Nasopharyngeal colonisation by Streptococcus pneumoniae in children: Impact of amoxicillin treatment

Abstract number: p797

Díaz  A., Garcia  R., García-Rey  C., Cuchí  E., Calbo  E., Tobeña  L., Díaz-Infantes  M., Martín-Herrero  J.E., Garau  J.


Nasopharynx of children is the main reservoir of Streptococcus pneumoniae (SP). The percentage of nasopharyngeal carriers of SP in <2 years-old children ranges from 26% to 62%. The aim of our study was to assess the effect of amoxicillin exposure on the nasopharyngeal colonization (NPC) and on the antibiotic susceptibility of SP in <5-year-old children.

Material and methods: 

From Dec 2001 to Feb 2004, <5-year-old children with respiratory symptoms and fever seen in the Emergency Department of our hospital and who were prescribed amoxicillin (40–90 mg/kg) were eligible. Three nasopharyngeal swabs were taken: at the time of the initial visit (IV), a second sample within 60 hours after amoxicillin discontinuation (end of treatment visit, ETV), and the third, 4 weeks later (follow-up visit, FUV). SP colonization, serotype distribution and antimicrobial resistance were evaluated over time.


134 children were included. In the IV 67/134 (50%) were colonized. SP was found in the nasopharynx of 10/17 (58.5%), 15/35 (42.9%) and 42/82 (51%) of <1, 1–2 and >2 years-old children, respectively. Vaccine Serotypes (VS) were identified in 80%, 40% and 55% of <1 year-old, 1–2 years-old and > 2 years-old children, respectively. The proportion of non-susceptible Penicillin SP (NPSP) was 60% in <1 year-old children, 43% in 1–2 years-old children and 40% in > 2 years-old children. 49 out of 134 (36.5%) children completed the three study visits and were the assessable group. 51%, 22.4% and 46.9% were colonized at IV, ETV and FUV, respectively. The percentage of resistant SP was 28%, 45.5% and 8.7% (p < 0.05) for penicillin, and 40%, 63.3% and 47.8% (NS) for erythromycin at IV, ETV and FUV, respectively.


In children <1 year of age a higher proportion SP colonization, presence of vaccine serotypes and non-susceptible penicillin SP was found. NPC dropped to a half in ETV and returned to baseline levels 1 month after amoxicillin discontinuation; however non-susceptible penicillin isolates decreased a 68% in FUV with respect to IV due to recolonization by "de novo" penicillin susceptible strains.

Session Details

Date: 01/08/2007
Time: 00:00-00:00
Session name: XXIst ISTH Congress
Location: Oxford, UK
Presentation type:
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