Treatment of chronic experimental Staphylococcus aureus osteomyelitis with LY146032 and vancomycin

Comparing the efficacy of different antibiotic regimens on osteomyelitis: A network meta-analysis of animal studies

Background

Despite the surge in the number of antibiotics used to treat preclinical osteomyelitis (OM), their efficacy remains inadequately assessed.

Objective

To establish network comparisons on the efficacy of antibiotic regimens on OM in animal studies.

Methods

PubMed, Embase, Web of Science, and The Cochrane Library were searched from inception to March 2022 for relevant articles. Odds ratios (ORs) were generated for dichotomous variants, and the standard mean difference (SMD) was calculated for constant variables. The predominant outcomes were the effective rate of sterility, also known as sterility rates, as well as the bacterial counts at the end of the experiments and antibiotic concentrations in serum or bone. All the network meta-analyses were performed using STATA MP 16.0. This study was registered in the International Prospective Register of Systematic Reviews (PROSPERO; no. CRD42022316544).

Results

A total of 28 eligible studies with 1,488 animals were included for data analysis, including 13 antibiotic regimens. Regarding the effective rate of sterility, glycopeptides (GLY), linezolid (LIN), rifampicin (RIF)+β-Lactam, and β-Lactam showed significant efficacy compared with placebo (OR ranging from 0.01 to 0.08). For radiological grade, only RIF+GLY (SMD: −5.92, 95%CI: −11.65 to −0.19) showed significant efficacy compared with placebo. As for reducing bacteria count, fosfomycin (FOS), tigecycline (TIG), GLY, LIN, RIF, RIF+β-Lactam, RIF+GLY, aminoglycosides (AMI), and clindamycin (CLI) showed significant efficacy compared with placebo (SMD ranging from −6.32 to −2.62). Moreover, the bone concentrations of GLY were higher 1 h after administration and the higher blood concentrations were higher after 1 h and 4 h compared with the other antibiotics.

Conclusion

Multiple antibiotic regimens showed significant efficacy in animals with OM, including increasing effective rates of sterility, reducing bacterial counts, and lowering radiological scores. Among them, RIF+GLY was the most promising treatment regimen owing to its optimal efficacy. Based on the preclinical studies included in our meta-analysis, head-to-head clinical randomized controlled trials are required to confirm these findings in humans.

Daptomycin compared to vancomycin for the treatment of osteomyelitis: a single-center, retrospective cohort study

BACKGROUND

Osteomyelitis (OM) is a serious infection with high rates of recurrence. Vancomycin has been used for decades in the treatment of OM, but, despite adequate dosing, 30% to 50% of patients experience infection recurrence within 12 months. Daptomycin, a novel lipopetide antibiotic, is also active against resistant gram-positive organisms, but there is little published about its efficacy and tolerability in the treatment of OM.

OBJECTIVE

Our aim was to compare the recurrence rates of OM in patients treated with daptomycin or vancomycin.

METHODS

A retrospective cohort study of all patients at a VA Medical Center between January 1, 2003, and July 31, 2009, who received daptomycin for the treatment of OM was undertaken. Patients with a diagnosis of OM who received at least 2 weeks of daptomycin and had at least 1 follow-up visit within 6 months after completion of therapy were included. Each patient was matched with 2 controls treated with at least 2 weeks of vancomycin for OM. Matching criteria included previous OM, diabetes, peripheral vascular disease, hardware involvement, and surgical therapy. Patients were excluded from the evaluation if they received <14 days of therapy, had no follow-up in the 6 months after therapy was discontinued, had an absolute neutrophil count <500 cells/mm(3), or were receiving vancomycin and daptomycin concurrently. The primary outcome was recurrence of infection within 6 months after the discontinuation of therapy. Secondary outcomes included mean change in creatine phosphokinase (CPK), incident thrombocytopenia, and mean doses of antibiotics. The χ(2) test was used to compare rates of recurrence between groups.

RESULTS

Seventeen patients received at least 2 weeks of daptomycin for the treatment of OM and were matched to 34 vancomycin controls. Twenty-nine percent of patients receiving daptomycin had a recurrence of infection compared with 61.7% in the vancomycin group (P = 0.029). The mean change in CPK for the daptomycin group was +28.8 U/L. No thrombocytopenia developed in any patients receiving daptomycin compared with 2 (5.9%) patients in the vancomycin group.

