Upper respiratory tract colonization withStreptococcus pneumoniaein adults

Abstract

Introduction: Most of the current evidence regarding pneumococcal upper respiratory colonization in adults suggests that despite high disease burden, carriage prevalence is low. Contemporary studies on adult pneumococcal colonization have largely followed the pediatric approach by which samples are obtained mostly from the nasopharynx and bacterial detection is evaluated by routine culture alone. Recent evidence suggests that the "pediatric approach" may be insufficient in adults and pneumococcal detection in this population may be improved by longitudinal studies that include samples from additional respiratory sites combined with more extensive laboratory testing.Areas covered: In this article, relevant literature published in peer review journals on adult pneumococcal colonization, epidemiology, detection methods, and recommendations were reviewed. Expert opinion:Respiratory carriage of Streptococcus pneumoniae has been underestimated in adults. Contemporary pneumococcal carriage studies in adults that collect samples from alternative respiratory sites such as the oropharynx, saliva, or nasal wash; are culture-enriched for pneumococcus; and use molecular diagnostic methods designed to target two pneumococcal DNA sequences should enhance pneumococcal detection in the adult respiratory tract. This finding may have implications for the interpretation of dynamics of pneumococcal transmission and vaccination.

The epidemiologic and biologic basis for classifying older age as a high-risk, immunocompromising condition for pneumococcal vaccine policy

“…The frequency [91] and density [43] of pneumococcal colonization are reported to be reduced in older adults, despite the incidence of pneumococcal CAP and IPD being highest in older age groups. However, recent studies appear to have resolved this seeming paradox, specifically by finding carriage prevalence of older adults approaching that in children when using molecular techniques and testing reservoirs other than the nasopharynx, such as the oropharynx and saliva [53,91,92]. Studies of experimental pneumococcal colonization indicate that colonization can be established in healthy older adults, but it failed to confer serotype-specific immunity [82].…”

The Challenges of Using Oropharyngeal Samples To Measure Pneumococcal Carriage in Adults

“…Assays targeting the lytA and piaB genes were conducted as previously described ( 17 , 37 ). An assay for the GntR-type transcriptional regulator gene bguR ( 38 ) (TIGR4 NCBI reference sequence, NC_003028 ; locus tag, SP_RS10220; old locus tag, SP_2020), also referred to as SP2020 ( 19 , 29 ), used forward primer (5′-AGTTTGCCTGTAGTCGAATGA-3′), reverse primer (5′-TTTGAGCTGCCACGAGAG-3′) and the probe (5′-6-carboxyfluorescein [FAM]-AAACGTGGGCAGGGAACCTTTGTT-BHQ1-3′) concentrations of 300 nM, 100 nM, and 200 nM, respectively. No-template controls (blanks) were included in each qPCR run, and runs were balanced with approximately equal numbers of NP and OP samples.…”

“…Both studies concluded that sampling the oropharynx was superior to sampling the nasopharynx. A recent review examining studies of upper respiratory tract carriage of S. pneumoniae in adults, including those that utilized molecular methods, also encourages the sampling of other respiratory sites, such as OP and/or saliva, in addition to NP sampling ( 19 ).…”

Prophylactic inhibition of colonization by Streptococcus pneumoniae with the secondary bile acid metabolite deoxycholic acid

“…Streptococcus pneumoniae (Spn) colonizes millions worldwide yearly, with a colonization prevalence particularly high in children and the elderly (1)(2)(3). In children, the prevalence of pneumococcal carriage can be as high as 90% in those from developing countries, or between 25-40% in children from industrialized nations (1,(4)(5)(6)(7).…”