Penicillin resistance is not extrapolable to amoxicillin resistance in Streptococcus pneumoniae isolated from middle ear fluid in children with acute otitis media.
OBJECTIVE
We evaluated the in vitro antibacterial activity of amoxicillin against penicillin-susceptible and -nonsusceptible Streptococcus pneumoniae strains isolated from children with acute otitis media (AOM).


METHODS
Children more than 3 months of age with AOM who were seen in the Dr Sótero del Rio and Luis Calvo Mackenna Hospitals in Santiago, Chile, between July 1998 and December 2002 were subjected to tympanic puncture for middle ear fluid culture. The penicillin and amoxicillin susceptibilities of the S pneumoniae isolates were determined by epsilometer test (E test).


RESULTS
A bacterial pathogen was isolated in 432 of 543 children (80%) as follows: S pneumoniae, 40%; Haemophilus influenzae, 29%; Moraxella catarrhalis, 7%; and Streptococcus pyogenes, 4%. Penicillin-susceptible S pneumoniae strains were less common than amoxicillin-susceptible strains (60% versus 95%; odds ratio [OR], 0.08; 95% confidence interval [CI], 0.04 to 0.18). Both intermediate- and high-resistance strains were more common for penicillin (22% versus 4.5%; OR, 5.6; 95% CI, 2.5 to 12.7) than for amoxicillin (18% versus 0.5%; OR, 41.3; 95% CI, 6.0 to 821).


CONCLUSIONS
Penicillin resistance is not extrapolable to amoxicillin among S pneumoniae strains isolated from middle ear fluid of children with AOM. Our results support the recommendation to evaluate the minimal inhibitory concentrations of penicillin-nonsusceptible S pneumoniae for amoxicillin and to continue use of this antimicrobial as a first-line antimicrobial choice for children with AOM.
Otorhinolaryngology Service, Hospital Dr Sótero del Rio, Santiago, Chile.
Andrés
A
Rosenblüt
María Elena
ME
Santolaya
Patricia
P
Gonzalez
Cecilia
C
Borel
José
J
Cofré
D000208:Acute Disease; D000658:Amoxicillin / Q000627:therapeutic use*; D000668:Ampicillin Resistance; D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D000907:Antibodies, Bacterial / Q000032:analysis; D005500:Follow-Up Studies; D006801:Humans; D066298:In Vitro Techniques; D007223:Infant; D008826:Microbial Sensitivity Tests; D010034:Otitis Media with Effusion / Q000188:drug therapy / Q000382:microbiology*; D010403:Penicillin Resistance; D011008:Pneumococcal Infections / Q000188:drug therapy / Q000382:microbiology*; D012189:Retrospective Studies; D013296:Streptococcus pneumoniae / Q000187:drug effects / Q000302:isolation & purification*
D000900:Anti-Bacterial Agents; D000907:Antibodies, Bacterial; D000658:Amoxicillin