By Mary Beth Nierengarten
CHICAGO -- September 26, 2008 -- Results of a retrospective chart review show that a high percentage of abscesses contain pathogens that are not sensitive to the commonly used antibiotic clindamycin.
In addition, the study showed that anaerobic bacteria of the Fusobacterium species are the most predominant species, contrary to previous research that showed the streptococci species as the most common pathogen in peritonsillar abscesses.
These findings suggest the need for a broad spectrum of antibiotics for adequate treatment, said the study's researchers at a presentation on September 21 here at the American Academy of Otolaryngology - Head and Neck Surgery Foundation (AAO-HNSF) 2008 Annual Meeting & OTO EXPO.
"Many practitioners use clindamycin as a single-agent antibiotic to treat these abscesses after draining them," said investigator Steven K. Burkhead, MD, Wilford Hall Medical Center, Department of Otolaryngology Head and Neck Surgery, Lackland Air Force Base, Texas.
"Our study questions the effectiveness of single-agent clindamycin for these common infections and raises the suspicion that possibly this may be partially responsible for the high recurrence rates for these infections," Dr. Burkhead said.
Dr. Burkhead and colleagues retrospectively reviewed the charts of 205 patients diagnosed with peritonsillar abscesses at 2 tertiary care hospitals between 2001 and 2005 to assess microbiology content and sensitivities to antibiotics, if any.
Culture results were available for 64 of 205 (31.2%) patients. Most cultures contained mixed organisms, with at least 35.9% showing anaerobic organisms.
The most common anaerobic organism found was Fusobacterium species (20.3%), and the most common aerobic organisms isolated were Group A Streptococcus pyogenes (18.8%), Group C Streptococcus (15.6%), and Streptococcus viridans (14.1%).
Results on 8 of the 64 cultures with available sensitivity results showed that 18.8% of the cultures would not be expected to be sensitive to clindamycin, either because the cultures yielded gram-negative organisms not typically sensitive to clindamycin or due to clindamycin-resistant species.
The investigators reported that "the overwhelming majority of cultures contained organisms expected to be sensitive to amoxicillin/clavulanate."
According to Dr. Burkhead, the study was not designed to assess what pathogens were more common in patients with recurrences or to assess what antibiotics were used to treat patients with recurrences.
Based on the data, Dr. Burkhead concluded, "The take-home message is that broad-spectrum antibiotics that adequately cover gram-negative, gram-positive, and anaerobic bacteria species should be used to treat peritonsillar abscesses, such as amoxicillin with clavulanate."
[Presentation title: The Evolving Microbiology of Peritonsillar Abscess in the Age of Antibiotic Resistance. Abstract S116]
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