Randomized comparison of linezolid (PNU-100766) versus oxacillin-dicloxacillin for treatment of complicated skin and soft tissue infections

Use of oxazolidinones (linezolid or tedizolid) for the treatment of breast infections. A case series from a tertiary referral hospital

OBJECTIVES

Mastitis is mainly caused by Gram-positive bacteria and usually involves treatment with beta-lactam antibiotics and clindamycin. Oxazolidinones show good results in the treatment of skin and soft tissue infections (SSTIs) due to its pharmacokinetic characteristics. We aimed to describe clinical characteristics and outcomes of patients who received oxazolidinones for the treatment of SSTIs of the mammary tissue.

METHODS

Retrospective single-centre study of patients with a diagnosis of breast infection who received treatment with oxazolidinones as initial or salvage therapy between September 2016 and November 2022. Patients were identified through the pharmacy database. The primary outcome was clinical cure.

RESULTS

Twenty-nine patients received oxazolidinones: 27 received linezolid and 2 tedizolid. Median age was 41 years (IQR 31.0-56.5) and 28 patients were female. Ten patients (35%) had a history of breast cancer, while three (10%) had an immunosuppressive condition. Microbiological isolation was obtained in 24 individuals (83%). Predominant isolations were methicillin-resistant Staphylococcus aureus (8, 28%) and methicillin-susceptible S. aureus (7, 24%). Twenty-four patients (83%) received oxazolidinones as a salvage therapy, with a median duration of 14 days (IQR 10-17). Clinical cure was achieved in 24 patients (83%), while 4 relapsed after a median of 15 days (IQR 4-34). One was lost to follow-up. Three patients (10%) were taking selective serotonin reuptake inhibitors, and one of them concurrently received linezolid for 4 days with no adverse events recorded. Cytopenia during treatment was observed in 2/12 individuals. Oxazolidinones allowed hospital discharge in 11/13 hospitalized patients.

CONCLUSIONS

Oxazolidinones could be considered as an alternative for treating breast infections.

Predictive Modeling of Drug-Related Adverse Events with Real-World Data: A Case Study of Linezolid Hematologic Outcomes

Electronic health records (EHRs) provide meaningful knowledge of drug-related adverse events (AEs) that are not captured in standard drug development and postmarketing surveillance. Using variables obtained from EHR data in the University of California San Francisco de-identified Clinical Data Warehouse, we aimed to evaluate the potential of machine learning to predict two hematological AEs, thrombocytopenia and anemia, in a cohort of patients treated with linezolid for 3 or more days. Features for model input were extracted at linezolid initiation (index), and outcomes were characterized from index to 14 days post-treatment. Random forest classification (RFC) was used for AE prediction, and reduced feature models were evaluated using cumulative importance (cImp) for feature selection. Grade 3+ thrombocytopenia and anemia occurred in 31% of 2,171 and 56% of 2,170 evaluable patients, respectively. Of the total 53 features, as few as 7 contributed at least 50% cImp, resulting in prediction accuracies of 70% or higher and area under the receiver operating characteristic curves of 0.886 for grade 3+ thrombocytopenia and 0.759 for grade 3+ anemia. Sensitivity analyses in strictly defined patient subgroups revealed similarly high predictive performance in full and reduced feature models. A logistic regression model with the same 50% cImp features showed similar predictive performance as RFC and good concordance with RFC probability predictions after isotonic calibration, adding interpretability. Collectively, this work demonstrates potential for machine learning prediction of AE risk in real-world patients using few variables regularly available in EHRs, which may aid in clinical decision making and/or monitoring.

Efficacy and safety of optional parenteral antimicrobial therapy for complicated skin and soft tissue infections: A systematic review and Bayesian network meta-analysis

BACKGROUND

Skin and soft tissue infections (SSTIs) carry significant economic burden, as well as morbidity and mortality, especially when caused by methicillin-resistant Staphylococcus aureus. This study aims to investigate the efficacy and safety of optional antimicrobial therapy for the treatment of complicated SSTIs (cSSTIs).

METHODS

We searched PubMed, Medline (Via Ovid SP), Embase (Via Ovid SP), and the Cochrane Central Register of Controlled Trials from their inception to March 22, 2021 for randomized controlled trials (RCTs) that studied the use of optional antimicrobial therapy for cSSTIs. Citations' screening, study selection, data extraction, and risk of bias assessment were independently performed by 2 authors. The primary outcomes were clinical and microbiological treatment success, and adverse events (AEs) were also assessed.

RESULTS

A total of 48 trials covering 24,381 patients assessing 20 types of antimicrobial treatment modalities were included. Overall, omadacycline was associated with the highest beneficial effect on clinical and microbiological treatment success and with the largest rank probability based on surface under the cumulative ranking curve values, avarofloxacin was closely followed. Both had, however, omadacycline was related to moderately safety profiles. Lefamulin ranked as the best option was associated with the lowest risk of severe AEs. Subgroup analysis showed similar results. The quality of primary outcomes was moderate to low.

CONCLUSIONS

The use of omadacycline was associated with higher rates of clinical and microbiological treatment success for the treatment of cSSTIs, with a relative low risk of AEs. Due to the limitations of the included RCTs, high-quality and well-designed RCTs are needed to further confirm the results.

Antibiotics for the Treatment of Staphylococcal Infections in the Obstetric Patient

This review addresses current epidemiology and treatment of obstetric staphylococcal infections. It also examines current prophylaxis methods and the efficacy of universal screening.

Combinatorial Drug Therapy for Controlling Pseudomonas aeruginosa and Its Association With Chronic Condition of Diabetic Foot Ulcer

Diabetic foot ulcer (DFU) is a major complication of diabetes mellitus, major observations of DFU cases have reported on amputation of foot region, and microbial bioburden during DFU is a major cause that affects healing of the wound regions. Pathogenic microbes are routinely isolated from these wound regions, especially Staphylococcus, Pseudomonas, Klebsiella, and Escherichia coli have been reported, whereas higher prevalence of Pseudomonas species during chronic condition in the deeper part of the wound, when left untreated, leads to gangrene. Multiple drug-resistant Pseudomonas strains are a new threat because of their biofilm-forming ability, making it more potent and incurable. Acyl homoserine lactones (AHL) are a group of signaling molecules that can regulate biofilm growth, and Las and Rhl operon generally work in tandem to initiate biofilm formation by Pseudomonas species. These signaling molecules also initiate virulence factors that correlates upregulation of inflammatory responses, and AHL can be a therapeutic target in order to prevent the efficacy of multiple drug-resistant strains that form biofilm and also can be an alternative solution against control of multiple drug-resistant strains.

Reappraisal of Linezolid Dosing in Renal Impairment To Improve Safety

Linezolid is administered as a fixed dose to all patients despite evidence of increased exposure and myelosuppression in renal impairment. The objectives of these studies were to assess the risk of thrombocytopenia with standard-dose linezolid in renal impairment and to identify an alternate dosing strategy. In study 1, data from adult patients receiving linezolid for ≥10 days were retrospectively reviewed to determine the frequency of thrombocytopenia in patients with and without renal impairment. Time-to-event analyses were performed using Cox proportional-hazards models. In study 2, population pharmacokinetic modeling was employed to build covariate-structured models using an independent data set of linezolid concentrations obtained during routine therapeutic drug monitoring (TDM). Monte Carlo simulations were performed to identify linezolid dosing regimens that maximized attainment of therapeutic trough concentrations (2 to 8 mg/liter) across various renal-function groups. Toxicity analysis (study 1) included 341 patients, 133 (39.0%) with renal impairment. Thrombocytopenia occurred more frequently among patients with renal impairment (42.9% versus 16.8%; P < 0.001), and renal impairment was independently associated with this toxicity in multivariable analysis (adjusted hazard ratio [aHR], 2.37; 95% confidence interval [CI], 1.52 to 3.68). Pharmacokinetic analyses (study 2) included 1,309 linezolid concentrations from 603 adult patients. Age, body surface area, and estimated glomerular filtration rate (eGFR) were identified as covariates of linezolid clearance. Linezolid dose reductions improved the probability of achieving optimal exposures in simulated patients with eGFR values of <60 ml/min. Thrombocytopenia occurs more frequently in patients with renal impairment receiving standard linezolid doses. Linezolid dose reduction and trough-based TDM are predicted to mitigate this treatment-limiting toxicity.

