Comparative in vitro study of teichomycin A2

Coagulase-negative staphylococci

The definition of the heterogeneous group of coagulase-negative staphylococci (CoNS) is still based on diagnostic procedures that fulfill the clinical need to differentiate between Staphylococcus aureus and those staphylococci classified historically as being less or nonpathogenic. Due to patient- and procedure-related changes, CoNS now represent one of the major nosocomial pathogens, with S. epidermidis and S. haemolyticus being the most significant species. They account substantially for foreign body-related infections and infections in preterm newborns. While S. saprophyticus has been associated with acute urethritis, S. lugdunensis has a unique status, in some aspects resembling S. aureus in causing infectious endocarditis. In addition to CoNS found as food-associated saprophytes, many other CoNS species colonize the skin and mucous membranes of humans and animals and are less frequently involved in clinically manifested infections. This blurred gradation in terms of pathogenicity is reflected by species- and strain-specific virulence factors and the development of different host-defending strategies. Clearly, CoNS possess fewer virulence properties than S. aureus, with a respectively different disease spectrum. In this regard, host susceptibility is much more important. Therapeutically, CoNS are challenging due to the large proportion of methicillin-resistant strains and increasing numbers of isolates with less susceptibility to glycopeptides.

Mechanism of action of oritavancin and related glycopeptide antibiotics

Oritavancin (LY333328) is a semisynthetic glycopeptide antibiotic having excellent bactericidal activity against glycopeptide-susceptible and -resistant Gram-positive bacteria. Oritavancin is the N-alkyl-p-chlorophenylbenzyl derivative of chloroeremomycin (LY264826) and is currently in phase III clinical trials for use in Gram-positive infections. Studies show that oritavancin and related alkyl glycopeptides inhibit bacterial cell wall formation by blocking the transglycosylation step in peptidoglycan biosynthesis in a substrate-dependent manner. As with other glycopeptide antibiotics, including vancomycin, the effects of oritavancin on cell wall synthesis are attributable to interactions with dipeptidyl residues of peptidoglycan precursors. Unlike vancomycin, however, oritavancin is strongly dimerized and can anchor to the cytoplasmic membrane, the latter facilitated by its alkyl side chain. Cooperative interactions derived from dimerization and membrane anchoring in situ can be of sufficient strength to enable binding to either dipeptidyl or didepsipeptidyl peptidoglycan residues of vancomycin-susceptible and -resistant enterococci, respectively. This review describes the antibacterial activity of oritavancin, and examines the evidence supporting the proposed mechanism of action for this agent and related analogs.

Bacteraemia caused by coagulase-negative staphylococci exhibiting decreased susceptibility to teicoplanin

The purpose of our study was to assess the prevalence of coagulase-negative staphylococci (CoNS) isolates with reduced susceptibility to glycopeptides among the isolates responsible for bloodstream infections and to describe the epidemiology of these isolates. CoNS isolates from bloodstream infections were collected and characterized by analysis of antibiotic susceptibility and restriction fragment length polymorphism using pulsed-field gel electrophoresis. The medical records of patients with positive cultures and trends in glycopeptide use were reviewed to determine the effect of previous antibiotic treatment on the susceptibility profile of these organisms. The crude incidence of CoNS bacteraemia was 0.51 per 1000 days of hospitalization. The 15 (28.8%) strains identified as having decreased susceptibility to teicoplanin by the reference method were all hospital-acquired and displayed 13 different DNA patterns. The relative risk of harbouring strains with decreased susceptibility to teicoplanin was 3.55 among patients previously treated with vancomycin (confidence interval 95%: 2.15-5.85). The teicoplanin consumption in our institution was constant and represented about 27% of the glycopeptide consumption in daily defined doses. The implementation of programmes aiming to reduce the unnecessary use of glycopeptides should have a significant impact on the reduced-susceptibility rate because strains probably become resistant as a result of antibiotic pressure.

