Nasopharyngeal carriage of individual Streptococcus pneumoniae serotypes during pediatric pneumonia as a means to estimate serotype disease potential

Interactions between respiratory syncytial virus and Streptococcus pneumoniae in the pathogenesis of childhood respiratory infections: a systematic review

Lower respiratory tract infections, commonly caused by respiratory syncytial virus (RSV) or Streptococcus pneumoniae (pneumococcus), pose a substantial global health burden, especially in children younger than 5 years of age. A deeper understanding of the relationship between RSV and pneumococcus would aid the development of health-care approaches to disease prevention and management. We completed a systematic review to identify and assess evidence pertaining to the relationship between RSV and pneumococcus in the pathogenesis of childhood respiratory infections. We found mechanistic evidence for direct pathogen-pathogen interactions and for indirect interactions involving host modulation. We found a strong seasonal epidemiological association between these two pathogens, which was recently confirmed by a parallel decrease and a subsequent resurgence of both RSV and pneumococcus-associated disease during the COVID-19 pandemic. Importantly, we found that pneumococcal vaccination was associated with reduced RSV hospitalisations in infants, further supporting the relevance of their interaction in modulating severe disease. Overall evidence supports a broad biological and clinical interaction between pneumococcus and RSV in the pathogenesis of childhood respiratory infections. We hypothesise that the implementation of next-generation pneumococcal and RSV vaccines and monoclonal antibodies targeting RSV will act synergistically to reduce global morbidity and mortality related to childhood respiratory infections.

Pneumococcal colonization and severity of pneumonia in hospitalized Cambodian children following introduction of the 13-valent pneumococcal conjugate vaccine

Objectives

This study sought to characterize pneumococcal colonization and clinical/radiological features in Cambodian children admitted to hospital with an illness compatible with pneumonia following national introduction of the 13-valent pneumococcal conjugate vaccine (PCV13).

Methods

Children aged 0-59 months admitted to Angkor Hospital for Children who met the World Health Organization (WHO) case definition for clinical pneumonia were enrolled over a 3-year period. Clinical, radiological and vaccination data were collected at enrolment. A nasopharyngeal swab was collected for detection of pneumococcal colonization using the WHO standard culture method.

Results

Between 1 September 2015 and 31August 2018, 2209 analysable illness episodes were enrolled. Pneumococci were detected in 943/2209 (42.7%) children. PCV13 serotypes were detected less frequently in children who had been vaccinated appropriately for their age compared with undervaccinated children: 309/567 (53.6%) vs 216/342 (63.2%) (P=0.006). Age-appropriate PCV13 vaccination was negatively associated with hypoxic presentation [adjusted odds ratio (aOR) 0.72, 95% confidence interval (CI) 0.60-0.87; P=0.0006] and primary endpoint pneumonia on chest x ray (aOR 0.69, 95% CI 0.54-0.90; P=0.006).

Conclusions

The introduction of PCV13 in Cambodia was associated with a decline in vaccine serotype nasopharyngeal colonization, and clinical and radiological severity in children hospitalized with clinical pneumonia.

Pneumococcal concentration and serotype distribution in preschool children with radiologically confirmed pneumonia compared to healthy controls prior to introduction of pneumococcal vaccination in Zanzibar: an observational study

BACKGROUND

The World Health Organization recommends pneumococcal vaccination (PCV) in the first year of life. We investigated pneumococcal serotypes in children with clinical or radiologically confirmed pneumonia and healthy controls prior to PCV13 vaccine introduction in Zanzibar.

METHODS

Children (n = 677) with non-severe acute febrile illness aged 2-59 months presenting to a health centre in Zanzibar, Tanzania April-July 2011 were included. Nasopharyngeal swabs collected at enrolment were analysed by real-time PCR to detect and quantify pneumococcal serotypes in patients (n = 648) and in healthy asymptomatic community controls (n = 161). Children with clinical signs of pneumonia according to the Integrated Management of Childhood illness guidelines ("IMCI pneumonia") were subjected to a chest-X-ray. Consolidation on chest X-ray was considered "radiological pneumonia".

RESULTS

Pneumococcal DNA was detected in the nasopharynx of 562/809 (69%) children (70% in patients and 64% in healthy controls), with no significant difference in proportions between patients with or without presence of fever, malnutrition, IMCI pneumonia or radiological pneumonia. The mean pneumococcal concentration was similar in children with and without radiological pneumonia (Ct value 26.3 versus 27.0, respectively, p = 0.3115). At least one serotype could be determined in 423 (75%) participants positive for pneumococci of which 33% had multiple serotypes detected. A total of 23 different serotypes were identified. One serotype (19F) was more common in children with fever (86/648, 13%) than in healthy controls (12/161, 7%), (p = 0.043). Logistic regression adjusting for age and gender showed that serotype 9A/V [aOR = 10.9 (CI 2.0-60.0, p = 0.006)] and 14 [aOR = 3.9 (CI 1.4-11.0, p = 0.012)] were associated with radiological pneumonia. The serotypes included in the PCV13 vaccine were found in 376 (89%) of the 423 serotype positive participants.

