Bactericidal activity and killing rate of serum in volunteers receiving teicoplanin alone or in combination with oral or intravenous rifampin

Oral rifampin for eradication of Staphylococcus aureus carriage from healthy and sick populations: a systematic review of the evidence from comparative trials

BACKGROUND

Rifampin has been used for the eradication of Staphylococcus aureus (S. aureus) colonization in various populations of healthy and sick people.

METHODS

We performed a systematic review of the evidence from randomized and nonrandomized controlled trials that compared the effectiveness and safety of a rifampin-based regimen with another regimen in eradicating S. aureus colonization from healthy and sick people.

RESULTS

Nine comparative trials (6 of which were randomized controlled trials) were included in our analysis. S. aureus was eradicated more commonly in patients receiving rifampin-containing regimens compared to monotherapy with other systemic agents (ciprofloxacin, cloxacillin, minocycline, or vancomycin), both during early and late (>1 month after therapy) post treatment evaluations (odds ratio [OR] 46.2, 95% confidence interval [CI] 14.4-148, and OR 8.8, 95% CI 3.4-22.5 respectively, 4 studies included). There was no statistically significant difference between rifampin monotherapy and combinations of rifampin with other topical (bacitracin) or systemic (cloxacillin and minocycline) antibiotics in eradicating S. aureus both in early and late evaluations (OR 1.5, 95% CI 0.5-4.4, and OR 1.6, 95% CI 0.7-3.7, respectively, 3 studies included). Eradication of methicillin-resistant S. aureus (MRSA) varied according to the type and duration of the rifampin-containing regimen. It ranged from 25% for the combination of rifampin with trimethoprim/sulfamethoxazole for 5 days to 100% for the combination of oral rifampin and minocycline for 14 days. Discontinuation of rifampin due to drug-related toxicity was necessary in 2% of 282 studied patients. Development of resistance of S. aureus to rifampin during and after treatment with a regimen containing rifampin ranged from 0% to 40% (7 studies) and overall 17% of the 236 patients for whom relevant data was reported.

CONCLUSION

The available evidence suggests that oral rifampin is an effective agent for the eradication of S. aureus carriage. However, development of antimicrobial resistance during and after treatment with rifampin occurs in a considerable proportion of patients; using rifampin in combination with another antimicrobial agent may decrease this resistance.

Oral rifampin for prevention of S. aureus carriage-related infections in patients with renal failure--a meta-analysis of randomized controlled trials

BACKGROUND

Rifampin has been studied as prophylaxis against Staphylococcus aureus-related infections in patients on dialysis.

METHODS

We performed a meta-analysis of randomized controlled trials (RCTs) that compared the effectiveness and safety of oral rifampin with another regimen or no therapy in reducing S. aureus-related infections in dialysis patients.

RESULTS

Four RCTs evaluated oral rifampin (administered for 5 days every 3 months, or for 5 days once) as prophylaxis in dialysis patients. Oral rifampin with or without bacitracin was associated with less access-site infections with S. aureus compared with no treatment (odds ratio = 0.16, 95% confidence intervals: 0.06-0.44, 3 RCTs). There was no difference between prophylaxis with oral rifampin and topical mupirocin applied at the catheter site, for all studied outcomes, in the RCT comparing these regimens. Withdrawal from the study due to drug-related toxicity occurred in 7/107 (6.6%) of the studied patients with renal failure. Development of resistance of S. aureus to rifampin ranged from 0 to 18.2% (reported in three out of four included RCTs).

CONCLUSION

Prophylactic use of oral rifampin reduces access-site infections with S. aureus in patients with renal failure undergoing dialysis. However, development of toxicity and antimicrobial resistance during the treatment with rifampin occur in considerable proportions of patients, limiting its use and supporting the guidelines that recommend the use of local antibiotics at the exit site, such as mupirocin, for these indications. The available data are rather limited and more studies should be performed to examine this important clinical question.

Antimicrobial interactions (synergy) of teicoplanin with two broad-spectrum drugs (cefotaxime, ofloxacin) tested against gram-positive isolates from Germany and the United States

Teicoplanin, a glycopeptide, has been widely used in some nations alone and in empiric therapy combinations to address infections caused by Gram-positive cocci. However, glycopeptide resistance and the increasing incidence of oxacillin-resistant staphylococci have compromised contemporary chemotherapy. In this study, teicoplanin was tested in combinations with ampicillin, cefotaxime with and without desacetylcefotaxime, and ofloxacin against 151 Gram-positive cocci to assess the potential for enhanced action. The strains included recent isolates from the United States and Germany having well-characterized resistance mechanisms (oxacillin-resistant staphylococci, vancomycin-resistant enterococci), each tested by NCCLS methods, checkerboard synergy tests, and kill-curves. Teicoplanin alone was active (MIC90s, 0.25-2 micrograms/mL) against all species except vanA enterococci. Drug interactions of teicoplanin with beta-lactams revealed synergy and partial synergy versus oxacillin-resistant Staphylococcus spp. (67-100%) and vancomycin-resistant enterococci (70-100%), many at clinically achievable drug concentrations. However, confirming kill-curve experiments showed static action and no significant bactericidal effect. Combinations of ofloxacin with teicoplanin or cefotaxime plus desacetylcefotaxime showed a dominant additive and indifferent interaction. Teicoplanin continues to be a viable alternative to vancomycin, especially in combination therapy with selected broad-spectrum cephalosporins or fluoroquinolones. Many emerging pathogens that test resistant to individual drugs appear to be inhibited by tested combinations, extending their potential clinical utility.