Vancomycin resistance in staphylococci

Recent emergence of vancomycin resistance in methicillin-resistant Staphylococcus aureus (VRSA) has posed a new threat to hospital infection control and antibiotic chemotherapy. Relatively low-level resistance of VRSA compared to that of vancomycin-resistant enterococci (VRE), and prevalence of S. aureus clinical strains heterogeneously resistant to vancomycin (hetero-VRSA), challenge the value of routine antibiotic susceptibility tests as a tool for the prediction of clinical efficacy of vancomycin therapy. This review summarizes the history of emergence of glycopeptide resistance in staphylococci and considers the mechanism of resistance in these organisms.

Teicoplanin

Teicoplanin, a new glycopeptide antibiotic similar to vancomycin, has proved effective in the treatment of various gram-positive infections in both the normal and the immunocompromised host. In vitro activity against most gram-positive organisms is equal to or greater than that of vancomycin. In both open and comparative clinical trials, teicoplanin has been well tolerated, rarely prompting discontinuation of treatment. Nephrotoxicity caused by teicoplanin is uncommon, even when used concomitantly with aminoglycosides or cyclosporin A. Favorable pharmacokinetics allow for intramuscular administration as well as intravenous bolus dosing, and, after appropriate loading doses, maintenance therapy may be given on a once-daily basis. The combination of all of these factors makes teicoplanin an effective, safe alternative to vancomycin in the treatment of gram-positive infections.

Teicoplanin pharmacokinetics in intravenous drug abusers being treated for bacterial endocarditis

The pharmacokinetics of teicoplanin were determined after multiple 30-min intravenous infusions of 10 to 15 mg/kg every 12 to 24 h in 11 intravenous drug abuse (IVDA) patients being treated for bacterial endocarditis. Multiple serum samples were obtained over 7 to 14 days. Twenty-four-hour urine collections were obtained on days 1 and 5. Serum concentration-time data were analyzed by using multiple-dose pharmacokinetic analysis (NONLIN84). Results were compared with pharmacokinetic parameters derived from previous studies in normal healthy volunteers following multiple intravenous infusions of teicoplanin (3 to 6 mg/kg/day). Total and renal clearances of teicoplanin in IVDA patients were found to be significantly greater and more highly variable than those observed previously in normal healthy volunteers. As a result, predicted steady-state trough concentrations in serum may vary up to fivefold. The mechanism responsible for this variation appears to be related to the glomerular filtration rate. In IVDA patients, individualized teicoplanin dosage may be required in the treatment of bacterial endocarditis.

Antistaphylococcal activities of teicoplanin and vancomycin in vitro and in an experimental infection

The efficacies of vancomycin and teicoplanin in an experimental Staphylococcus aureus infection in granulocytopenic mice were related to their activities in vitro and their pharmacokinetic profiles. In vitro teicoplanin had a higher intrinsic activity than vancomycin did; and it also had a more favorable pharmacokinetic profile, resulting in higher peak concentrations in plasma, a longer elimination half-life, and a larger area under the concentration-time curve than those of vancomycin. To predict the antibacterial efficacies of the drugs in vivo on the basis of their activities in vitro and pharmacokinetics, a mathematical model was applied. In the model the in vitro effect was expressed as the difference in growth rate between control cultures and those in the presence of the antibiotic (ER), and the in vivo effect was expressed as the difference between numbers of CFU in control and antibiotic-treated animals (EN). The integral of ER against time, ERt, was calculated by using the concentrations found in vivo. A significant linear relationship was found between EN and ERt for different dosages at the same times (4 h) after drug administration as well as for the same doses at consecutive times, although at the lowest doses of teicoplanin the observed effect was less than the predicted effect.

Teicoplanin. A review of its antibacterial activity, pharmacokinetic properties and therapeutic potential

Teicoplanin is a glycopeptide antibiotic with a molecular structure which is related to that of vancomycin. Gram-positive bacteria such as staphylococci (including methicillin-resistant strains), streptococci, enterococci and many anaerobic Gram-positive bacteria are susceptible to teicoplanin in vitro. Teicoplanin has an exceptionally long half-life, allowing once-daily intramuscular or intravenous administration. Teicoplanin is clinically and bacteriologically effective against a wide variety of Gram-positive infections such as septicaemia, endocarditis, skin and soft tissue infections and infections associated with venous catheters. The drug is equally efficacious against methicillin-resistant and -susceptible staphylococci. Adverse effects with teicoplanin are generally limited to local effects or hypersensitivity reactions. While teicoplanin has the potential for ototoxicity and nephrotoxicity, the incidence appears to be quite low when recommended serum concentrations are maintained. Teicoplanin is a valuable alternative to vancomycin, and providing controlled comparative studies prove equivalent safety and efficacy between the 2 glycopeptides the more easily administered teicoplanin should become the preferred antibacterial agent.

