prolonged administration of linezolid (34.3%), requiring treatment discontinuation in 12.8%. The most common event was anaemia (13.4%) followed by gastrointestinal symptoms (11.1%). In conclusion, linezolid seems a good oral treatment alternative for orthopaedic implant infections due to Gram-positive cocci resistant to β-lactams and fluoroquinolones. However, close monitoring of adverse events is required.

A Retrospective Review of the Clinical Experience of Linezolid with or Without Rifampicin in Prosthetic Joint Infections Treated with Debridement and Implant Retention

Introduction

Debridement and prosthesis retention, combined with a prolonged antibiotic regimen including rifampicin, is an accepted therapeutic approach when the duration of symptoms is less than 4 weeks and there are no radiological signs of loosening. The outcome of patients managed with this strategy has been previously assessed in several articles with success rates of 60–90%. This study aims to review the clinical experience with linezolid in 3 different hospitals from Spain and France in patients with prosthetic joint infection (PJI) managed with debridement, retention of the implant and treated with linezolid with or without rifampicin.

Methods

Patients with an acute PJI who underwent open debridement with implant retention treated with linezolid for more than 7 days in 3 hospitals from Barcelona, Tours and Lille between 2005 and 2011 were retrospectively reviewed. Relevant information about demographics, co-morbidity, type of implant, surgical treatment, microorganism isolated, antimicrobial therapy, adverse events (AEs) and outcomes were recorded from patients.

Results

A total of 39 patients were retrospectively reviewed. The mean age (SD) was 70.5 (8.8) years and 9 patients had diabetes mellitus (23%). There were 25 (64%) knee prostheses, 13 (33%) hips and 1 shoulder (3%). The median interquartile range (IQR) days from arthroplasty to infection diagnosis was 17 (19–48) and 33 (85%) cases were diagnosed within the first 60 days. The median (IQR) duration of antibiotic treatment was 70.5 (34–96) days and the median (IQR) number of days on linezolid treatment was 44.5 (30–81). AEs were observed in 15 patients (38%), with gastrointestinal complaints in 8 cases and anemia in 5 being the most frequent. After a median (IQR) follow-up of 2.5 (1.8–3.6) years, there were 11 failures (28%) (8 relapses and 3 new infections). The failure rate was higher in the rifampicin group (36% vs. 18%) mainly due to a higher relapse rate (27% vs. 12%) although differences were not statistically significant.

Conclusion

Management of acute PJIs with debridement and retention of the implant linezolid, with or without rifampicin, is associated with a high remission rate and it is an alternative treatment for infections due to fluoroquinolone and/or rifampicin-resistant staphylococci.

Electronic supplementary material

The online version of this article (doi:10.1007/s40121-014-0032-z) contains supplementary material, which is available to authorized users.

Prosthesis infections after orthopedic joint replacement: the possible role of bacterial biofilms

Prosthesis-related infection is a serious complication for patients after orthopedic joint replacement, which is currently difficult to treat with antibiotic therapy. Consequently, in most cases, removal of the infected prosthesis is the only solution to cure the infection. It is, therefore, important to understand the comprehensive interaction between the microbiological situation and the host immune responses that lead to prosthesis infections. Evidence indicates that prosthesis infections are actually biofilm-correlated infections that are highly resistant to antibiotic treatment and the host immune responses. The authors reviewed the related literature in the context of their clinical experience, and discussed the possible etiology and mechanism leading to the infections, especially problems related to bacterial biofilm, and prophylaxis and treatment of infection, including both microbiological and surgical measures. Recent progress in research into bacterial biofilm and possible future treatment options of prosthesis-related infections are discussed.

Diagnosis and management of prosthetic joint infection

PURPOSE OF REVIEW

Prosthetic joint infection remains a devastating complication of arthroplasty associated with significant patient morbidity. The demand for arthroplasty is rapidly growing with a corresponding increase in the number of infections involving the prosthesis. The diagnosis and treatment of prosthetic joint infections presents a significant challenge to orthopaedic and infectious diseases clinicians.