CONCLUSION

The PCV13 vaccine introduced in 2012 targets a great majority of the identified serotypes. Infections with multiple serotypes are common. PCR-determined concentrations of pneumococci in nasopharynx were not associated with radiologically confirmed pneumonia. Trial registration Clinicaltrials.gov (NCT01094431).

Decline in Pneumococcal Disease in Young Children During the Coronavirus Disease 2019 (COVID-19) Pandemic in Israel Associated With Suppression of Seasonal Respiratory Viruses, Despite Persistent Pneumococcal Carriage: A Prospective Cohort Study

BACKGROUND

The incidence of invasive pneumococcal disease (IPD) declined during the COVID-19 pandemic. Previous studies hypothesized that this was due to reduced pneumococcal transmission resulting from nonpharmaceutical interventions. We used multiple ongoing cohort surveillance projects in children <5 years to test this hypothesis.

METHODS

The first SARS-CoV-2 cases were detected in February 2020, resulting in a full lockdown, followed by several partial restrictions. Data from ongoing surveillance projects captured the incidence dynamics of community-acquired alveolar pneumonia (CAAP), nonalveolar lower respiratory infections necessitating chest X-rays (NA-LRIs), nasopharyngeal pneumococcal carriage in nonrespiratory visits, nasopharyngeal respiratory virus detection (by polymerase chain reaction), and nationwide IPD. Monthly rates (January 2020 through February 2021 vs mean monthly rates 2016-2019 [expected rates]) adjusted for age and ethnicity were compared.

RESULTS

CAAP and bacteremic pneumococcal pneumonia were strongly reduced (incidence rate ratios [IRRs]: .07 and .19, respectively); NA-LRIs and nonpneumonia IPD were also reduced by a lesser magnitude (IRRs: .46 and .42, respectively). In contrast, pneumococcal carriage prevalence was only slightly reduced, and density of colonization and pneumococcal serotype distributions were similar to previous years. The decline in pneumococcus-associated disease was temporally associated with a full suppression of respiratory syncytial virus, influenza viruses, and human metapneumovirus, often implicated as co-pathogens with pneumococcus. In contrast, adenovirus, rhinovirus, and parainfluenza activities were within or above expected levels.

CONCLUSIONS

Reductions in pneumococcal and pneumococcus-associated diseases occurring during the COVID-19 pandemic in Israel were not predominantly related to reduced pneumococcal carriage and density but were strongly associated with the disappearance of specific respiratory viruses.

Decline in pneumococcal nasopharyngeal carriage in children 6-23 months with respiratory illnesses following pneumococcal conjugate vaccine implementation

BACKGROUND

Following pneumococcal conjugate vaccines (PCVs) implementation, worldwide, pneumococcal carriage rates remained stable, indicating full replacement of vaccine-serotypes (VT) with non-VT. However, data are scarce regarding PCV impact on pneumococcal carriage rates in healthy vs. sick children. We assessed pneumococcal carriage rates dynamics in healthy and sick children 6-23 months, following PCV introduction.

METHODS

This is a prospective, population-based surveillance conducted during the years 2009-2017, in southern Israel. Three groups were defined as follows: Children without respiratory infection signs (the healthy/non-respiratory group); Children who had a chest radiography at the hospital (the Hosp-CXR group); and children with community-acquired alveolar pneumonia (CAAP). Rate ratios (RRs; 95% CI) were calculated, comparing between late-13-valent PCV (PCV13) period (2016-2017) and early-PCV period (2009-2010). Rate ratios were adjusted for antibiotic administration, seasonality and ethnicity, and separate calculations were performed for 6-11 and 12-23 month old children.

RESULTS

Overall, 51% of 8627 nasopharyngeal cultures were positive. In 2009-2010 (early-PCV period), the overall carriage rate was 55%; serotypes included in the PCV13 carriage rates were 28%, 31% and 38% in the healthy/non-respiratory, Hosp-CXR, and CAAP groups, respectively. Overall carriage rates in healthy/non-respiratory episodes were stable (~54%) when comparing between 2016 and 17 and 2009-10 (RR = 0.98; 0.84-1.15). In contrast, rates significantly declined for Hosp-CXR (RR = 0.78; 0.63-0.98) and CAAP (RR = 0.65; 0.47-0.89). These trends were driven by ~ 80% VT reductions, coupled with non-VT increase.

CONCLUSIONS

Following 7-valent PCV/ PCV13 introduction, pneumococcal carriage rates declined in respiratory diseases, but not in healthy children and children without respiratory infections. These trends suggest that a reduction in pneumococcal carriage rates during respiratory infections indicates a decline in respiratory infections caused by VT, while carriage rates in non-respiratory cases reflect non-VT predominance, that have low disease potential for respiratory disease.