In vitro activities of vancomycin and teicoplanin against coagulase-negative staphylococci isolated from neutropenic patients

This study reports the in vitro activities of vancomycin and teicoplanin against 185 coagulase-negative staphylococcal strains isolated from 80 neutropenic patients who received different antibiotic treatments. All strains were susceptible to vancomycin: MICs for 50 and 90% of strains tested were 2 and 4 mg/liter, respectively. Teicoplanin was less active, and MICs displayed a wider range. For only teicoplanin was there a correlation between resistance and previous treatment. At the 4- and 32-mg/liter breakpoint levels, only 20% of the strains isolated from patients without glycopeptide treatment were intermediate or resistant, whereas 49.2% of the strains from patients who had received vancomycin or teicoplanin or both were intermediate or resistant.

Efficacy of teicoplanin in two dosage regimens for experimental endocarditis caused by a beta-lactamase-producing strain of Enterococcus faecalis with high-level resistance to gentamicin

Optimal therapy for the treatment of infections caused by strains of enterococci demonstrating high-level resistance to gentamicin and other aminoglycosides has not been established. The present study examined the efficacy of teicoplanin, a glycopeptide antibiotic active against gram-positive bacterial infections in various animal models, in the treatment of experimental endocarditis due to a beta-lactamase-producing strain of Enterococcus faecalis with high-level resistance to gentamicin. Vancomycin was used as a comparative antibiotic. In the first set of experiments, both antimicrobial agents were administered by continuous intravenous infusion for 5 days at dosages which yielded comparable mean levels in serum (plus or minus the standard deviation) of 14.6 +/- 4.3 micrograms/ml for teicoplanin and 14.3 +/- 2.2 micrograms/ml for vancomycin. These regimens proved similarly effective in sterilizing cardiac vegetations (38 versus 50% of treated animals, respectively; P greater than 0.05). Mean (plus or minus the standard deviation) residual bacterial titers within vegetations were reduced to 3.2 +/- 1.2 log10 CFU/g and 3.4 +/- 1.7 log10 CFU/g, respectively. In separate experiments, the potential of teicoplanin to cure endocarditis was assessed, using two dosage regimens: (i) 30 mg/kg per day (mean level in serum, 13 micrograms/ml) for 10 days or (ii) 150 mg/kg per day (mean level in serum, 84 micrograms/ml) for 5 days. Surviving animals were sacrificed 10 days after the discontinuation of therapy. Both teicoplanin regimens were more effective than the comparative vancomycin (150 mg/kg per day) regimen: 92 versus 43% cured (P =0.025) in the standard-dose group, and 82 versus 37% cured (P = 0.015) in the high-dose group. Results in this rat model of enterococcal endocarditis show that teicoplanin may prove useful in the treatment of serious infections due to high level-gentamicin-resistant enterococci in humans.

Effects of dosage, peak and trough concentrations in serum, protein binding, and bactericidal rate on efficacy of teicoplanin in a rabbit model of endocarditis

The effect of dosage and the relative importance of peak and trough concentrations in serum for efficacy of teicoplanin were examined in a rabbit model of aortic valve endocarditis. Concentrations of teicoplanin in serum exceeded the MIC by several hundredfold, yet teicoplanin was less rapidly bactericidal than penicillin both in vitro and for endocarditis caused by a strain of Streptococcus sanguis. Because teicoplanin was 90% protein bound in rabbit serum, low free-drug concentrations probably resulted in less activity in vivo than in vitro. Because teicoplanin has a relatively low bactericidal rate and a high degree of protein binding, a sustained concentration in serum several times greater than the MIC may be important for efficacy in vivo. An intravenous regimen with relatively high peak concentrations in serum was less effective than an intramuscular regimen for endocarditis caused by a strain of Staphylococcus aureus, indicating that high peaks are unlikely to be an important determinant of efficacy. The therapeutically more relevant concentration in serum may be the trough.

