Antimicrobial resistance in the nasopharyngeal flora of children with acute maxillary sinusitis and maxillary sinusitis recurring after amoxicillin therapy

Objective: To investigate the antimicrobial susceptibility of the organisms isolated from the nasopharynx of children who present with acute maxillary sinusitis (AMS) or maxillary sinusitis that recurred (RMS) after amoxicillin therapy. Methods: Analysis of nasopharyngeal cultures obtained from 70 patients, 42 with AMS and 28 with RMS. Results: Thirty-eight potentially pathogenic organisms were recovered in 36 (86%) of the children from the AMS group, and 40 were isolated from 26 (93%) of the children from the RMS group. The organisms isolated were Streptococcus pneumoniae (21 isolates), Haemophilus influenzae non-type b (17), Moraxella catarrhalis (15), Streptococcus pyogenes (13) and Staphylococcus aureus (12). Resistance to the eight antimicrobial agents used was found in 34 instances in the AMS group compared to 93 instances in the RMS group (P < 0.005). The difference between AMS and RMS was significant with S. pneumoniae resistance to amoxicillin (P < 0.0025), to co-amoxiclav (P < 0.0025), to trimethoprim-sulfamethoxazole (P < 0.05), to cefixime (P < 0.05), and to azithromycin (P < 0.05), and for H. influenzae to amoxicillin (P < 0.025). Conclusions: These data illustrate the higher recovery rate of antimicrobial-resistant S. pneumoniae and H. influenzae from the nasopharynx of children who had maxillary sinusitis that recurred after amoxicillin therapy than those with AMS.