Detection of Neisseria meningitidis in saliva and oropharyngeal samples from college students

Carriage of Neisseria meningitidis is an accepted endpoint in monitoring meningococcal vaccines effects. We have assessed N. meningitidis and vaccine-type genogroup carriage prevalence in college students at the time of MenACWY vaccine introduction in the Netherlands, and evaluated the feasibility of saliva sampling for the surveillance of carriage. For this, paired saliva and oropharyngeal samples collected from 299 students were cultured for meningococcus. The DNA extracted from all bacterial growth was subjected to qPCRs quantifying meningococcal and genogroup-specific genes presence. Samples negative by culture yet positive for qPCR were cultured again for meningococcus. Altogether 74 (25%) of students were identified as meningococcal carrier by any method. Sixty-one students (20%) were identified as carriers with qPCR. The difference between number of qPCR-positive oropharyngeal (n = 59) and saliva (n = 52) samples was not significant (McNemar’s test, p = 0.07). Meningococci were cultured from 72 students (24%), with a significantly higher (p < 0.001) number of oropharyngeal (n = 70) compared with saliva (n = 54) samples. The prevalence of genogroups A, B, C, W, and Y was none, 9%, 1%, 1% and 6%, respectively, and 8% of students carried MenACWY vaccine-type genogroup meningococci. Saliva is easy to collect and when combined with qPCR detection can be considered for meningococcal carriage studies.

‘B Part of It’ School Leaver study: a repeat cross-sectional study to assess the impact of increasing coverage with meningococcal B (4CMenB) vaccine on carriage of Neisseria meningitidis

Background Recombinant protein-based vaccines targeting serogroup B meningococci protect against invasive disease, but impacts on carriage are uncertain. This study assessed carriage prevalence of disease-associated meningococci from 2018-2020, as the proportion of vaccinated adolescents increased following introduction of a school-based 4CMenB immunisation program. Methods Eligible participants who completed high school (age 17-25) in South Australia in the previous year had an oropharyngeal swab taken and completed a risk factor questionnaire. Disease-associated meningococci (genogroups A, B, C, W, X, Y) were detected by meningococcal and genogroup-specific polymerase chain reaction. Results The final analysis included 4104 participants in 2018, 2690 in 2019, and 1338 in 2020. The proportion vaccinated with 4CMenB increased from 43% in 2018, to 78% in 2019, and 76% in 2020. Carriage prevalence of disease-associated meningococci in 2018 was 225/4104 (5.5%). There was little difference between the carriage prevalence in 2019 (134/2690, 5.0%, adjusted odds ratio [aOR] 0.82, 95% CI 0.64-1.05) and 2020 (68/1338, 5.1% aOR 0.82, 95% CI 0.57-1.17) compared to 2018. Conclusions Increased 4CMenB uptake in adolescents was not associated with a decline in carriage of disease-associated meningococci. 4CMenB immunisation programs should focus on direct (individual) protection for groups at greatest risk of disease.

89Factors associated with pneumococcal nasopharyngeal carriage: a systematic review

Background Pneumococcal disease is a major contributor to global childhood morbidity and mortality. Pneumococcal carriage is a prerequisite for pneumococcal disease. Identifying factors associated with pneumococcal carriage can aid public health intervention programs. It is unknown if risk factors for pneumococcal carriage differ between low, middle, and high-income countries. We present preliminary findings of our systematic review of factors associated with pneumococcal carriage in community settings, in all ages. Methods A systematic search for pneumococcal nasopharyngeal carriage studies, published in English before July 2019. Two researchers independently reviewed studies that described factors associated with pneumococcal nasopharyngeal carriage. Study quality was assessed using the NIH Study Quality Assessment Tools. Results are presented as narrative summaries due to heterogeneity amongst factor definitions. Results Preliminary results are shown. Sixty-seven studies were included. 49% were conducted in high-income countries. Pneumococcal prevalence ranged from 0.3%-97%, 2.6%-89.6%, 14%-73%, 1.6%-82.4% in low-, lower-middle, upper-middle, and high-income classifications. Age, respiratory tract infection symptoms, living with young children, poverty, exposure to smoke, and season were positively associated with pneumococcal carriage in all income classifications. Conclusions Pneumococcal carriage prevalence was highest in low-income classifications. Pneumococcal carriage is associated with similar factors across income classifications. Differences in prevalence of risk factors associated with pneumococcal carriage by income classification may contribute to differences in carriage prevalence by income classifications. Key messages Pneumococcal carriage is considered a prerequisite for pneumococcal disease. Pneumococcal carriage prevalence is highest in low-income countries, however preliminary results suggest risk factors for carriage may be similar across income classifications.

