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

This randomized, double-blind, multicenter trial compared the efficacy and safety of linezolid, an oxazolidinone, with those of oxacillin-dicloxacillin in patients with complicated skin and soft tissue infections. A total of 826 hospitalized adult patients were randomized to receive linezolid (600 mg intravenously [i.v.]) every 12 h or oxacillin (2 g i.v.) every 6 h; following sufficient clinical improvement, patients were switched to the respective oral agents (linezolid [600 mg orally] every 12 h or dicloxacillin [500 mg orally] every 6 hours). Primary efficacy variables were clinical cure rates in both the intent-to-treat (ITT) population and clinically evaluable (CE) patients and microbiological success rate in microbiologically evaluable (ME) patients. Safety and tolerability were evaluated in the ITT population. Demographics and baseline characteristics were similar across treatment groups in the 819 ITT patients. In the ITT population, the clinical cure rates were 69.8 and 64.9% in the linezolid and oxacillin-dicloxacillin groups, respectively (P = 0.141; 95% confidence interval -1.58 to 11. 25). In 298 CE linezolid-treated patients, the clinical cure rate was 88.6%, compared with a cure rate of 85.8% in 302 CE patients who received oxacillin-dicloxacillin. In 143 ME linezolid-treated patients, the microbiological success rate was 88.1%, compared with a success rate of 86.1% in 151 ME patients who received oxacillin-dicloxacillin. Both agents were well tolerated; most adverse events were of mild-to-moderate intensity. No serious drug-related adverse events were reported in the linezolid group. These data support the use of linezolid for the treatment of adults with complicated skin and soft tissue infections.     

A Randomized,Evaluator-Blind,Phase 2 Study Comparing the Safety and Efficacy of Omadacycline to Those of Linezolid for Treatment of Complicated Skin and Skin Structure Infections

A randomized, investigator-blind, multicenter phase 2 trial involving patients with complicated skin and skin structure infections (cSSSI) compared the safety and efficacy of omadacycline, a broad-spectrum agent with activity against methicillin-resistant Staphylococcus aureus (MRSA), to those of linezolid (with or without aztreonam). Patients were randomized 1:1 to omadacycline (100 mg intravenously [i.v.] once a day [QD] with an option to transition to 200 mg orally QD) or linezolid (600 mg i.v. twice daily [BID] with an option to transition to 600 mg orally BID) at 11 U.S. sites. Patients suspected or documented to have infections caused by Gram-negative bacteria were given aztreonam (2 g i.v. every 12 h [q12h]) if randomized to linezolid or matching placebo infusions if randomized to omadacycline. Adverse events were reported in 46 (41.4%) omadacycline-treated and 55 (50.9%) linezolid-treated patients. Adverse events related to treatment were assessed by investigators in 24 (21.6%) omadacycline-treated and 33 (30.6%) linezolid-treated patients. The gastrointestinal tract was most commonly involved, with adverse events reported in 21 (18.9%) patients exposed to omadacycline and 20 (18.5%) exposed to linezolid. Rates of successful clinical response in the intent-to-treat (ITT) and clinical evaluable (CE) populations favored omadacycline (ITT, 88.3% versus 75.9%; 95% confidence interval [CI], 1.9 to 22.9; CE, 98.0% versus 93.2%; 95% CI, −1.7 to 11.3). For microbiologically evaluable (ME) patients with S. aureus infections, the clinical success rates were 97.2% (70/72) in omadacycline-treated and 92.7% (51/55) in linezolid-treated patients. This phase 2 experience supports conclusions that omadacycline is well tolerated in cSSSI patients and that this aminomethylcycline has potential to be an effective treatment for serious skin infections.     

Linezolid compared with teicoplanin for the treatment of suspected or proven Gram-positive infections

The efficacy, safety and tolerability of linezolid was compared with teicoplanin in a randomized, controlled, open-label, multicentre study of 430 patients with suspected or proven Gram-positive infection. Patients received intravenous (iv) +/- oral linezolid 600 mg every 12 h (n = 215) or iv or intramuscular teicoplanin (n = 215) for up to 28 days. Clinical outcomes in the intent-to-treat (ITT) and clinically-evaluable populations and microbiological success rates in microbiologically evaluable patients were assessed at follow-up (test of cure). Investigator assessed clinical cure rates at end of treatment (EOT) in ITT patients treated with linezolid (95.5%) were superior to those of teicoplanin (87.6%) for all infections combined, indicating a 7.9% statistically significant treatment advantage for linezolid (P = 0.005, 95% CI: 2.5, 13.2). Clinical cure rates by baseline diagnosis were consistently higher at EOT for the linezolid versus teicoplanin groups with skin and soft tissue infection (96.6% versus 92.8%), pneumonia (96.2% versus 92.9%) and bacteraemia (88.5% versus 56.7%). The 31.8% treatment advantage in bacteraemic patients (but not for those seen in the other infection categories) for linezolid-treated patients was statistically significant (P = 0.009, 95% CI: 10.2, 53.4). Bacterial eradication rates for linezolid exceeded those of teicoplanin for all infection sites combined but this did not reach statistical significance (81.9% versus 69.8%, respectively; P = 0.056). Adverse event rates were similar between the treatment groups, were mild to moderate in severity, and resolved quickly following treatment. The linezolid group experienced a higher incidence of drug related adverse events (30% versus 17%; P = 0.002), and notably of gastrointestinal effects (13.0% versus 1.9%, P = 0.001). However, antibiotic discontinuation rates as a result of drug related adverse events were similar (4.7% in the linezolid group versus 3.7%). Linezolid was clinically superior to teicoplanin in the treatment of Gram-positive infections.     