Serotypes of Streptococcus pneumoniae in Children Aged <5 Years Hospitalized With or Without Pneumonia in Developing and Emerging Countries: A Descriptive, Multicenter Study

BACKGROUND

Improving knowledge regarding Streptococcus pneumoniae distribution in pneumonia cases is important to better target preventive and curative measures. The objective was to describe S. pneumoniae serotypes in children with or without pneumonia.

METHODS

It was a case-control study carried out in 8 developing and emerging countries between 2010 and 2014. Cases were children aged <5 years admitted to the hospital for pneumonia. Controls were children admitted for surgery or routine outpatient care.

RESULTS

In nasopharyngeal samples, S. pneumoniae were detected in 68.2% of the cases and 47.5% of the controls (P < .001). Nasopharyngeal carriage was associated with a higher risk of being a case in 6/8 study sites (adjusted odds ratio ranged from 0.71 [95% confidence interval [CI], .39-1.29; P = .26] in India [Pune/Vadu] to 11.86 [95% CI, 5.77-24.41; P < .001] in Mongolia). The 13-valent pneumococcal conjugate vaccine (PCV13) serotypes were more frequently detected in cases with nasopharyngeal carriage (67.1%) than in controls with nasopharyngeal carriage (54.6%), P < .001. Streptococcus pneumoniae was detected in blood by polymerase chain reaction in 8.3% of the cases. Of 34 cases with an S. pneumoniae serotype detected in blood, 27 (79%) had the same serotype in the nasopharyngeal sample.

CONCLUSIONS

The results confirm the assumption that the isolate carrying or causing disease in an individual is of the same serotype. Most serotypes independently associated with nasopharyngeal carriage or pneumonia are covered by PCV13, suggesting that increased PCV coverage would reduce the burden of S. pneumoniae-related pneumonia.

Pneumococcal nasopharyngeal carriage among Bhutanese children hospitalized with clinical pneumonia: serotypes and viral co-infection

BACKGROUND

Pneumococcal nasopharyngeal colonization (PNC) generally precedes pneumococcal disease. The purpose of this study was to determine the prevalence of PNC and to identify the pneumococcal serotypes circulating among Bhutanese children under five years of age admitted with clinical pneumonia, before the introduction of pneumococcal conjugate vaccine (PCV13) in the country. We also aimed to contribute to the understanding of the interplay between PNC and viral co-infection among this population.

METHODS

This was a prospective study conducted at the Jigme Dorji Wangchuck National Referral Hospital in Bhutan over 12 consecutive months. Children aged 2 to 59 months admitted with WHO-defined clinical pneumonia were eligible for recruitment. We collected blood for bacterial culture and molecular identification of S. pneumoniae, and nasopharyngeal washing for screening of respiratory viruses, and for the detection and capsular typing of S. pneumoniae by real-time polymerase chain reaction (RT-PCR).

RESULTS

Overall, 189 children were recruited, and PNC was tested in 121 of them (64.0%). PNC was found in 76/121 children (62.8%) and S. pneumoniae was identified in blood (both by culture and RT-PCR) in a single child. Respiratory viruses were detected in a similar proportion among children with (62/70; 88.6%) and without PNC (36/40; 90.0%; p = 1.000), but rhinovirus detection was less common among children with PNC (20/70; 28.6% versus 19/40; 47.5%; p = 0.046). Capsular typing identified 30 different serotypes. Thirty-nine children (51.3%) were colonised with two to five different serotypes. A third of the children presented with serotypes considered highly invasive. Over half of the children (44/76; 57.9%) were carrying at least one serotype included in PCV13.

CONCLUSIONS

This study provides baseline information on the status of PNC among Bhutanese children admitted with clinical pneumonia prior to the introduction of PCV13, which is valuable to monitor its potential impact. PCV13 could theoretically have averted up to 58% of the pneumococcal infections among the children in this study, suggesting a future role for the vaccine to significantly reduce the burden associated with S. pneumoniae in Bhutan.

Unique Features of Hospitalized Children with Alveolar Pneumonia Suggest Frequent Viral-Bacterial Coinfections

BACKGROUND

The World Health Organization Pneumonia Expert Group (WHO-PEG) defined a standardized radiologic endpoint for childhood community-acquired alveolar pneumonia (RD-CAAP), as the most likely to be pneumococcal, not ruling out other bacteria or coinfecting viruses. We aimed to determine the characteristics associated with hospitalization among children <5 years old presenting to the pediatric emergency room (PER) with RD-CAAP.

METHODS

This study was a part of an ongoing prospective population-based surveillance on hospital visits for RD-CAAP. RD-CAAP was determined according to the WHO-PEG. The study was conducted in the prepneumococcal conjugate vaccine era (2004-2008).

