Pharyngeal Colonization by Streptococcus pneumoniae in Older Children and Adolescents in a Geographical Area Characterized by Relatively Limited Pneumococcal Vaccination Coverage

Abstract

These results show the absence of any long-term effect of PCV7 on colonization, and raise doubts concerning the recent suggestion to use carriage to evaluate the efficacy of PCVs. The high prevalence of carriers in all of the age groups independent of previous pneumococcal vaccination indicates that further studies are needed to evaluate whether the extensive use of PCVs in healthy older children and adolescents might reduce pharyngeal colonization of these subjects thereby increasing herd immunity.

Streptococcus pneumoniae oropharyngeal colonization in children and adolescents with cystic fibrosis

“…Both these findings were partially expected. A progressive reduction in pneumococcal colonization with an increase in age has been repeatedly demonstrated in healthy children [18,19]. This is explained by the maturation of the immune system and by the reduced role of factors such as day-care attendance that can significantly enhance the horizontal spread of pneumococcal strains among attendees.…”

Interaction between Streptococcus pneumoniae and Staphylococcus aureus in paediatric patients suffering from an underlying chronic disease

“…In this study, children who had received PCV7 several years before were colonised by the same serotypes included in the vaccine, and despite this vaccination, they were frequently colonised by S. aureus. The waning of immune protection against pneumococcal colonisation some years after the last vaccine dose has been already demonstrated in healthy children 35 and can be the cause of the persistence of carriage of PCV7 serotypes in the children enrolled in this study despite previous vaccination. Finally, with very few exceptions, S. aureus was not associated with any of the serotypes included in both PCV7 and PCV13, confirming that in this study S. pneumoniae and S aureus colonisation were completely independent.…”

“…34 However, these studies were carried out only a few months after vaccine use and the waning of vaccine-induced immunity with time could explain the finding, as already suggested by the data recently collected in healthy older children and adolescents. 35 On the other hand, this could be a problem because the waning of immunity against carriage could favour the development of diseases due to the initial elimination of the same serotypes and suggests the use of further booster vaccine doses to maintain protection. 33 Regarding S. aureus colonisation, it cannot be forgotten that, from a theoretical point of view, the presence of S. pneumoniae in the pharynx should reduce S. aureus carriage.…”

“…These findings are in contrast with those reported in healthy subjects who displayed a negative relationship between S. pneumoniae and S. aureus and a positive effect of PCV7 administration in conditioning S. aureus carriage. 35 The lack of a negative interaction between the two pathogens is difficult to explain. Bacterial colonisation with a single infectious agent depends on several factors.…”

Streptococcus pneumoniaepharyngeal colonization in school-age children and adolescents with cancer

“…A progressive reduction in pneumococcal colonization with increasing age is a common finding in otherwise healthy children. 19,20 This observation has been attributed to the continuous exposure to circulating pneumococcal serotypes that evokes a protective immunity and the reduced role of risk factors, which can significantly enhance the horizontal spread of pneumococcal strains. Moreover, the reduction of pneumococcal carriage in cancer patients who receive co-trimoxazole prophylaxis is consistent with previous findings that in Italy this antibiotic remains effective against more than 70% of pneumococcal strains, although its prolonged use is accompanied by a selection of resistant strains.…”