RECENT FINDINGS

The underlying pathogenesis of prosthetic joint infections is due to the ability of the microorganisms to form a biofilm. The biofilm provides protection against host immune responses and antimicrobial therapy. In addition, it impedes standard laboratory diagnostic techniques. This review will examine new investigations to improve the diagnostic yield and rapidity of diagnosis of infections, including the use of sonication to disrupt the biofilm, new molecular tests to improve the detection of infecting microorganisms and new imaging techniques such as (18)F-fluoro-deoxyglucose PET.

SUMMARY

The successful treatment of prosthetic joint infections is dependent on eliminating the biofilm dwelling microorganisms whilst maintaining patient mobility and quality of life. This review will examine current understanding of management approaches for these infections, with a particular focus on antimicrobial therapy with activity against the biofilm, such as rifampicin and fluoroquinolones.

Prevention of Orthopaedic Implant Infection in Patients Undergoing Dental Procedures

The Prevention of Orthopaedic Implant Infection in Patients Undergoing Dental Procedures evidence-based clinical practice guideline was codeveloped by the American Academy of Orthopaedic Surgeons (AAOS) and the American Dental Association. This guideline replaces the previous AAOS Information Statement, "Antibiotic Prophylaxis in Bacteremia in Patients With Joint Replacement," published in 2009. Based on the best current evidence and a systematic review of published studies, three recommendations have been created to guide clinical practice in the prevention of orthopaedic implant infections in patients undergoing dental procedures. The first recommendation is graded as Limited; this recommendation proposes that the practitioner consider changing the long-standing practice of routinely prescribing prophylactic antibiotic for patients with orthopaedic implants who undergo dental procedures. The second, graded as Inconclusive, addresses the use of oral topical antimicrobials in the prevention of periprosthetic joint infections. The third recommendation, a Consensus statement, addresses the maintenance of good oral hygiene.

Diagnosis and management of prosthetic joint infection: clinical practice guidelines by the Infectious Diseases Society of America

These guidelines are intended for use by infectious disease specialists, orthopedists, and other healthcare professionals who care for patients with prosthetic joint infection (PJI). They include evidence-based and opinion-based recommendations for the diagnosis and management of patients with PJI treated with debridement and retention of the prosthesis, resection arthroplasty with or without subsequent staged reimplantation, 1-stage reimplantation, and amputation.

Immediate hematological toxicity of linezolid in healthy volunteers with different body weight: a phase I clinical trial

Linezolid is an important therapeutic option for infections from multi-drug resistant Gram-positive pathogens. However, prolonged linezolid treatment (>14 days) is considered to increase the risk of hematological adverse events. We aimed to evaluate the hematological safety profile of an i.v. single dose of linezolid in healthy volunteers of different body weight. We conducted a phase I clinical trial involving 20 healthy male Chinese volunteers that received an i.v. single dose of linezolid (600 mg). The study participants were assigned to two groups: low-weight (LW) group: 50 kg <body weight ≤55 kg and high-weight (HW) group: ≥80 kg. A significant decrease in the hemoglobin (Hb) levels and red blood cell (RBC) count was observed at the end of administration of the study drug in both groups. White blood cell (WBC) count was simultaneously decreased in the HW group. In the LW group, Hb levels and RBC count were also significantly decreased at 5, 7 and 24 h. In the HW group, both values were significantly decreased at 5 h. At 48 h all values were normal. The observed decreases were numerically higher in the LW group compared with the HW group. Yet, no statistical significance was noted. No difference was observed in the platelet count in both the groups. Our findings suggest that linezolid-associated hematological toxicity may also occur shortly after the i.v. administration of the drug in both LW and HW healthy volunteers. Early initiated continuous monitoring of hematological values and linezolid dosage adjustment for body weight are recommended.

