Get past bacterial resistance with ocular antibiotic armamentarium

July 1, 2010

Continued evolution in the landscape of bacterial resistance and antimicrobial agents is mandating careful prescribing of anti-infective medications to optimize success in prophylactic and therapeutic indications and to minimize future problems associated with pathogen resistance.

"The first successful clinical use of an antibiotic was 80 years ago and was for an ocular infection. We've come a long way since then in developing new antibiotics with new mechanisms of action, but we have also managed to use these agents in ways where many no longer work," noted Dr. May, who is in private practice in northern Mississippi and serves as adjunct faculty for Southern College of Optometry, Memphis, TN.

Dr. May explained that subtherapeutic and long-term dosing are both culprits in promoting bacterial resistance so that it is important to not taper antibiotic treatment regimens and use only a short-term course when prescribing an anti-infective agent as surgical prophylaxis.

Antimicrobial choices

Currently, fluoroquinolones are the most widely used anti-infective agents for ocular infections. However, older peptide antibiotics, bacitracin and polymixin B, and folic acid synthesis inhibitors, such as sulfacetamide and trimethoprim, can be a useful and cost-effective option in appropriately selected situations.

Proper prescribing depends on understanding the spectrum of activity of the various agents and whether they are bacteriostatic or bactericidal.

The folic acid synthesis inhibitors are bacteriostatic agents that have good activity against gram-positive bacteria. However, these agents should not be used in anyone with known sulfonamide sensitivity or in the management of more serious infections because they are bacteriostatic agents.