CONCLUSIONS

In a limited number of cases, significantly fewer patients treated with daptomycin for OM had a recurrence of their infection. Daptomycin may be a tolerable and effective alternative to vancomycin for the treatment of OM.

Daptomycin, fosfomycin, or both for treatment of methicillin-resistant Staphylococcus aureus osteomyelitis in an experimental rat model

The in vivo activities of daptomycin, fosfomycin, and a combination of both antibiotics against a clinical isolate of methicillin-resistant Staphylococcus aureus (daptomycin MIC, 0.25 μg/ml; fosfomycin MIC, 0.5 μg/ml) were evaluated in a rat model of osteomyelitis. A total of 37 rats with experimental osteomyelitis were treated for 4 weeks with either 60 mg/kg of body weight of daptomycin subcutaneously once daily, 75 mg/kg fosfomycin intraperitoneally once daily, a combination of both drugs, or a saline placebo. After the completion of treatment, animals were euthanized, and the infected tibiae were processed for quantitative bacterial culture. Bone cultures were found to be positive for methicillin-resistant S. aureus in 9 of 9 (100%) animals of the placebo group, in 9 of 9 (100%) animals treated with daptomycin, in 1 of 10 (10%) fosfomycin-treated rats, and in 1 of 9 (22.2%) rats comprising the combination group. Results of bacterial counts in the bone samples were expressed as log(10) CFU/g of bone and analyzed by using the Mann-Whitney U test followed by Bonferroni's multiple-comparison test. Based on bacterial counts, treatment with daptomycin was significantly superior to placebo, although it remained inferior to treatment with fosfomycin. No synergistic or antagonistic effect was observed for the combination therapy. No development of resistance against daptomycin or fosfomycin was observed after the 4-week treatment period.

Efficacy of daptomycin combined with rifampicin for the treatment of experimental meticillin-resistant Staphylococcus aureus (MRSA) acute osteomyelitis

Daptomycin exhibits rapid bactericidal activity against Gram-positive organisms, including meticillin-resistant Staphylococcus aureus (MRSA). Daptomycin in combination with rifampicin needs to be assessed in bone infection. An MRSA acute osteomyelitis model was used. Daptomycin and vancomycin were compared, alone or in combination with rifampicin, over 4 days. Surviving bacteria were counted in bone, bone marrow and joint fluid. Vancomycin and daptomycin as single therapies were ineffective, but both combinations were significantly more effective than the corresponding monotherapy. Combination of daptomycin and rifampicin could prevent S. aureus from developing resistance. This combination could be a useful alternative to treat MRSA osteomyelitis at an early stage.

New therapeutic choices for infections caused by methicillin-resistant Staphylococcus aureus

In recent years, a marked increase in the incidence of infections caused by methicillin-resistant Staphylococcus aureus (MRSA) has occurred in many countries. This review addresses the effectiveness and limitations of drugs classically used for the treatment of MRSA, e.g. vancomycin, and also newer anti-MRSA antimicrobials, e.g. second-generation glycolipopeptides, tigecycline, and beta-lactams.

Daptomycin in bone and joint infections: a review of the literature

INTRODUCTION

To review the pharmacology, pharmacokinetics, efficacy, and safety of daptomycin, a novel antibiotic for the treatment of bone and joint infections, a literature search of relevant articles was conducted.

MATERIALS AND METHODS

A PubMed/MEDLINE search (1990-April 2008) to identify relevant English-language literature was conducted. Search terms included bone and joint infection, osteomyelitis, daptomycin, and methicillin-resistant Staphylococcus aureus (MRSA). Additional articles were identified by reviewing the bibliographies of articles cited. Programs and abstracts from infectious disease meetings were searched, and prescribing information of antibiotics indicated for bone and joint infections consulted. All articles identified from data sources published in English were evaluated.

RESULTS

Caused primarily by Gram-positive pathogens such as S. aureus and, to a lesser extent, Enterococcus faecalis, bone and joint infections are difficult to treat successfully. Surgical intervention and prolonged courses of antibiotics are frequently required, and failure of first-line antibiotic therapy is common. The emergence of S. aureus strains with reduced susceptibility to vancomycin, the longstanding gold standard for bone and joint infections, has complicated the clinical scenario. Few randomized trials comparing the efficacy of different antibiotics for bone and joint infections exist. Daptomycin, a novel intravenous lipopeptide antibiotic, has shown potent in vitro activity against a broad spectrum of Gram-positive bacteria, including many resistant pathogens commonly associated with bone and joint infections such as MRSA and vancomycin-resistant E. faecalis. Early clinical investigation of daptomycin in bone and joint infections unresponsive to antibiotics, such as vancomycin, has found a cure rate of approximately 80%, with a low incidence of adverse events and drug resistance.

