Daptomycin non-susceptible Staphylococcus aureus at a US medical centre

Daptomycin

Daptomycin is a cyclic lipopeptide antibiotic used for the treatment of Gram-positive infections including complicated skin and skin structure infections, right-sided infective endocarditis, bacteraemia, meningitis, sepsis and urinary tract infections. Daptomycin has distinct mechanisms of action, disrupting multiple aspects of cell membrane function and inhibiting protein, DNA and RNA synthesis. Although daptomycin resistance in Gram-positive bacteria is uncommon, there are increasing reports of daptomycin resistance in Staphylococcus aureus, Enterococcus faecium and Enterococcus faecalis. Such resistance is seen largely in the context of prolonged treatment courses and infections with high bacterial burdens, but may occur in the absence of prior daptomycin exposure. Furthermore, use of inadequate treatment regimens, irregular drug supply and poor drug quality have also been recognized as other important risk factors for emergence of daptomycin-resistant strains. Antimicrobial susceptibility testing of Gram-positive bacteria, communication between clinicians and laboratories, establishment of internet-based reporting systems, development of better and more rapid diagnostic methods and continuous monitoring of drug resistance are urgent priorities.

A Phase 3, Randomized, Double-Blind, Multicenter Study To Evaluate the Safety and Efficacy of Intravenous Iclaprim versus Vancomycin for Treatment of Acute Bacterial Skin and Skin Structure Infections Suspected or Confirmed To Be Due to Gram-Positive Pathogens (REVIVE-2 Study)

Iclaprim is a novel diaminopyrimidine antibiotic that may be an effective and safe treatment for serious skin infections. The safety and effectiveness of iclaprim were assessed in a global phase 3, double-blind, randomized, active-controlled trial. Six hundred thirteen adults with acute bacterial skin and skin structure infections (ABSSSIs) suspected or confirmed to be due to Gram-positive pathogens were randomized to iclaprim (80 mg) or vancomycin (15 mg/kg of body weight), both of which were administered intravenously every 12 h for 5 to 14 days. The primary endpoint was a ≥20% reduction in lesion size compared with that at the baseline at 48 to 72 h after the start of administration of study drug in the intent-to-treat population. Among patients randomized to iclaprim, 78.3% (231 of 295) met this primary endpoint, whereas 76.7% (234 of 305) of those receiving vancomycin met this primary endpoint (difference, 1.58%; 95% confidence interval, -5.10% to 8.26%). This met the prespecified 10% noninferiority margin. Iclaprim was well tolerated, with most adverse events being categorized as mild. In conclusion, iclaprim was noninferior to vancomycin in this phase 3 clinical trial for the treatment of acute bacterial skin and skin structure infections. On the basis of these results, iclaprim may be an efficacious and safe treatment for skin infections suspected or confirmed to be due to Gram-positive pathogens. (This trial has been registered at ClinicalTrials.gov under identifier NCT02607618.).

Holospinal epidural abscess of the spinal axis: two illustrative cases with review of treatment strategies and surgical techniques

Despite the increasing prevalence of spinal infections, the subcategory of holospinal epidural abscesses (HEAs) is extremely infrequent and requires unique management. Panspinal imaging (preferably MRI), modern aggressive antibiotic therapy, and prompt surgical intervention remain the standard of care for all spinal axis infections including HEAs; however, the surgical decision making on timing and extent of the procedure still remain ill defined for HEAs. Decompression including skip laminectomies or laminoplasties is described, with varied clinical outcomes. In this review the authors present the illustrative cases of 2 patients with HEAs who were treated using skip laminectomies and epidural catheter irrigation techniques. The discussion highlights different management strategies including the role of conservative (nonsurgical) management in these lesions, especially with an already identified pathogen and the absence of mass effect on MRI or significant neurological defects. Among fewer than 25 case reports of HEA published in the past 25 years, the most important aspect in deciding a role for surgery is the neurological examination. Nearly 20% were treated successfully with medical therapy alone if neurologically intact. None of the reported cases had an associated cranial infection with HEA, because the dural adhesion around the foramen magnum prevented rostral spread of infection. Traditionally a posterior approach to the epidural space with irrigation is performed, unless an extensive focal ventral collection is causing cord compression. Surgical intervention for HEA should be an adjuvant treatment strategy for all acutely deteriorating patients, whereas aspiration of other infected sites like a psoas abscess can determine an infective pathogen, and appropriate antibiotic treatment may avoid surgical intervention in the neurologically intact patient.

