ABSTRACT
BACKGROUND: Natural immunity to Streptococcus pneumoniae is thought to be induced by exposure to S. pneumoniae or cross-reactive antigens. No longitudinal studies of carriage of and immune responses to S. pneumoniae have been conducted using sophisticated immunological laboratory techniques. METHODS: We enrolled 121 families with young children into this study. Nasopharyngeal (NP) swabs were collected monthly for 10 months from all family members and were cultured in a standard fashion. Cultured S. pneumoniae isolates were serotyped. At the beginning (month 0) and end (month 10) of the study, venous blood was collected from family members >18 years old. Serotype-specific antipolysaccharide immunoglobulin G (IgG) and functional antibody and antibodies to pneumolysin, pneumococcal surface protein A (PspA), and pneumococcal surface antigen A (PsaA) were measured in paired serum samples. RESULTS: Levels of anticapsular IgG increased significantly after carriage of serotypes 9V, 14, 18C, 19F, and 23F by an individual or family member. For serotype 14, a higher level of anticapsular IgG at the beginning of the study was associated with reduced odds of carriage (P = .006). There was a small (approximately 20%) but significant increase in titers of antibodies to PsaA and pneumolysin but no change in titers of antibody to PspA. CONCLUSIONS: Adults respond to NP carriage by mounting anticapsular and weak antiprotein antibody responses, and naturally induced anticapsular IgG can prevent carriage.
Subject(s)
Carrier State , Nasopharynx/microbiology , Pneumonia, Pneumococcal/transmission , Streptococcus pneumoniae/immunology , Adult , Antibody Formation , Child, Preschool , England , Family Characteristics , Humans , Longitudinal Studies , Pneumonia, Pneumococcal/epidemiology , Serotyping , Streptococcus pneumoniae/classification , Streptococcus pneumoniae/isolation & purificationABSTRACT
Vaccines have been instrumental in preventing childhood morbidity as well as mortality. It is imperative that health professionals have all the necessary information about a vaccine before its introduction into the routine immunisation schedule. This article looks at the possible introduction of a new pneumococcal conjugate vaccine and reviews a longitudinal carriage study of pneumococcus in UK families to determine pneumococcal carriage rates.