CONCLUSION

Further studies are warranted to determine if limited clinical evidence, described in individual case reports and a daptomycin-specific retrospective registry, suggests daptomycin is a promising option for patients with bone and joint infections such as MRSA osteomyelitis.

Daptomycin: The First Approved Lipopeptide Antimicrobial

OBJECTIVE

To review the literature concerning the first Food and Drug Administration-approved lipopeptide antimicrobial, daptomycin.

DATA SOURCES

A PUBMED search was conducted to identify pertinent English-language journal articles between 1985 and November 2003, and additional references were obtained from the bibliographies of these articles. Abstracts from the Interscience Conference on Antimicrobial Agents and Chemotherapy meetings from 1985 through 2003 also were reviewed.

STUDY SELECTION

All studies evaluating any aspect of daptomycin.

DATA SYNTHESIS

Daptomycin is a semisynthetic lipopeptide, the first such antimicrobial agent to reach the marketplace. Its mechanism of action differs from that of the related agent vancomycin in that much of its effect is not because of inhibition of peptidoglycan biosynthesis, but instead is a result of alterations in cell-membrane electrical charge and transport. It exhibits a broad spectrum of activity against gram-positive aerobes and anaerobes, including methicillin-, penicillin-, aminoglycoside-, and vancomycin-resistant strains. In subjects with normal renal function, the terminal disposition half-life is about 7 to 10 hours. It is principally eliminated as unchanged drug in the urine. Available clinical trial data demonstrate efficacy in complicated skin and skin-structure infections resulting from susceptible gram-positive pathogens, but not in pneumonia. The principal adverse event of concern, although rare, is myotoxicity, manifested by muscle pain and/or weakness and elevated serum creatine phosphokinase (CPK) concentrations. The approved dosage regimen is 4 mg/kg intravenously over 30 minutes once daily for 7 days to 14 days. Studies are underway evaluating doses of up to 8 mg/kg once daily.

CONCLUSIONS

Daptomycin, the first lipopeptide antimicrobial to be marketed, exhibits activity against multiresistant gram-positive pathogens, including linezolid- and quinupristindalfopristin-resistant strains. As such, it is a potentially valuable agent to treat infections resulting from such pathogens. To preserve its utility, it should not be used indiscriminately for infections resulting from pathogens sensitive to other antimicrobials. It is probably best used with restricted access and used only for multiresistant gram-positive pathogens where alternative agents cannot be employed. If used, careful monitoring for the signs and symptoms of myotoxicity, including obtaining weekly serum CPK levels, is mandatory. In addition, bacterial sensitivities to this agent should be prospectively monitored by national antimicrobial surveillance programs like SENTRY, TRUST, and LIBRA.

Clinical experience with daptomycin for the treatment of patients with osteomyelitis

Data from a registry were analyzed to describe the clinical experience with daptomycin (Cubicin; Cubist Pharmaceuticals, Inc., Lexington, MA) for the treatment of patients with osteomyelitis. The Cubicin Outcomes Registry and Experience (CORE) 2004 database was used to identify patients treated for osteomyelitis. Posttherapy follow-up outcome assessments were collected for a subset of these patients. A total of 67 patients with osteomyelitis were clinically evaluable for outcome at the end of daptomycin therapy and had outcome assessed at a posttherapy visit. The median follow-up interval after the last dose of daptomycin was 76 days (range, 1 to 547 days). The median initial dose was 5.6 mg/kg (range, 3.2 to 7.5 mg/kg), and the median duration of therapy was 35 days (range, 3 to 546 days). Daptomycin was given concurrently with other antibiotics in 48% of cases. Methicillin-resistant Staphylococcus aureus was the most common pathogen (45%). Clinical outcomes at follow-up were cure, 42 (63%); improved, 13 (19%); failure, 7 (10%); and nonevaluable, 5 (7%). A total of 82% of patients with an orthopedic device (n = 17) were successfully treated, as were 88% of patients with concurrent bacteremia (n = 16). Failures were more likely if surgical debridement was not performed (24% vs. 5%; P = 0.045). The clinical success rate for patients treated with an initial daptomycin dose >4 mg/kg was significantly higher than for patients treated with an initial dose < or =4 mg/kg (88% vs. 65%; P = 0.013, chi2 test). Daptomycin had a 94% success rate when used alone with no follow-up antibiotics. The results indicate that daptomycin is being used in clinical practice to treat patients with osteomyelitis caused by gram-positive pathogens including MRSA. Prospective, controlled clinical trials of daptomycin are warranted that include rigorous data collection and long-term follow-up analysis.

