Antibiotics for Acute Otitis Media and Bacterial Sinusitis
Historically, the relative proportion of bacterial agents in AOM was Streptococcus pneumoniae at 40%, Haemophilus influenzae at 25% and Moraxella catarrhalis at 12%. The original distribution of bacterial pathogens in acute bacterial sinusitis was S. pneumoniae at 30% and H. influenzae and M. catarrhalis at 20% each. Streptococcus pyogenes was a minor cause of both entities, accounting for 2% to 4% of cases.
For many years, amoxicillin 45 mg/kg/day in 3 divided doses was the drug of choice for AOM. The preference for amoxicillin relates to its excellent safety profile, relatively narrow spectrum, low cost and general effectiveness. The first challenge to the effectiveness of amoxicillin arose in the mid-1970s when the issue of β-lactamase production among H. influenzae emerged. The decision to continue to recommend amoxicillin for children with AOM was based on a calculation which involved multiplying the proportion of cases of AOM caused by H. influenzae, by the proportion of isolates that were β-lactamase positive; the rate of probable spontaneous cure was also taken into consideration. In the past, when H. influenzae caused 25% of cases of AOM and β-lactamase production occurred in 20%–30% of isolates, it could be calculated that a middle ear isolate would be resistant to amoxicillin in 6% of cases. Although M. catarrhalis produces β-lactamase nearly 100% of the time, it was isolated less frequently and was thought to have a very high rate of spontaneous resolution. Accordingly, amoxicillin remained a good choice.
History of Microbiology and Treatment of Aom
Historically, the relative proportion of bacterial agents in AOM was Streptococcus pneumoniae at 40%, Haemophilus influenzae at 25% and Moraxella catarrhalis at 12%. The original distribution of bacterial pathogens in acute bacterial sinusitis was S. pneumoniae at 30% and H. influenzae and M. catarrhalis at 20% each. Streptococcus pyogenes was a minor cause of both entities, accounting for 2% to 4% of cases.
For many years, amoxicillin 45 mg/kg/day in 3 divided doses was the drug of choice for AOM. The preference for amoxicillin relates to its excellent safety profile, relatively narrow spectrum, low cost and general effectiveness. The first challenge to the effectiveness of amoxicillin arose in the mid-1970s when the issue of β-lactamase production among H. influenzae emerged. The decision to continue to recommend amoxicillin for children with AOM was based on a calculation which involved multiplying the proportion of cases of AOM caused by H. influenzae, by the proportion of isolates that were β-lactamase positive; the rate of probable spontaneous cure was also taken into consideration. In the past, when H. influenzae caused 25% of cases of AOM and β-lactamase production occurred in 20%–30% of isolates, it could be calculated that a middle ear isolate would be resistant to amoxicillin in 6% of cases. Although M. catarrhalis produces β-lactamase nearly 100% of the time, it was isolated less frequently and was thought to have a very high rate of spontaneous resolution. Accordingly, amoxicillin remained a good choice.