High Levels of Detection of Nonpneumococcal Species of Streptococcus in Saliva from Adults in the United States

Hislop, Maikel S; Allicock, Orchid M; Thammavongsa, Darani A; Mbodj, Sidiya; Nelson, Allison; Shaw, Albert C.; Weinberger, Daniel M; Wyllie, Anne L.

doi:10.1128/spectrum.05207-22

Cited by 8 publications

(5 citation statements)

References 42 publications

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“…This was also observed when testing samples for SP2020 (Supplementary Figure 2). However, concordance between lytA and SP2020 was weaker, with high rates of samples positive for only one of these targets, indicating a reduced specificity of both the lytA 31 and SP2020 qPCR assays (Supplementary Figure 3) and as such, supported our reasoning to rely solely on piaB for determining sample positivity for pneumococcus. As expected for these carriers without pneumonia, none of the urine samples collected tested positive for pneumococcal antigens using either the UAD or the BinaxNOW® test.…”

Section: Population Characteristicssupporting

confidence: 58%

“…Moreover, we observed a high prevalence of non-pneumococcal Streptococci in our samples as evident through high rates of positivity in the lytA qPCR assay (see Supplementary Figure 2), while negative for piaB. 31 These Streptococci can have capsules that are identical to pneumococcal capsules in their structure, and whose capsular biosynthesis genes are nearly identical to pneumococcal genes. 44 Therefore, all qPCR assays were tested on a set of samples that were lytA positive and piaB negative (indicating presence of Streptococcus spp., but not pneumococcus) to determine the background rate of detection.…”

Section: Discussionmentioning

confidence: 61%

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Contact with young children is a major risk factor for pneumococcal colonization in older adults

Wyllie,

Yolda-Carr,

Hislop

et al. 2024

Preprint

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BackgroundImportant questions remain about the sources of transmission of pneumococcus to older adults in the community. This is a critical question for understanding the potential indirect effects of using pneumococcal conjugate vaccines (PCVs) in children and older adults. For non-institutionalized individuals, the most likely source of adult-to-adult transmission is in the household. The goal of this study was to characterize the dynamics and risk factors for acquisition of pneumococcus in older adults.MethodsWe designed a longitudinal study to sample adults >60 years of age living in the same household (New Haven, CT, USA), and without younger contacts residing in the household. Saliva samples and questionnaires regarding social behaviors and health status were obtained every 2 weeks for a period of 10 weeks. DNA extracted from culture-enriched saliva was tested using qPCR for pneumococcus genespiaBandlytA.ResultsAcross two study seasons (November 2020-August 2021, November 2021-September 2022), 121 individuals from 61 households were followed for 6 study visits; 62 individuals were enrolled in both seasons. Overall, 52/1088 (4.8%) samples tested positive for pneumococcus based onpiaB, with 27/121 (22.3%) individuals colonized on at least one time point. Several individuals were colonized at multiple timepoints including two individuals who were colonized throughout the 10-week sampling period; two others were colonized at 5 of 6 time points. In 5 instances, both members of the household were carriers in the same season, though not necessarily at the same time point. Pneumococcal carriage was substantially higher among individuals who had contact with children (10.0% vs 1.6%). Participants who reported recent contact with <5-year-olds and 5-9-year-olds had particularly elevated prevalence (13.8%; 14.1%, respectively).ConclusionsContact with young children was the most important factor that influenced pneumococcal acquisition rates. While there were several instances where both adult household members were colonized at the same time or at sequential visits, these individuals also both typically had contact with children.

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Section: Population Characteristicssupporting

confidence: 58%

Section: Discussionmentioning

confidence: 61%

Contact with young children is a major risk factor for pneumococcal colonization in older adults

Wyllie,

Yolda-Carr,

Hislop

et al. 2024

Preprint

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“…30,32 Therefore, to evaluate our sample processing methods for their impact on pneumococcal carriage detection and to exclude confounding from other streptococci, we limited our analyses to piaB. 19,30 Nonetheless, results obtained here, when testing the culture-enriched saliva samples using piaB, highly correlated with results obtained when targeting the lytA gene in the same culture-enriched saliva samples (see Supplementary Figure 2). However, a multiplex PCR assay of the key targets used for pneumococcal carriage detection could be further evaluated.…”