Linezolid plus rifampin as a salvage therapy in prosthetic joint infections treated without removing the implant

The aim of this study is to describe our experience with linezolid plus rifampin as a salvage therapy in prosthetic joint infections (PJIs) when other antibiotic regimens failed or were not tolerated. A total of 161 patients with a documented prosthetic joint infection were diagnosed with a PJI and prospectively followed up from January 2000 to April 2007. Clinical characteristics, inflammatory markers, microbiological and radiological data, and antibiotic treatment were recorded. After a 2-year follow-up, patients were classified as cured when the prosthesis was not removed, symptoms of infection disappeared, and inflammatory parameters were within the normal range. Any other outcome was considered a failure. The mean age of the entire cohort (n = 161) was 67 years. Ninety-five episodes were on a knee prosthesis (59%), and 66 were on a hip prosthesis (41%). A total of 49 patients received linezolid plus rifampin: 45 due to failure of the previous antibiotic regimen and 4 due to an adverse event associated with the prior antibiotics. In no case was the implant removed. The mean (standard deviation) duration of treatment was 80.2 (29.7) days. The success rate after 24 months of follow-up was 69.4% (34/49 patients). Three patients developed thrombocytopenia and 3 developed anemia; however, it was not necessary to stop linezolid. Linezolid plus rifampin is an alternative salvage therapy when the implant is not removed.

Outcome and predictors of treatment failure in early post-surgical prosthetic joint infections due to Staphylococcus aureus treated with debridement

Experience with debridement and prosthesis retention in early prosthetic joint infections (PJI) due to Staphylococcus aureus is scarce. The present study aimed to evaluate the outcome and predictors of failure. Patients prospectively registered with an early PJI due to S. aureus and 2 years of follow-up were reviewed. Demographics, co-morbidity, type of implant, clinical manifestations, surgical treatment, antimicrobial therapy and outcome were recorded. Remission was defined when the patient had no symptoms of infection, the prosthesis was retained and C-reactive protein (CRP) was ≤ 1 mg/dL. Univariate and multivariate analysis were performed. Fifty-three patients with a mean ± SD age of 70 ± 10.8 years were reviewed. Thirty-five infections were on knee prosthesis and 18 were on hip prosthesis. The mean ± SD duration of intravenous and oral antibiotics was 10.6 ± 6.7 and 88 ± 45.9 days, respectively. After 2 years of follow-up, 40 (75.5%) patients were in remission. Variables independently associated with failure were the need for a second debridement (OR 20.4, 95% CI 2.3-166.6, p 0.006) and a CRP > 22 mg/dL (OR 9.8, 95% CI 1.5-62.5, p 0.01). The onset of the infection within the 25 days after joint arthroplasty was at the limit of significance (OR 8.3, 95% CI 0.8-85.6, p 0.07). Debridement followed by a short period of antibiotics is a reasonable treatment option in early PJI due to S. aureus. Predictors of failure were the need for a second debridement to control the infection a CRP > 22 mg/dL and the infection onset within the first 25 days after joint arthroplasty.

Treatment with linezolid or vancomycin in combination with rifampin is effective in an animal model of methicillin-resistant Staphylococcus aureus foreign body osteomyelitis

Rifampin monotherapy was compared to the combination of linezolid or vancomycin with rifampin in an experimental rat model of methicillin-resistant Staphylococcus aureus (MRSA) chronic foreign body osteomyelitis. MRSA was inoculated into the proximal tibia, and a titanium wire was implanted. Four weeks after infection, rats were treated intraperitoneally for 21 days with rifampin alone (n = 16), linezolid plus rifampin (n = 14), or vancomycin plus rifampin (n = 13). Thirteen animals received no treatment. At completion of treatment, qualitative cultures of the wire and quantitative cultures of the bone (reported as median values) were performed. Quantitative cultures from the control, rifampin monotherapy, linezolid-plus-rifampin, and vancomycin-plus-rifampin groups revealed 4.54, 0.71, 0.10, and 0.50 log₁₀ CFU/gram of bone, respectively. The bacterial load was significantly reduced in all treatment groups compared to that in the control group. Rifampin resistance was detected in isolates from 10, 2, and 1 animal in the rifampin, linezolid-plus-rifampin, and vancomycin-plus-rifampin groups, respectively. Cultures of the removed wire revealed bacterial growth in 1 and 2 animals in the rifampin and linezolid-plus-rifampin groups, respectively, with no growth in the vancomycin-plus-rifampin group and growth from all wires in the untreated group. In conclusion, we demonstrated that combination treatment with linezolid plus rifampin or vancomycin plus rifampin is effective in an animal model of MRSA foreign body osteomyelitis in the context of retention of the infected foreign body.

