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Microbiology of acute otitis media recently treated with aminopenicillins
S L Block1, J A Hedrick, R D Tyler
1Kentucky Pediatric Research, University of Louisville, Louisville, KY, USA. slblock@pol.net
Introduction:
Sparse recent data are available in the United States regarding the pathogens of acute otitis media (AOM) most likely to be recovered from children recently treated with the two most frequently prescribed antibiotics, amoxicillin or amoxicillin/clavulanate (AMC).
Methods:
Of the 704 rural Kentucky children with culture-positive AOM who underwent a single tympanocentesis or culture of otorrhea between 1992 and 1998, 96 pathogens were recovered from 90 children during therapy or within 7 days posttherapy with an aminopenicillin. Identification and susceptibility testing of AOM pathogens were performed by routine National Committee for Clinical Laboratory Standards methods.
Results:
Pathogens recovered from children with AOM recently treated (0 to 7 days) with amoxicillin (n = 38) and AMC (n = 58), respectively, were as follows: Haemophilus influenzae (beta-lactamase-negative), 16 and 29%; H. influenzae (beta-lactamase-positive), 11 and 22%; penicillin-susceptible Streptococcus pneumoniae, 26 and 12%; intermediately penicillin-nonsusceptible S. pneumoniae (PNSP), 20 and 10%; resistant PNSP 13 and 17%; Moraxella catarrhalis (beta-lactamase-positive), 13 and 7%; and Streptococcus pyogenes, 3 and 2%. H. influenzae was also isolated from 8 (75%) of 12 children treated with high dose AMC ( approximately 80 mg/kg/day amoxicillin component). Significantly fewer children recently treated with amoxicillin were otitis-prone than those given AMC (24% vs. 74%, P < 0.0001).
Conclusions:
The predominant pathogen recovered from children with AOM recently treated with amoxicillin was S. pneumoniae (59%) rather than beta-lactamase-producing organisms (24%). H. influenzae was the predominant (51%) pathogen, rather than PNSP (27%), recovered from children recently treated with AMC.
Insights
Recent data on acute otitis media (AOM) pathogens in children treated with amoxicillin or amoxicillin/clavulanate (AMC) are scarce. Streptococcus pneumoniae was the primary pathogen after amoxicillin, while Haemophilus influenzae predominated after AMC treatment.
Area of Science:
- Pediatrics
- Infectious Diseases
- Microbiology
Background:
- Limited recent data exist in the U.S. on pathogens causing acute otitis media (AOM) in children previously treated with amoxicillin or amoxicillin/clavulanate (AMC).
- Understanding pathogen prevalence post-antibiotic therapy is crucial for effective AOM management.
Purpose of the Study:
- To identify the predominant pathogens recovered from children with AOM following recent treatment with amoxicillin or AMC.
- To compare pathogen profiles and treatment outcomes between amoxicillin and AMC in pediatric AOM cases.
Main Methods:
- A retrospective analysis of 96 pathogens from 90 children with culture-positive AOM in rural Kentucky (1992-1998).
- Children had undergone tympanocentesis or otorrhea culture during or within 7 days of aminopenicillin therapy.
- Pathogen identification and susceptibility testing followed standard National Committee for Clinical Laboratory Standards methods.
Main Results:
- Streptococcus pneumoniae (59%) was the predominant pathogen after amoxicillin, versus beta-lactamase-producing organisms (24%).
- Haemophilus influenzae (51%) was the predominant pathogen after AMC, versus penicillin-nonsusceptible S. pneumoniae (PNSP) (27%).
- H. influenzae was also prevalent in children receiving high-dose AMC.
Conclusions:
- Pathogen prevalence in AOM differs based on recent antibiotic exposure (amoxicillin vs. AMC).
- S. pneumoniae remains a key pathogen after amoxicillin, while H. influenzae is more common after AMC.
- These findings inform antibiotic selection for pediatric AOM.