Cephapirin therapy in infective endocarditis

A systematic review of optimal pharmacokinetic/pharmacodynamic parameters for beta-lactam therapy in infective endocarditis

BACKGROUND

Beta-lactam antibiotics are the mainstay of therapy for most bacterial causes of infective endocarditis (IE). Traditionally considered as agents with a broad therapeutic index, there is increasing recognition that standard doses may be subtherapeutic or toxic in critically ill patients. Optimizing therapy for efficacy requires a defined pharmacokinetic (PK)/pharmacodynamic (PD) target associated with clinical and microbiological cure.

OBJECTIVES

To elucidate the factors that influence beta-lactam PK and PD variability in IE and to examine optimal PK/PD target parameters for therapy.

METHODS

The review was conducted in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Clinical and laboratory in vivo animal or human studies examining PK and/or PD of beta-lactam antibiotics in IE were eligible. Ovid MEDLINE, Embase and Cochrane Central Registry were searched using defined terms. The Office of Health Assessment and Translation (OHAT) tool was used for assessing risk of bias.

RESULTS

From 2677 abstracts, 62 articles were selected for review and synthesis, comprising: 45 animal studies investigating the broad categories of beta-lactam diffusion into vegetations, PK/PD determinants of outcome, mode of antibiotic delivery and synergistic impact of agents; and 17 human studies totalling 347 participants. Findings supported the importance of time-dependent killing for beta-lactams but heterogeneous data limited the determination of an optimal PK/PD target for IE treatment.

CONCLUSION

Beta-lactam PK and PD in endocarditis are variable and specific to the particular antibiotic-organism combination. Time-dependent killing is important, consistent with non-endocarditis studies, but there is little agreement on optimal drug exposure. Clinical studies examining PK/PD targets in endocarditis are required to further inform drug selection and dosing.

The role of aminoglycosides in combination with a beta-lactam for the treatment of bacterial endocarditis: a meta-analysis of comparative trials

BACKGROUND

The addition of an aminoglycoside to a beta-lactam for the treatment of patients with infective endocarditis has been supported by data from laboratory and animal studies.

PURPOSE

We sought to review the evidence from the available comparative clinical trials regarding the role of aminoglycosides in combination with a beta-lactam for the treatment of bacterial endocarditis caused by Gram-positive cocci.

DATA SOURCES

The studies for our meta-analysis were retrieved from searches of the PubMed and Cochrane Central Register of Controlled Trials databases, as well as from the references cited in relevant articles. No limits were set regarding the language and date of publication of the studies.

STUDY SELECTION

Included studies were prospective studies that provided comparative data regarding the effectiveness of the treatment and/or mortality in patients receiving monotherapy with a beta-lactam or beta-lactam/aminoglycoside combination therapy.

DATA EXTRACTION

Two independent reviewers performed the literature search, study selection and extraction of data from relevant studies.

DATA SYNTHESIS

No clinical trial comparing beta-lactam monotherapy with beta-lactam/aminoglycoside combination therapy for the treatment of enterococcal endocarditis was found. We performed a meta-analysis of five available comparative trials [four randomized controlled trials (RCTs) and one comparative prospective trial], which included 261 patients with bacterial endocarditis in native valves due to Staphylococcus aureus (four studies) or streptococci of the viridans group (one study). There was no statistically significant difference between beta-lactam monotherapy and beta-lactam/aminoglycoside combination therapy regarding mortality [odds ratio (OR) = 0.59, 95% confidence interval (95% CI) = 0.21-1.66], treatment success (OR = 1.25, 95% CI = 0.49-3.05), treatment success without surgery (OR = 1.66, 95% CI = 0.64-4.30) or relapse of endocarditis (OR = 0.79, 95% CI = 0.15-4.29). Nephrotoxicity was less common in the beta-lactam monotherapy arm than in the beta-lactam/aminoglycoside combination therapy arm (OR = 0.38, 95% CI = 0.16-0.88, P = 0.024). No difference between the two treatment arms was found in subanalyses of the four studies that included only patients with staphylococcal infections in terms of mortality (OR = 0.69, 95% CI = 0.26-1.86, fixed effects model), treatment success (OR = 1.27, 95% CI = 0.47-3.43, fixed effects model) or relapse (OR = 0.76, 95% CI = 0.12-4.92, fixed effects model).

LIMITATIONS

The relatively small number of available comparative trials was the major limitation of this meta-analysis.

CONCLUSIONS

The limited evidence from the available prospective comparative studies does not offer support for the addition of an aminoglycoside to beta-lactam treatment of patients with endocarditis caused by Gram-positive cocci. A large multicentre RCT is necessary to reach a definitive conclusion on this issue.