Clinical experience with daptomycin treatment of foot or ankle osteomyelitis: a preliminary study

We retrospectively reviewed 25 patients with foot or ankle osteomyelitis reported to a registry who were treated with daptomycin. The patients' clinical experience was analyzed and described at a median dose of 6 mg/kg (range, 4-6.2 mg/kg) and a median duration of 38 days (range, 6-59 days). Twenty-three patients received daptomycin as secondary or tertiary therapy, primarily for not responding to their prior antibiotic therapy (n = 15). Concomitant antibiotics were given to 11 patients, mostly for Gram-negative and/or anaerobic coverage. Methicillin-resistant Staphylococcus aureus was the most common pathogen overall (15 of 25 patients). The median followup interval was 9 weeks (range, 0.5-77 weeks). Outcomes at the end of therapy were 16 patients' symptoms resolved, eight patients improved, and one patient did not respond to therapy; at followup, 19 patients' symptoms resolved, three patients improved, and three patients did not respond to therapy. Ongoing antibiotics were given to 52% of patients for a minimum of 8 days (median, 30 days; range, 8-232 days). Four patients with an implant (all removed) were successfully treated. Daptomycin appears promising for foot and ankle osteomyelitis caused by Gram-positive bacteria. Prospective, controlled clinical trials of daptomycin for osteomyelitis are warranted.

Pharmacodynamics of antibiotics to treat multidrug-resistant Gram-positive hospital infections

Hospital infection due to multidrug-resistant Gram-positive bacteria may often represent a life-threatening challenge; thus, to appropriately combat them, clinicians should be confident and systematically apply several important pharmacodynamic concepts. The concept of 'correct antibiotic treatment' should include, in addition to an appropriate choice in terms of antimicrobial susceptibility, an appropriate dosage and administration schedule consistent with the pharmacodynamic principles. In the next few years, it is expected that some of the anti-Gram-positive antimicrobial agents that are currently under investigation will be added to the therapeutic armamentarium. However, optimization of the usage of old drugs still remains a clinical priority and a scientific challenge, whose dignity may be considered of similar importance to that of the assessment of the possible therapeutic role of the new compounds.

Experimental osteomyelitis: what have we learned from animal studies about the systemic treatment of osteomyelitis?

Clinical trials of systemic antibiotic treatment of osteomyelitis are difficult to perform for many reasons, such as low incidence rate of osteomyelitis, variety of anatomic locations, stage and etiologic agents. In this article, we reviewed the experimental studies on osteomyelitis available in the English medical literature since 1968, to ascertain their actual and potential impact on the treatment of human osteomyelitis. Major results are summarized and topics of major interest, such as reproducibility of animal models, predictive value of animal models, correlation of pharmacokinetics between different animals and humans, and the correlation of outcome between animal and clinical studies are discussed. Most of the reviewed animal models are reproducible and dependable. However, establishing the right dose regimen in animals appeared a critical factor, which might undermine the predictive value of the experimental study. Due to difficulties in comparing results of animal and human studies, the predictive value of animal studies about osteomyelitis is still unclear. However, animal models gave valuable information to the clinician for choosing the minimal duration of antibiotic treatment. Even though the use of antibiotic combinations was associated with better outcome in the majority of animal studies, such a finding seems to have limited impact on clinical practice.

Uncertain efficacy of daptomycin for prosthetic joint infections: a prospective case series

Daptomycin is an option for prosthetic joint infection (PJI) because it is bactericidal against gram-positive bacteria, including multiple-resistant isolates, and active against stationary-phase bacteria in biofilm present on implants. To evaluate its possible utility, we prospectively monitored 12 adults with gram-positive PJI who were not candidates for vancomycin. Pathogens included methicillin-resistant Staphylococcus aureus (n = 7), methicillin-resistant-coagulase-negative Staphylococci (n = 4), and methicillin-sensitive Staphylococcus aureus (n = 1). All patients completed a 6-week course of daptomycin 4 mg/kg/day. One died of an unrelated cause shortly after completing therapy. After a followup of 7 to 13 months, six patients had no clinical, laboratory, or radio-graphic signs of recurrence. One patient failed a first course and was subsequently treated with hardware removal and a second course with no recurrence. Five patients had culture-confirmed failure-all due to MRSA-including two during therapy despite hardware removal and three 1 to 10 months after completing daptomycin but with retained hardware. The efficacy of daptomycin 4 mg/kg/day is uncertain in patients with PJI, especially when hardware is retained. Further study is needed to determine why in vitro data did not predict clinical success and to ascertain any potential benefit from higher doses.