Linezolid versus vancomycin for the treatment of infections caused by methicillin-resistant Staphylococcus aureus in Japan

OBJECTIVES: To compare the efficacy and safety of linezolid and vancomycin for the treatment of methicillin-resistant Staphylococcus aureus (MRSA) infections in Japan. METHODS: Patients with nosocomial pneumonia, complicated skin and soft-tissue infections or sepsis caused by MRSA were randomized to receive linezolid (600 mg every 12 h) or vancomycin (1 g every 12 h). RESULTS: One hundred patients received linezolid and 51 received vancomycin with outcomes evaluated at the end of therapy (EOT) and at the follow-up (FU), 7-14 days later. At EOT, clinical success rates in the MRSA microbiologically evaluable population were 62.9% and 50.0% for the linezolid and vancomycin groups, respectively; and microbiological eradication rates were 79.0% and 30.0% in the two groups, respectively (P < 0.0001). At FU, the clinical success rates were 36.7% for both groups and the microbiological eradication rates were 46.8% and 36.7%, respectively. Reversible anaemia (13%) and thrombocytopenia (19%) were reported more frequently in linezolid patients; laboratory analysis showed mild decrease in platelet counts with full recovery by FU. The mean platelet count in linezolid patients with thrombocytopenia was 101,000/mm(3). Significantly low platelet counts (<50,000/mm(3)) were observed more frequently in patients receiving vancomycin than in linezolid patients (6% versus 3%). Mean changes in haemoglobin levels between the two groups were not different. CONCLUSIONS: Linezolid is as effective as vancomycin for the treatment of MRSA infections and may be more effective than vancomycin in achieving microbiological eradication. Haematological adverse events were reported more frequently in linezolid-treated patients; analysis of laboratory data showed a mild reversible trend towards lower platelet counts.     

Retrospective analysis of the safety profile of oral and intravenous ciprofloxacin in a geriatric population

BACKGROUND: Ciprofloxacin is a broad-spectrum fluoroquinolone antibiotic used in the treatment of a wide range of mild to moderate gram-positive and gram-negative infections. Although extensive information is available on the safety profile of ciprofloxacin in adults, few published data exist regarding the tolerability and toxicity of this drug in patients aged > or = 65 years. OBJECTIVES: The objectives of this retrospective analysis were to compare the safety profile of ciprofloxacin in patients aged > or = 65 years versus patients aged <65 years and to compare the adverse-event profile of ciprofloxacin with that of other comparator antimicrobial agents used in clinical trials. METHODS: We retrospectively reviewed 23 prospective, controlled anti-infective clinical trials in the US Bayer ciprofloxacin database that included patients aged > or = 65 years. These trials comprised the submission file of the original and supplemental New Drug Application for ciprofloxacin. The incidence of treatment-emergent and drug-related adverse events was assessed. RESULTS: Of the 6863 patients in these 23 clinical trials, 3579 received ciprofloxacin therapy and 3284 received comparator antimicrobial agents. Of the ciprofloxacin-treated patients, 898 (25.1%) were aged > or = 65 years; 887 (27.0%) of the patients who received comparator antimicrobial agents were aged > or = 65 years. Among ciprofloxacin-treated patients, drug-related adverse events were reported more often in those aged <65 years (24.0%) compared with those aged > or = 65 years (17.9%). The incidence of drug-related adverse events in the comparator group was also higher in those aged <65 years (25.1%) than in those aged > or = 65 years (16.8%). Premature discontinuation due to any adverse event was reported in 3.9% (105 of 2681) and 3.7% (33 of 898) of ciprofloxacin-treated patients aged <65 years and > or = 65 years, respectively. Corresponding rates for the comparator antimicrobial group were 3.9% (93 of 2397) and 3.8% (34 of 887), respectively, for patients aged <65 years and > or = 65 years. The most common drug-related adverse events reported for ciprofloxacin-treated patients aged <65 years and > or = 65 years were digestive system-related (18.1% and 11.4%, respectively) and central nervous system-related events (6.6% and 4.9%, respectively). CONCLUSIONS: This retrospective analysis suggests that there is no clinically important difference in the safety profile of ciprofloxacin in patients aged > or = 65 years versus patients aged <65 years.     