Consensus document on controversial issues in the diagnosis and treatment of prosthetic joint infections

BACKGROUND

Joint replacement surgery has been on the increase in recent decades and prosthesis infection remains the most critical complication. Many aspects of the primary prevention and clinical management of such prosthesis infections still need to be clarified.

CONTROVERSIAL ISSUES

The aim of this GISIG (Gruppo Italiano di Studio sulle Infezioni Gravi) working group - a panel of multidisciplinary experts - was to define recommendations for the following controversial issues: (1) Is a conservative surgical approach for the management of prosthetic joint infections effective? (2) Is the one-stage or the two-stage revision for the management of prosthetic joint infections more effective? (3) What is the most effective treatment for the management of prosthetic joint infections due to methicillin-resistant staphylococci? Results are presented and discussed in detail.

METHODS

A systematic literature search using the MEDLINE database for the period 1988 to 2008 of randomized controlled trials and/or non-randomized studies was performed. A matrix was created to extract evidence from original studies using the CONSORT method to evaluate randomized clinical trials and the Newcastle-Ottawa Quality Assessment Scale for case-control studies, longitudinal cohorts, and retrospective studies. The GRADE method for grading quality of evidence and strength of recommendation was applied.

Tolerability of prolonged linezolid therapy in bone and joint infection: protective effect of rifampicin on the occurrence of anaemia?

BACKGROUND

Linezolid therapy has shown high rates of clinical success in patients with osteomyelitis and prosthetic joint infections caused by Gram-positive cocci. Recent studies have demonstrated that linezolid/rifampicin combination therapy prevents the emergence of rifampicin-resistant mutations in vitro. However, linezolid/rifampicin combination-related haematological and neurological toxicities have not been evaluated.

OBJECTIVES

To assess the tolerability of prolonged linezolid/rifampicin combination therapy compared with other linezolid-containing regimens in patients with bone and joint infections.

METHODS

We reviewed the medical records of 94 patients who had received linezolid for >4 weeks after bone and joint infections. Anaemia was defined as a ≥2 g/dL reduction in haemoglobin, leucopenia as a total leucocyte count <4 × 10(9)/L, and thrombocytopenia as a reduction in platelet count to <75% of baseline.

RESULTS

Anaemia was less frequent among patients on linezolid/rifampicin combination therapy than among patients on linezolid alone or in combination with other drugs (9.3%, 44% and 52%, respectively; P<0.01). In multivariate analysis, age and treatment group were independently associated with anaemia. Thrombocytopenia was reported in 44% of patients on linezolid/rifampicin combination therapy, in 48% of patients on linezolid alone and in 57.7% of patients on other linezolid-containing regimens. Age was the only variable associated with thrombocytopenia (P=0.019) in univariate analysis.

CONCLUSIONS

Linezolid/rifampicin combination therapy was associated with a significantly reduced incidence of anaemia among patients with bone and joint infections, but it did not have an effect on thrombocytopenia and peripheral neuropathy rates. Linezolid/rifampicin combination therapy was not associated with poor clinical outcomes.

Clinical efficacy and tolerability of linezolid in pediatric patients: a systematic review

BACKGROUND

Linezolid is marketed for the treatment of severe, vancomycin-resistant infections with gram-positive bacteria in adults. Most information regarding the pharmacokinetic profile, efficacy, and tolerability of linezolid is derived from adult studies.

OBJECTIVE

The aim of this review was to summarize evidence regarding the use of linezolid in infants and children, focusing on the drug's clinical efficacy data and tolerability profile.

