Acute otitis media caused by Streptococcus pneumoniae in children's hospitals between 1994 and 1997

Objective. To determine patterns of resistance for isolates of Streptococcu s pneumoniae recovered from middle ear fluids of children from eight childr en's hospitals between September, 1994, and August, 1997, Methods. Data were extracted retrospectively from the medical records of ei ght children's hospitals. A standardized data form was completed for each e pisode of pneumococcal infection. Systemic isolates (blood and pleural, syn ovial and spinal fluids) of S, pneumoniae were collected during the same pe riod, All isolates of S. pneumoniae from each center were sent to a central laboratory. Susceptibility to penicillin and ceftriaxone was determined by microbroth dilution, Organisms were considered nonsusceptible to penicilli n if the minimum inhibitory concentration was greater than or equal to 0.1 mug/ml and nonsusceptible to ceftriaxone if the minimum inhibitory concentr ation was greater than or equal to 1.0 mug/ml. Results. S. pneumoniae was recovered from the middle ear fluids of 707 chil dren from all centers during the study period. Thirty-nine (5.5%) were infe ctions recorded at 4 centers which evaluated middle ear fluid only sporadic ally and were not included in this analysis. The remaining 668 infections r eported by the 4 remaining participating hospitals reflect the experience o f 608 children. There were 54% boys; 440 (73%) were Caucasian, 111 (18%) we re African-American, 38 (6%) mere Hispanic and for 19 (3%) the race was not recorded. The children ranged in age from 16 days to 13.8 years with a mea n (+/-SD) of 26.0 (+/- 26.1) months. Children who received antibiotics in t he 30 days before the middle ear isolate was recovered were more likely to harbor a resistant strain of S. pneumoniae than children who had not recent ly received an antibiotic (P < 0.001). Isolates recovered from children wit h spontaneous otorrhea were more likely to be susceptible to penicillin tha n isolates recovered during myringotomy, with or without the insertion of t ympanostomy tubes (P < 0.01), There was wide variation in the susceptibilit y of middle ear isolates to penicillin and ceftriaxone according to geograp hic location; however, in every locale the middle ear isolates were less li kely to be susceptible to penicillin and ceftriaxone than systemic isolates of S, pneumoniae. Conclusion. The prevalence of penicillin-resistant and cephalosporin-resist ant S, pneumoniae in middle ear isolates derived from children cared for at four different children's hospitals was quite variable. In some locations the prevalence of resistance is still increasing, whereas in other areas th e rate of resistance was at a plateau during the period of surveillance. Th e prevalence of isolates of S, pneumoniae susceptible to penicillin and cef triaxone was always less common among middle ear isolates than among system ic isolates. Previous antibiotic use remains the most predictive factor for the recovery of isolates resistant to penicillin and ceftriaxone.