Microbiology of acute otitis media recently treated with aminopenicillins.
BACKGROUND
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.
Block
S L
SL
Kentucky Pediatric Research, University of Louisville, Louisville, KY, USA. slblock@pol.net
Hedrick
J A
JA
Tyler
R D
RD
Smith
R A
RA
Harrison
C J
CJ
D000208:Acute Disease; D000293:Adolescent; D000658:Amoxicillin / Q000494:pharmacology / Q000627:therapeutic use*; D019980:Amoxicillin-Potassium Clavulanate Combination / Q000494:pharmacology / Q000627:therapeutic use*; D001424:Bacterial Infections / Q000188:drug therapy / Q000382:microbiology; D002648:Child; D002675:Child, Preschool; D024901:Drug Resistance, Multiple, Bacterial; D004359:Drug Therapy, Combination / Q000494:pharmacology / Q000627:therapeutic use*; D005260:Female; D006193:Haemophilus influenzae / Q000187:drug effects / Q000472:pathogenicity; D006801:Humans; D007223:Infant; D008297:Male; D008826:Microbial Sensitivity Tests; D001936:Moraxella catarrhalis / Q000187:drug effects / Q000472:pathogenicity; D010034:Otitis Media with Effusion / Q000188:drug therapy* / Q000382:microbiology*; D010406:Penicillins / Q000494:pharmacology / Q000627:therapeutic use*; D012189:Retrospective Studies; D013296:Streptococcus pneumoniae / Q000187:drug effects / Q000472:pathogenicity; D013297:Streptococcus pyogenes / Q000187:drug effects / Q000472:pathogenicity; D018440:beta-Lactam Resistance
D010406:Penicillins; D019980:Amoxicillin-Potassium Clavulanate Combination; D000658:Amoxicillin