Antimicrobial resistance in the nasopharyngeal flora of children with acute otitis media and otitis media recurring after amoxicillin therapy

Departments of Pediatrics, Georgetown University School of Medicine, 4431 Albemarle St NW, Washington DC 20016, USA Correspondence Itzhak Brook ib6{at}georgetown.edu Received July 12, 2004 Accepted September 20, 2004 The objective of this study was to investigate the antimicrobial susceptibility of the organisms isolated from the nasopharynx of children who presented with acute otitis media (AOM) or otitis media that recurred after amoxicillin therapy. Nasopharyngeal cultures obtained from 72 patients, 40 with AOM and 32 with recurrent otitis media (ROM), were analysed. Thirty-six potentially pathogenic organisms were recovered in 34 (85 %) of the children from the AOM group, and 42 were isolated from 29 (91 %) of the children from the ROM group. The organisms isolated were Streptococcus pneumoniae ( n = 26), Haemophilus influenzae non-type b ( n = 22), Moraxella catarrhalis ( n = 13), Streptococcus pyogenes ( n = 8) and Staphylococcus aureus ( n = 9). Resistance to the eight antimicrobial agents used was found in 37 instances in the AOM group as compared to 99 instances in the ROM group ( P < 0.005). The difference between AOM and ROM was significant with Streptococcus pneumoniae resistance to amoxicillin ( P < 0.005), to amoxicillin/clavulanate ( P < 0.005), to trimethoprim/sulfamethoxazole ( P < 0.01), to cefixime ( P < 0.01) and to azithromycin ( P < 0.01), and for H. influenzae resistance to amoxicillin ( P < 0.025). These data illustrate the higher recovery rate of antimicrobial-resistant Streptococcus pneumoniae and H. influenzae from the nasopharynx of children who had otitis media that recurred after amoxicillin therapy than those with AOM. Abbreviations: AOM, acute otitis media; ROM, recurrent otitis media.