Prospective, randomized study comparing quinupristin-dalfopristin with linezolid in the treatment of vancomycin-resistant Enterococcus faecium infections

OBJECTIVES: Quinupristin-dalfopristin and linezolid have been shown to be efficacious in the treatment of vancomycin-resistant Enterococcus faecium (VREF) infections. However, the two antibiotics have not been compared in terms of safety and efficacy in a prospective randomized study. The objective of this study was to compare the safety and efficacy of the two drugs in the treatment of VREF infections in cancer patients. PATIENTS AND METHODS: Forty cancer patients with VREF infection were randomized to receive linezolid 600 mg every 12 h or quinupristin-dalfopristin 7.5 mg/kg every 8 h. All patients were followed up for 30 days after discontinuation of study drugs. RESULTS: Linezolid and quinupristin-dalfopristin had comparable clinical responses (58% and 43%, respectively, P = 0.6). Myalgias and/or arthralgias occurred at a frequency of 33% in patients who received quinupristin-dalfopristin, but were not observed in the linezolid group (P = 0.03). In contrast, drug-related thrombocytopenia occurred in 11% of patients who received linezolid, but was not observed in the quinupristin-dalfopristin group (P = 0.2). CONCLUSION: In cancer patients, quinupristin-dalfopristin treatment is associated with a relatively high frequency of myalgias/arthralgias; however, profound thrombocytopenia might limit the choice of linezolid in a subpopulation of cancer patients.     

Safety and tolerability of linezolid

Clinical trials have shown that linezolid (600 mg twice daily in adults) is safe and generally well tolerated for up to 28 days. Drug-related adverse events, which are typically mild to moderate in intensity and of limited duration, include diarrhoea, nausea and headache in adults, and diarrhoea, loose stools and vomiting in children. Clostridium difficile-related complications with linezolid are uncommon. Linezolid is a weak, reversible monoamine oxidase inhibitor: foods containing high concentrations of tyramine should be avoided, and linezolid should be used with caution in patients taking adrenergic or serotonergic agents or in those with uncontrolled hypertension. In the majority of patients, linezolid has minimal adverse effects on blood chemistry or haematology. There have been case reports of reversible thrombocytopenia, anaemia and neutropenia associated with linezolid therapy. In Phase III studies, 2.4% of patients treated with linezolid and 1.5% of patients treated with comparator drugs developed reversible thrombocytopenia (P = 0.066), but there was no evidence of an increased risk of agranulocytosis, aplastic anaemia or other irreversible blood dyscrasias. Reduced platelet counts were associated with linezolid treatment for >/=2 weeks; complete blood counts should be monitored weekly in patients receiving linezolid for more than 14 days and treatment should be discontinued if there is evidence of myelosuppression.     

Safety,Tolerability, and Efficacy of GSK1322322 in the Treatment of Acute Bacterial Skin and Skin Structure Infections

GSK1322322 represents a new class of antibiotics that targets an essential bacterial enzyme required for protein maturation, peptide deformylase. This multicenter, randomized, phase IIa study compared the safety, tolerability, and efficacy of GSK1322322 at 1,500 mg twice daily (b.i.d.) with that of linezolid at 600 mg b.i.d. in patients suspected of having Gram-positive acute bacterial skin and skin structure infections (ABSSSIs). The primary endpoint was assessment of the safety of GSK1322322, and a key secondary endpoint was the number of subjects with a ≥20% decrease in lesion area from the baseline at 48 and 72 h after treatment initiation. GSK1322322 administration was associated with mild-to-moderate drug-related adverse events, most commonly, nausea, vomiting, diarrhea, and headache. Adverse events (86% versus 74%) and withdrawals (28% versus 11%) were more frequent in the GSK1322322-treated group. Treatment with GSK1322322 and linezolid was associated with ≥20% decreases from the baseline in the lesion area in 73% (36/49) and 92% (24/26) of the patients, respectively, at the 48-h assessment and in 96% (44/46) and 100% (25/25) of the patients, respectively, at the 72-h assessment. Reductions in exudate/pus, pain, and skin infection scores were comparable between the GSK1322322 and linezolid treatments. The clinical success rates within the intent-to-treat population and the per-protocol population that completed this study were 67 and 91%, respectively, in the GSK1322322-treated group and 89 and 100%, respectively, in the linezolid-treated group. These results will be used to guide dose selection in future studies with GSK1322322 to optimize its tolerability and efficacy in patients with ABSSSIs. (This study has been registered at ClinicalTrials.gov under registration no. {"type":"clinical-trial","attrs":{"text":"NCT01209078","term_id":"NCT01209078"}}NCT01209078 and at http://www.gsk-clinicalstudyregister.com [PDF113414].)     