The optimal duration of treatment for skin and soft tissue infections and acute bacterial skin and skin structure infections

PURPOSE OF REVIEW

To summarize the current finding on SSTIs/ABSSSIs treatment duration.

RECENT FINDINGS

In 2013, the FDA approved the definition of acute bacterial skin and skin structure infections (ABSSSIs). From a clinical point of view, the new definition may present some advantages: the definition of the severity of the disease, the measurement of reduction in lesion size, and effectiveness of treatment primary endpoint at 48-72 h after treatment initiation. New therapeutic options with improved efficacy, safety, and/or pharmacodynamics are available for ABSSSIs and so far, several questions still need to be addressed for the management of these infections, including treatment duration.

SUMMARY

There is a wide variation of duration of antimicrobial treatment in skin and soft tissue infections. Plenty of published data available suggest that we should focus on the early response to shorten duration of treatment, and that the antimicrobial stewardship perspective is extremely helpful in underscoring the need for composite outcomes in clinical practice, as multiple tools are available to increase cost-efficacy, including reduction of treatment changes, early oral switch, early discharge (even from the Emergency Department), outpatient antimicrobial treatment, long-acting antibiotics, and all together, de-escalation treatment strategies.

In vitro antimicrobial efficacy of laser exposed chlorpromazine against Gram-positive bacteria in planktonic and biofilm growth state

Aqueous chlorpromazine solutions exposed to 266 nm generated as fourth harmonic of Nd:YAG pulsed laser along time intervals from 1 min to 240 min were investigated for their antimicrobial activity against planktonic and adherent Gram-positive bacterial strains. Qualitative and quantitative assays based on microbiological methods and flow cytometry assays were performed to establish the minimum inhibitory and minimum biofilm eradication concentrations and to reveal some of the possible mechanisms of antimicrobial activity. Optimal irradiation conditions and combinations of photoproducts for achieving the best antimicrobial and antibiofilm effects are suggested. It was confirmed that chlorpromazine solutions irradiated for 15 min and 30 min have the best antimicrobial and antibiofilm activity against Staphylococcus aureus ATCC 6538, methicillin susceptible Staphylococcus aureus, methicillin resistant Staphylococcus aureus, Enterococcus faecium 17-VAR, Enterococcus faecalis 2921, and Bacillus subtilis 6633. Flow cytometry revealed that two of the possible mechanisms of the antimicrobial activity of irradiated chlorpromazine are the inhibition of efflux pumps activity and induction of cellular membrane lesions.

Management of complicated skin and soft tissue infections with a special focus on the role of newer antibiotics

Complicated skin and soft tissue infections (cSSTIs) represent the severe form of infectious disease that involves deeper soft tissues. Involvement of methicillin-resistant Staphylococcus aureus (MRSA) further complicates cSSTI with increased hospitalization, health care costs, and overall mortality. Various international guidelines provide recommendations on the management of cSSTIs, with the inclusion of newer antibiotics. This literature-based review discusses the overall management of cSSTI, including appropriate use of antibiotics in clinical practice. Successful treatment of cSSTIs starts with early and precise diagnosis, including identification of causative pathogen and its load, determination of infection severity, associated complications, and risk factors. The current standard-of-care for cSSTIs involves incision, drainage, surgical debridement, broad-spectrum antibiotic therapy, and supportive care. In recent years, the emergence of newer antibiotics (eg, ceftaroline, tigecycline, daptomycin, linezolid, etc) has provided clinicians wider options of antimicrobial therapy. Selection of antibiotics should be based on the drug characteristics, effectiveness, safety, and treatment costs, alongside other aspects such as host factors and local multidrug resistance rates. However, larger studies on newer antibiotics are warranted to refine the decision making on the appropriate antimicrobial therapy. Local Antimicrobial Stewardship Program strategies in health care settings could guide clinicians for early initiation of specific treatments to combat region-specific antimicrobial resistance, minimize adverse effects, and to improve outcomes such as reduction in Clostridium difficile infections. These strategies involving iv-to-oral switch, de-escalation to narrow-spectrum antibiotics, and dose optimization have an impact on the overall improvement of cSSTI therapy outcomes, especially in countries like Singapore that has a high disease burden.

Pharmacokinetics and pharmacodynamics of Linezolid in burn patients

Burns induce complex physiological changes such as modification of distribution volume, increased clearance of elements and decrease of protein binding. The pharmacokinetics of many antibiotics may then be modified, which requires dose adjustment. We attempted to evaluate the pharmacokinetics of linezolid in burn patients at a standard dose of 600 mg intravenously thrice a day. A prospective study was conducted in a 20-bed adult burn ICU at a university-affiliated teaching hospital in Tunis. Thirteen adult burned patients with documented and/or suspected multi drug resistant (MDR) gram-positive bacterium-related infections were enrolled in the study. Our study suggests that linezolid dosing at 600mg thrice a day leads to adequate pharmacodynamic/pharmacokinetic exposure to linezolid with a Cmin > 2mg/l in 84.6% of cases, T > MIC in about 87.5% and AUC/MIC > 100 in 61.5% of cases. However, a high variability in linezolid serum concentrations with a substantial percentage of sub-therapeutic levels was observed in a few patients, 15% of cases. Therefore, therapeutic drug monitoring of linezolid might be helpful for adequate dosing of linezolid in burned patients, to avoid the risk of treatment failure or of dose-dependent toxicity.

Efficacy and safety of linezolid compared with other treatments for skin and soft tissue infections: a meta-analysis

Linezolid with other treatments for skin and soft tissue infections (SSTIs) has been evaluated in several studies. However, the conclusions remain controversial. By searching PubMed, EMBASE, and Cochrane library databases, we conducted a meta-analysis to evaluate linezolid and other treatments for skin and soft tissue infections. The study was summarized, and the risk ratio (RR) and its 95% confidence interval (CI) were calculated. Eleven related articles were included in the meta-analysis. Our results revealed that linezolid was associated with a significantly better clinical (RR = 1.09, 95% CI: 1.02–1.16, P_{heterogeneity} = 0.326, I² = 13.0%) and microbiological cure rates (RR = 1.08, 95% CI: 1.01–1.16, P_{heterogeneity} = 0.089, I² = 41.7%) when comparing with vancomycin. There was no significant difference in the incidence of anemia, nausea, and mortality; however, the incidence of vomiting, diarrhea, and thrombocytopenia in patients treated with linezolid is significantly higher than that with other treatments. Our study confirmed that linezolid seems to be more effective than vancomycin for treating people with SSTIs. It is recommended that linezolid be monitored for thrombocytopenia, vomiting, and diarrhea. Further studies with larger dataset and well-designed models are required to validate our findings.

