Beta-Lactams Often the Best Prophylactic Choice in Cardiac Surgery

Glycopeptides are no more effective than beta-lactam antibiotics for preventing surgical site infections (SSIs) after cardiothoracic surgery, suggest results of a meta-analysis published in the May 15th issue of Clinical Infectious Diseases.

“Data from the randomized trials done to date do not support switching cardiac surgery prophylaxis to a glycopeptide, but further trials need to be performed in settings with high prevalence of methicillin-resistant bacteria,” Dr. Maureen K. Bolon from Northwestern University Feinberg School of Medicine told Reuters Health.

“Current decisions about choice of antibiotic prophylaxis are made in the setting of changing resistance patterns of gram-positive bacteria,” Dr. Bolon continued, “and the very reasonable concern on the part of clinicians that beta-lactam antibiotics may provide inadequate coverage for organisms like S. epidermidis and methicillin-resistant S. aureus.”

To investigate whether a switch from beta-lactams to glycopeptides for cardiac surgery might be advisable, Dr. Bolon and colleagues pooled data from 5761 cardiac surgical procedures from 7 randomized trials comparing SSIs in patients receiving glycopeptide prophylaxis with SSIs in those receiving beta-lactams. A total of 515 SSIs were detected, for an overall prevalence of 8.9%.

For the primary outcome — prevention of SSI at 30 days — neither antibiotic family proved to be superior. In subgroup analyses, however, beta-lactams were superior to glycopeptides for the prevention of chest SSIs and “approached superiority” for the prevention of deep-chest SSIs and SSIs caused by gram-positive bacteria.

“Unexpectedly,” the team reports, glycopeptides approached superiority for the prevention of leg vein harvest site infection, and were clearly superior for SSIs caused by methicillin-resistant gram-positive bacteria, with risk ratios of 0.77 and 0.54.

In an accompanying editorial, Dr. Giorgio Zanetti from Lausanne, Switzerland and Dr. Richard Platt from Boston, Massachusetts note that “his analysis “allows us to conclude that there is no empirical evidence supporting a switch from beta-lactams to glycopeptides for routine prophylaxis for cardiac surgery.”

However, they also point out that many of the studies included were published in the late 1980s and 1990s and therefore, are “unlikely to reflect the current prevalence of bacteriological resistance.”

Clin Infect Dis 2004;38:1357-1366.