Nasopharyngeal carriage of Streptococcus pneumoniae in healthy children: implications for the use of heptavalent pneumococcal conjugate vaccine.

Paola Marchisio,Roberta Cavagna,Nicola Principi,Susanna Esposito,Anna Marchese,Gian Carlo Schito

doi:10.3201/eid0805.010235

Abstract

We assessed the prevalence of Streptococcus pneumoniae serotypes in the nasopharynx of healthy children, antimicrobial susceptibility patterns, risk factors for carriage, and the coverage of heptavalent pneumococcal conjugate vaccine. In 2,799 healthy infants and children, the S. pneumoniae carrier rate was 8.6% (serotypes 3, 19F, 23F, 19A, 6B, and 14 were most common). Most pneumococci (69.4%) were resistant to one or more antimicrobial classes. The rate of penicillin resistance was low (9.1%); macrolide resistance was high (52.1%). Overall, 63.2% of the isolates belonged to strains covered by the heptavalent pneumococcal vaccine. This percentage was higher in children <2 years old (73.1%) and in those >2-5 years old(68.9%). Sinusitis in the previous 3 months was the only risk factor for carrier status; acute otitis media was the only risk factor for the carriage of penicillin-resistant S. pneumoniae. Most the isolated strains are covered by the heptavalent conjugate vaccine, especially in the first years of life, suggesting that its use could reduce the incidence of pneumococcal disease.

Highlights

We assessed the prevalence of Streptococcus pneumoniae serotypes in the nasopharynx of healthy children, antimicrobial susceptibility patterns, risk factors for carriage, and the coverage of heptavalent pneumococcal conjugate vaccine
The asymptomatic nasopharyngeal carriage of Streptococcus pneumoniae is widely prevalent in young children and has been related to the development of disease and the spread of the pathogen [4,5]; nasopharyngeal colonization by antibiotic-resistant S. pneumoniae has steadily increased over the last few years [6,7]
The nasopharyngeal cultures were injected into Stuart transport medium tubes (Venturi Transystem, Brescia, Italy), which were sent to the microbiology laboratory of the individual hospitals within 1-3 hours and immediately processed

Summary

Introduction

We assessed the prevalence of Streptococcus pneumoniae serotypes in the nasopharynx of healthy children, antimicrobial susceptibility patterns, risk factors for carriage, and the coverage of heptavalent pneumococcal conjugate vaccine. The bacteria carried in the nasopharynx of healthy children reflect the infection-causing strains currently circulating in the community [3], and so studies of the prevalence of different pathogens and their resistance patterns can provide useful indications for more rational therapeutic and preventive strategies. Antibiotic-resistant strains are more often carried by infants and young children than adults and belong to a limited number of serotypes that are some of the most common causes of invasive pediatric diseases [8,9,10]. We assessed the prevalence of different S. pneumoniae serotypes in the nasopharynx of healthy children attending day-care centers and primary schools, determined their

Methods

Results

Conclusion