Use of Oritavancin in Moderate-to-Severe ABSSSI Patients Requiring IV Antibiotics: A U.S. Payer Budget Impact Analysis

BACKGROUND

It is estimated that acute bacterial skin and skin structure infections (ABSSSI) account for nearly 10% of hospital admissions and 3.4-3.8 million emergency department visits per year in the United States. Analyses of hospital discharge records indicate 74% of ABSSSI admissions involve empiric treatment with methicillin-resistant Staphylococcus aureus (MRSA) active antibiotics. Analysis has shown that payer costs could be reduced if moderate-to-severe ABSSSI patients were treated to a greater extent in the observational unit followed by discharge to outpatient parenteral antibiotic therapy (OPAT). Oritavancin is a lipoglycopeptide antibiotic with bactericidal activity against gram-positive bacteria, including MRSA.

OBJECTIVE

To estimate the impact on a U.S. payer's budget of using single-dose oritavancin in ABSSSI patients with suspected MRSA involvement who are indicated for intravenous antibiotics.

METHODS

A decision analytic model based on current clinical practice was developed to estimate the economic value of decreased hospital resource consumption by using single-dose oritavancin over a 1-year time horizon. Use of antibiotics was informed by an analysis of the Premier Research Database. Demographic and clinical data were derived from a targeted literature review. Emergency department, observation, laboratory, and administration costs used were Medicare National Limitation amounts. Drug costs were 2014 wholesale acquisition costs.

RESULTS

For a hypothetical U.S. payer with 1,000,000 members, it is expected that approximately 14,285 members per year will be diagnosed with ABSSSI severe enough to indicate intravenous antibiotics with MRSA activity. Based on this simulation, use of single-dose oritavancin in 26% of these patients was estimated to reduce the number of inpatient admissions, reduce length of stay for patients requiring admission, and reduce the number of days a patient needs to receive daily infusions in the OPAT clinic. The total patient days decreased from 171,125 to 133,435 with a total annual budget impact of -$12,550,000 or -$1.05 per member per month (PMPM). Total inpatient and outpatient costs were reduced by $9,970,000 (19.7%) and $2,580,000 (4.2%), respectively. Inpatient cost savings were derived from a reduction in admissions, length of stay, and lower drug administration burden. Outpatient costs were reduced by lower drug administration burden in the OPAT setting. A sensitivity analysis demonstrated that the model was most sensitive to population estimates.

CONCLUSIONS

Use of single-dose oritavancin in moderate-to-severe ABSSSI patients, including those with suspected MRSA, was projected to deliver an estimated cost reduction to U.S. payers of $1.05 PMPM by avoiding hospitalization in appropriate patients and reducing outpatient costs associated with multiday parenteral antibiotic therapy.

DISCLOSURES

This work was funded by The Medicines Company. Jensen, Wu, and Cyr are employees of ICON Health Economics, which provides consulting services to the biopharmaceutical industry, including The Medicines Company. Fan and Sulman are employees and shareholders of The Medicines Company. Dufour and Lodise have provided consulting services to The Medicines Company. Nicolau provided model input but did not receive an honorarium for contributions on this project. Nicolau is a speaker for The Medicines Company. Study concept and design were contributed by Jensen and Wu, along with the other authors. Jensen, Wu, Fan, and Sulham collected the data, with assistance from Cyr. Data interpretation was performed by Sulham, Jensen, Wu, and Fan, assisted by Lodise, Nicolau, and Dufour. The manuscript was written by Jensen, Wu, and Sulham, with assistance from Cyr, and revised by Lodise, Nicolau, and Dufour, with assistance from the other authors.

Characterization of Neurologic and Ophthalmologic Safety of Oral Administration of Tedizolid for Up to 21 Days in Healthy Volunteers

BACKGROUND

Antibacterials that inhibit protein synthesis may be associated with mitochondrial toxicity, manifested as serious optic or peripheral neuropathy or myelosuppression. Tedizolid is a novel oxazolidinone antibacterial that may have reduced the potential for mitochondrial toxicity.

STUDY QUESTION

Based on the results of 2 studies (NCT01623401 and NCT00671814) conducted early in the tedizolid development program, what is the potential for drug-induced optic and peripheral neuropathies with tedizolid treatment?

METHODS

Two phase-1 studies were conducted in healthy volunteers. The first was an open-label study in which subjects received 200 mg of oral tedizolid phosphate once daily for 10 days. The second was a double-blind, placebo- and active-controlled, dose-escalating (multiple-administration) study in which subjects received 200, 300, or 400 mg of oral tedizolid phosphate once daily or 600 mg of oral linezolid twice daily or oral placebo for 21 days. Overall safety and tolerability were assessed, and extensive ophthalmologic and neurologic assessments were performed in both studies.

RESULTS

In these 2 studies in healthy subjects, tedizolid administered for up to 21 days was not associated with drug-related ophthalmologic or neurologic adverse events. Incidences of adverse events involving the eye or the nervous system were generally low, and no clinically meaningful changes in ophthalmologic or neurologic test results were recorded during either study.

CONCLUSIONS

Using an extensive battery of ophthalmologic tests and detailed neurologic clinical examination, there was no evidence of clinical or subclinical neurologic or ophthalmologic changes suggestive of peripheral or optic neuropathy in healthy volunteers who received therapeutic and supratherapeutic doses of oral tedizolid for periods of up to 21 days.

Proposal for shorter antibiotic therapies

OBJECTIVES

Reducing antibiotic consumption has now become a major public health priority. Reducing treatment duration is one of the means to achieve this objective. Guidelines on the therapeutic management of the most frequent infections recommend ranges of treatment duration in the ratio of one to two. The Recommendation Group of the French Infectious Diseases Society (SPILF) was asked to collect literature data to then recommend the shortest treatment durations possible for various infections.

METHODS

Analysis of the literature focused on guidelines published in French and English, supported by a systematic search on PubMed. Articles dating from one year before the guidelines publication to August 31, 2015 were searched on the website.

RESULTS

The shortest treatment durations based on the relevant clinical data were suggested for upper and lower respiratory tract infections, central venous catheter-related and uncomplicated primary bacteremia, infective endocarditis, bacterial meningitis, intra-abdominal, urinary tract, upper reproductive tract, bone and joint, skin and soft tissue infections, and febrile neutropenia. Details of analyzed articles were shown in tables.

CONCLUSION

This work stresses the need for new well-conducted studies evaluating treatment durations for some common infections. Following the above-mentioned work focusing on existing literature data, the Recommendation Group of the SPILF suggests specific study proposals.

Linezolid: a promising option in the treatment of Gram-positives

Linezolid, an oxazolidinone antimicrobial agent that acts by inhibiting protein synthesis in a unique fashion, is used in the treatment of community-acquired pneumonia, skin and soft-tissue infections and other infections caused by Gram-positive bacteria including VRE and methicillin-resistant staphylococci. Currently, linezolid resistance among these pathogens remains low, commonly <1.0%, although the prevalence of antibiotic resistance is increasing in many countries. Therefore, the development of resistance by clinical isolates should prompt increased attention of clinical laboratories to routinely perform linezolid susceptibility testing for this important agent and should be taken into account when considering its therapeutic use. Considering the importance of linezolid in the treatment of infections caused by Gram-positive bacteria, this review was undertaken to optimize the clinical use of this antibiotic.

