An amoxicillin/clavulanate combination was significantly more effective than azithromycin in eliminating bacterial acute otitis media, including penicillin-resistant strains, reported Alejandro Hoberman, M.D., of the Children's Hospital of Pittsburgh, and his colleagues.
In a randomized, investigator-blinded study sponsored in part by GlaxoSmithKline, 730 children aged 6–30 months were randomized to receive either a 90-mg amoxicillin and a 6.4-mg clavulanate/kg combination daily in 2 divided doses for 10 days, or a 10-mg/kg dose of azithromycin once daily for 1 day, followed by 5 mg/kg once daily for 4 days.
The study was conducted at 34 centers worldwide, including ones in Bulgaria, Chile, the Dominican Republic, Guatemala, Israel, Peru, Romania, Latvia, Mexico, and the United States from April 2001 to November 2002.
The evolution of antimicrobial resistance among pathogens that cause acute otitis media (AOM) and the approval of a large-dose pediatric formulation of amoxicillin/clavulanate prompted the study.
At baseline, 494 (68%) of the children had at least one protocol-defined pathogen. Of those, 249 were in the amoxicillin/clavulanate group and 245 were in the azithromycin group.
Of these, 19 (8%) children in the amoxicillin/clavulanate group and 38 (16%) in the azithromycin group had more than one pathogen at baseline (Pediatr. Infect. Dis. J. 2005:24:525–32).
The children without discernible pathogens at baseline (118 in each group) were included in the safety analysis.
In addition, of the 229 total Streptococcus pneumoniae isolates (111 children in the amoxicillin/clavulanate group and 118 children in the azithromycin group), 49%, 11%, and 21% were not susceptible to penicillin, amoxicillin, and azithromycin, respectively.
Overall, clinical success rates among children with baseline AOM pathogens were significantly greater in the amoxicillin/clavulanate group (91%), compared with the azithromycin group (81%).
Clinical success was defined as the lessening or complete resolution of acute ear infection and inflammation, with or without middle-ear effusion, to the extent that no additional antibiotics were needed.
Clinical response at 12–14 days after the start of therapy served as the primary end point of the study.
Bacteriologic success was defined as the eradication of the initial AOM pathogen with or without a new pathogen, based on a lack of middle-ear fluid.
Bacteriologic success at an “on-therapy” visit 4–6 days after the start of treatment was associated with clinical success at the end of the therapy in 96 of 105 children (91%) in the group treated with the amoxicillin/clavulanate combo and in 80 of 89 (90%) children in the azithromycin group.
The distribution of pathogens was similar between the two groups.
H. influenzae was the more common. It was found in 49% of the group that was treated with amoxicillin/clavulanate and in 51% of the azithromycin group.
In the subset of 101 amoxicillin/clavulanate patients and 82 azithromycin patients who demonstrated bacteriologic responses after 4–6 days, amoxicillin/clavulanate was significantly more effective than azithromycin against penicillin-resistant S. pneumoniae, with eradication in 23 of 25 cases (92%) vs. 12 of 22 cases (55%), respectively.
Although significantly more children in the amoxicillin/clavulanate group withdrew from the study due to an adverse event, compared with the azithromycin group (21 vs. 7), the total number of adverse events was not significantly different between the two groups (139 vs. 128).
Fever was the most common adverse event reported, and it occurred in approximately 10% of the patients in each group.
Diarrhea occurred in 6% of patients taking amoxicillin/clavulanate and 4% of those taking azithromycin.
Overall, the compliance rates were high in both groups: 86% in the amoxicillin/clavulanate group and 91% in the azithromycin group.