SAN FRANCISCO — Several factors can help guide empiric therapy for acute otitis media by flagging patients at higher risk for infection with multiple organisms or resistant organisms, Dr. Mendel E. Singer said in a poster presentation at the annual Interscience Conference on Antimicrobial Agents and Chemotherapy.
Patients with bilateral infection, those with a history of acute otitis media, or patients infected in the fourth quarter of the year may warrant high-dose aminopenicillin therapy rather than low doses, said Dr. Singer, an epidemiologist at Case Western Reserve University, Cleveland.
He and associates retrospectively analyzed pooled data from 14 studies of patients aged 3–36 months treated at Soroka University Medical Center, Beer Sheva, Israel, for acute otitis media from 1994 to 2004. Among 967 patients, 23% were infected with multiple pathogens.
The 63% of patients with bilateral ear infections were 53% more likely to have multiple pathogens than patients with unilateral infections, he said at the meeting, sponsored by the American Society for Microbiology.
Analysis of drug resistance in a subset of 333 patients infected with Streptococcus pneumoniae found that 33% had organisms resistant to the treatment drug. Data showed high rates of resistance to trimethoprim-sulfamethoxazole (in 67% of patients treated with these drugs) and to the cephalosporins cefdinir, cefaclor, or cefuroxime (in 59% of patients treated with these). There was moderate resistance to azithromycin (in 23%) and to low-dose regimens of the aminopenicillins amoxicillin or amoxicillin clavulanate (in 16% of patients given these drugs). Only 1% of isolates treated with high-dose aminopenicillins were resistant to therapy.
S. pneumoniae was 32% more likely to be drug-resistant in girls than in boys. A history of prior acute otitis media nearly tripled the risk for resistant S. pneumoniae. Infection in the fourth quarter of the year doubled the risk for resistance.
The study suggests that patients with any of these risk factors might best be treated empirically with high-dose amoxicillin or amoxicillin-clavulanate, Dr. Singer said. Patients without these characteristics may respond sufficiently to low doses of these drugs or to treatment with the other medications used in the study.
Dr. Singer has no affiliations with the companies that market the drugs discussed.
Besides S. pneumoniae, infection with Haemophilus influenzae was common, found in nearly half of patients, the physician said.