Ecological effects on the oro- and nasopharyngeal microflora in children after treatment of acute otitis media with cefuroxime axetil or amoxycillin-clavulanate as suspensions

Objective To evaluate if the extent of normal microflora disturbances diffe red between treatment with amoxycillin-clavulanate administered in an activ e form and cefuroxime axetil administered as an inactive prodrug. Methods Twenty-eight children, 0.5-5 years old, diagnosed with acute otitis media (AOM), were treated with either amoxycillin-clavulanate (13.3 mg/kg 3 times daily) or cefuroxime axetil (15 mg/kg twice daily) for 7 days. Sali va samples and nasopharyngeal swabs were collected before, directly after a nd 2 weeks after treatment. The saliva samples were quantitatively and qual itatively analyzed and the nasopharyngeal swabs were qualitatively analyzed . All isolated strains were tested for beta -lactamase production. Results Both treatment regimens gave rise to similar alterations of the nor mal oropharyngeal microflora. In both groups, the amount of Streptococcus s alivarius was significantly reduced (P < 0.05). The most common causative p athogens of acute otitis were S. pneumoniae, Haemophilus influenzae and Mor axella catarrhalis. On the day of enrollment, approximately half of the pat ients, in both groups, were infected with more than one pathogen. The rate of infection or colonization with more than one potential pathogen was low on day 7 but recurred 2 weeks after treatment to similar levels as on day 0 . The total number of patients with reinfection, recolonization or recurren ce of pathogens on day 21 was 11/12 in the amoxycillin-clavulanate group an d 4/7 in the cefuroxime axetil group. The most common <beta>-lactamase prod ucer was M. catarrhalis. Conclusion The local high concentration of antibiotics in the oropharynx im mediately after intake of antibiotic suspensions seem to have little or no impact on the extent of disturbance of the microflora in this region. Child ren of this age group seem prone to either reinfection, recolonization or p ersistence of pathogens within 2 weeks after treatment. Furthermore, co-inf ection with more than one pathogen seems common in children with AOM and in fection with beta -lactamase producing microorganisms occurs frequently.