<i>Streptococcus pneumoniae</i> carriage and salivary antibodies induced by pneumococcus in Vilnius preschool children

Abstract

Background. Streptococcus pneumoniae (pneumococcus) is a potential respiratory pathogen causing high-risk diseases, particularly in young children. Otherwise, carriage of pneumococcus may be asymptomatic depending on the serotype and the immune system of the individual. The aim of this study was to determine nasopharyngeal carriage rates, serotype distribution and to evaluate the mucosal immune response to S. pneumoniae infection in healthy 2-7-year-old children attending day care centres in Vilnius, Lithuania.Materials and methods. Nasopharyngeal (n = 601) and saliva samples were collected randomly. A pneumotest kit (Statens Serum Institute, Denmark) was used for serogrouping / serotyping; the sandwich ELISA with a double monoclonal system was used for immunoglobulin concentration measurement.Results. Carriage rate in the children's population was 43%; from 33 serotypes found, the following six prevailed: 19F, 23F, 6B, 6A, 3 and 18C, which accounted for 58% of isolates. The carriage rates in children over four were found to be decreased. The concentrations of total and specific salivary antibodies of three isotypes (IgA, IgM and IgG) in carriers of six pneumococcal serotypes (3, 6B, 14, 18C, 19F and 23F) were measured.Conclusions. The carriage rates and prevalent serotypes of S. pneumoniae in healthy preschool Lithuanian children were similar as in the neighbouring states. The response of total and specific salivary antibodies was found to be serotypespecific. The pneumococcal carriage stimulated the production of not only specific antibodies, but also of total immunoglobulins of S-IgA, IgM and IgG isotypes.

Streptococcus pneumoniae nasopharyngeal colonisation in children aged under six years with acute respiratory tract infection in Lithuania, February 2012 to March 2013

“…The carriage rate seen was similar to those observed in healthy children in Estonia (44%), Czech Republic (38.1%) and Hungary (37.71%) [9,29,30]. It is also similar to those reported in healthy children in Vilnius in 2006 (43%) and slightly lower than that in 1999 and 2001 (51% and 55%, respectively) [26][27][28]. [32].…”

“…The prevalence of serotype 3 decreased from 13% in 1999 to 3% in our study, while serotype 14 became three times more common than in 2006 according to our data (3.2% and 9.5%, respectively). Serotype 15 constituted 9% of all isolated pneumococci in 1999; it was 2.5% in 2006 [26,27] and 10% in our study. The distribution of other SPn serotypes remained stable, with small differences in their rates.…”

“…Previously reported data on SPn colonisation show that serogroups 6, 19 and 23 were the most common before widespread use of PCV routine vaccination in other European countries such as Estonia, Poland, Italy, Hungary, Romania, France and the Netherlands [4,[7][8][9][10][11][12]. Serotypes 19F, 23F and 6B were also predominant among nasopharyngeal isolates in healthy Lithuanian children in 2006 [26,27].…”

“…Three studies of SPn nasopharyngeal carriage in healthy children have been performed in Lithuania (in 1999, 2001 and 2006) [26][27][28], in which a total of 1,625 children from the same 13 day-care centres were enrolled. On average, SPn was found in the nasopharynx of every second child (51% in 1999, 55% in 2001 and 43% in 2006) and the most prevalent serotypes were 19F, 23F, 6B, 6A, 3 and 18C.…”