Use of Oritavancin in Acute Bacterial Skin and Skin Structure Infections Patients Receiving Intravenous Antibiotics: A US Hospital Budget Impact Analysis

Background and Objective

Nearly 10 % of all US hospital admissions are attributed to acute bacterial skin and skin structure infections (ABSSSIs). While most antibacterials used to treat these infections require multi-day and multi-dose regimens, a single-dose treatment is now available. The objective of this analysis is to estimate the annual budget impact of using single-dose oritavancin in patients with moderate to severe ABSSSIs receiving intravenous methicillin-resistant Staphylococcus aureus (MRSA)-active antibacterials from a US hospital perspective.

Methods

A decision-analytic model based on current clinical practice was developed to estimate the economic impact of oritavancin. Utilization of antibacterials and rates of hospital admission were derived from the Premier Research Database. Demographic and clinical data were informed by the published literature and 2014 wholesale drug acquisition costs were used. Other costs were based on the published literature and Medicare National Limitation amounts. All costs were inflated to 2014 US dollars. Two base-case scenarios were considered: one for hospitals with ambulatory services and one for hospitals without ambulatory services.

Results

For a US hospital with ambulatory services with 1000 ABSSSI patients receiving intravenous MRSA antibiotics annually, use of oritavancin in 26 % of patients is estimated to reduce the total annual budget by 12.9 % (US$1.23 million), or approximately US$1234.67 per patient. Total inpatient costs will be reduced by 22.3 % (US$1.40 million) and outpatient costs will increase slightly by 1.7 % (US$55,310). Pharmaceutical cost increases are offset by savings in the inpatient setting from fewer hospital admissions. Hospitals without ambulatory services are estimated to receive overall cost savings of 9.3 % (US$0.63 million).

Conclusion

Use of single-dose oritavancin in select ABSSSI patients with suspected or confirmed MRSA involvement is estimated to save US hospitals approximately 9.3–12.9 % per year by reducing hospital admissions and lowering drug administration burden.

Electronic supplementary material

The online version of this article (doi:10.1007/s40261-015-0365-8) contains supplementary material, which is available to authorized users.

Diabetic MRSA foot infection — role of linezolid therapy

Diabetic foot ulceration is common and disabling, often leading to amputation of the leg. Foot ulcers commonly become infected and MRSA infection is becoming more prevalent. MRSA is becoming a major public health problem because of its associated high morbidity and mortality, due to difficulty in its eradication with conventional antibiotics. Although vancomycin is the present mainstay of treatment of MRSA infection, a recently introduced antibiotic, linezolid may have benefits. Linezolid can be given orally, obviating the need for i.v. monitoring and offering potential savings in hospital costs with earlier discharge because of its suitability for out-patient eradication of MRSA.

Interaction between Warfarin and Linezolid in Patients with Left Ventricular Assist System in Japan

OBJECTIVE

The purpose of this study was to investigate the possible interaction between warfarin and linezolid in patients with a left ventricular assist system (LVAS) for the treatment of severe heart failure.

METHODS

Patients with LVAS who were treated with linezolid for the treatment of infections from January 2003 to March 2013 were identified from medical records. The impact of linezolid on the clotting function, as well as the dose of warfarin during the first 10 days of linezolid therapy, was investigated. The mean prothrombin time-international normalized ratio (PT-INR) and mean doses of warfarin during 7 days before and 10 days after the initiation of linezolid therapy were calculated for individual patients. The PT-INR per mg of WF dose on the previous day (X) was calculated. The warfarin dose, PT-INR, and warfarin sensitivity index (WSI) value before and after the initiation of linezolid were compared to evaluate the impact of linezolid on the effect of warfarin.

RESULTS

Sixteen patients were enrolled in the study. Although the mean PT-INR increased from 3.74 to 4.06, no significant difference was observed (p=0.05). A significant difference was observed in the mean dose of warfarin before and after the initiation of linezolid administration, with a decrease from 3.23 to 2.69 mg/day (p=0.001). In contrast, the mean WSI value significantly increased from 1.37 to 1.82 (p=0.014). After 10 days of linezolid administration, the mean X values increased over the baseline value by 31.7%.

CONCLUSION

These findings suggest that co-administration of linezolid results in increased PT-INR in patients with LVAS treated with warfarin.

Systemic antibiotics for treating diabetic foot infections

BACKGROUND

Foot infection is the most common cause of non-traumatic amputation in people with diabetes. Most diabetic foot infections (DFIs) require systemic antibiotic therapy and the initial choice is usually empirical. Although there are many antibiotics available, uncertainty exists about which is the best for treating DFIs.

OBJECTIVES

To determine the effects and safety of systemic antibiotics in the treatment of DFIs compared with other systemic antibiotics, topical foot care or placebo.

SEARCH METHODS

In April 2015 we searched the Cochrane Wounds Group Specialised Register; The Cochrane Central Register of Controlled Trials (CENTRAL; The Cochrane Library); Ovid MEDLINE, Ovid MEDLINE (In-Process & Other Non-Indexed Citations); Ovid EMBASE, and EBSCO CINAHL. We also searched in the Database of Abstracts of Reviews of Effects (DARE; The Cochrane Library), the Health Technology Assessment database (HTA; The Cochrane Library), the National Health Service Economic Evaluation Database (NHS-EED; The Cochrane Library), unpublished literature in OpenSIGLE and ProQuest Dissertations and on-going trials registers.

SELECTION CRITERIA

Randomised controlled trials (RCTs) evaluating the effects of systemic antibiotics (oral or parenteral) in people with a DFI. Primary outcomes were clinical resolution of the infection, time to its resolution, complications and adverse effects.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected studies, assessed the risk of bias, and extracted data. Risk ratios (RR) were estimated for dichotomous data and, when sufficient numbers of comparable trials were available, trials were pooled in a meta-analysis.

MAIN RESULTS

We included 20 trials with 3791 participants. Studies were heterogenous in study design, population, antibiotic regimens, and outcomes. We grouped the sixteen different antibiotic agents studied into six categories: 1) anti-pseudomonal penicillins (three trials); 2) broad-spectrum penicillins (one trial); 3) cephalosporins (two trials); 4) carbapenems (four trials); 5) fluoroquinolones (six trials); 6) other antibiotics (four trials).Only 9 of the 20 trials protected against detection bias with blinded outcome assessment. Only one-third of the trials provided enough information to enable a judgement about whether the randomisation sequence was adequately concealed. Eighteen out of 20 trials received funding from pharmaceutical industry-sponsors.The included studies reported the following findings for clinical resolution of infection: there is evidence from one large trial at low risk of bias that patients receiving ertapenem with or without vancomycin are more likely to have resolution of their foot infection than those receiving tigecycline (RR 0.92, 95% confidence interval (CI) 0.85 to 0.99; 955 participants). It is unclear if there is a difference in rates of clinical resolution of infection between: 1) two alternative anti-pseudomonal penicillins (one trial); 2) an anti-pseudomonal penicillin and a broad-spectrum penicillin (one trial) or a carbapenem (one trial); 3) a broad-spectrum penicillin and a second-generation cephalosporin (one trial); 4) cephalosporins and other beta-lactam antibiotics (two trials); 5) carbapenems and anti-pseudomonal penicillins or broad-spectrum penicillins (four trials); 6) fluoroquinolones and anti-pseudomonal penicillins (four trials) or broad-spectrum penicillins (two trials); 7) daptomycin and vancomycin (one trial); 8) linezolid and a combination of aminopenicillins and beta-lactamase inhibitors (one trial); and 9) clindamycin and cephalexin (one trial).Carbapenems combined with anti-pseudomonal agents produced fewer adverse effects than anti-pseudomonal penicillins (RR 0.27, 95% CI 0.09 to 0.84; 1 trial). An additional trial did not find significant differences in the rate of adverse events between a carbapenem alone and an anti-pseudomonal penicillin, but the rate of diarrhoea was lower for participants treated with a carbapenem (RR 0.58, 95% CI 0.36 to 0.93; 1 trial). Daptomycin produced fewer adverse effects than vancomycin or other semi-synthetic penicillins (RR 0.61, 95%CI 0.39 to 0.94; 1 trial). Linezolid produced more adverse effects than ampicillin-sulbactam (RR 2.66; 95% CI 1.49 to 4.73; 1 trial), as did tigecycline compared to ertapenem with or without vancomycin (RR 1.47, 95% CI 1.34 to 1.60; 1 trial). There was no evidence of a difference in safety for the other comparisons.