RESULTS

Of 24,432 episodes with chest radiographs, 3871)15.8%) were RD-CAAP: 2319 required hospitalization and 1552 were discharged (outpatients). Compared with outpatients, hospitalized children had lower temperature, peripheral white cell and absolute neutrophil counts and C reactive protein serum levels, but higher rates of hypoxemia, rhinorrhea, cough and respiratory virus detection. PER visits during the respiratory virus season presented a 1.83 times higher risk of hospitalization than visits during nonrespiratory season.

CONCLUSIONS

Although RD-CAAP is most often a bacterial infection, the unique characteristics of those visiting the PER and subsequently hospitalized suggest a frequent involvement of respiratory viruses, potentially as viral-bacterial coinfections, compared with outpatients.

Understanding the Evolution of Antibiotic-nonsusceptible Pneumococcal Nasopharyngeal Colonization Following Pneumococcal Conjugate Vaccine Implementation in Young Children

BACKGROUND

Four main processes determine pneumococcal conjugate vaccine (PCV) antibiotic-nonsusceptible Streptococcus pneumoniae (ANSP) carriage: reduction of PCV serotypes, increase of non-PCV serotypes, potential overall reduction in carriage, and within-serotype nonsusceptibility resulting from continuous antibiotic pressure. The post-PCV implementation dynamics of these components were examined in young children from 2 distinct ethnic populations: Jewish and Bedouin.

METHODS

We performed ongoing, prospective, population-based, active surveillance initiated at the time of 7- and 13-valent PCVs (PCV7; PCV13) implementation. Nasopharyngeal cultures for S. pneumoniae were obtained daily from children aged <5 years who visited the only pediatric emergency room in the district during a 6-year period (2009 to 2015).

RESULTS

Of 8446 nasopharyngeal samples, 48.3% were positive (42.0% and 52.8% for Jewish and Bedouin children, respectively; P < .001). Nonsusceptibility was significantly more frequent among PCV serotypes than among non-PCV serotypes and among Bedouin children than among Jewish children. PCV serotype carriage declined by 80%, while that of non-PCV serotypes increased by 140%. The overall (all serotypes) pneumococcal carriage significantly declined (33% and 11% in Bedouin and Jewish children, respectively). Among non-PCV isolates, the proportion of ANSP significantly increased with time in both populations. As a summation of all 4 processes, ANSP carriage significantly decreased among both Bedouin and Jewish children.

CONCLUSIONS

PCV impact on ANSP nasopharyngeal carriage is a dynamic, multicomponent process, highly dependent on antibiotic consumption in the community, which may result in a continuous increase in antibiotic resistance in the replacing serotypes.

Pneumococcal colonization prevalence and density among Thai children with severe pneumonia and community controls

Background

Pneumococcal colonization prevalence and colonization density, which has been associated with invasive disease, can offer insight into local pneumococcal ecology and help inform vaccine policy discussions.

Methods

The Pneumonia Etiology Research for Child Health Project (PERCH), a multi-country case-control study, evaluated the etiology of hospitalized cases of severe and very severe pneumonia among children aged 1–59 months. The PERCH Thailand site enrolled children during January 2012–February 2014. We determined pneumococcal colonization prevalence and density, and serotype distribution of colonizing isolates.

Results

We enrolled 224 severe/very severe pneumonia cases and 659 community controls in Thailand. Compared to controls, cases had lower colonization prevalence (54.5% vs. 62.5%, p = 0.12) and lower median colonization density (42.1 vs. 210.2 x 10³ copies/mL, p <0.0001); 42% of cases had documented antibiotic pretreatment vs. 0.8% of controls. In no sub-group of assessed cases did pneumococcal colonization density exceed the median for controls, including cases with no prior antibiotics (63.9x10³ copies/mL), with consolidation on chest x-ray (76.5x10³ copies/mL) or with pneumococcus detected in whole blood by PCR (9.3x10³ copies/mL). Serotype distribution was similar among cases and controls, and a high percentage of colonizing isolates from cases and controls were serotypes included in PCV10 (70.0% and 61.8%, respectively) and PCV13 (76.7% and 67.9%, respectively).

Conclusions

Pneumococcal colonization is common among children aged <5 years in Thailand. However, colonization density was not higher among children with severe pneumonia compared to controls. These results can inform discussions about PCV introduction and provide baseline data to monitor PCV impact after introduction in Thailand.

Insights into pneumococcal pneumonia using lung aspirates and nasopharyngeal swabs collected from pneumonia patients in The Gambia

Background

We investigated the pathogenesis of pneumococcal pneumonia using clinical specimens collected for pneumonia surveillance in The Gambia.

Methods

Lung aspirates and nasopharyngeal swabs from 31 patients were examined by culture, quantitative polymerase chain reaction (qPCR), whole genome sequencing, serotyping, and reverse-transcription qPCR.

Results

Five lung aspirates cultured pneumococci, with a matching strain identified in the nasopharynx. Three virulence genes including ply (pneumolysin) were upregulated >20-fold in the lung compared with the nasopharynx. Nasopharyngeal pneumococcal density was higher in pediatric pneumonia patients compared with controls (P < .0001).

