Bacterial isolates and efficacy of antibiotics in acute otitis media in children

This research was done for study of bacterial isolates and efficacy of the antibiotics, amoxicillin, calvulanate amoxicillin and cefaclor, in AOM in children. 148 children with AOM were randomly assigned to receive a 10 day course of either treatment regimen. Aspiration of middle ear fluid for culture was done initially and repeated during treatment if fluid persisted. Bacterial isolates in initial aspirates were S. pneumonia [42%], H. influenzae[34%], S. pyogenes [9%], B. catarrhalis[6%], Staph. Aureus [5%] and nonpathogens [7%]. Isolated main strains were susceptible to the study antibiotics except 24% of isolates of H. influenzae, 67% of B. catarrhalis and 71% of Staph. Aureus were resistant to amoxicillin. Clinical responses were assessed at 3 and 10 days and 4 weeks later. On day 10 patients were either cured or unresolved with either drainage or persistent effusion. The cure rates were 71% for amoxicillin, 88% for clavulanate amoxicillin and 81% for cefaclor. However, the differences are not statistically significant. Recurrences during 4 weeks after treatment occurred in 15 children, 7 in amoxicillin, 3 antibiotics. While, in those with H. influenzae, cure rates were 60% for amoxicillin and 76% for cefaclor. Favorable clinical results were obtained with clavulanate amoxicillin and cefaclor as compared with amoxicillin, mainly in cases with H, Influenzae, B. catarrhalis and Staph. Aureus. This relates to amoxicillin resistant strains. Therefore, it would be prudent to consider them in the event of treatment failure and persistent effusion after amoxyclillin treatment or as initial therapy

Antibiotic concentrations in middle ear effusions

Concentrations of amoxicillin, clavulanate amoxicillin and cefaclor, were determined in middle ear fluid in 106 children with otitis media with effusion after the administration of single oral dose. One to four hours after administration, tympanocentesis was done and middle ear fluid and venous blood specimens were obtained. Concentrations of antibiotic in both specimens were determined with microbiological assays by disk diffusion method. The peak concentrations of amoxicillin and clavulanate amoxicillin in middle ear fluid were detected three hours after administration and one hour after their peak in serum, while that of cefaclor was detected after one hour and simultaneously with its peak in serum. Both clavulanate amoxicillin and cefaclor penetrated readily into middle ear fluid in concentrations greater than minimal inhibitory concentration for S. pneumonia, amoxicillin sensitive and resistant H. influenzae and S. pyogenes. Amoxycillin penetrated in concentrations greater than MICS for these pathogens except for resistant H. influenzae. So clavulanate amoxicillin or cefaclor can be considered either as reasonazble choice to amoxicillin for treatment of acute otitis media or as alternative antibiotics for treatment failure with amoxicillin due to resistant strains of H. influenzae