Daptomycin treatment of Staphylococcus aureus experimental chronic osteomyelitis

BACKGROUND

Infection due to methicillin-resistant Staphylococcus aureus (MRSA) is increasingly common in nosocomial and community settings. Daptomycin is a cyclic lipopeptide anti-infective with activity against MRSA, approved for treatment of complicated skin and skin structure infections. Daptomycin may be useful in systemic or local treatment of chronic osteomyelitis.

METHODS

We measured mechanical strength of daptomycin- and vancomycin-loaded polymethylmethacrylate (PMMA), assayed in vivo release of daptomycin and vancomycin from daptomycin- and vancomycin-loaded PMMA, respectively, and compared the efficacy of two systemic doses of daptomycin with that of vancomycin, each with or without the respective anti-infective loaded into PMMA, using a rat model of MRSA chronic osteomyelitis.

RESULTS

Neither tensile nor compressive strength of PMMA was impacted by impregnation with these antimicrobials at a concentration of 7.5% by weight. The peak concentrations of daptomycin and vancomycin in rat tibial bone surrounding a 7.5% daptomycin- and vancomycin-loaded 3 mm PMMA bead were 178 and 49 mg/L, respectively. In the treatment of experimental osteomyelitis, rats assigned to no treatment, daptomycin 50 mg/kg subcutaneously twice daily, daptomycin 60 mg/kg subcutaneously twice daily, and vancomycin 50 mg/kg intraperitoneally twice daily had 6.4, 4.1, 4.0 and 4.5 median log10 cfu/g of bone at the end of 21 days of therapy. All systemic anti-infectives studied were more active than was no treatment. Daptomycin- or vancomycin-loaded PMMA did not, however, exhibit microbiological efficacy alone or adjunctively, as assessed 21 days after implantation.

CONCLUSIONS

Daptomycin is released from PMMA in vivo at a rate similar to that of vancomycin. Systemic daptomycin is as active as vancomycin in a rat model of chronic MRSA experimental osteomyelitis.

Daptomycin: a novel cyclic lipopeptide antimicrobial

PURPOSE

The development, activity, pharmacokinetics, pharmacodynamics, clinical efficacy, adverse effects, and dosage and administration of daptomycin are reviewed.

SUMMARY

Daptomycin, a novel cyclic lipopeptide antimicrobial, is bactericidal against a range of gram-positive bacteria, including many multiple-drug-resistant isolates. It has only minimal activity against anaerobic bacteria and no activity against gram-negative bacteria. Daptomycin exhibits linear pharmacokinetics, and the plasma concentration-versus-time relationship is best described by a two-compartment model with first-order elimination. The initial bactericidal activity is rapid, extensive, and concentration related. In clinical trials, daptomycin has shown efficacy in treating complicated skin and skin-structure infections (CSSSIs); the drug carries FDA-approved labeling for same. The adverse effects of daptomycin appear comparable to those of vancomycin and semisynthetic penicillins. The dosage for CSSSIs is 4 mg/kg by i.v. infusion every 24 hours.

CONCLUSION

Daptomycin is bactericidal against gram-positive organisms and offers an option in the treatment of CSSSIs.

Daptomycin: a cyclic lipopeptide antimicrobial agent

Objectives:

The aims of this article were: to summarize the pharmacology, pharmacokinetics, and efficacy ofdaptomycin; to explore its safety profile; and to discuss its current and potential roles as an antimicrobial therapy.

Methods:

A literature search was conducted using the MEDLINE (1966–August 2004) and InternationalPharmaceutical Abstracts (1970–August 2004) databases with the search terms daptomycin, LY146032, and lipopeptide antibiotics. Abstracts of the Interscience Conference on Antimicrobial Agents and Chemotherapy and documents submitted to the US Food and Drug Administration were also reviewed.