Efficacy and safety of linezolid for Gram-positive orthopedic infections: a prospective case series

Linezolid is an attractive alternative for orthopedic infections because of oral bioavailability and activity against methicillin-resistant staphylococci and vancomycin-resistant enterococci. To determine efficacy and safety, we prospectively monitored 51 consecutive adults who were not vancomycin candidates and who received linezolid for 53 Gram-positive orthopedic infections, usually chronic osteomyelitis (n = 25) or prosthetic joint infection (n = 23). Pathogens were usually Staphylococcus aureus (n = 27) or coagulase-negative staphylococci (n = 19); 38 were methicillin resistant. After remission, 17 infections required long-term suppression, usually because of retained hardware. Clinical and microbiologic failure occurred in only one patient. The most common adverse events were thrombocytopenia (n = 5) and anemia (n = 5), necessitating treatment discontinuation in 3 patients. One patient developed reversible optic and irreversible peripheral neuropathy after 24 months of linezolid. Linezolid, with surgery, may be a reasonable alternative for Gram-positive orthopedic infections. We recommend weekly hematologic monitoring, and, if therapy lasts >2 months, periodic ophthalmologic monitoring.     

Linezolid for the treatment of resistant gram-positive cocci

OBJECTIVE: To provide a comprehensive review of linezolid, the first of a new class of antibiotics, the oxazolidinones. Therapeutic issues regarding the emergence of multidrug-resistant bacteria and a brief history of the oxazolidinones are also discussed. DATA SOURCES: A MEDLINE search (1966-March 2001) was conducted to identify pertinent literature, including preclinical trials, clinical trials, and reviews. Unpublished clinical data, adverse effects, and dosing information were abstracted from product labeling. STUDY SELECTION: Clinical efficacy data were extracted from clinical trials, case reports, and abstracts that mentioned linezolid. Additional information concerning antibiotic resistance, the oxazolidinones, in vitro susceptibility and the pharmacokinetic profile of linezolid also was reviewed. DATA SYNTHESIS: Linezolid exhibits activity against many gram-positive organisms, including vancomycin-resistant Enterococcus faecium, methicillin-resistant Staphylococcus aureus, and penicillin-resistant Streptococcus pneumoniae. Linezolid inhibits bacterial protein synthesis at an early step in translation and is rapidly and completely absorbed from the gastrointestinal tract following oral administration. Efficacy has been demonstrated in a number of unpublished clinical trials in adults with pneumonia, skin and skin structure infections, and vancomycin-resistant E. faecium infections. The adverse effect profile is similar to that of comparator agents (beta-lactams, clarithrornycin, vancomycin). CONCLUSIONS: Linezolid is the first oral antimicrobial agent approved for the treatment of vancomycin-resistant enterococci. Since the oxazoildinones have a unique mechanism of action and expanded spectrum of activity against virulent and highly resistant gram positive pathogens, linezolid is a valuable alternative to currently available treatment options. Clinical trials evaluating linezolid and other oxazolidinones for antibiotic-resistant gram-positive infections, as well as comparator studies comparing linezolid with other candidate drugs, such as quinupristin/dalfopristin and choramphenicol, will further define the role of linezolid.     

Linezolid: an oxazolidinone antimicrobial agent

BACKGROUND: Linezolid is the first oxazolidinone anti-infective agent marketed in the United States. It is indicated for the treatment of nosocomial pneumonia, complicated skin and skin-structure infections caused by methicillin-sensitive or methicillin-resistant Staphylococcus aureus and other susceptible organisms, and vancomycin-resistant Enterococcus faecium infections. It also is indicated for the treatment of uncomplicated skin and skin-structure infections caused by methicillin-sensitive S. aureus or Streptococcus pyogenes, and community-acquired pneumonia caused by penicillin-sensitive Streptococcus pneumoniae. OBJECTIVE: This article reviews the pharmacologic properties and clinical usefulness of linezolid. METHODS: Using the terms linezolid, PNU-100766, and oxazolidinone, we performed a literature search of the following databases: MEDLINE (1966 to September 2000), HealthSTAR (1993 to September 2000), Iowa Drug Information Service (1966 to September 2000), International Pharmaceutical Abstracts (1970 to September 2000), PharmaProjects (January 2000 version), and meeting abstracts of the Infectious Diseases Society of America and the Interscience Conference on Antimicrobial Agents and Chemotherapy (1996 to 2000). RESULTS: Linezolid has a unique structure and mechanism of action, which targets protein synthesis at an exceedingly early stage. Consequently, cross-resistance with other commercially available antimicrobial agents is unlikely. It is primarily effective against gram-positive bacteria. To date, resistance to linezolid has been reported in patients infected with enterococci. The pharmacokinetic parameters of linezolid in adults are not altered by hepatic or renal function, age, or sex to an extent requiring dose adjustment. Linezolid is metabolized via morpholine ring oxidation, which is independent of the cytochrome P450 (CYP450) enzyme system; as a result, linezolid is unlikely to interact with medications that stimulate or inhibit CYP450 enzymes. Compassionate-use trials and other clinical studies involving mainly adult hospitalized patients with gram-positive infections have shown that linezolid administered intravenously or orally is effective in a variety of nosocomial and community-acquired infections, including those caused by resistant gram-positive organisms. Reported adverse effects include thrombocytopenia. diarrhea, headache, nausea, vomiting, insomnia, constipation, rash, and dizziness. Preliminary pharmacoeconomic data indicate that a significantly higher percentage of patients receiving linezolid therapy versus comparator could be discharged from the hospital by day 7 (P = 0.005). CONCLUSIONS: Linezolid appears to be effective while maintaining an acceptable tolerability profile. Due to the risk of bacterial resistance, linezolid should be reserved for the treatment of documented serious vancomycin-resistant enterococcal infections.     