Section: Discussionmentioning

confidence: 63%

“…Oral samples have emerged as a promising sample type for the surveillance of respiratory pathogens. 30 For the detection of pneumococcus, the recommended approach for polymicrobial samples such as saliva, is to culture-enrich samples, preferably on blood agar plates supplemented with gentamicin and perform a qPCR on DNA extracted from the culture-enriched samples. 14 Deviating from this recommended approach could impact the sensitivity of detection, as culture-enrichment increases the pneumococcal load in the sample and the DNA extraction processes concentrates the DNA through its elution into a smaller volume compared to the input volume of saliva.…”

Section: Discussionmentioning

confidence: 99%

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A low-cost culture- and DNA extraction-free method for the molecular detection of pneumococcal carriage in saliva

Peno,

Lin,

Hislop

et al. 2023

Preprint

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BackgroundMolecular methods have improved the sensitivity of detection of pneumococcal carriage in saliva. However, they typically require sample culture-enrichment and nucleic acid extraction, prior to performing the detection assay. These factors may limit scalability for extensive surveillance of pneumococcus, particularly in low-resource settings. In this study, we evaluated the performance of a DNA-extraction-free method for the detection of pneumococcus in saliva.MethodsWe developed a streamlined qPCR-based protocol for the detection of pneumococcus, omitting culture-enrichment and DNA extraction. Using saliva samples collected from children attending childcare centers (New Haven, CT, USA), we evaluated detection of pneumococcus using saliva lysates as compared to purified DNA extracted from culture-enriched aliquots of the paired samples using qPCR targeting the pneumococcalpiaBgene.ResultsOf 759 saliva samples tested from 92 children (median age 3.65 years; IQR (2.46-4.78), pneumococcus was detected in 358 (47.2%) saliva lysates prepared using the extraction-free protocol and in 369 (48.6%) DNA extracted from the culture-enriched samples. We observed a near-perfect agreement between the two protocols (Cohen’s kappa: 0.92; 95%CI: 0.90-0.95). While we also observed a high correlation between the qPCR CTvalues generated by the two methods (r=0.93,p<0.0001), the CTvalues generated from the extraction-free, saliva lysates were higher (lower concentration) than those obtained from DNA extracted from culture-enriched samples (ΔCT= 6.68,p<0.00001).ConclusionsFor pneumococcal carriage surveillance in children, our findings suggest that a DNA extraction-free approach may offer a cost-effective alternative to the resource-intensive culture-enrichment method. While, as expected, we observed higher qPCR CTvalues (lower bacterial load) in the absence of culture-enrichment, the overall rate of detection remained unaffected.

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Contact with young children is a major risk factor for pneumococcal colonization in older adults

Wyllie,

Yolda-Carr,

Hislop

et al. 2024

FEMS Microbes

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Background Important questions remain about the sources of transmission of pneumococcus to older adults in the community. This is critical for understanding the potential effects of using pneumococcal conjugate vaccines (PCVs) in children and older adults. For non-institutionalized individuals, we hypothesized that the most likely source of adult-to-adult transmission is within the household. Methods We designed a longitudinal study to sample adults ≥60 years of age living in the same household (New Haven, CT, USA), without younger residents in the household. Saliva samples and social and health questionnaires were obtained every 2 weeks for a period of 10 weeks. DNA extracted from culture-enriched saliva was tested using qPCR for pneumococcus genes piaB, lytA, and serotype. Results Across two study seasons (November 2020-August 2021, November 2021-September 2022), 121 individuals from 61 households completed all 6 visits; 62 individuals were enrolled in both seasons. Overall, 52/1088 (4.8%) samples tested positive for pneumococcus, with 27/121 (22.3%) individuals colonized at least once. Several individuals were colonized at multiple timepoints; two individuals were colonized at 5/6 time points and two at all six. In 5 instances, both household members were carriers in the same season, though not necessarily at the same time. Pneumococcal carriage was substantially higher among individuals who had contact with children (10.0% vs 1.6%). Conclusions Contact with young children was the most important factor that influenced pneumococcal acquisition rates. While there were several instances where both adult household members were colonized at the same time or at sequential visits, these individuals typically had contact with children. As such, PCV immunization can directly protect older adults who have contact with children.

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High Levels of Detection of Nonpneumococcal Species of Streptococcus in Saliva from Adults in the United States

Cited by 8 publications

References 42 publications

Contact with young children is a major risk factor for pneumococcal colonization in older adults

Contact with young children is a major risk factor for pneumococcal colonization in older adults

A low-cost culture- and DNA extraction-free method for the molecular detection of pneumococcal carriage in saliva

Contact with young children is a major risk factor for pneumococcal colonization in older adults

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