Pneumococcal exposure routes for infants: a nested cross-sectional survey in Nha Trang, Vietnam

Background: Infants are at highest risk of pneumococcal disease. Their added protection through herd effects is a key part in the considerations on optimal pneumococcal vaccination strategies. Yet, little is currently known about the main transmission pathways to this vulnerable age group. Methods and findings: We conducted a nested cross-sectional contact and nasopharyngeal swabbing survey in randomly selected infants across all 27 communes of Nha Trang, Vietnam. Bayesian logistic regression models were used to estimate age specific carriage prevalence in the population, a proxy for the probability that a contact of a given age could lead to pneumococcal exposure for the infant. We used another Bayesian logistic regression model to estimate the correlation between infant carriage and the probability that at least one of their reported contacts carried pneumococci, controlling for age and locality. In total 1583 infants between 4 and 13 months old participated, with 7428 contacts reported. Few infants (5%) attended day care and carriage prevalence was 22%. Most infants (61%) had less than a 25% probability to have had close contact with a pneumococcal carrier on the surveyed day. Pneumococcal infection risk and contact behaviour were highly correlated: if adjusted for age and locality the odds of an infant's carriage increased by 22% (95%CI:15-29) per 10 percentage points increase in the probability to have had close contact with at least one pneumococcal carrier. Two to six year old children contributed 51% (95%CI: 39-63) to the total pneumococcal exposure risks to infants in this setting. Conclusions: Cross-sectional contact and infection studies can help identify pneumococcal transmission routes. In Nha Trang, preschool age children are the largest reservoir for pneumococcal transmission to infants.

Colistin Sensitivity and Factor H-Binding Protein Expression among Commensal Neisseria Species

This study highlights the need for further work to accurately determine the pharyngeal carriage prevalence of Neisseria commensal bacteria (e.g., N. cinerea and N. polysaccharea ) among the general population. Previous studies have clearly demonstrated the suppressive effect these commensal species can have on meningococcal colonization, and so the carriage prevalence of these species could be an important factor in the spread of meningococci through the population.

Detection of Neisseria meningitidis in Saliva and Oropharyngeal Samples from College Students

Objectives: Since conjugated polysaccharide vaccines reduce carriage of vaccine-type Neisseria meningitidis strains, meningococcal carriage is an accepted endpoint in monitoring vaccine effects. We have assessed vaccine-type genogroup carriage prevalence in students at the time of MenACWY vaccine introduction in The Netherlands. In addition, we evaluated the feasibility of saliva sampling and qPCR-based detection method for the surveillance of meningococcal carriage. Methods: Paired saliva and oropharyngeal samples, collected from 299 students, were cultured for meningococcus. The DNA extracted from all bacterial growth was subjected to qPCRs quantifying meningococcal presence and genogroup-specific genes. Samples negative by culture yet positive for qPCR were cultured again for meningococcus. Results for saliva were compared with oropharyngeal samples. Results: Altogether 74 (25% of 299) students were identified as meningococcal carrier by any method used. Sixty-one students (20%) were identified as carriers with qPCR. The difference between number of qPCR-positive oropharyngeal (n=59) and saliva (n=52) samples was not significant (McNemars test, p=0.07). Meningococci were cultured from 72 students (24%), with a significantly higher (p<0.001) number of oropharyngeal (n=70) compared with saliva (n=54) samples. The prevalence of genogroups A, B, C, W, and Y was none, 9%, 1% and 6%, respectively, and 8% of students carried MenACWY vaccine-type genogroup meningococci. Conclusions: We show that the detected prevalence of meningococcal carriage between oropharyngeal and saliva samples was nondifferent with qPCR and moreover, detection with both samples was highly concordant. Saliva is easy to collect and when combined with qPCR detection can be considered for meningococcal carriage studies.