Randomized,double-blind,multicenter comparison of oral cefditoren 200 or 400 mg BID with either cefuroxime 250 mg BID or cefadroxil 500 mg BID for the treatment of uncomplicated skin and skin-structure infections

BACKGROUND: Uncomplicated skin and skin-structure infections are commonly observed in medical practice. Because these infections typically are confined to the superficial layers and seldom lead to the destruction of skin structures and resultant systemic dissemination, in general they can be treated with an oral antibiotic with potent microbiologic activity against gram-positive pathogens. OBJECTIVE: This paper compares the efficacy and tolerability of 3 beta-lactam antibiotics in patients with uncomplicated skin and skin-structure infections. METHODS: Two double-blind, multicenter, parallel-group studies were conducted, in which patients aged > or = 12 years with uncomplicated skin and skin-structure infections were randomized to receive cefditoren 200 or 400 mg, cefuroxime 250 mg, or cefadroxil 500 mg, each BID for 10 days. Study 1 compared cefditoren with cefuroxime; Study 2 compared cefditoren with cefadroxil. Clinical and microbiologic responses were assessed at a posttreatment visit (within 48 hours of treatment completion) and test-of-cure visit (7-14 days after treatment completion). Patients were monitored closely throughout the study with the use of physical examinations, clinical laboratory tests, and assessment of adverse events. RESULTS: A total of 1,685 patients (855 males, 830 females; mean age, 41.1 years [range, 12-95 years]) were enrolled. Within both studies, the 3 treatment groups were similar at baseline based on demographic characteristics and types of infection. Cellulitis (26%), wound infection (25%), and simple abscess (15%) were the most common infections. Clinical cure rates at the test-of-cure visit were 85% (443/523) for cefditoren 200 mg, 83% (427/516) for cefditoren 400 mg, 88% (234/265) for cefuroxime, and 85% (211/248) for cefadroxil. At the test-of-cure visit, cefditoren 200 mg had eradicated significantly fewer of the causative pathogens isolated before treatment in microbiologically evaluable patients than did cefuroxime in Study 1 (P = 0.043) but significantly more of the pathogens than did cefadroxil in Study 2 (P = 0.018). Eradication rates for the most commonly isolated pathogens were generally similar in the 3 treatment groups in both studies, with the only significant difference favoring cefditoren 200 and 400 mg over cefadroxil for Peptostreptococcus species in Study 2 (P = 0.016 and P = 0.003, respectively). A minority of patients (< or = 5% in any treatment group) discontinued study-drug treatment prematurely due to a treatment-related adverse event, with statistically higher rates for cefditoren 400 mg than for cefditoren 200 mg and the comparator cephalosporins (each P < 0.05). All 3 cephalosporins were generally well tolerated. Most adverse events (>93%) were categorized as mild to moderate, with the most common being diarrhea, nausea, and headache. CONCLUSION: In this population of patients with uncomplicated skin and skin-structure infections, including those due to Staphylococcus aureus or Streptococcus pyogenes, the clinical cure rate and tolerability of cefditoren were comparable to those of cefuroxime and cefadroxil.     