AUTHORS' CONCLUSIONS

The evidence for the relative effects of different systemic antibiotics for the treatment of foot infections in diabetes is very heterogeneous and generally at unclear or high risk of bias. Consequently it is not clear if any one systemic antibiotic treatment is better than others in resolving infection or in terms of safety. One non-inferiority trial suggested that ertapenem with or without vancomycin is more effective in achieving clinical resolution of infection than tigecycline. Otherwise the relative effects of different antibiotics are unclear. The quality of the evidence is low due to limitations in the design of the included trials and important differences between them in terms of the diversity of antibiotics assessed, duration of treatments, and time points at which outcomes were assessed. Any further studies in this area should have a blinded assessment of outcomes, use standardised criteria to classify severity of infection, define clear outcome measures, and establish the duration of treatment.

Comparative efficacy of antibiotics for the treatment of acute bacterial skin and skin structure infections (ABSSSI): a systematic review and network meta-analysis

OBJECTIVE

The objective was to conduct a systematic review and network meta-analysis (NMA) of existing treatments for ABSSSI focusing on the novel lipoglycopeptide oritavancin.

METHODS

EMBASE, MEDLINE, MEDLINE in Process, CENTRAL (Cochrane), and select conferences were searched for randomized controlled trials investigating antimicrobial agents for the treatment of ABSSSI. NMA was used to estimate the odds ratios of the Test-Of-Cure (TOC) and Early Clinical Response (ECR) outcomes for treatments relative to vancomycin in the ITT populations. Sub-group analyses in MRSA and MSSA populations were conducted for TOC; sensitivity analyses investigated the use of the clinically evaluable (CE) populations and the restriction to trials following the recent FDA guidelines for clinical trials.

RESULTS

The systematic review identified 52 trials. The most commonly investigated treatments were vancomycin and linezolid; most trials reported TOC, but not ECR. The posterior mean and 95% credible intervals for odds ratios of TOC for antimicrobial agents relative to vancomycin were: linezolid (1.55; 0.91-2.57), daptomycin (2.18; 0.90-5.42), and oritavancin 1200 mg (1.06; 0.80-1.43). The odds ratio of ECR for oritavancin 1200 mg was 1.02 (0.23-4.33). In the MRSA sub-group the odds ratios relative to vancomycin for TOC were: linezolid (1.55; 0.96-2.46), daptomycin (0.74; 0.13-3.66), and oritavancin 1200 mg (0.94; 0.44-2.02). In the MSSA sub-group they were linezolid (1.36; 0.15-13.34) and oritavancin 1200 mg (0.82; 0.08-7.83). These results were robust to the sensitivity analyses.

CONCLUSIONS

This NMA provides a unified framework for the comparison of all available antimicrobial agents used in the treatment of ABSSSI and is the first to assess the ECR end-point. The results suggest equivalence of clinical efficacy between vancomycin, daptomycin, linezolid, and novel antimicrobial agents including oritavancin for the treatment of ABSSSI at TOC. The wide uncertainty margins indicate the heterogeneity of the available evidence and the need for further research.

Systematic Review and Meta-Analysis To Estimate Antibacterial Treatment Effect in Acute Bacterial Skin and Skin Structure Infection

A systematic literature review and meta-analysis were conducted to estimate the antibacterial treatment effect for linezolid and ceftaroline to inform on the design of acute bacterial skin and skin structure infection (ABSSSI) noninferiority trials. The primary endpoints included an early clinical treatment response (ECTR) defined as cessation of lesion spread at 48 to 72 h postrandomization and the test-of-cure (TOC) response defined as total resolution of the infection at 7 to 14 days posttreatment. The systematic review identified no placebo-controlled trials in ABSSSI, 4 placebo-controlled trials in uncomplicated skin and soft tissue infection as a proxy for placebo in ABSSSI, 12 linezolid trials in ABSSSI, 3 ceftaroline trials in ABSSSI, and 2 trials for nonantibacterial treatment. The ECTR rates at 48 to 72 h and corresponding 95% confidence intervals (CI) were 78.7% (95% CI, 61.1 to 96.3%) for linezolid, 74.0% (95% CI, 69.7 to 78.3%) for ceftaroline, and 59.0% (95% CI, 52.8 to 65.3%) for nonantibacterial treatment. The early clinical treatment effect could not be estimated, given no available placebo or proxy for placebo data for this endpoint. Clinical, methodological, and statistical heterogeneity influenced the selection of trials for the meta-analysis of the TOC treatment effect estimation. The pooled estimates of the TOC treatment response were 31.0% (95% CI, 6.2 to 55.9%) for the proxy for placebo, 88.1% (95% CI, 81.0 to 95.1%) for linezolid, and 86.1% (95% CI, 83.7 to 88.6%) for ceftaroline. The TOC clinical treatment effect estimation was 25.1% for linezolid and 27.8% for ceftaroline. The antibacterial treatment effect estimation at TOC will inform on the design and analysis of future noninferiority ABSSSI clinical trials.

Staphylococcus aureus infections: epidemiology, pathophysiology, clinical manifestations, and management

Staphylococcus aureus is a major human pathogen that causes a wide range of clinical infections. It is a leading cause of bacteremia and infective endocarditis as well as osteoarticular, skin and soft tissue, pleuropulmonary, and device-related infections. This review comprehensively covers the epidemiology, pathophysiology, clinical manifestations, and management of each of these clinical entities. The past 2 decades have witnessed two clear shifts in the epidemiology of S. aureus infections: first, a growing number of health care-associated infections, particularly seen in infective endocarditis and prosthetic device infections, and second, an epidemic of community-associated skin and soft tissue infections driven by strains with certain virulence factors and resistance to β-lactam antibiotics. In reviewing the literature to support management strategies for these clinical manifestations, we also highlight the paucity of high-quality evidence for many key clinical questions.

Tedizolid Phosphate: a Next-Generation Oxazolidinone

Treatment of multidrug-resistant Gram-positive infections continues to challenge clinicians as the emergence of new resistance mechanisms outpaces introduction of novel antimicrobial agents. Tedizolid phosphate is a next-generation oxazolidinone with activity against both methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococcus spp. Tedizolid has consistently shown potency advantages over linezolid against Gram-positive microorganisms including those with reduced susceptibility to linezolid. Of particular significance, minimum inhibitory concentrations of tedizolid appear to be largely unaffected by the chloramphenicol-florfenicol resistance (cfr) gene, which has been implicated in a number of published linezolid-resistant organism outbreaks. Tedizolid phosphate also has been found to have a favorable pharmacokinetic profile allowing for once-daily dosing in both oral and intravenous forms. Potency and pharmacokinetic advantages have allowed for lower total daily doses of tedizolid, compared to linezolid, being needed for clinical efficacy in the treatment of acute bacterial skin and skin structure infections (ABSSSI). The decreased total drug exposure produced may in part be responsible for a decrease in the observed adverse effects including thrombocytopenia. Tedizolid phosphate is currently indicated for the treatment of ABSSSI and under investigation for the treatment of nosocomial pneumonia. Although much of the role of tedizolid remains to be defined by expanding clinical experience, tedizolid is likely a welcomed addition to the mere handful of agents available for the treatment of multidrug-resistant Gram-positive infections.

