Global serotype distribution among Streptococcus pneumoniae isolates causing otitis media in children: Potential implications for pneumococcal conjugate vaccines

Abstract

Acute otitis media (AOM) is the most common infection following pneumococcal colonization of the upper respiratory tract. Streptococcus pneumoniae causes 30–60% of AOM cases worldwide. However, not all pneumococcal serotypes cause disease and an association exists with nasopharyngeal colonization by certain serotypes and their propensity to cause AOM. This review examines the global serotype distribution relationship between pneumococcal serotypes and AOM in children aged <18 years and demonstrates that the most common pneumococcal serotypes causing AOM globally are 3, 6A, 6B, 9V, 14, 19A, 19F, and 23F.

Introduction

Acute otitis media (AOM) is the most common infection following pneumococcal colonization of the upper respiratory tract [1] and accounts for a substantial proportion of health care facility visits, sequelae, and direct and indirect health care costs. A longitudinal follow-up of children demonstrated that 83% had experienced one or more episodes of AOM by 3 years of age [2]. AOM is the most common infection for which antibiotics are prescribed for children in the U.S. [3]. The most recently available U.S. national data reported that there were 1.8 million emergency department visits by children aged ≤17 years for AOM, and antibiotics were prescribed in 91.3% of these cases [4]. Data from the National Ambulatory Medical Care Surveys and the National Hospital Ambulatory Medical Care Surveys demonstrated that 5.18 million episodes of AOM occurred annually in the U.S. at a cost of approximately $2.98 billion, including direct and indirect costs [5].

Streptococcus pneumoniae has been the most frequent pathogen isolated from middle ear fluid (MEF), identified in 30–60% of AOM cases worldwide [6], [7]. More than 90 distinct pneumococcal serotypes varying in capsular polysaccharide structure have been described. Most S. pneumoniae serotypes can cause serious disease [8]. Positive associations also exist with colonization of the upper respiratory tract by certain serotypes and their propensity to cause AOM [9], [10], [11]. In addition, temporal dynamics exist in the distribution of colonizing nasopharyngeal serotypes and their antimicrobial susceptibility profiles.

Data on serotypes causing AOM are important, but should not be the sole criteria to predict the potential impact of pneumococcal conjugate vaccination on AOM. Knowledge of causative serotypes should be coupled with incidence of pneumococcal AOM, immunogenicity, and efficacy of the vaccine to fully understand the burden of preventable AOM and to assess the potential impact of pneumococcal conjugate vaccination.

To fully comprehend the burden of preventable pneumococcal disease and to assess the potential impact of pneumococcal conjugate vaccination on AOM, this review examines the serotype distribution relationship between pneumococcal serotypes and AOM in children aged <18 years.