Anaerobic Coverage: Does Double Equal Trouble?

Double anaerobic antimicrobioal therapy is unnecessary and exposes patients unnecessarily to unpleasant adverse events.

Advances in environmental sanitation, immunizations, antimicrobial therapy, and medical research have greatly reduced the impact of infectious diseases on our communities. Nonetheless infections and the cost of treating them remain a burden to the health care system.

In primary care practice, we may spend more time making referrals for suspected ID than actually treating infected patients. Here, as a brush up, is the first in our series of 10 practical ID pearls.

1. Do beta-lactam/beta-lactamase inhibitors provide adequate anaerobic coverage or is additional coverage required?

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Answer: Beta-lactam/beta-lactamase inhibitors such as ampicillin/sulbactam (Unasyn), pipercillin/tazobactam (Zosyn), and amoxcillin/clavulinic acid (Augmentin) provide excellent anaerobic coverage.

There is no need for double coverage. The addition of metronidazole or clindamycin will only expose the patient to additional relatively common adverse effects, such as loss of appetite, nausea, vomiting, and diarrhea. Combination therapy with metronidazole can also lead to more serious events, such as seizures, neuropathies, or encephalopathy. The addition of clindamycin can lead to jaundice, agranulocytosis, or-most importantly-Clostridium difficile-associated diarrhea.1   

1. Njoku JC. Double anaerobic coverage: What is the role in clinical practice? Nebraska Medical Center, education programs. Accessed August 1, 2013.

Click here for Practical ID Pearl #2