Conclusions

Findings suggest that changes in pneumococcal gene expression occurring in the lung environment may be important in pathogenesis.

Impact of 13-Valent Pneumococcal Conjugate Vaccine on Colonization and Invasive Disease in Cambodian Children

BACKGROUND

Cambodia introduced the 13-valent pneumococcal conjugate vaccine (PCV13) in January 2015 using a 3 + 0 dosing schedule and no catch-up campaign. We investigated the effects of this introduction on pneumococcal colonization and invasive disease in children aged <5 years.

METHODS

There were 6 colonization surveys done between January 2014 and January 2018 in children attending the outpatient department of a nongovernmental pediatric hospital in Siem Reap. Nasopharyngeal swabs were analyzed by phenotypic and genotypic methods to detect pneumococcal serotypes and antimicrobial resistance. Invasive pneumococcal disease (IPD) data for January 2012-December 2018 were retrieved from hospital databases. Pre-PCV IPD data and pre-/post-PCV colonization data were modelled to estimate vaccine effectiveness (VE).

RESULTS

Comparing 2014 with 2016-2018, and using adjusted prevalence ratios, VE estimates for colonization were 16.6% (95% confidence interval [CI] 10.6-21.8) for all pneumococci and 39.2% (95% CI 26.7-46.1) for vaccine serotype (VT) pneumococci. There was a 26.0% (95% CI 17.7-33.0) decrease in multidrug-resistant pneumococcal colonization. The IPD incidence was estimated to have declined by 26.4% (95% CI 14.4-35.8) by 2018, with a decrease of 36.3% (95% CI 23.8-46.9) for VT IPD and an increase of 101.4% (95% CI 62.0-145.4) for non-VT IPD.

CONCLUSIONS

Following PCV13 introduction into the Cambodian immunization schedule, there have been declines in VT pneumococcal colonization and disease in children aged <5 years. Modelling of dominant serotype colonization data produced plausible VE estimates.

Nasal Pneumococcal Density Is Associated with Microaspiration and Heightened Human Alveolar Macrophage Responsiveness to Bacterial Pathogens

Rationale: Pneumococcal pneumonia remains a global health problem. Colonization of the nasopharynx with Streptococcus pneumoniae (Spn), although a prerequisite of infection, is the main source of exposure and immunological boosting in children and adults. However, our knowledge of how nasal colonization impacts on the lung cells, especially on the predominant alveolar macrophage (AM) population, is limited.Objectives: Using a controlled human infection model to achieve nasal colonization with 6B serotype, we investigated the effect of Spn colonization on lung cells.Methods: We collected BAL from healthy pneumococcal-challenged participants aged 18-49 years. Confocal microscopy and molecular and classical microbiology were used to investigate microaspiration and pneumococcal presence in the lower airways. AM opsonophagocytic capacity was assessed by functional assays in vitro, whereas flow cytometry and transcriptomic analysis were used to assess further changes on the lung cellular populations.Measurements and Main Results: AMs from Spn-colonized individuals exhibited increased opsonophagocytosis to pneumococcus (11.4% median increase) for approximately 3 months after experimental pneumococcal colonization. AMs also had increased responses against other bacterial pathogens. Pneumococcal DNA detected in the BAL samples of Spn-colonized individuals were positively correlated with nasal pneumococcal density (r = 0.71; P = 0.029). Similarly, AM-heightened opsonophagocytic capacity was correlated with nasopharyngeal pneumococcal density (r = 0.61, P = 0.025).Conclusions: Our findings demonstrate that nasal colonization with pneumococcus and microaspiration prime AMs, leading to brisker responsiveness to both pneumococcus and unrelated bacterial pathogens. The relative abundance of AMs in the alveolar spaces, alongside their potential for nonspecific protection, render them an attractive target for novel vaccines.

Assessment of an Antibody-in-Lymphocyte Supernatant Assay for the Etiological Diagnosis of Pneumococcal Pneumonia in Children

