Predictive value of pneumococcal nasopharyngeal cultures for the assessment of nonresponsive acute otitis media in children

Background Nonresponsive acute otitis media (NR-AOM) is reported in >10% of children with AOM treated with antibiotics. Drug-resistant Streptococcus p neumoniae is currently considered the leading cause of antibiotic failures in AOM. Nasopharyngeal colonization with S. pneumoniae was found to increas e significantly during episodes of AOM. Objectives. To investigate the nasopharyngeal colonization with S. pneumoni ae during NR-AOM and compare it with that found in AOM mit recently treated with antibiotics (NT-AOM); to assess the predictive value of nasopharyngea l pneumococcal cultures results for the bacteriologic assessment of NR-AOM. Materials and methods. Patients age 3 to 48 months with NT-AOM and NR-AOM w ere prospectively studied. Simultaneous nasopharyngeal cultures for S. pneu moniae and middle ear fluid cultures were obtained at enrollment, Antibioti c susceptibility testing was performed in all S. pneumoniae isolates. Penic illin and ceftriaxone MICs for S, pneumoniae were determined by E-test. The sensitivity, specificity and positive and negative predictive values of po sitive or negative nasopharyngeal cultures for the presence of S. pneumonia e in middle ear fluid were calculated. Results. We studied 362 and 217 children with NT-AOM and NR-AOM, respective ly. Of the children with NT-AOM and NR-AOM, 95 and 97%, respectively, were younger than 2 years of age. S. pneumoniae was isolated in the nasopharynx of 66 and 58% of children with NT-AOM and NR-AOM, respectively. Penicillin- nonsusceptible S. pneumoniae was isolated more frequently from the nasophar ynx of patients with NR-AOM than from those with NT-AOM (84% vs. 47%; P < 0 .01). Antibiotic susceptibility patterns were similar for S. pneumoniae iso lates recovered from the nasopharynx and those from the middle ear fluid in both NT-AOM and NR-AOM. A positive nasopharyngeal culture had only little predictive value for the presence of S. pneumoniae in middle ear fluid (41 and 51% for NT-AOM and NR-AOM, respectively). However, the negative predict ive value of nasopharyngeal cultures for recovery of S. pneumoniae in NR-AO M was high and significantly higher in NR-AOM than in NT-AOM (91% vs. 78%, respectively; P = 0.009). The negative predictive value of nasopharyngeal c ultures for recovery of antibiotic-resistant S. pneumoniae was 95 and 93% i n NT-AOM and NR-AOM, respectively. Conclusions. A significantly higher nasopharyngeal colonization rate with a ntibiotic-resistant S. pneumoniae was found in patients with NR-AOM than in those with NT-AOM. Negative nasopharyngeal culture for antibiotic-resistan t S. pneumoniae practically rules out its presence in middle ear fluid.