Bacteriological findings and persistence of middle ear effusion in otitis media with effusion.

The bacteriology of middle ear effusion (MEE) of asymptomatic otitis media with effusion (OME) was studied in 165 children, aged 5 months to 12 years, from the MEE samples obtained during tympanostomy under general anaesthesia in 1993-1994. MEE had persisted for 1 to 12 (mean 3.5) months. Major otitis pathogens (S. pneumoniae, H. Influenzae, B. catarrhalis and S. pyogenes) were cultured in 41% of the children under 2 years of age and in 17% of older children (p < 0.001). Respiratory infections and attacks of acute otitis media (AOM) during the last 6 months were also more frequent in children younger than 2 years (p < 0.001). The proportion of S. pneumoniae (25%) and H. influenzae (38%), but not of other bacteria, was higher in the children with less than 2 months' persistence of MEE as compared with those with a longer duration (8% and 3%) (p < 0.01). After 2 months, the occurrence of different bacteria remained relatively unchanged until 6 months' persistence of MEE, and thereafter no pathogens were culturable. Among the children adenotomized earlier, the proportion of those with major otitis pathogens in MEE was 8% compared with 32% in non-adenotomized children (p = 0.02). S. pneumoniae, B. catarrhalis or S. pyogenes were not culturable in any of the adenotomized children, while MEE grew them in 25% of the non-adenotomized children (p < 0.001). Since the MEE bacteriology of OME with less than 2 months' persistence resembles that of AOM, it may be that these cases represent a transitory phase between AOM and an established OME.