Clinical efficacy and safety of teicoplanin in the treatment of gram-positive infections

This study was an open efficacy and safety study of teicoplanin in hospitalized patients with gram-positive infections. 26 patients entered the study. Teicoplanin was administered by intravenous bolus injection at a dose of 200 mg or 400 mg every 24 h, and in all cases an initial loading dose of 400 mg was given. The mean duration of treatment was 9.4 days (range four to 20 days). The infections included 18 skin/soft tissue, four lower respiratory tract, two urinary tract and two joint/bone. Clinical cure and improvement occurred in 20 of the 26 patients. Only two adverse events (moderate diarrhoea and mild pain at injection site) related to teicoplanin occurred in one patient. It was concluded that teicoplanin was effective and well tolerated in the treatment of gram-positive infections.

Therapeutic update on glycopeptide and lipopeptide antibiotics

Glycopeptide antibiotics in the form of vancomycin have been available for almost 30 years. In the past, vancomycin usually was reserved as an alternative agent to treat staphylococcal and streptococcal infection in patients with a penicillin allergy or hemodialysis shunt infection. With the increasing frequency of both methicillin-resistant Staphylococcus aureus and Staphylococcus epidermidis, now it is often used as a first-line agent. Over a 10-year period, vancomycin sales have increased by almost $1 hundred million. Several new glycopeptide and lipopeptide antibiotics are in various stages of evaluation. While vancomycin resistance to date is a rare phenomenon, these drugs represent a potentially more potent and safer antibiotic alternative to vancomycin. Teicoplanin and daptomycin are two of these investigational agents.

Teicoplanin- A New Agent for Gram-Positive Bacterial Infections

Gram-positive bacterial infections remain a serious challenge for infectious disease practitioners. Many gram-positive organisms are developing new methods of antibiotic resistance, thus rendering our standard antimicrobial agents ineffective. Penicillin G resistance, methicillin-resistant Staphylococcus aureus and recently, a laboratory strain of vancomycin-resistant S aureus have become catalysts in the search for effective alternatives in the treatment of gram-positive bacterial infections. This review will briefly describe an investigational agent (investigational in the US, although used widely overseas) that has been very successful in treating gram-positive bacterial infections. The antibiotic, named teicoplanin. (Merrell-Dow Pharmaceuticals) may be approved for release in the United States in the future.

Originally known as teichomycin A, teicoplanin is a glycopeptide antibiotic, chemically similar to the vancomycin-ristocetin antibiotic group. Teicoplanin was discovered following the fermentation process of Actinoplanes teichomyceticus The antibiotic has a linear heptapeptide structure and weighs approximately 2000 daltons.

Teicoplanin--a new agent for gram-positive bacterial infections

Gram-positive bacterial infections remain a serious challenge for infectious disease practitioners. Many gram-positive organisms are developing new methods of antibiotic resistance, thus rendering our standard antimicrobial agents ineffective. Penicillin G resistance, methicillin-resistant Staphylococcus aureus and recently, a laboratory strain of vancomycin-resistant S aureus have become catalysts in the search for effective alternatives in the treatment of gram-positive bacterial infections. This review will briefly describe an investigational agent (investigational in the US, although used widely overseas) that has been very successful in treating gram-positive bacterial infections. The antibiotic, named teicoplanin. (Merrell-Dow Pharmaceuticals) may be approved for release in the United States in the future.

Originally known as teichomycin A, teicoplanin is a glycopeptide antibiotic, chemically similar to the vancomycin-ristocetin antibiotic group. Teicoplanin was discovered following the fermentation process of Actinoplanes teichomyceticus The antibiotic has a linear heptapeptide structure and weighs approximately 2000 daltons.

