Antibiotics: Not much new under the sun

October 6, 2007

Little has changed in the world of antibiotics in the past five to 10 years. Meanwhile drug resistance continues to grow in all settings, including family practice.

Little has changed in the world of antibiotics in the past five to 10 years. Meanwhile drugresistance continues to grow in all settings, including family practice.

"There are relatively few antibiotics that are brand new," said Thomas Kintanar, MD, privatepractice family physician in Indiana. "And there is a great increase in infectious disease deaths dueto resistant organisms."

The phenomenon of drug resistance is nothing new, Dr Kintanar said during a Saturday lectureat the American Academy of Family Physicians 2007 Scientific Assembly in Chicago. Penicillinresistance was first reported more than 50 years ago, not long after the agent was introduced intowidespread use.

Initial guidelines on the appropriate use of antimicrobials were published nearly 20 years ago.Family physicians still see patients every week who demand antibiotics for the common cold, otitismedia, and other conditions for which they are not effective.

"It is a well-known fact that we overuse antibiotics," Dr Kintanar said. "The problem is thatwe all have patients who insist on walking out with a prescription. And too often it is faster andeasier to give them what they want than to take the time to explain the realities of appropriate useand resistance. We must remain committed to the science of medicine while we practice theart."

A study by the Centers for Disease Control and Prevention published in 1998 found thatone-third of antibiotic prescriptions were inappropriate for the diagnosis involved, he said.

"The issue of inappropriate use may well have escalated at this point in time," headded.

The emergence of community acquired methicillin-resistant Staphylococcus aureus, or MRSA,over the past 15 to 20 years helped catapult the issue of drug resistance into public recognition.But resistance is a growing problem with Enterococci and many other pathogens.

At this point, Dr Kintanar said, there remains only one antibiotic, daptomycin, for which resistancehas not been widely documented. Daptomycin remains effective against MRSA and vancomycin-resistantEnterococci (VRE), primarily because it was recently approved and is not yet widely used.

The list of new antimicrobials approved since 2000 is short, Dr Kintanar continued. Linezolid, anoxazolidone agent approved in 2000, has already lost favor because of resistance linked to widespreaduse immediately following approval.

Ertapenem, the newest carbapenem agent available in the United States, has once-daily dosing as itschief advantage.

Cefditoren pivoxil is the newest third generation cephalosporin. It is occasionally useful, DrKintanar reported, but clinicians have encountered widespread resistance to all third-generationcephalosporins.

Cefepime, an intravenous agent, and is used almost exclusively in the hospital setting.

Daptomycin is the first cyclic lipopeptide, a new class of antimicrobial agents. It is available foroutpatient use, Dr Kintanar noted, but is still found primarily in the hospital setting. It isindicated for use against severe skin and skin structure infections.

Daptomycin is probably the last line of defense we have right now," he said. "There are a few moreagents in the FDA approval process, but there doesn't seem to be a lot of funding for research inthis area."