Impact of the combination of daptomycin and trimethoprim-sulfamethoxazole on clinical outcomes in methicillin-resistant Staphylococcus aureus infections

Complicated Staphylococcus aureus infections, including bacteremia, are often associated with treatment failures, prolonged hospital stays, and the emergence of resistance to primary and even secondary therapies. Daptomycin is commonly used as salvage therapy after vancomycin failure for the treatment of methicillin-resistant S. aureus (MRSA) infections. Unfortunately, the emergence of daptomycin resistance, especially in deep-seated infections, has been reported, prompting the need for alternative or combination therapy. Numerous antibiotic combinations with daptomycin have been investigated clinically and in vitro. Of interest, the combination of daptomycin and trimethoprim-sulfamethoxazole (TMP-SMX) has proved to be rapidly bactericidal in vitro to strains that are both susceptible and nonsusceptible to daptomycin. However, to date, there is limited clinical evidence supporting the use of this combination. This was a multicenter, retrospective case series of patients treated with the combination of daptomycin and TMP-SMX for at least 72 h. The objective of this study was to describe the safety and effectiveness of this regimen in clinical practice. The most commonly stated reason that TMP-SMX was added to daptomycin was persistent bacteremia and/or progressive signs and symptoms of infection. After the initiation of combination therapy, the median time to clearance of bacteremia was 2.5 days. Microbiological eradication was demonstrated in 24 out of 28 patients, and in vitro synergy was demonstrated in 17 of the 17 recovered isolates. Further research with this combination is necessary to describe the optimal role and its impact on patient outcomes.

Antimicrobial resistance: impact on clinical and economic outcomes and the need for new antimicrobials

INTRODUCTION

Antimicrobial resistance is a well-recognized global threat; thus, the development of strong infection control policies coupled with antimicrobial stewardship strategies and new therapies is required to reverse this process. In its 2013 report on antimicrobial resistance, the Centers for Disease Control and Prevention focused on this problem while presenting estimated annual rates of infections with antimicrobial-resistant organisms and their related mortality rates. Whereas some resistant pathogens were considered less threatening, others such as carbapenem-resistant Enterobacteriaceae were associated with higher mortality rates owing to limited treatment options.

AREAS COVERED

An overview of the most common antimicrobial-resistant pathogens, focusing on risk factors for acquisition, clinical and economic outcomes, as well as current treatment options. Strategies to optimize antimicrobial therapy with currently available agents, in addition to newly developed antimicrobials are also discussed.

EXPERT OPINION

The emergence of pathogens with a variety of resistance mechanisms has intensified the challenges associated with infection control and treatment strategies. Therefore, prudent use of currently available antimicrobial agents, as well as implementing measures to limit spread of resistance is paramount. Although several new antimicrobials have been recently approved or are in the pipeline showing promise in the battle against resistance, the appropriate use of these agents is required as the true benefits of these treatments are to be recognized in the clinical care setting.

The impact of initial antibiotic therapy (linezolid, vancomycin, daptomycin) on hospital length of stay for complicated skin and soft tissue infections

Background

Empiric therapy of inpatient skin and soft tissue infections (SSTIs) generally require methicillin resistant Staphylococcus aureus (MRSA) coverage. Limited data are available to directly compare the effect of initial antibiotic choice on treatment outcomes and length of stay (LOS).

Objective

To assess potential differences in length of hospital stay when inpatients with complex skin and soft tissue infections (SSTIs) were initially treated with either vancomycin, linezolid, or daptomycin.

Methods

A retrospective review of 219 patients diagnosed with inpatient SSTI who received linezolid, vancomycin, or daptomycin for >48 hours was performed. Data collected included demographics, comorbidities, microbiologic/laboratory data, additional management (surgical, non-study antibiotics), hospital LOS, treatment outcome and morbidity/mortality.

Results

The three groups evaluated were linezolid (n = 45), vancomycin (n = 90) daptomycin (n = 84). There was no difference between the three groups with respect to gender, age, comorbidities, leukocytosis, fever, antibiotics prior to admission, site of infection culture results and surgical intervention. One death was recorded, not associated with diagnosis of SSTI. No significant difference in LOS was found (P = 0.525) between the 3 groups. The mean LOS in entire cohort was 4.5 days (SD ± 2.5); thirty patients had prolonged LOS for non-SSTI reasons; reanalyzing the data without these 30 patients did not produce any difference in the mean LOS between the 3 groups. Switching vancomycin just prior to discharge to facilitate outpatient therapy was common but did not impact LOS.

Conclusions

No difference was detected in hospital length of stay with respect to the initial choice of antibiotic (linezolid, vancomycin, or daptomycin) for SSTI. The three antibiotic regimens were equally effective in treating SSTIs as judged by LOS, irrespective of age, gender, comorbidities or baseline severity of SSTI. Given the large standard deviation in LOS, this result should be confirmed by larger studies.