Host factors and early therapeutic response in acute otitis media

To evaluate the relationship between eradication of bacterial infection and clinical improvement in children with otitis media, we reviewed the clinical outcome of bacterial otitis media in patients enrolled in double-blind trials of antibacterial therapy from 1979 to 1988. Cultures of middle ear exudates showed the distribution of bacterial pathogens to be similar to that observed in other geographic areas. Two hundred ninety-three patients had otitis media caused by bacterial pathogens and underwent repeat tympanocentesis after 3 to 6 days of therapy. Bacteriologic success was demonstrated in 253 patients (86%); 40 patients (14%) had bacteriologic failure. Children who had bacteriologic failure were younger than those with bacteriologic success (median age 10.6 vs 18.5 months; p = 0.001); 38% of patients who had bacteriologic failure were black, compared with 18% of patients with bacteriologic success (p = 0.007). Gender, history of frequent otitis media, and presence of bilateral otitis media were not risk factors for bacteriologic failure. Clinical success was demonstrated in 261 patients (89%); 32 patients (11%) had clinical failure. Agreement between clinical and bacteriologic response was 86% (95% confidence interval: 81.6% to 89.6%). Ninety-three percent (236/253) of subjects whose infection was eliminated had clinical resolution, whereas 37% (15/40) of those with bacteriologic failure had persisting symptoms or signs of clinical failure. We conclude that failure to eliminate bacteria from the middle ear is often associated with persistent signs and symptoms. Bacteriologic failure affects children less than 18 months of age almost exclusively. Bacteriologic and clinical failure are frequently discordant; mechanisms unrelated to the bacterial infection may explain some of the persisting clinical signs.