December 1996
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Diagram shows the relationship between outer, middle and inner
ear.
BOSTON — Some researchers are questioning the necessity of treating acute otitis media with antimicrobials. In the era of pneumococcal resistance, is it necessary to treat all children with AOM?
Jerome O. Klein, MD, professor of pediatrics at Boston University School of Medicine, addressed this issue at the recent annual meeting of the American Academy of Pediatrics here.
Physicians in a number of European countries, particularly in The Netherlands and Eastern Europe, do not treat children with AOM immediately with an antimicrobial agent. Instead, they wait and see if the illness will spontaneously resolve. If the symptoms don't resolve, the children are treated. As a result, these countries have a lower amount of pneumococcal resistance. They also have a higher number of children suffering from mastoiditis, said Klein, who is vice-chairman for academic affairs, department of pediatrics at the Boston Medical Center.
At this time, Klein comes down on the side of treating AOM because of the possible adverse events from letting the disease go untreated.
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The incidence of resistant pneumococci is rising. Surveillance by the Centers for Disease Control and Prevention showed that resistance was about 5% in 1990. It's about 20% today.
Organisms are classified as either susceptible, intermediately resistant or highly resistant. Klein said that highly resistant organisms are the cause of most concern, and these are low even in the United States. "It is the high resistance group with MICs of 2 mg or more that is the critical area in terms of clinical failure or efficacy," he said.
"One has to know the incidence figures for your own community to respond appropriately," he said. Those figures should be available through your state health department or the CDC.
Nasopharyngeal isolates and middle ear isolates have higher incidence than blood or spinal fluid. This may because of prior antimicrobial use. "The patient who comes in with an invasive event, meningitis, may not have had prior antimicrobial agent, where the child who had a tympanocentesis is likely to either be on a drug or to have had a drug previously," he said.
Risk factors for harboring a resistant organism are previous antibiotic use, prior hospitalization and day care attendance. Children appear to harbor more resistant strains than adults, probably because of day care attendance. "Day care attendance is an exposure issue," he explained. "If one child has a resistant strain, it spreads quickly to the others."
Otitis media was not always treated with antimicrobials. Before penicillin, OM was observed, or a physician did a myrongotomy and drained the middle ear abscess. Spontaneous resolution was frequent, although many ear drums perforated and the ear drained spontaneously. At this time, OM was a frequent reason for hospitalization. In 1932, 27% of admissions to Belvue Hospital was for mastoiditis; intracranial complications were common among those hospitalized children.
Mastoiditis used to be a common part of OM until physicians began to use antimicrobials. For countries, such as The Netherlands, that do not treat OM immediately, mastoiditis is still a problem. Resistance in these countries is very low, however; The Netherlands reports 0.9% resistance.
There are arguments against immediate treatment. One-third of cases are not caused by a bacterial pathogen; they are either a viral or allergic etiology and will not respond to antibiotics. Forty percent are caused by Pneumococcus, 25% by Haemophilus influenzae, 3% by group A streptococcus; and about 10% by Moraxella catarrhalis. "So about one-third of children will not respond because it is not a bacterial disease," Klein said. "And another 20% will clear spontaneously."
The problem for the clinician is that there is no way to tell by an examination in the office whether the OM suffered by a child will clear spontaneously or is caused by a viral infection, instead of bacteria.
"I think this is the problem for investigation. That there are undoubtedly a significant portion of children, perhaps the majority, with otitis media which will clear spontaneously or don't have a bacterial pathogen and would do fine without an antimicrobial agent. I think the problem that we have currently is we cannot distinguish between the group that would benefit from an antimicrobial agent from the group that would not benefit from an antimicrobial agent. So, we are left with this perplexing situation in which we need to treat all to cover the group that would benefit," he explained.
Klein said that criteria need to be established before a physician can withhold treatment from the selected group who is nontoxic. Until that time, Klein said he would treat OM.
"The pneumococcal resistant story is one that is more potential in management of otitis than actual, we probably will be talking about not treating otitis in the future, but currently, it remains a treatable disease."
Klein said that amoxicillin is still the first-line treatment for OM. Most organisms remain susceptible or intermediately resistant and will respond. With a 10-mg dose of amoxicillin, one can achieve 5 mg to 10 mg in the middle ear — in excess to 2 mg needed to overcome resistance in intermediately resistant organism. "The usual dose of amoxicillin ought to be able to take care of the intermediate-resistant strains; perhaps there might be some difficulties with the highly resistant strains. But even some of those should be covered," Klein said. "So, at least for this winter, I think we can still use amoxicillin."
There are no good answers yet, he said, for children who fail to respond to antibiotics or who suffer breakthrough episodes while on long-term therapy. "It certainly is one of the gaps we need to fill," Klein admitted.
He would choice a broader spectrum drug that is b-lactamase stable and that has good activity against the pneumococci.
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