Teicoplanin: a new glycopeptide antibiotic complex

The chemistry, microbiology, pharmacokinetics, clinical efficacy, and adverse effect profile of teicoplanin are reviewed and, where appropriate, compared with vancomycin. Teicoplanin is a glycopeptide antibiotic with potent bactericidal activity against a wide variety of aerobic and anaerobic gram-positive bacteria. In contrast to the structurally related vancomycin, teicoplanin has a prolonged elimination half-life of approximately 60 hours and it may be safely administered by the intramuscular route. Adverse effects of teicoplanin include ototoxicity, nephrotoxicity, skin rash, eosinophilia, neutropenia, and transient elevation of serum aminotransferases. Teicoplanin may be beneficial as an alternative to vancomycin for patients with poor vascular access and in those requiring long-term outpatient therapy. The role of teicoplanin in the treatment and prophylaxis of gram-positive infections will ultimately depend on its unfolding safety and efficacy profile.

Determination of teicoplanin in human plasma and urine by affinity and reversed-phase high-performance liquid chromatography

A sensitive, highly selective and simple high-performance liquid chromatographic method for the determination of teicoplanin, a novel glycopeptide antibiotic, composed of six components, in human plasma and urine is described. After an isolation step by affinity chromatography, the antibiotic substances were chromatographed on a Nucleosil C18 column with phosphate buffer-acetonitrile according to a gradient profile. All the components were detected by their UV absorption at 240 nm. The concentration of teicoplanin was determined by using the external standard procedure. This method was applied to the sum of the six major components as well as to each of them separately. The linearity of the method was checked between 0.5 and 50 micrograms/ml for plasma and between 2 and 50 micrograms/ml for urine. The limit of detection was 0.1 microgram/ml for both biological fluids. The coefficients of variation of the between-day assays did not exceed 8.6 and 8.9% in plasma and urine, respectively. The application of the method to a pharmacokinetic study of teicoplanin after a single intravenous therapeutic dose in a patient is reported. This rapid technique also appears to be suitable for drug monitoring.

Imipenem/cilastatin. A review of its antibacterial activity, pharmacokinetic properties and therapeutic efficacy

Imipenem is the first available semisynthetic thienamycin and is administered intravenously in combination with cilastatin, a renal dipeptidase inhibitor that increases urinary excretion of active drug. In vitro studies have demonstrated that imipenem has an extremely wide spectrum of antibacterial activity against Gram-negative and Gram-positive aerobic and anaerobic bacteria, even against many multiresistant strains of bacteria. It is very potent against species which elaborate beta-lactamases. Imipenem in combination with equal doses of cilastatin has been shown to be generally well tolerated and an effective antimicrobial for the treatment of infections of various body systems. It is likely to be most valuable as empirical treatment of mixed aerobic and anaerobic infections, bacteraemia in non-neutropenic patients and serious hospital-acquired infections.

Clinical evaluation of efficacy, pharmacokinetics, and safety of teicoplanin for serious gram-positive infections

Nineteen patients hospitalized for serious gram-positive infections were treated with teicoplanin, a new glycopeptide antibiotic. A variety of infections were treated, including endocarditis, septic thrombophlebitis, osteomyelitis, pyogenic arthritis, and soft tissue infection. Of 13 infections that could be evaluated in 12 patients, there were 8 clinical cures, 2 improvements, 1 recurrence, and 2 failures. Of the eight patients with Staphylococcus aureus bacteremia, seven were clinically cured or improved with teicoplanin therapy. Of the nine patients in whom the bacteriological response to treatment could be fully evaluated, six were cured; there was recurrence of infection in one, and treatment failed in two patients. In vitro testing showed the 13 bacterial isolates (9 S. aureus, 3 S. epidermidis, and 1 group B streptococcus) to be uniformly susceptible to teicoplanin, with MICs ranging from 0.12 to 0.5 microgram/ml. Every isolate was more susceptible in vitro to teicoplanin than to vancomycin. Three of the staphylococcal isolates were resistant to methicillin. Pharmacokinetic studies demonstrated that after an initial drug-accumulation period, a single daily dose adequately maintained the teicoplanin concentrations in serum within therapeutic ranges. Teicoplanin also penetrated well into synovial fluid. The drug was well tolerated by either intravenous or intramuscular administration. The most significant adverse reaction was an urticarial rash which required discontinuation of therapy in one patient; a second patient experienced a modest decrease in high-frequency auditory threshold. Asymptomatic eosinophilia and mild elevation of serum transaminases were noted as well. The results of this study suggest that teicoplanin is a safe and effective new agent for treatment of serious infections caused by gram-positive organisms.