New diagnostic tests for the etiology of childhood pneumonia are needed. We evaluated the antibody-in-lymphocyte supernatant (ALS) assay to detect immunoglobulin (Ig) G secretion from ex vivo peripheral blood mononuclear cell (PBMC) culture, as a potential diagnostic test for pneumococcal pneumonia. We enrolled 348 children with pneumonia admitted to Patan Hospital, Kathmandu, Nepal between December 2015 and September 2016. PBMCs sampled from participants were incubated for 48 h before harvesting of cell culture supernatant (ALS). We used a fluorescence-based multiplexed immunoassay to measure the concentration of IgG in ALS against five conserved pneumococcal protein antigens. Of children with pneumonia, 68 had a confirmed etiological diagnosis: 12 children had pneumococcal pneumonia (defined as blood or pleural fluid culture-confirmed; or plasma CRP concentration ≥60 mg/l and nasopharyngeal carriage of serotype 1 pneumococci), and 56 children had non-pneumococcal pneumonia. Children with non-pneumococcal pneumonia had either a bacterial pathogen isolated from blood (six children); or C-reactive protein <60 mg/l, absence of radiographic consolidation and detection of a pathogenic virus by multiplex PCR (respiratory syncytial virus, influenza viruses, or parainfluenza viruses; 23 children). Concentrations of ALS IgG to all five pneumococcal proteins were significantly higher in children with pneumococcal pneumonia than in children with non-pneumococcal pneumonia. The concentration of IgG in ALS to the best-performing antigen discriminated between children with pneumococcal and non-pneumococcal pneumonia with a sensitivity of 1.0 (95% CI 0.73-1.0), specificity of 0.66 (95% CI 0.52-0.78) and area under the receiver-operating characteristic curve (AUROCC) 0.85 (95% CI 0.75-0.94). Children with pneumococcal pneumonia were older than children with non-pneumococcal pneumonia (median 5.6 and 2.0 years, respectively, p < 0.001). When the analysis was limited to children ≥2 years of age, assay of IgG ALS to pneumococcal proteins was unable to discriminate between children with pneumococcal pneumonia and non-pneumococcal pneumonia (AUROCC 0.67, 95% CI 0.47-0.88). This method detected spontaneous secretion of IgG to pneumococcal protein antigens from cultured PBMCs. However, when stratified by age group, assay of IgG in ALS to pneumococcal proteins showed limited utility as a test to discriminate between pneumococcal and non-pneumococcal pneumonia in children.

Nasopharyngeal Carriage of Invasive Pneumococcal Serotypes During Childhood Community-Acquired Alveolar Pneumonia Is Associated With Specific Clinical Presentation

Background

Streptococcus pneumoniae (Pnc) serotypes differ in invasive potential. We examined whether community-acquired alveolar pneumonia (CAAP) in children carrying commonly recognized pneumonia invasive pneumococcal serotypes ([PnIST] 1, 5, 7F, 14, and 19A) differs from CAAP in children carrying less invasive serotypes (non-PnIST) or no Pnc (Pnc-neg).

Methods

Children <5 years, visiting the only regional Pediatric Emergency Room, with radiologically proven CAAP were enrolled. Nasopharyngeal cultures were processed for pneumococcal isolation and serotyping. Clinical and demographic characteristics were recorded. The study was conducted before pneumococcal conjugate vaccine implementation in Israel.

Results

A total of 1423 CAAP episodes were recorded: PnIST, 300 (21.1%); non-PnIST, 591 (41.5%); and Pnc-neg, 532 (37.4%). After adjustment for age, ethnicity, seasonality, and previous antibiotics, the following variables were positively associated with PnIST carriage compared with both groups: temperature ≥39°C, peripheral white blood cell count ≥20 000/mm3, C-reactive protein ≥70.0 mg/L, and serum sodium <135 mEq/L. Lower oxygen saturation, viral detection, and comorbidities were negatively associated with Pn-IST carriage (odds ratios, <1.0). Differences between non-PnIST carriers and Pnc-neg groups were smaller or nonsignificant.

Conclusions

Young children with CAAP carrying common PnIST had a lower proportion of comorbidities, hypoxemia, and viral detection and had more intense systemic inflammatory response than those carrying non-PnIST or not carrying Pnc.

Using pneumococcal carriage studies to monitor vaccine impact in low- and middle-income countries

Pneumococcal disease is a leading cause of childhood mortality, globally. The pneumococcal conjugate vaccine (PCV) has been introduced to many countries worldwide. However there are few studies evaluating PCV impacts in low- and middle-income countries (LMIC) because measuring the impact of PCV on pneumococcal disease in LMICs is challenging. We review the role of pneumococcal carriage studies for the evaluation of PCVs in LMICs and discuss optimal methods for conducting these studies. Fifteen carriage studies from 13 LMICs quantified the effects of PCV on carriage, and identified replacement carriage serotypes in the post-PCV era. Ten studies reported on the indirect effects of PCV on carriage. Results can be used to inform cost-effectiveness evaluations, guide policy decisions on dosing and product, and monitor equity in program implementation. Critically, we highlight gaps in our understanding of serotype replacement disease in LMICs and identify priorities for research to address this gap.

Nasopharyngeal carriage of Streptococcus pneumoniae serotypes among children in India prior to the introduction of pneumococcal conjugate vaccines: a cross-sectional study

BACKGROUND

Streptococcus pneumoniae is a major cause of pneumonia, meningitis, and other serious infections among children in India. India introduced the 13-valent pneumococcal conjugate vaccine (PCV) in several states in 2017, and is expected to expand to nationwide coverage in the near future. To establish a baseline for measuring the impact of PCV in India, we assessed overall and serotype-specific nasopharyngeal carriage in two pediatric populations.