Safety profile of sparfloxacin, a new fluoroquinolone antibiotic

The safety profile of sparfloxacin, a newer fluoroquinolone antibiotic, was examined through an integrated analysis of safety data from 6 multicenter phase III trials. These consisted of 5 double-masked, randomized, comparative trials of sparfloxacin (a 400-mg oral loading dose followed by 200 mg/d for 10 days) versus standard therapies (erythromycin, cefaclor, ofloxacin, clarithromycin, and ciprofloxacin) and I open-label trial (noncomparative) in patients with: community-acquired pneumonia (2 trials); acute bacterial exacerbations of chronic bronchitis (1 trial); acute maxillary sinusitis (2 trials, one of which was the noncomparative trial); and complicated skin and skin-structure infections (1 trial). Overall, 401 (25.3%) of 1585 patients treated with sparfloxacin and 374 (28.1%) of 1331 receiving a comparator regimen experienced at least 1 adverse event considered to be related to the study medication. Photosensitivity reactions, usually of mild-to-moderate severity, were seen more frequently with sparfloxacin (7.4%) than with comparator agents (0.5%), whereas gastrointestinal reactions (diarrhea, nausea, dyspepsia, abdominal pain, vomiting, and flatulence), insomnia, and taste perversion were more common in patients taking comparator drugs (22.3% vs 12.1%, 4.3% vs 1.5%, and 2.9% vs 1.2%, respectively). Analysis of electrocardiographic findings showed that the mean change from baseline in QT interval corrected for heart rate (QTc) was significantly greater in sparfloxacin-treated patients (10 msec) than in patients given comparator drugs (3 msec), but no associated ventricular arrhythmias were detected. Adverse events led to discontinuation of study medication in 104 (6.6%) patients receiving sparfloxacin and 118 (8.9%) given com parator drugs. Sparfloxacin may be considered an appropriate choice for the treatment of certain community-acquired infections for patients who are not at risk for photosensitivity reactions or adverse events associated with prolongation of the QTc interval.     

The efficacy and safety of linezolid as treatment for Staphylococcus aureus infections in compassionate use patients who are intolerant of,or who have failed to respond to,vancomycin

OBJECTIVE: The incidence of infections caused by methicillin-resistant Staphylococcus aureus continues to increase annually. Unfortunately, only a few therapeutic agents are available for the treatment of patients with such infections and all of the existing drugs have limitations. A pressing need exists, therefore, to identify new antibiotics for use in this clinical setting. The efficacy and safety of linezolid were studied in a compassionate use treatment programme and the results of treating a subset of patients with S. aureus infections are presented here. METHODS: Patients received linezolid in a dosage of 600 mg intravenously (iv) and/or orally twice daily. Clinical and bacteriological responses were assessed after a minimum of 7 days and following completion of therapy. RESULTS: Seven hundred and ninety-six patients who suffered 828 episodes of infection were enrolled in the linezolid compassionate use protocol. Of these, 183 patients received linezolid for 191 infections caused by S. aureus; in 151 cases, patients were intolerant of vancomycin, had a mixed S. aureus/vancomycin-resistant enterococcal infection or had no iv access, and, in 40 cases, patients had failed to respond to treatment with vancomycin. The median age of the patients was 57 years (range 14-93 years) and 53.9% were female. The predominant sites of infection were as follows: bone or joint (27.2%); skin and skin structure (25.1%); bloodstream (20.9%); and lower respiratory tract (12.6%). The clinical success rates in the clinically evaluable and all-treated populations were 83.9% and 62.3%, respectively, whereas the bacteriological eradication rates were 76.9% and 70.2% in the bacteriologically evaluable and all-treated populations, respectively. Linezolid was well tolerated. In 76 (39.8%) of the 191 episodes of infection, patients experienced one or more adverse events or exhibited one or more abnormal laboratory results; in 35 (18.3%) of the 191 cases it was necessary to discontinue treatment. Gastrointestinal tract-related symptoms (nausea, vomiting and diarrhoea) were the most common possibly or probably related adverse events and the most common reasons for drug discontinuation. CONCLUSIONS: Linezolid was effective and well tolerated in patients with S. aureus infections who were enrolled in this compassionate use protocol.     

Analysis of the Phase 3 ESTABLISH Trials of Tedizolid versus Linezolid in Acute Bacterial Skin and Skin Structure Infections

Tedizolid, a novel oxazolidinone with activity against a wide range of Gram-positive pathogens, was evaluated in two noninferiority phase 3 acute bacterial skin and skin structure infection trials. The data from individual trials showed its noninferior efficacy compared to that of linezolid and a favorable tolerability profile. To evaluate potential differences, the pooled data were analyzed. The patients received 200 mg of tedizolid once daily for 6 days or 600 mg of linezolid twice daily for 10 days. Efficacy was evaluated at 48 to 72 h (primary endpoint), on days 11 to 13 (end of therapy [EOT]), and 7 to 14 days after the EOT (posttherapy evaluation). Treatment-emergent adverse events and hematologic and clinical laboratory parameters were collected. The baseline characteristics were comparable between the treatment groups: 852/1,333 (64%) patients were from North America, and the majority of infections were caused by Staphylococcus aureus. Tedizolid was noninferior to linezolid (early clinical responses, 81.6% versus 79.4%, respectively). The early responses remained relatively consistent across various host/disease factors and severity measures. Nausea was the most frequently reported adverse event (tedizolid, 8.2%; linezolid, 12.2%; P = 0.02), with onset occurring primarily during the first 6 days. Fewer tedizolid than linezolid patients had platelet counts of <150,000 cells/mm³ at the EOT (tedizolid, 4.9%; linezolid, 10.8%; P = 0.0003) and during the postbaseline period through the last day of active drug visit (tedizolid, 6.4%; linezolid, 12.6%; P = 0.0016). Efficacy was achieved with a 6-day once-daily course of therapy with the option of an intravenous/oral regimen, and fewer low platelet counts and gastrointestinal side effects were reported with tedizolid than with linezolid, all of which aligns well with antimicrobial stewardship principles. (These studies have been registered at ClinicalTrials.gov under registration no. {"type":"clinical-trial","attrs":{"text":"NCT01170221","term_id":"NCT01170221"}}NCT01170221 and {"type":"clinical-trial","attrs":{"text":"NCT01421511","term_id":"NCT01421511"}}NCT01421511.)     

