Resistance to antimicrobials used for therapy of otitis media and sinusitis: Effect of previous antimicrobial therapy and smoking

We undertook to identify the antimicrobial susceptibility of the pathogens isolated from patients with otitis media or maxillary sinusitis who failed to respond to antimicrobial therapy, and correlate it with previous antimic robial therapy and smoking. We analyzed isolates recovered from 2 consecuti ve cultures obtained from middle ear aspirate obtained through an open perf oration in 22 children with otitis, and maxillary sinus aspirate collected by endoscopy from 20 patients. Forty-seven isolates were repeatedly recover ed from 42 culture-positive individuals. The organisms isolated were Strept ococcus pneumoniae (15 isolates), Haemophilus influenzae (14), Staphylococc us aureus (7), Moraxella catarrhalis (6), and Streptococcus pyogenes (5). R esistance of at least 2 tube dilutions to the antimicrobial agents used was found in 23 of the 47 (49%) isolates that were found in 20 (48%) of the pa tients. These included 10 of 15 (67%) isolates of S pneumoniae, 4 of 14 (29 %) H influenzae (all were beta-lactamase producers), 4 of 7 (57%) S aureus (all beta-lactamase producers), 5 of 6 (83%) M catarrhalis tall beta-lactam ase producers), and none of 5 S pyogenes. In the 21 patients who failed to respond to amoxicillin, H influenzae and S pneumoniae predominated. Strepto coccus pneumoniae was recovered from 4 of the 11 (36%) after trimethoprim-s ulfamethoxazole, 4 of 21 (19%) after amoxicillin, 2 of 3 (67%) after azithr omycin dihydrate, and 1 of 4 (25%) after cefixime. A statistically signific ant higher recovery of resistant organisms was noted in those treated 2 to 6 months previously, and in those with sinusitis;who smoked. The data illus trate the relationship between resistance to antimicrobials and failure of patients with otitis media and sinusitis to improve.