Randomized study of vancomycin versus teicoplanin for the treatment of gram-positive bacterial infections in immunocompromised hosts

Seventy-four immunocompromised patients with severe infection due to gram-positive organisms were randomized to receive either vancomycin or teicoplanin. Extensive cancer was present in 71 patients, of whom 47 died within a month. The types of infections were 46 bacteremias (39 associated with central catheters), 24 skin and soft tissue infections (3 with bacteremia), and 7 others (mainly bronchopneumonia). The most frequent pathogen was Staphylococcus epidermidis, followed by Staphylococcus aureus. Microbiological eradication was obtained in 23 of 35 evaluable patients treated with vancomycin (65.7%) and 28 of 36 patients treated with teicoplanin (77.8%) (P = 0.4). Clinical cure and improvement were obtained in 26 of 35 patients (74.3%) and 27 of 36 patients (75.0%), respectively. No significant side effects were observed with teicoplanin, in contrast to reversible increases in serum creatinine (three patients) and skin rashes (four patients) with vancomycin. Superinfection was observed in five patients treated with vancomycin and two patients treated with teicoplanin. No relation was found between peak concentration in serum (at steady state) or bactericidal titers and outcome.

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.

Ex vivo study of serum bactericidal titers and killing rates of daptomycin (LY146032) combined or not combined with amikacin compared with those of vancomycin

Twelve volunteers, in two groups of six, received daptomycin at a dose of 1 or 2 mg/kg. In addition, they received in a randomly allocated order amikacin (500 mg), daptomycin-amikacin, and vancomycin (500 mg). Thirty-five clinical isolates, including Staphylococcus aureus, S. epidermidis, Corynebacterium sp. group JK, and Enterococcus faecalis, were tested in vitro for the measure of the serum bactericidal titers and killing rates. The mean peak concentrations of daptomycin in serum 1 h after the administration of 1 and 2 mg/kg were 11 and 20 micrograms/ml, respectively. At 24 h after the administration of 2 mg/kg, the mean level in serum was 1.9 micrograms/ml, which is higher than the MICs for susceptible pathogens. Daptomycin and amikacin provided identical concentrations in serum whether given alone or in combination. Among the six regimens tested, those including daptomycin provided the highest and the most prolonged serum bactericidal titers against S. aureus, S. epidermidis, and E. faecalis. The killing rates measured by the killing curves were correlated with the concentration/MIC and concentration/MBC ratios of daptomycin for all strains tested. Significant killing occurred once the concentration of daptomycin in the serum 4- to 6-fold the MIC or 1- to 1.2-fold the MBC. The combination of daptomycin and amikacin had no effect on either the serum bactericidal titers or the rates of killing. Only vancomycin provided significant killing of the strains of Corynebacterium sp. group JK.

Antipseudomonal activity of simulated infusions of gentamicin alone or with piperacillin assessed by serum bactericidal rate and area under the killing curve

The objectives of this study were to (i) determine which of three simulated dosing regimens (gentamicin alone, simultaneous infusions of gentamicin and piperacillin, or staggered infusions of gentamicin and piperacillin) produced the fastest killing rate of Pseudomonas aeruginosa in serum, using the serum bactericidal rate (SBR) assay; and (ii) describe an alternative method of analysis of killing curves, the area under the killing curve (AUKC). Gentamicin alone or combined with piperacillin was added to heat-inactivated human serum to approximate drug concentrations achieved after the above-mentioned types of infusion. By a microdilution technique, seven strains of P. aeruginosa were exposed to no drug (control) and gentamicin alone or with piperacillin; colony counts were determined at hourly intervals for 5 h, and log10 CFU per milliliter was plotted versus time. Linear regression was used to calculate the slope (SBR) of each timed killing curve for each drug concentration tested alone or in combination. In addition, the AUKC for each curve was calculated. To compare simulated infusion regimens further, the cumulative AUKC (the sum of AUKCs for specific time points along the serum concentration-time curve for each simulated regimen) was calculated. With the SBR assay or AUKC determination, there was a significant increase in the rate of killing of all test strains by the combination compared with gentamicin alone only at gentamicin concentrations which exceeded the MIC (8, 5, and 2.5 micrograms/ml). Mean cumulative AUKC of the simultaneous-infusion regimen was significantly less (indicating faster killing) than either the staggered-infusion regimen or the gentamicin infusion alone. Both the SBR and AUKC have the potential for integration of in vitro microbiologic effects and in vivo pharmacokinetics of antimicrobial agents.

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.

Serum bactericidal test

The serum bactericidal test represents one of the few in vitro tests performed in the clinical microbiology laboratory that combines the interaction of the pathogen, the antimicrobial agent, and the patient. Although the use of such a test antedates the antimicrobial era, its performance, results, and interpretation have been subject to question and controversy. Much of the confusion concerning the serum bactericidal test can be avoided by an understanding of the various factors which influence bactericidal testing. In addition, the methodologic aspects of the serum bactericidal test have recently been addressed and should place this test on firmer ground. New information on the clinical utility of this test is becoming available; additional data are needed to establish more clearly the usefulness of the serum bactericidal test in specific infections. Such clinical trials from multiple centers will enable firmer recommendations for the future use of the serum bactericidal test.