Clinical evaluation of teicoplanin for therapy of severe infections caused by gram-positive bacteria

Teicoplanin was evaluated in 47 patients with severe infections, including 14 patients with bone infections, 11 patients with soft-tissue infections, 7 patients with endocarditis, 5 patients with pneumonia, 3 patients with septic thrombophlebitis, 3 patients with septicemia of unknown origin, and 4 patients with miscellaneous infections. Overall, bacteremia was documented in 24 patients. The pathogens isolated were 35 strains of Staphylococcus aureus (including 8 methicillin-resistant strains), 4 strains of Staphylococcus epidermidis, 4 strains of Streptococcus faecalis, 2 strains of Streptococcus pneumoniae, 5 strains of other streptococci, and 1 Micrococcus luteus strain. A total of 22 patients (46.8%) were clinically cured, 8 patients (17.0%) improved, 2 patients (4.3%) had relapses after initial improvement, and 15 patients (31.9%) failed to respond. The results were better in nonbacteremic patients (19 of 23 patients [82.6%] were cured or improved) than in patients with bacteremia (12 of 24 patients [50%] were cured or improved). Bacteriological cure occurred in 25 patients (53.2%), and superinfections were documented in 6 patients (12.8%). No major adverse effects were observed. We conclude that teicoplanin is a potentially effective and well-tolerated antimicrobial agent for therapy of nonbacteremic infections caused by gram-positive bacteria.

Review of the in vitro spectrum of activity of imipenem

Imipenem (N-formimidoyl thienamycin, MK0787), a new carbapenem was found to have the widest antimicrobial activity of currently available beta-lactam drugs. Enterobacteriaceae had minimal inhibitory concentrations of imipenem of 8.0 micrograms/ml or less for 99.8 percent of clinical isolates. Only rare strains of Enterobacter species and Proteus mirabilis have higher imipenem minimal inhibitory concentration results. Hemophilus and Neisseria species were inhibited, but minimal inhibitory concentrations of imipenem were higher than those reported for third-generation cephalosporins. Only Pseudomonas maltophilia and Pseudomonas cepacia strains were imipenem resistant (MIC50 greater than 32 micrograms/ml) among the commonly isolated non-enteric gram-negative bacilli. All anaerobes were found susceptible to imipenem with the exception of some strains of Clostridium difficile. Staphylococcus species and non-enterococcal streptococci were very susceptible to imipenem. Streptococcus faecalis had higher minimal inhibitory concentrations of imipenem (MIC90 3.1 micrograms/ml) and S. faecium strains were frankly resistant. Methicillin-resistant S. aureus isolates had a MIC90 of 27.2 micrograms imipenem/ml. Imipenem was generally bactericidal except for marked minimal inhibitory and minimal bactericidal concentration differences with enterococci, Listeria, methicillin-resistant staphylococci, and some P. aeruginosa strains. The minimal inhibitory and minimal bactericidal concentrations of imipenem were not significantly influenced by organism inoculum size, probably because of its beta-lactamase stability to nearly all commonly encountered bacterial enzymes. Imipenem was found to be an excellent inhibitor of beta-lactamases and a potent enzyme inducer. The induction characteristic seems responsible for the antagonistic interactions of imipenem with some enzyme-labile beta-lactams in combination. Imipenem had limited stability in some in vitro susceptibility test systems. The 10 micrograms disk test or dry-form broth micro-dilution systems were preferred, applying the interpretive criteria from the National Committee for Clinical Laboratory Standards (M2-A3). Imipenem-resistant strains were rarely found in clinical practice and bacteria resistant to newer beta-lactams and aminoglycosides were generally very susceptible to this new carbapenem.