A pragmatic health centre-based evaluation comparing the effectiveness of a PCV13 schedule change from 3+0 to 2+1 in a high pneumococcal carriage and disease burden setting in Malawi: a study protocol

IntroductionStreptococcus pneumoniae (the pneumococcus) is commonly carried as a commensal bacterium in the nasopharynx but can cause life-threatening disease. Transmission occurs by human respiratory droplets and interruption of this process provides herd immunity. A 2017 WHO Consultation on Optimisation of pneumococcal conjugate vaccines (PCV) Impact highlighted a substantial research gap in investigating why the impact of PCV vaccines in low-income countries has been lower than expected. Malawi introduced the 13-valent PCV (PCV13) into the national Expanded Programme of Immunisations in 2011, using a 3+0 (3 primary +0 booster doses) schedule. With evidence of greater impact of a 2+1 (2 primary +1 booster dose) schedule in other settings, including South Africa, Malawi’s National Immunisations Technical Advisory Group is seeking evidence of adequate superiority of a 2+1 schedule to inform vaccine policy.MethodsA pragmatic health centre-based evaluation comparing impact of a PCV13 schedule change from 3+0 to 2+1 in Blantyre district, Malawi. Twenty government health centres will be randomly selected, with ten implementing a 2+1 and 10 to continue with the 3+0 schedule. Health centres implementing 3+0 will serve as the direct comparator in evaluating 2+1 providing superior direct and indirect protection against pneumococcal carriage. Pneumococcal carriage surveys will evaluate carriage prevalence among children 15–24 months, randomised at household level, and schoolgoers 5–10 years of age, randomly selected from school registers. Carriage surveys will be conducted 18 and 33 months following 2+1 implementation.AnalysisThe primary endpoint is powered to detect an effect size of 50% reduction in vaccine serotype (VT) carriage among vaccinated children 15–24 months old, expecting a 14% and 7% VT carriage prevalence in the 3+0 and 2+1 arms, respectively.Ethics and disseminationThe study has been approved by the Malawi College of Medicine Research Ethics Committee (COMREC; Ref: P05.19.2680), the University College London Research Ethics Committee (Ref: 8603.002) and the University of Liverpool Research Ethics Committee (Ref: 5439). The results from this study will be actively disseminated through manuscript publications and conference presentations.Trial registration numberNCT04078997.

Approach to Identifying Causative Pathogens of Community-Acquired Pneumonia in Children Using Culture, Molecular, and Serology Tests

Determining the causative pathogen(s) of community-acquired pneumonia (CAP) in children remains a challenge despite advances in diagnostic methods. Currently available guidelines generally recommend empiric antimicrobial therapy when the specific etiology is unknown. However, shifts in epidemiology, emergence of new pathogens, and increasing antimicrobial resistance underscore the importance of identifying causative pathogen(s). Although viral CAP among children is increasingly recognized, distinguishing viral from bacterial etiologies remains difficult. Obtaining high quality samples from infected lung tissue is typically the limiting factor. Additionally, interpretation of results from routinely collected specimens (blood, sputum, and nasopharyngeal swabs) is complicated by bacterial colonization and prolonged shedding of incidental respiratory viruses. Using current literature on assessment of CAP causes in children, we developed an approach for identifying the most likely causative pathogen(s) using blood and sputum culture, polymerase chain reaction (PCR), and paired serology. Our proposed rules do not rely on carriage prevalence data from controls. We herein share our perspective in order to help clinicians and researchers classify and manage childhood pneumonia.

Circulating sex-steroids and Staphylococcus aureus nasal carriage in a general female population

Objective Staphylococcus aureus is a major human pathogen, and nasal carriers have an increased risk for infection and disease. The exploration of host determinants for nasal carriage is relevant to decrease infection burden. Former studies demonstrate lower carriage prevalence in women and among users of progestin-only contraceptives. The aim of this study was to investigate the possible associations between circulating sex-steroid hormones and nasal carriage of Staphylococcus aureus in a general population. Methods In the population-based sixth Tromsø study (2007-2008) nurses collected nasal swab samples from 724 women aged 30-87 not using any exogenous hormones, and 700 of the women had a repeated nasal swab taken (median interval 28 days). We analysed a panel of serum sex-steroids by Liquid Chromatography tandem Mass Spectrometry, and collected information about lifestyle, health and anthropometric measures. Multivariable logistic regression was used to study the association between circulating sex-steroids and Staphylococcus aureus carriage (one swab) and persistent carriage (two swabs), while adjusting for potential confounding factors. Women in luteal phase were excluded in the analysis of androgens. Results Staphylococcus aureus persistent nasal carriage prevalence was 22%. One standard deviation increase in testosterone and bioavailable testosterone was associated with lower odds of persistent nasal carriage, (OR=0.57; 95% CI=0.35-0.92 and OR=0.52, 95%CI=0.30-0.92), respectively. Analysis stratified by menopause gave similar findings. Persistent carriers had lower average levels of androstenedione and dehydroepiandrosterone, however not statistically significant. Conclusion This large population-based study supports that women with lower levels of circulating testosterone may have increased probability of Staphylococcus aureus persistent carriage.