Change in nasopharyngeal carriage of Streptococcus pneumoniae resulting from antibiotic therapy for acute otitis media in children.
BACKGROUND
Acute otitis media is the leading reason for antibiotic prescriptions in childhood. The increase in antibiotic resistance of Streptococcus pneumoniae is generally attributed to the extensive use of antibiotics and the selective pressure on the bacterial strains of the nasopharyngeal flora.


OBJECTIVE
To evaluate the change in nasopharyngeal carriage of S. pneumoniae during antibiotic therapy prescribed for acute otitis media.


METHODS
Between October, 1993, and March, 1994, we conducted a clinical trial comparing cefpodoxime-proxetil and amoxicillin-clavulanate in acute otitis media. From 364 children, 4 months to 4.5 years old, a nasopharyngeal sample was obtained before and after treatment. Antibiotic susceptibility was established by determining minimal inhibitory concentrations by the agar dilution method. Serotype and randomly amplified polymorphic DNA analysis were used to compare pre- and posttreatment S. pneumoniae strains.


RESULTS
The risk for a child to carry penicillin-resistant S. pneumoniae (MIC > or = 0.125 mg/l) did not increase after antibiotic treatment: 84 of 364 (23.1%) before, 70 of 364 (19.2%) after. There was a significant decrease of penicillin-susceptible S. pneumoniae carriage, 117 of 364 (32.1%) before treatment compared with 24 of 364 (6.6%) (P = 0.0001) after treatment. However, among the children carrying S. pneumoniae at the end of the treatment there was an increase in the percentage of penicillin-resistant pneumococci: 84 of 201 (41.8%) before treatment and 70 of 94 (74.5%) after treatment. Among the 94 children carrying S. pneumoniae at the end of the treatment, 22 did not harbor pneumococcus before, 16 carried another genotypically different serotype and 56 harbored the same serotype. Among these 56 children 2 patients harbored strains that had increased MICs for the tested beta-lactam antibiotics. The randomly amplified polymorphic DNA analysis showed that in one case, the strains were genetically different.


CONCLUSIONS
These data illustrate that antibiotic therapy did not increase the rate at which children carried penicillin-resistant S. pneumoniae, but there was an increase in the rate of resistance among the children carrying pneumococci at the end of the treatment, mainly as a result of reduction of susceptible strains.
Cohen
R
R
Microbiology Laboratory, CHI, Créteil, France. 107112044@compuserve.com
Bingen
E
E
Varon
E
E
de La Rocque
F
F
Brahimi
N
N
Levy
C
C
Boucherat
M
M
Langue
J
J
Geslin
P
P
D000208:Acute Disease; D000658:Amoxicillin / Q000627:therapeutic use; D019980:Amoxicillin-Potassium Clavulanate Combination; D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D015296:Ceftizoxime / Q000031:analogs & derivatives* / Q000627:therapeutic use; D002675:Child, Preschool; D002969:Clavulanic Acids / Q000627:therapeutic use; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D009305:Nasopharynx / Q000382:microbiology*; D010033:Otitis Media / Q000188:drug therapy* / Q000382:microbiology; D010403:Penicillin Resistance; D011446:Prospective Studies; D013296:Streptococcus pneumoniae / Q000187:drug effects*; D000097627:Cefpodoxime Proxetil
D000658:Amoxicillin; D019980:Amoxicillin-Potassium Clavulanate Combination; D000900:Anti-Bacterial Agents; D015296:Ceftizoxime; D002969:Clavulanic Acids; D000097627:Cefpodoxime Proxetil