Hospitalist perspective on the treatment of skin and soft tissue infections

The prevalence of skin and soft tissue infections (SSTIs) has been increasing in the United States. These infections are associated with an increase in hospital admissions. Hospitalists play an increasingly important role in the management of these infections and need to use hospital resources efficiently and effectively. When available, observation units are useful for treating low-risk patients who do not require hospital admission. Imaging tools may help to exclude abscesses and necrotizing soft tissue infections; however, surgical exploration remains the principal means of diagnosing necrotizing soft tissue infections. The most common pathogens that cause SSTIs are streptococci and Staphylococcus aureus. Methicillin-resistant S aureus (MRSA) is a prevalent pathogen, and concerns are increasing regarding the unclear distinctions between community-acquired and hospital-acquired MRSA. Other less frequent pathogens that cause SSTIs include Enterococcus species, Escherichia coli, Klebsiella species, Enterobacter species, and Pseudomonas aeruginosa. Cephalexin and clindamycin are suitable options for infections caused by streptococcal species and methicillin-susceptible S aureus. The increasing resistance of S aureus and Streptococcus pyogenes to erythromycin limits its use in these infections, and better alternatives are available. Parenteral cefazolin, nafcillin, or oxacillin can be used in hospitalized patients with nonpurulent cellulitis caused by streptococci and methicillin-susceptible S aureus. When oral MRSA therapy is indicated, clindamycin, doxycycline, trimethoprim-sulfamethoxazole, or linezolid is appropriate. Vancomycin, linezolid, daptomycin, tigecycline, telavancin, and ceftaroline fosamil are intravenous options that should be used in MRSA infections that require patient hospitalization. In the treatment of patients with SSTIs, hospitalists are at the forefront of providing proper patient care that reduces hospital costs, duration of therapy, and therapeutic failures. This review updates guidelines on the management of SSTIs with a focus on infections caused by S aureus, particularly MRSA, and outlines the role of the hospitalist in the effective management of SSTIs.

Novel antibiotic treatment for skin and soft tissue infection

PURPOSE OF REVIEW

Acute bacterial skin and skin structure infection (ABSSSI) is a common and significant indication for antibiotic treatment. The microbial aetiology is becoming more resistant to available antibiotics and the treatment of patients is additionally challenged by extremes of age, obesity, diabetes and other co-morbidities. This review examines recent antimicrobial developments.

RECENT FINDINGS

In many parts of the world, multidrug-resistant (MDR) staphylococci are the predominant cause of ABSSSI in both the community and in hospital. Increasing resistance in Gram-negative organisms presents problems in the management of surgical-site infections. Most new antibiotics have been developed to treat MDR Gram-positive bacteria and there are few agents to treat infections caused by MDR Gram-negative pathogens.

SUMMARY

A number of novel agents are available clinically, with other agents of related chemical structure under development. There are no entirely new classes of antibiotics. Maintaining the efficacy of antimicrobial treatment require effective antibiotic stewardship, good infection prevention and the development of further new antibiotics.

Using daptomycin in hospitalised patients with cSSTI caused by Staphylococcus aureus has an impact on costs

BACKGROUND

The aim was to assess the cost impact of daptomycin compared to vancomycin treatment in patients hospitalised for complicated skin and soft-tissue infection (cSSTI) with suspected methicillin-resistant Staphylococcus aureus infection in the UK.

METHODS

A decision model was developed to estimate the costs associated with cSSTI treatment. Data on efficacy, treatment duration and early discharge from published clinical trials were used, with data gaps on standard clinical practice being filled by means of clinician interviews.

RESULTS

Total health-care costs per patient were GBP 6,214 and GBP 6,491 for daptomycin and vancomycin, respectively. A sensitivity analysis suggested that modifying the parameters within a reasonable range does not impact on the conclusion that the higher cost of daptomycin is likely to be offset by lower costs of monitoring and hospitalisation.

CONCLUSIONS

This study demonstrates that daptomycin not only provides an alternative treatment for multiple resistant infections, but may also reduce National Health Service costs.

Role of linezolid in the treatment of complicated skin and soft tissue infections

Staphylococcus aureus is the most common cause of complicated skin and soft tissue infections (cSSTIs). Antibiotic choices for these infections continue to evolve. History has seen penicillin progress to antistaphylococcal penicillins and cephalosporins, but these drugs are now giving way to drugs that are effective against methicillin-resistant S. aureus (MRSA). While vancomycin has been the gold standard to treat MRSA infections, newer therapeutic options have been developed over the last 5 years. These include quinupristin-dalfopristin, daptomycin, tigecycline and linezolid, which is the focus for this review. Linezolid is efficacious in the treatment of cSSTIs (including diabetic foot infections) caused by Gram-positive organisms (including MRSA), with a well-defined safety profile and straightforward dosing. It is also approved for nosocomial pneumonia, community-acquired pneumonia and uncomplicated skin and skin structure infections. Linezolid has an oral and parenteral formulation, which are equivalent. The oral formulation has the potential to offer economic benefits as compared with other therapies. Currently, there are only a few new antibiotics in development with MRSA activity. The proper use of all antibiotics, including these newer agents, is increasingly important if we are to slow the evolution of microbial resistance.

A review of linezolid: the first oxazolidinone antibiotic

Resistance of Gram-positive bacterial pathogens, such as Staphylococcus aureus and Enterococcus faecium, to existing antibiotics continues to increase, and new antibiotics with activity against these pathogens are in demand. Linezolid (Zyvox, Pharmacia and Upjohn) is the first agent of a new class of antibiotics called the oxazolidinones. Linezolid possesses excellent microbial activity against a wide variety of Gram-positive pathogens including those resistant to methicillin and vancomycin (Vancocin, Eli Lilly). Linezolid is available for intravenous and oral administration and possesses excellent bioavailability. It exhibits good penetration into pulmonary, as well as skin and related structure tissues, and does not require dosage adjustment in hepatic or renal dysfunction. Linezolid is generally well-tolerated, with the predominant adverse effect manifesting as a duration dependent, reversible thrombocytopenia. Linezolid possesses monoamine oxidase inhibitor activity and caution is warranted with coadministration of adrenergic or seritonergic medications. Clinical trials conducted with linezolid in skin and structure infections, lower respiratory tract infections and vancomycin-resistant enterococcal infections demonstrate that linezolid is an effective therapy. Recent data suggest that linezolid may be superior to vancomycin for the treatment of infections caused by methicillin-resistant S. aureus. Linezolid is an excellent and promising new antibiotic for the treatment of resistant Gram-positive pathogens.

Linezolid-induced black hairy tongue: a case report

INTRODUCTION

Linezolid-induced black hairy tongue has been rarely reported. The purpose of this paper is to report a case of linezolid-induced black hairy tongue and review the literature.

CASE PRESENTATION

A 56-year-old Caucasian man was admitted with community-acquired pneumonia that failed to respond to levofloxacin 750mg daily. He was started on linezolid and meropenem and was subsequently discharged home on oral linezolid 600mg every 12 hours and intravenous ertapenem 1g daily. On a follow-up clinic visit, day 14 of linezolid therapy, he complained of dysgeusia and his tongue examination was consistent with black hairy tongue. After he finished his antibiotic course, his complaints resolved with regular tongue brushing.