METHODS

A cross-sectional study was conducted in Palwal District, Haryana, from December 2016 to July 2017, prior to vaccine introduction. Children 2-59 months of age with clinical pneumonia seeking healthcare and those in the community with no clear illness were targeted for enrollment. A nasopharyngeal swab was collected and tested for pneumococcus using conventional culture and sequential multiplex PCR. Isolates were tested for antimicrobial resistance using an E test. Children were considered colonized if pneumococcus was isolated by culture or PCR. The prevalence of pneumococcal and serotype-specific colonization was compared between groups of children using log-binomial regression.

RESULTS

Among 601 children enrolled, 91 had clinical pneumonia and 510 were community children. The proportion colonized with S. pneumoniae was 74.7 and 54.5% among children with clinical pneumonia and community children, respectively (adjusted prevalence ratio: 1.38; 95% confidence interval: 1.19, 1.60). The prevalence of PCV13 vaccine-type colonization was similar between children with clinical pneumonia (31.9%) and community children (28.0%; p = 0.46). The most common colonizing serotypes were 6A, 6B, 14, 19A, 19F, and 23F, all of which are included in the PCV13 vaccine product. Antimicrobial resistance to at least one drug was similar between isolates from children with clinical pneumonia (66.1%) and community children (61.5%; p = 0.49); while resistance to at least two drugs was more common among isolates from children with clinical pneumonia (25.8% vs. 16.4%; p = 0.08). Resistance for all drugs was consistently higher for PCV13 vaccine-type serotypes compared to non-vaccine serotypes in both groups.

CONCLUSION

This study provides baseline information on the prevalence of serotype-specific pneumococcal colonization among children prior to the introduction of PCV in India. Our results suggest a role for pneumococcal vaccines in reducing pneumococcal colonization and antimicrobial resistant isolates circulating in India.

Evaluation of a phased pneumococcal conjugate vaccine introduction in Mongolia using enhanced pneumonia surveillance and community carriage surveys: a study protocol for a prospective observational study and lessons learned

Background

Streptococcus pneumoniae causes substantial morbidity and mortality among children. The introduction of pneumococcal conjugate vaccines (PCV) has the potential to dramatically reduce disease burden. As with any vaccine, it is important to evaluate PCV impact, to help guide decision-making and resource-allocation. Measuring PCV impact can be complex, particularly to measure impact on one of the most common and significant diseases caused by the pneumococcus, namely pneumonia. Here we outline the protocol developed to evaluate the impact of 13-valent PCV (PCV13) on childhood pneumonia in Mongolia, and a number of lessons learned in implementing the evaluation that may be helpful to other countries seeking to undertake pneumonia surveillance.

Methods

From 2016 PCV13 was introduced in a phased manner into the routine immunisation programme with some catch-up by the Government of Mongolia. We designed an evaluation to measure vaccine impact in children aged 2–59 months with hospitalised radiological pneumonia as a primary outcome, with secondary objectives to measure impact on clinically-defined pneumonia, nasopharyngeal carriage of S. pneumoniae among pneumonia patients and in the community, and severe respiratory infection associated with RSV and/or influenza. We enhanced an existing hospital-based pneumonia surveillance system by incorporating additional study components (nasopharyngeal swabbing using standard methods, C-reactive protein, risk factor assessment) and strengthening clinical practices, such as radiology as well as monitoring and training. We conducted cross-sectional community carriage surveys to provide data on impact on carriage among healthy children.

Discussion

Establishing a robust surveillance system is an important component of monitoring the impact of PCV within a country. The enhanced surveillance system in Mongolia will facilitate assessment of PCV13 impact on pneumonia, with radiological confirmed disease as the primary outcome. Key lessons arising from this evaluation have included the importance of establishing a core group of in-country staff to be responsible for surveillance activities and to work closely with this team; to be aware of external factors that could potentially influence disease burden estimates; to be flexible in data collection processes to respond to changing circumstances and lastly to ensure a consistent application of the pneumonia surveillance case definition throughout the study period.

Prophage Excision in Streptococcus pneumoniae Serotype 19A ST320 Promote Colonization: Insight Into Its Evolution From the Ancestral Clone Taiwan 19F-14 (ST236)

Streptococcus pneumoniae 19A ST320, a multidrug-resistant strain with high disease severity that notoriously spread before the use of expanded pneumococcal conjugate vaccines, was derived from a capsular switching event between an international strain Taiwan 19F-14 (ST236) and a serotype 19A strain. However, the molecular mechanisms underlying the adaptive evolution of 19F ST236 to 19A ST320 are unknown. In this study, we compared 19A ST320 to its ancestral clone, 19F ST236, in terms of adherence to respiratory epithelial cells, whole transcriptome, and ability to colonize a young mouse model. Serotype 19A ST320 showed five-fold higher adherence to A549 cells than serotype 19F ST236. High-throughput mRNA sequencing identified a prophage region located between dnaN and ychF in both strains; however, the genes in this region were expressed at significantly higher levels in 19A ST320 than in 19F ST236. Analysis by polymerase chain reaction (PCR) showed that the prophage is able to spontaneously excise from the chromosome and form a circular episome in 19A ST320, but not in 19F ST236. Deletion of the integrase in the prophage of 19A ST320 decreased spontaneous excision and cell adherence, which were restored by complementation. Competition experiments in mice showed that the integrase mutant was six-fold less competitive than the 19A ST320 parent (competitive index [CI]: 0.16; p = 0.02). The 19A ST320 prophage-deleted strain did not change cell adherence capacity, whereas prophage integration strains (integrase mutant and 19F) had decreased expression of the down-stream ychF gene compared to that of 19A ST320. Further deletion of ychF significantly reduced cell adherence. In conclusions, these findings suggest that spontaneous prophage induction confers a competitive advantage to virulent pneumococci.