Linezolid versus vancomycin in treatment of complicated skin and soft tissue infections

Skin and soft tissue infections (SSTIs) are a common cause of morbidity in both the community and the hospital. An SSTI is classified as complicated if the infection has spread to the deeper soft tissues, if surgical intervention is necessary, or if the patient has a comorbid condition hindering treatment response (e.g., diabetes mellitus or human immunodeficiency virus). The purpose of this study was to compare linezolid to vancomycin in the treatment of suspected or proven methicillin-resistant gram-positive complicated SSTIs (CSSTIs) requiring hospitalization. This was a randomized, open-label, comparator-controlled, multicenter, multinational study that included patients with suspected or proven methicillin-resistant Staphylococcus aureus (MRSA) infections that involved substantial areas of skin or deeper soft tissues, such as cellulitis, abscesses, infected ulcers, or burns (<10% of total body surface area). Patients were randomized (1:1) to receive linezolid (600 mg) every 12 h either intravenously (i.v.) or orally or vancomycin (1 g) every 12 h i.v. In the intent-to-treat population, 92.2% and 88.5% of patients treated with linezolid and vancomycin, respectively, were clinically cured at the test-of-cure (TOC) visit (P=0.057). Linezolid outcomes (124/140 patients or 88.6%) were superior to vancomycin outcomes (97/145 patients or 66.9%) at the TOC visit for patients with MRSA infections (P<0.001). Drug-related adverse events were reported in similar numbers in both the linezolid and the vancomycin arms of the trial. The results of this study demonstrate that linezolid therapy is well tolerated, equivalent to vancomycin in treating CSSTIs, and superior to vancomycin in the treatment of CSSTIs due to MRSA.     

Daptomycin for treating infected diabetic foot ulcers: evidence from a randomized, controlled trial comparing daptomycin with vancomycin or semi-synthetic penicillins for complicated skin and skin-structure infections

OBJECTIVES: The predominant pathogens causing diabetic foot infections are Gram-positive cocci, many of which are now resistant to commonly prescribed antibiotics. Daptomycin is a new agent that is active against most Gram-positive pathogens. To compare the effectiveness of daptomycin against semi-synthetic penicillins or vancomycin, we analysed the subset of diabetic patients with an infected ulcer enrolled in two randomized, controlled investigator-blind trials of patients with complicated skin and soft-tissue infections presumptively caused by Gram-positive organisms. PATIENTS AND METHODS: Patients with a diabetic ulcer infection were prospectively stratified to ensure they were equally represented in the treatment groups, then randomized to either daptomycin [4 mg/kg every 24 h intravenously (iv)] or a pre-selected comparator (vancomycin or a semi-synthetic penicillin) for 7-14 days. RESULTS: Among 133 patients with a diabetic ulcer infection, 103 were clinically evaluable; 47 received daptomycin and 56 received a comparator. Most infections were monomicrobial, and Staphylococcus aureus was the predominant pathogen. Success rates for patients treated with daptomycin or the comparators were not statistically different for clinical (66% versus 70%, respectively; 95% CI, -14.4, 21.8) or microbiological (overall or by pathogen) outcomes. Both treatments were generally well tolerated, with most adverse events of mild to moderate severity. CONCLUSIONS: The clinical and microbiological efficacy and safety of daptomycin were similar to those of commonly used comparator antibiotics for treating infected diabetic foot ulcers caused by Gram-positive pathogens. Daptomycin should be considered for treating these infections, especially those caused by resistant Gram-positive pathogens.     

Comparison of single-dose cefuroxime axetil with ciprofloxacin in treatment of uncomplicated gonorrhea caused by penicillinase-producing and non-penicillinase-producing Neisseria gonorrhoeae strains.