[Perioperative cefamandole prevention in aortocoronary bypass operations: the course of serum levels in extracorporeal circulation]

Antibiotic prophylaxis with 2 g Cefamandole at induction of anaesthesia was performed in 12 male patients undergoing aortocoronary bypass surgery. Caused by hemodilution, there was a marked decrease of serum concentration at the beginning of extracorporeal circulation, from 110.96 +/- 40.29 mcg/ml to 70.89 +/- 34.65 mcg/ml within 10 min. During extracorporeal circulation, elimination was as fast as before and after perfusion. 240 min after application, mean serum concentrations of 16.80 +/- 9.32 mcg/ml were measured. Failure of antibiotic prophylaxis in operations exceeding 4 h might be due to unadaequate antibiotic concentrations, beyond the minimal inhibitory concentration for the pathogens, reported to cause infections after cardiac operations.

In vitro activity and human pharmacokinetics of teicoplanin

The in vitro activity of teicoplanin, a new antibiotic related to vancomycin, was determined against 456 gram-positive cocci. The activity of teicoplanin in comparison with that of vancomycin was similar against staphylococci but 4 to 40 times higher against enterococci and beta-hemolytic and viridans streptococci. The single-dose pharmacokinetics of teicoplanin were studied in six healthy volunteers after administration of 3 and 6 mg/kg intravenously and of 3 mg/kg intramuscularly. The kinetic parameters after both intravenous doses were very similar. The curves for concentration in plasma for the 3- and 6-mg/kg intravenous doses showed a triexponential decline with elimination half-lives of 47.3 and 44.1 h, respectively. The percentages of the doses recovered in urine (0 to 102 h) were 43.2 and 44.1%, respectively. The areas under the plasma curves were dose related: 256.5 and 520.9 micrograms/h per ml, respectively. The bioavailability of teicoplanin after injection of 3 mg/kg intramuscularly was 90%, and the peak level was 7.1 micrograms/ml. The mean levels in plasma 24 h after the 3-mg/kg doses were 2.1 and 2.3 micrograms/ml, respectively, and the mean level in plasma 24 h after the 6-mg/kg intravenous dose was 4.2 micrograms/ml.

Teicoplanin versus nafcillin and vancomycin in the treatment of experimental endocarditis caused by methicillin-susceptible or -resistant Staphylococcus aureus

In rabbits with experimentally induced endocarditis, the efficacy of teicoplanin compared favorably both with that of nafcillin for infection by a methicillin-susceptible strain of Staphylococcus aureus and with that of vancomycin for infection by a methicillin-resistant strain of S. aureus. In a 4-day treatment regimen, teicoplanin was as effective as either nafcillin or vancomycin in eliminating organisms from aortic valve vegetations in the respective infection. In a 10-day regimen for methicillin-resistant S. aureus endocarditis, both teicoplanin and vancomycin sterilized the vegetations of some rabbits, but the relapse rate was high for both. These results justify further investigation into the role of teicoplanin for the treatment of serious infections caused by S. aureus.

Comparative in vitro activities of teichomycin and vancomycin alone and in combination with rifampin and aminoglycosides against staphylococci and enterococci

The activity of teichomycin A2 was compared with that of vancomycin in vitro against clinical isolates of staphylococci and enterococci. Teichomycin A2 was more active than vancomycin active against all isolates tested. Synergistic studies also demonstrated that teichomycin A2 combined with rifampin is more active than vancomycin combined with rifampin against Staphylococcus aureus and Staphylococcus epidermidis isolates. Teichomycin A2, either singly or in combination with an aminoglycoside, was more active against Streptococcus faecalis isolates.

In vitro activity of teichomycin compared with those of other antibiotics

The glycopeptide antibiotic teichomycin had in vitro activity comparable to that of vancomycin against most gram-positive species, and it inhibited methicillin-resistant Staphylococcus aureus and Staphylococcus epidermidis. It was twofold more active against many S. aureus and S. epidermidis isolates than was vancomycin. Teichomycin had activity comparable to that of vancomycin against Listeria monocytogenes and Streptococcus faecalis. It was generally more active against streptococci than was vancomycin. There were no major differences between minimal inhibitory concentrations and minimal bactericidal concentrations of these drugs. Teichomycin acted synergistically with gentamicin against some bacteria.