Determination of Nasopharyngeal Carriage of Streptococcus pneumoniae and Response to the Pneumococcal Polysaccharide Vaccine in Children with Recurrent Infections

In asymptomatic patients, nasopharyngeal carriage of Streptococcus pneumoniae plays an important role in pneumococcal transmission and usually precedes invasive pneumococcal illness (IPD). The impact of nasopharyngeal pneumococcal carriage on pneumococcal vaccine antibody response has yet to be determined.

The goal of this study was to see how pneumococcal nasopharyngeal carriage affected the antibody response to the pneumococcal polysaccharide vaccine in a paediatric cohort.

Methods: Twenty paediatric patients with recurrent respiratory infections from a Santiago outpatient Immunology clinic participated in this prospective trial (Chile). All of the patients had previously undergone an immunological test. In a nasal and pharyngeal swab sample, the nasopharyngeal carriage of Streptococcus pneumoniae was studied, and bacteriological culture and serotyping for 10 pneumococcal serotypes were done. All children received a 23-valent pneumococcal polysaccharide vaccination (Pneumo-23®, Sanofi Pasteur) during their inclusion visit. Antibodies to 10 serotypes of pneumococcal anti-polysaccharide IgG class were detected in a blood sample at study enrollment, 45-60 days, and 12 months after immunisation. The groups were compared based on nasopharyngeal carriage and vaccination antibody response.

Ten patients (5 women, mean age 9, range 4-14 years) had nasopharyngeal carriage (group 1), while ten patients did not have the pneumococcus (group 2 control). S1 = 4, S5 = 3, S6B, S14, and S19A, one each, were the isolated serotypes (S). Before vaccination, there were no differences in IgG levels between the group with nasopharyngeal pneumococcus carriage and the group that did not have pneumococcus in any of the 10 serotypes tested. In the group with positive carriage of pneumococcus in nasopharyngeal secretion, specific IgG levels were substantially higher for S1 (p0.05), S5 (p0.05), and S9 (p0.02) at 45-60 days after vaccination, as well as for S1 (p0.05) and S5 (p0.05) at 12 months after vaccination, compared to group 2.

Conclusions: Nasopharyngeal carriage of Streptococcus pneumonia had no effect on the IgG antibody response generated by the 23-valent pneumococcal polysaccharide vaccination in this series of children older than 4 years with recurrent respiratory infections and no immunodeficiencies. Carriage was found in 50% of the patients, with S1 and S5 being the most common serotypes isolated. It’s possible that having these two serotypes increases the likelihood of a positive vaccination response.

Author(S) Details

Intty Leiva
Immunorheumatology Unit, Children´s Hospital Dr. Exequiel Gonzalez Cortes (HEGC), Santiago, Chile.

Jaime Inostroza
Clinical Laboratory, University of La Frontera, Jeffrey Modell Centre, Temuco, Chile.

Arnoldo Quezada
Department of Pediatrics School of Medicine, University of Chile, Santiago, Chile.

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