Streptococcus pneumoniae in Saliva of Dutch Primary School Children

Abstract

While nasopharyngeal sampling is the gold standard for the detection of Streptococcus pneumoniae carriage, historically seen, saliva sampling also seems highly sensitive for pneumococcal detection. We investigated S. pneumoniae carriage in saliva from fifty schoolchildren by conventional and molecular methods. Saliva was first culture-enriched for pneumococci, after which, DNA was extracted from all bacterial growth and tested by quantitative-PCR (qPCR) for pneumococcus-specific genes lytA and piaA. Next, serotype composition of the samples was determined by serotype-specific qPCRs, conventional-PCRs (cPCR) and sequencing of cPCR amplicons. Although only 2 (4%) of 50 samples were positive by conventional diagnostic culture, 44 (88%) were positive for pneumococci by qPCR. In total, we detected the presence of at least 81 pneumococcal strains representing 20 serotypes in samples from 44 carriers with 23 carriers (52%) positive for multiple (up to 6) serotypes. The number of serotypes detected per sample correlated with pneumococcal abundance. This study shows that saliva could be used as a tool for future pneumococcal surveillance studies. Furthermore, high rates of pneumococcal carriage and co-carriage of multiple pneumococcal strains together with a large number of serotypes in circulation suggests a ubiquitous presence of S. pneumoniae in saliva of school-aged children. Our results also suggest that factors promoting pneumococcal carriage within individual hosts may weaken competitive interactions between S. pneumoniae strains.

Interaction between the nasal microbiota and S. pneumoniae in the context of live-attenuated influenza vaccine

“…In contrast, especially in individuals who failed to become colonized, we observed strong mucosal responses combined with increased microbiota profile changes following challenge were observed. This finding was in line with previous observations by our group, demonstrating that pneumococcal exposure not followed by colonization was still associated with augmented anti-protein immunoglobulin responses, suggesting induction of host immune Pre (69) Pre (26) All (105) Pep (50) All (33) Cor (52) Por (32) Vei (58) GM-CSF VEGF Pep (5) Dol (4) Fus (10) Hae (9) Mor (6) Act (22) Cor (3) Ana (11) Str (7) Non-carriers…”

“…Next, nasal washes were processed as described previously 28,29 . As per the study protocol, pneumococcal detection was performed using (1) conventional culture [28][29][30][31] and (2) qPCR targeting the pneumococcal lytA gene 32 . Nasal lining fluid samples (Nasosorption™, Hunt Developments) for Luminex analysis were collected and stored at −80°C as previously described 33 .…”

Pneumococcal Capsular Polysaccharide Immunity in the Elderly

“…For example, salivary PCR in children can suggest rates of colonization approaching 100% (24), but this has yet to be correlated with immunological endpoints, the incidence of clinical disease, or protection against future acquisition. False-positive PCR results from other oral streptococci are also a concern, although steps have been taken to increase the test specificity in recent studies.…”

Nasopharyngeal Colonization with Streptococcus pneumoniae

“…Colonization can occur with a single pneumococcal strain, although multiple studies have shown that carriage with more than one strain also occurs [51,52]. The duration of colonization in children is inversely related to age, with children under the age of 1 being colonized for longer than older children and adults [53,54].…”