CONCLUSION

Black hairy tongue is characterized by abnormal hypertrophy and elongation of filiform papillae. Five reported cases of linezolid-induced black hairy tongue were identified in a MEDLINE search (from January 2000 to June 2012). The Naranjo Probability Scale revealed a probable adverse drug reaction of linezolid-induced black hairy tongue. Potential contributing factors included other antibiotics, drug-drug interaction and poor oral hygiene. Health care professionals should be aware of the possibility of linezolid-induced black hairy tongue. Thorough history for other possible contributing factors should be obtained. Patients on linezolid should be counseled to perform good oral hygiene.

Medical management of diabetic foot infections

Diabetic foot infections (DFIs) are a commonly encountered medical problem. They are associated with an increased frequency and length of hospitalization and risk for lower-extremity amputation. Furthermore, they have substantial economic consequences. Patients with diabetes mellitus are particularly susceptible to foot infections because of neuropathy, vascular insufficiency, and diminished neutrophil function. The approach to managing DFIs starts with determining if an infection exists. If an infection exists, then the type, severity, extent of infection, and risk factors for resistant organisms should be determined through history, physical examination, and additional laboratory and radiological testing. Optimal management requires surgical debridement, pressure offloading, effective antibiotic therapy, wound care and moisture, maintaining good vascular supply, and correction of metabolic abnormalities, such as hyperglycemia, through a multidisciplinary team. Empiric antibiotics for DFIs vary based on the severity of the infection, but must include anti-staphylococcal coverage.

Surgical site infection prophylaxis strategies for cardiothoracic surgery: a decision-analytic model

BACKGROUND

Methicillin-resistant Staphylococcus aureus (MRSA) is a common cause of invasive surgical site infection (SSI) in the USA. Antimicrobial prophylaxis for SSI typically includes a cephalosporin. Vancomycin is used to provide MRSA coverage, but the timing of administration is challenging. Linezolid is an attractive agent for SSI prophylaxis, particularly for the prevention of SSI due to MRSA.

METHODS

We developed a decision-analytic model to evaluate linezolid use for cardiothoracic SSI prophylaxis. A theoretical cohort of 10,000 cardiothoracic surgery patients was followed through 2 stages: (1) occurrence of SSI, and (2) mortality after SSI. All patients were administered cefuroxime, vancomycin, or linezolid between 1 and 180 min prior to surgical incision. SSIs were categorized into 3 pathogen categories: (1) methicillin-susceptible Gram-positive, (2) methicillin-resistant Gram-positive, and (3) other organisms. The most effective strategy resulted in the fewest SSIs. Assumptions for antibiotic effectiveness, impact of administration time, and pathogens were based on the published literature.

RESULTS

Compared with cefuroxime, there was a 1% increase in the total number of SSIs in the linezolid group (mean SSI increase = 7), while there was a 12% increase in the vancomycin group (mean SSI increase = 86). Linezolid prophylaxis resulted in fewer SSIs due to methicillin-resistant Gram-positive infections (n = 108) compared with cefuroxime (n = 200, 46% reduction in the linezolid group) and vancomycin (n = 119, 9% reduction in the linezolid group).

CONCLUSIONS

This simulation indicates that linezolid may offer benefits for SSI prophylaxis over existing prophylactic agents, particularly for the prevention of SSI due to Gram-positive methicillin-resistant pathogens.

Clinical update on linezolid in the treatment of Gram-positive bacterial infections

Gram-positive pathogens are a significant cause of morbidity and mortality in both community and health care settings. Glycopeptides have traditionally been the antibiotics of choice for multiresistant Gram-positive pathogens but there are problems with their use, including the emergence of glycopeptide-resistant strains, tissue penetration, and achieving and monitoring adequate serum levels. Newer antibiotics such as linezolid, a synthetic oxazolidinone, are available for the treatment of resistant Gram-positive bacteria. Linezolid is active against a wide range of Gram-positive bacteria and has been generally available for the treatment of Gram-positive infections since 2000. There are potential problems with linezolid use, including its bacteriostatic action and the relatively high incidence of reported adverse effects, particularly with long-term use. Long-term use may also be complicated by the development of resistance. However, linezolid has been shown to be clinically useful in the treatment of several serious infections where traditionally bacteriocidal agents have been required and many of its adverse effects are reversible on cessation. It has also been shown to be a cost-effective treatment option in several studies, with its high oral bioavailability allowing an early change from intravenous to oral formulations with consequent earlier patient discharge and lower inpatient costs.

Role of intravenous cloxacillin for inpatient infections

One of the issues of antibiotic treatment is to warrant its optimal effectiveness while minimizing the risk for emergence of resistance. The time above minimal inhibiting concentration (MIC) (T>MIC) is the best predictive pharmacological parameter of effectiveness for antibiotics with time-dependent activity, such as cloxacillin. Cloxacillin is the first line antibiotic in a great number of clinical situations generated by methicillin sensitive staphylococci, because of its intrinsic properties: bactericidal effect, tissue distribution and safety. The most recent anti-staphylococcal agents do not improve treatment of MSSA infections compared to penicillin M and especially cloxacillin. Cloxacillin has a narrow microbiological spectrum. This ecological feature is in line with the recommendation to use antibiotics with the narrowest spectrum to reduce the pressure of selection. The consensus is to have T>MIC for at least 40% of the dosing interval and is achieved by infusing 2g of cloxacillin per day (T>MIC=50%) or four infusions of 3g per day (T>MIC=42%) in adults.

Effectiveness and use of linezolid in hospitalisation wards

OBJECTIVE

To describe the use and effectiveness of linezolid as an alternative treatment for methicillin-resistant Staphylococcus aureus.

METHOD

Demographic, clinical and safety data were collected from hospitalised patients. The information sources were the clinical records and the pharmacy programme.

RESULTS

Thirty patients were treated with linezolid (median age 69.3, 63% male). The median duration of treatment was 8 days. The most prevalent indication was soft tissues and skin infections (46.7%). The indications were off-label in 40% of cases. Linezolid was used as a targeted therapy in 53%, especially for coagulase-negative Staphylococcus. Clinical healing occurred in 83.3%, and microbiological healing in 40%. Three patients (10%) experienced side effects from using linezolid.

CONCLUSION

The effectiveness and safety of linezolid is similar to that described in the trials. Its off-label use and the high number of empirical treatments mean that new strategies must be developed.

A critical review of oxazolidinones: an alternative or replacement for glycopeptides and streptogramins?

OBJECTIVE

To review the available data on the oxazolidinones linezolid and eperezolid.

DATA SELECTION

Published reports were obtained by searching MEDLINE for articles published between 1992 and 2000, inclusive. References of published papers were also obtained and reviewed. Abstracts from scientific proceedings were reviewed.

DATA EXTRACTION

Due to the limited data available regarding these agents, the criteria for study inclusion were not restrictive.

DATA SYNTHESIS

The oxazolidinones (eg, linezolid) are a new antimicrobial class with a unique mechanism of action. They are active against resistant Gram-positive cocci including methicillin-susceptible and -resistant Staphylococcus aureus (MRSA), methicillin-susceptible and -resistant Staphylococccus epidermidis, vancomycin-resistant enterococci (VRE) and penicillin-resistant Streptococcus pneumoniae (PRSP). Linezolid is active against anaerobes and displays modest activity against fastidious Gram-negative pathogens such as Haemophilus influenzae, but is not active against Enterobacteriaceae. Linezolid is available both orally and parenterally, and has a bioavailability of 100%. Clinical trials comparing linezolid with standard therapy have demonstrated similar bacteriological and clinical cures rates to standard therapy in community- and hospital-acquired pneumonia, uncomplicated and complicated skin and soft tissue infections, and infections caused by MRSA and VRE. Adverse effects have been minor and infrequent; however, platelets should be monitored in patients who have received more than two weeks of linezolid therapy. It is expected that these agents will have a bright future due to their excellent spectrum of activity against antibiotic-resistant Gram-positive organisms, such as MRSA, VRE and PRSP, and their excellent bioavailability.

