Role of glycopeptides in the treatment of septic complications after cardiac surgery.

Agents like Staphylococcus epidermidis and Staphylococcus aureus are common agents in both early and late prosthetic valve endocarditis (PVE). Streptococci, especially vividans and enterococci are more apt to occur late. Diphtheroids and gram-negative bacteria are also frequent in early and late PVE. Fungi are found at a frequency of 5 to 8% and a variety of unusual organisms are found in individual case reports. Treatment is based on parenteral therapy with a bactericidal agent that can achieve trough serum levels in excess of 8-10 X MICs of the infecting organisms. Initially the antibiotic selection should be active against the most common isolates. Because most S. epidermidis are beta-lactam-resistant, vancomcyin must be part of the initial empiric regimen. Vancomycin should be combined with rifampin or an aminoglycoside (usually gentamicin) or both. When there is a high level of resistance to aminoglycoside, vancomycin may be used alone until susceptibility data are available and then rifampin can be given together with an aminoglycoside or a quinolone to which the organism is susceptible. The aminoglycoside should be given for a maximum of 2 weeks, to avoid nephrotoxicity, and vancomycin for 6 weeks. Surgery is required in case of major emboli, hemodynamic decompensation, and uncontrolled infection. The presence of bacteremia for more than 1 week may warrant surgical intervention but, if the patient appears to be well and without emboli or hemodynamic problems, serum levels of antibiotic, particularly vancomycin, should be evaluated. Dosage regimen should be modified to achieve trough levels of vancomycin between 15 to 20 microg/ml. Use of vancomycin by continuous infusion may be considered with a targeted blood concentration of 15 to 20 microg/ml.