Background: Dynamics of bacteria during acute otitis media (AOM) has not been thoroughly studied because it requires repeated tympanocentesis. AOM with tympanostomy tube otorrhea provides a unique opportunity to study the appearance and disappearance of pathogens during the course of the disease without stressing the child.
Methods: Middle ear fluid (MEF) samples were taken before treatment (amoxicillin clavulanate or placebo) and then daily during follow-up from 75 children having AOM with otorrhea through a tympanostomy tube. Bacteria were identified by culture, and typical AOM pathogens also by polymerase chain reaction.
Results: Bacteria were initially shown in 67 (89%) children. New bacteria appeared in MEF more often in placebo than in amoxicillin clavulanate recipients [9 of 38 (24%) versus 2 of 37 (5%); P = 0.032]. During the follow-up, new occurrences of Moraxella catarrhalis were detected in MEF more frequently than those of Streptococcus pneumoniae or Haemophilus influenzae. Of the 28 patients with bilateral otorrhea, 11 (39%) had disparate bacteria at study entry and/or during the follow-up.
Conclusions: Changes in bacterial findings during the course of AOM are common in patients not receiving treatment, and even possible despite adequate treatment. In bilateral otorrhea, disparate bacterial findings are common.