CONCLUSION

The oxazolidinones represent a new class of antimicrobials with a unique mechanism of action. They have excellent activity against susceptible and resistant Gram-positive organisms such as MRSA, methicillin-susceptible S epidermidis, VRE and PRSP, and a good adverse effect profile; they can be administered both intravenously and orally. Their potential use in Canada may be as an intravenous and oral alternative to glycopeptides and streptogramins.

Treatment of skin and soft tissue infections in the elderly: A review

BACKGROUND

Skin and soft tissue infections (SSTIs) have become the second most common type of infection among persons residing in long-term care facilities.

OBJECTIVE

The purpose of this article was to review the latest information on SSTIs among the elderly, including age-related changes, challenges, and treatment strategies in the era of emerging bacterial resistance.

METHODS

Relevant information was identified through a search of MEDLINE (1970-April 2010), International Pharmaceutical Abstracts (1970-April 2010), and Google Scholar using the terms skin and soft tissue infection, skin and skin structure infection, cellulitis, treatment guidelines, and elderly. Additional publications were found by searching the reference lists of the identified articles. Trials published since 1970 were selected for this review if they prospectively evaluated mostly adults (≥18 years of age), included >50 patients, and reported diagnostic criteria as well as clinical outcomes in patients treated for simple or complicated SSTIs.

RESULTS

Fifty-eight of 664 identified studies were selected and included in this review. A search of the literature did not identify any prospective clinical trials that were conducted exclusively in the elderly. Information on the treatment of SSTIs in the elderly was based solely on clinical studies that were conducted in adults in general. As recommended by the Infectious Diseases Society of America (IDSA) 2008 update, SSTIs should be suspected in elderly patients who have skin lesions and present with a decline in functional status, with or without fever. Patients who present with symptoms of systemic toxicity should be hospitalized for further evaluation. Current challenges in the management of SSTIs include the rapid emergence of community-acquired, methicillin-resistant Staphylococcus aureus (CA-MRSA), the emergence of macrolide-resistant streptococci within the past decade, and the lack of a reliable algorithm to differentiate potentially life-threatening SSTIs that require aggressive interventions and prompt hospitalization from those that can be managed in an outpatient setting. S aureus was the most common cause of SSTIs, being isolated in 42.8% (5015/11,723) of wounds, followed by streptococci. Common SSTIs in the elderly such as shingles, diabetic foot infections, infected pressure ulcers, and scabies, and their treatment were also discussed. Based on reviews of published trials, treatment of simple SSTIs generally consisted of administration of agents with activity against S aureus and Streptococcus species such as a penicillinase-resistant β-lactam, a first-generation cephalosporin, or clindamycin. Broadening of the antimicrobial spectrum to include gram-negative and anaerobic organisms should be implemented for complicated SSTIs such as diabetic foot infections and infected pressure ulcers. Local rates of MRSA, CA-MRSA, and macrolide-resistant streptococci should be considered when selecting empiric therapy.

CONCLUSIONS

A search of the literature did not identify any prospective clinical trials on the treatment of SSTIs in the elderly; therefore, it is recommended to follow treatment based on the current IDSA guidelines. More research and publications are needed to establish proper selection of antimicrobial agents, treatment strategies, and duration of therapy of SSTIs in the elderly population.

Complicated skin and soft tissue infection

Skin and soft tissue infections (SSTIs) are common, and complicated SSTIs (cSSTIs) are the more extreme end of this clinical spectrum, encompassing a range of clinical presentations such as deep-seated infection, a requirement for surgical intervention, the presence of systemic signs of sepsis, the presence of complicating co-morbidities, accompanying neutropenia, accompanying ischaemia, tissue necrosis, burns and bites. Staphylococcus aureus is the commonest cause of SSTI across all continents, although its epidemiology in terms of causative strains and antibiotic susceptibility can no longer be predicted with accuracy. The epidemiology of community-acquired and healthcare-acquired strains is constantly shifting and this presents challenges in the choice of empirical antibiotic therapy. Toxin production, particularly with Panton-Valentine leucocidin, may complicate the presentation still further. Polymicrobial infection with Gram-positive and Gram-negative organisms and anaerobes may occur in infections approximating the rectum or genital tract and in diabetic foot infections and burns. Successful management of cSSTI involves prompt recognition, timely surgical debridement or drainage, resuscitation if required and appropriate antibiotic therapy. The mainstays of treatment are the penicillins, cephalosporins, clindamycin and co-trimoxazole. β-Lactam/β-lactamase inhibitor combinations are indicated for polymicrobial infection. A range of new agents for the treatment of methicillin-resistant S. aureus infections have compared favourably with the glycopeptides and some have distinct pharmacokinetic advantages. These include linezolid, daptomycin and tigecycline. The latter and fluoroquinolones with enhanced anti-Gram-positive activity such as moxifloxacin are better suited for polymicrobial infection.

Treatment of complicated skin and soft-tissue infections caused by resistant bacteria: value of linezolid, tigecycline, daptomycin and vancomycin

Antibiotic-resistant organisms causing both hospital- and community-acquired complicated skin and soft-tissue infections (cSSTI) are increasingly reported. A substantial medical and economical burden associated with MRSA colonisation or infection has been documented. The number of currently available appropriate antimicrobial agents is limited. Good quality randomised, controlled clinical trial data on antibiotic efficacy and safety is available for cSSTI caused by MRSA. Linezolid, tigecycline, daptomycin and vancomycin showed efficacy and safety in MRSA-caused cSSTI. None of these drugs showed significant superiority in terms of clinical cure and eradication rates.To date, linezolid offers by far the greatest number of patients included in controlled trials with a strong tendency of superiority over vancomycin in terms of eradication and clinical success.. - Tigecycline is an alternative in polymicrobial infections except by diabetic foot infections. Daptomycin might be a treatment option for cases of cSSTI with MRSA bacteremia. cSSTI caused by resistant Gram-negative bacteria are a matter of great concern. The development of new antibiotics in this area is an urgent priority to avoid the risk of a postantibiotic era with no antimicrobial treatment options. An individual approach for every single patient is mandatory to evaluate the optimal antimicrobial treatment regimen.

Emerging drugs for complicated skin and skin-structure infections

IMPORTANCE OF THE FILED: With the worldwide surge of MRSA, skin and skin-structure infection (SSTI) treatment has become a challenge for physicians. Cultures and antibiotic susceptibility tests for SSTIs are the rule due to the implication in morbidity and mortality rates associated with MRSA infections. The need for new antibiotics is evident and the effort to decrease antibiotic resistance is a world priority.

AREAS COVERED IN THIS REVIEW

This manuscript accesses the actual treatments and the developing of antibiotics for MRSA SSTIs.

WHAT THE READER WILL GAIN

This is a review of the data on the available and emerging treatments for MRSA SSTIs.

TAKE HOME MESSAGE

There is an unmet medical need for new antibiotics in the new millennium. As physicians, we must assure all appropriate procedures are completed in order to reduce the bacterial resistance, especially for MRSA.