Results:

Phase III study results suggest no difference in efficacy or tolerability between daptomycin 4 mg/kgIV QD and vancomycin or semisynthetic penicillins for complicated skin and skin-structure infections. Animal studies suggest daptomycin may be useful for the treatment of endocarditis. Daptomycin is not indicated for pneumonia, with poorer outcomes than conventional treatment It is available as an IV medication and exhibits 92% plasma protein binding in vitro. In healthy adult humans, daptomycin has a volume of distribution of 0.1 Ukg and a plasma elimination half-life of ∼9 hours, and is eliminated primarily by renal excretion (∼54%). In patients with reduced renal function, including those receiving hemodialysis and peritoneal dialysis, the dose interval should be 48 hours. No dosage adjustment appears to be necessary for mild to moderate hepatic impairment. The use of daptomycin in patients with severe hepatic impairment has not been assessed. The most commonly reported adverse events include constipation, nausea, injection-site reactions, headache, and diarrhea. Patients should also be monitored regularly for skeletal muscle toxicity.

Conclusions:

Daptomycin may be useful for complicated skin and skin-structure infections and gram-positive pathogens resistant to conventional antimicrobials. However, limited data are currently available for duration of treatment beyond 14 days and at doses >4 mg/kg QD.

Daptomycin: a novel agent for Gram-positive infections

The alarming increase in the incidence of Gram-positive infections, including those caused by resistant bacteria, has sparked renewed interest in novel antibiotics. One such agent is daptomycin, a novel lipopeptide antibiotic with proven bactericidal activity in vitro against all clinically relevant Gram-positive bacteria. These include resistant pathogens, such as vancomycin-resistant enterococci (VRE), methicillin-resistant Staphylococcus aureus (MRSA), glycopeptide intermediately susceptible Staphylococcus aureus (GISA), coagulase-negative staphylococci (CNS) and penicillin-resistant Streptococcus pneumoniae (PRSP), for which there are very few therapeutic alternatives. Daptomycin provides rapid, concentration-dependent killing and a relatively prolonged concentration-dependent post-antibiotic effect in vitro. Spontaneous acquisition of resistance to daptomycin occurs rarely. Daptomycin exhibits linear pharmacokinetics, minimal accumulation with once-daily dosing, and low plasma clearance and volume of distribution. Phase II clinical trials indicate that daptomycin at doses of 2 mg/kg q24 h and 3 mg/kg q12 h is efficacious against skin and soft tissue infections and bacteremia, respectively. In addition, results in endocarditis suggested potential efficacy with higher doses. On the basis of clinical trials to date, it appears that daptomycin has an excellent safety profile, with the incidence and nature of serious adverse events comparable to those observed with conventional therapy. Adverse events associated with other classes of antimicrobials (nephrotoxicity, local irritation, ototoxicity, hypersensitivity, and gastrointestinal effects) were uncommon with daptomycin. Minimal skeletal muscle toxicity was seen at only the highest dose tested (4 mg/kg q12 h), predicted by elevations in serum creatinine phosphokinase, and readily reversible upon discontinuation of treatment. There were no signs of toxicity in cardiac or smooth muscle. Phase II and III clinical trials are underway to evaluate daptomycin for the treatment of Gram-positive bacteremia and complicated skin and soft tissue infections, respectively. Daptomycin holds promise as a rapidly acting and highly effective antibiotic for Gram-positive infections.

Novel agents for resistant Gram-positive infections--a review

Gram-positive infections have increased in recent years, particularly those that are of nosocomial origin, leading to a broad use of agents with activity against these pathogens. Concomitantly, antimicrobial resistance of these pathogens also became widespread. Among the most common Gram-positive resistant pathogens are: Streptococcus pneumoniae, resistant to penicillin and macrolides, methicillin-resistant Staphylococcus aureus (MRSA), glycopeptide-intermediately-resistant S. aureus (GISA), methicillin-resistant S. epidermidis, glycopeptide-resistant enterococci and vancomycin-resistant enterococci (VRE). The response of the pharmaceutical industry to this challenge was the development of new antibiotics active against these pathogens. Among these antibiotics, this review will focus on: linezolid, an oxazolidinone; GAR-936, a tetracycline derivative; daptomycin, a lipopeptide; and ortivancin (LY-333328), a glycopeptide related to vancomycin. Except for linezolid, which has been recently launched in many countries, all other agents referred to in this review are still at various developmental stages. It is hoped that in the near future most of these agents will be approved and thus the grim outlook of patients infected with resistant Gram-positive bacteria may improve.