A randomized, multicenter, investigator-blind trial was conducted to compare the efficacies of cefuroxime axetil and ciprofloxacin for treatment of patients with uncomplicated gonorrhea caused by penicillinase-producing Neisseria gonorrhoeae (PPNG). A total of 832 patients (434 females and 398 males) received a single oral dose of cefuroxime axetil (1,000 mg [417 patients]) or ciprofloxacin (500 mg [415 patients]). N. gonorrhoeae was eradicated from the cervix in 114 of 118 (97%) and 118 of 119 (99%) bacteriologically evaluable females treated with cefuroxime axetil and ciprofloxacin, respectively (P = 0.213; difference, -2%; 95% confidence interval, -6 to 1%), and from the urethra in 154 of 166 (93%) and 171 of 171 (100%) bacteriologically evaluable male patients treated with cefuroxime axetil and ciprofloxacin, respectively (P < 0.001; difference, -7%; 95% confidence interval, -11 to -3%). Both treatments were effective in eradicating N. gonorrhoeae in females with rectal infections (cefuroxime axetil, 29 of 30 [97%]; ciprofloxacin, 25 of 25 [100%]; P = 1.00). In small numbers of patients, cefuroxime axetil was less effective than ciprofloxacin in treating males with pharyngeal infections (eradication in 4 of 10 and in 8 of 8 patients, respectively; P = 0.013). PPNG was eradicated from the cervix in 22 of 23 (96%) and 32 of 32 (100%) bacteriologically evaluable female patients treated with cefuroxime axetil and ciprofloxacin, respectively (P = 0.418; difference, -4%; 95% confidence interval, -13 to 4%), and from the urethra in 35 of 36 (97%) and 34 of 34 (100%) bacteriologically evaluable male patients treated with cefuroxime axetil and ciprofloxacin, respectively (P = 1.00; difference, -3%; 95% confidence interval, -8 to 3%). The incidences of drug-related adverse events were similar for the two study drugs. In summary, treatment with a single oral dose of cefuroxime axetil is as effective as treatment with a single oral dose of ciprofloxacin in eradicating PPNG from males and females with uncomplicated gonorrhea (urethral and endocervical), and both regimens are well-tolerated. However, in the present study, cefuroxime axetil was less effective than ciprofloxacin in treating urethral gonococcal infections in male patients, although both study drugs were highly effective in treating cervical gonococcal infections in female patients.     

Randomized, double-blind, phase II, multicenter study evaluating the safety/tolerability and efficacy of JNJ-Q2, a novel fluoroquinolone, compared with linezolid for treatment of acute bacterial skin and skin structure infection

JNJ-Q2 is a fluoroquinolone with broad coverage including methicillin-resistant Staphylococcus aureus (MRSA). A double-blind, multicenter, phase II noninferiority study treated 161 patients for 7 to 14 days, testing the efficacy of JNJ-Q2 (250 mg, twice a day [BID]) versus linezolid (600 mg, BID) in patients with acute bacterial skin and skin structure infections (ABSSSI). The prespecified criterion for noninferiority was 15%. Primary intent-to-treat analysis was unable to declare noninferiority, as the risk difference lower bound of the 95% confidence interval between treatments was 19% at 36 to 84 h postrandomization for the composite end point of lesion assessment and temperature. Prespecified clinical cure rates 2 to 14 days after completion of therapy were similar (83.1% for JNJ-Q2 versus 82.1% for linezolid). Post hoc analyses revealed that JNJ-Q2 was statistically noninferior to linezolid (61.4% versus 57.7%, respectively; P = 0.024) based on the 2010 FDA guidance, which defines treatment success as lack of lesion spread and afebrile status within 48 to 72 h postrandomization. Despite evidence of systemic disease, <5% of patients presented with fever, suggesting fever is not a compelling surrogate measure of systemic disease resolution for this indication. Nausea and vomiting were the most common adverse events. Of the patients, 86% (104/121) had S. aureus isolated from the infection site; 63% of these were MRSA. The results suggest JNJ-Q2 shows promise as an effective treatment for ABSSSI, demonstrating (i) efficacy for early clinical response (i.e., lack of spread of lesions and absence of fever at 48 to 72 h), and (ii) cure rates for ABSSSI pathogens (especially MRSA) consistent with the historical literature.     

Ampicillin/sulbactam versus cefazolin or cefoxitin in the treatment of skin and skin-structure infections of bacterial etiology

This randomized, double-blind study compared 1 g of ampicillin plus 0.5 g of sulbactam with 0.5 g of cefazolin in the treatment of cellulitis and with 1 g of cefoxitin in other skin and skin-structure infections. Study drugs were administered intravenously every 6 hours to 58 hospitalized patients. Each indication was evaluated separately. In cellulitis, ampicillin/sulbactam and cefazolin produced clinical cure or improvement in 100% and 91.7% of patients, respectively; duration of hospitalization was 7.7 and 7.2 days. In other skin and skin-structure infections, results for ampicillin/sulbactam and cefoxitin, respectively, were clinical cure or improvement, 80% and 64.7%; treatment failures, 0% and 11.8%; bacterial eradication, 40% and 53%; and duration of hospitalization, 7.7 and 9.4 days. No unusual or unexpected adverse experiences related to any study drug occurred. One patient treated with ampicillin/sulbactam died of a pulmonary embolism, and 1 patient treated with cefoxitin was discontinued from the study following amputation of an infected foot. These events were not considered drug-related. The treatment groups showed no statistically significant differences in efficacy or safety.