Impact of amoxicillin on pneumococcal colonization compared with other therapies for acute otitis media.
BACKGROUND
This study compared the effects of 4 outpatient antibiotic regimens on colonization by penicillin-susceptible and -nonsusceptible pneumococci to assess their relative potential to promote colonization with Streptococcus pneumoniae with reduced susceptibility to penicillin.


METHODS
Children presenting with acute otitis media were randomized to receive amoxicillin, cefprozil, ceftriaxone or azithromycin. Nasopharyngeal specimens were collected on days 0, 3-5, 10-14 and 28-30 and assessed for the presence of S. pneumoniae. At each visit, the proportions of penicillin-susceptible and -nonsusceptible pneumococci were compared among treatment groups.


RESULTS
Among 1009 enrollees, the prevalence of colonization by S. pneumoniae at baseline was 23.5%, of which 41.1% were penicillin-nonsusceptible. Colonization by nonsusceptible pneumococci was unaltered during the observation period in all treatment groups, with no detectable differences among groups at each visit. By contrast, there was a substantial reduction in the prevalence of colonization by penicillin-susceptible organisms, most notably in subjects treated with amoxicillin. This resulted in a proportional shift toward resistant organism colonization in all groups, with this shift being significantly more pronounced among amoxicillin recipients than in the other groups at 10-12 days (P < 0.02 for each comparison with amoxicillin).


CONCLUSIONS
Treatment with amoxicillin for acute otitis media resulted in a larger shift toward nonsusceptible organism colonization among those children still colonized postexposure than did treatment with 3 comparison agents. This phenomenon raises theoretical concerns that at the population level, amoxicillin produces conditions that promote the dissemination of the nonsusceptible phenotype more readily than other outpatient antibiotics. Confirmation of these results requires further study.
Toltzis
Philip
P
Department of Pediatrics, Rainbow Babies and Children's Hospital, Case Western Reserve University School of Medicine, Cleveland, OH, USA.
Dul
Michael
M
O'Riordan
Mary Ann
MA
Toltzis
Hasida
H
Blumer
Jeffrey L
JL
D000208:Acute Disease; D000658:Amoxicillin / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use*; D000900:Anti-Bacterial Agents / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use*; D002648:Child; D002675:Child, Preschool; D024881:Drug Resistance, Bacterial; D006801:Humans; D007223:Infant; D008826:Microbial Sensitivity Tests; D009305:Nasopharynx / Q000382:microbiology*; D010033:Otitis Media / Q000188:drug therapy* / Q000382:microbiology*; D011008:Pneumococcal Infections / Q000188:drug therapy* / Q000382:microbiology; D013296:Streptococcus pneumoniae / Q000187:drug effects / Q000254:growth & development*; D016896:Treatment Outcome
D000900:Anti-Bacterial Agents; D000658:Amoxicillin