METHODS

A literature search was conducted of the Cochrane Library, EMBASE, and MEDLINE databases, from their inception through July 20, 2009, using the following terms: linezolid, newborn, infant, child, pediatrics, adolescent, human, clinical trial, and case report. Articles were excluded if they were redundant or not pertinent. (Articles that did not focus on the use of linezolid in children were considered not pertinent.) Bibliographies of all relevant articles were also evaluated.

RESULTS

Forty-seven publications regarding the use of linezolid in children were included in the review: 5 pharmacokinetic studies, 32 case reports, 6 randomized clinical trials (RCTs), 2 uncontrolled trials, 1 subanalysis of 2 published RCTs, and 1 subanalysis of published data about linezolid's tolerability. Pharmacokinetic data on linezolid use in children were derived from studies that enrolled 447 children. Plasma pharmacokinetics of linezolid in pediatric patients were found to be age dependent. Results from 6 vancomycinor cefadroxil-controlled RCTs (including 1480 children) evaluating linezolid treatment in children reported variable clinical cure rates, ranging from 75.0% to 93.2% in children with skin and skin-structure infections and from 77.5% to 90.0% in children with bacteremia or pneumonia. No significant difference in clinical cure rates between the linezolid group and the comparator group was observed in any study. The most frequently reported adverse events were diarrhea (from 3.1% to 16.8%), nausea and/or vomiting (from 2.9% to 11.9%), and thrombocytopenia (from 1.9% to 4.7%). To date, 3 cases of neuropathy have been described in children.

CONCLUSIONS

The reviewed pediatric studies in skin and skin-structure infections, bacteremia, or pneumonia found that linezolid was associated with high clinical cure rates (75.0%-93.2%) that did not differ significantly from those of vancomycin or cefadroxil. RCTs enrolling children with other types of infection (eg, osteomyelitis, endocarditis), as well as long-term studies, are needed to draw definitive conclusions about linezolid's efficacy and tolerability in pediatric patients. Careful monitoring for adverse events and possible linezolid resistance continues to be essential.

Linezolid alone or combined with rifampin against methicillin-resistant Staphylococcus aureus in experimental foreign-body infection

We investigated the activity of linezolid, alone and in combination with rifampin (rifampicin), against a methicillin-resistant Staphylococcus aureus (MRSA) strain in vitro and in a guinea pig model of foreign-body infection. The MIC, minimal bactericidal concentration (MBC) in logarithmic phase, and MBC in stationary growth phase were 2.5, >20, and >20 microg/ml, respectively, for linezolid; 0.01, 0.08, and 2.5 microg/ml, respectively, for rifampin; and 0.16, 0.63, >20 microg/ml, respectively, for levofloxacin. In time-kill studies, bacterial regrowth and the development of rifampin resistance were observed after 24 h with rifampin alone at 1x or 4x the MIC and were prevented by the addition of linezolid. After the administration of single intraperitoneal doses of 25, 50, and 75 mg/kg of body weight, linezolid peak concentrations of 6.8, 12.7, and 18.1 microg/ml, respectively, were achieved in sterile cage fluid at approximately 3 h. The linezolid concentration remained above the MIC of the test organism for 12 h with all doses. Antimicrobial treatments of animals with cage implant infections were given twice daily for 4 days. Linezolid alone at 25, 50, and 75 mg/kg reduced the planktonic bacteria in cage fluid during treatment by 1.2 to 1.7 log(10) CFU/ml; only linezolid at 75 mg/kg prevented bacterial regrowth 5 days after the end of treatment. Linezolid used in combination with rifampin (12.5 mg/kg) was more effective than linezolid used as monotherapy, reducing the planktonic bacteria by >or=3 log(10) CFU (P < 0.05). Efficacy in the eradication of cage-associated infection was achieved only when linezolid was combined with rifampin, with cure rates being between 50% and 60%, whereas the levofloxacin-rifampin combination demonstrated the highest cure rate (91%) against the strain tested. The linezolid-rifampin combination is a treatment option for implant-associated infections caused by quinolone-resistant MRSA.