Study of Healthcare Personnel with Influenza and other Respiratory Viruses in Israel (SHIRI): study protocol

Background

The Study of Healthcare Personnel with Influenza and other Respiratory Viruses in Israel (SHIRI) prospectively follows a cohort of healthcare personnel (HCP) in two hospitals in Israel. SHIRI will describe the frequency of influenza virus infections among HCP, identify predictors of vaccine acceptance, examine how repeated influenza vaccination may modify immunogenicity, and evaluate influenza vaccine effectiveness in preventing influenza illness and missed work.

Methods

Cohort enrollment began in October, 2016; a second year of the study and a second wave of cohort enrollment began in June 2017. The study will run for at least 3 years and will follow approximately 2000 HCP (who are both employees and members of Clalit Health Services [CHS]) with routine direct patient contact. Eligible HCP are recruited using a stratified sampling strategy. After informed consent, participants complete a brief enrollment survey with questions about occupational responsibilities and knowledge, attitudes, and practices about influenza vaccines. Blood samples are collected at enrollment and at the end of influenza season; HCP who choose to be vaccinated contribute additional blood one month after vaccination. During the influenza season, participants receive twice-weekly short message service (SMS) messages asking them if they have acute respiratory illness or febrile illness (ARFI) symptoms. Ill participants receive follow-up SMS messages to confirm illness symptoms and duration and are asked to self-collect a nasal swab. Information on socio-economic characteristics, current and past medical conditions, medical care utilization and vaccination history is extracted from the CHS database. Information about missed work due to illness is obtained by self-report and from employee records. Respiratory specimens from self-collected nasal swabs are tested for influenza A and B viruses, respiratory syncytial virus, human metapneumovirus, and coronaviruses using validated multiplex quantitative real-time reverse transcription polymerase chain reaction assays. The hemagglutination inhibition assay will be used to detect the presence of neutralizing influenza antibodies in serum.

Discussion

SHIRI will expand our knowledge of the burden of respiratory viral infections among HCP and the effectiveness of current and repeated annual influenza vaccination in preventing influenza illness, medical utilization, and missed workdays among HCP who are in direct contact with patients.

Trial registration

NCT03331991. Registered on November 6, 2017.

Electronic supplementary material

The online version of this article (10.1186/s12879-018-3444-7) contains supplementary material, which is available to authorized users.

Pneumococcal carriage and serotype distribution among children with and without pneumonia in Mozambique, 2014-2016

Background

Pneumococcal colonization is a precursor to pneumonia, and pneumococcal conjugate vaccines (PCV) can decrease vaccine-type (VT) colonization. Pneumococcal colonization studies are traditionally done among healthy children in the community; however, VT colonization prevalence may differ between these children and those with pneumonia. We assessed overall and VT pneumococcal colonization and factors associated with colonization among children with and without pneumonia after Mozambique introduced 10-valent PCV (PCV10) in 2013.

Methods

We used data from ongoing pneumonia surveillance in children aged <5 years and from cross-sectional nasopharyngeal colonization surveys conducted in October 2014 –April 2015 and October 2015 –May 2016. Pneumonia was defined using WHO standard criteria for radiologically confirmed pneumonia. Children with pneumonia enrolled from January 2014 –April 2016 were compared to children without pneumonia enrolled from the cross-sectional surveys. Clinical data and nasopharyngeal (NP) swabs were collected from each child. NP specimens were cultured for pneumococci, and culture-negative specimens from children with pneumonia underwent polymerase chain reaction (PCR).

Results

Of 778 and 927 children with and without pneumonia, 97.4% and 27.0% were exposed to antibiotics before swab collection, respectively. Based on culture, pneumococcal colonization was 45.1% for children with and 84.5% for children without pneumonia (P<0.001); VT pneumococcal colonization was 18.6% for children with and 23.4% for children without pneumonia (P = 0.02). The addition of PCR in children with pneumonia increased overall and VT-pneumococcal colonization to 79.2% and 31.1%, respectively. In multivariable analysis including PCR results, pneumonia was associated with VT pneumococcal colonization (adjusted OR: 1.4, 95%CI: 1.10–1.78).

Conclusion

Vaccine-type pneumococcal colonization remains common among children with and without pneumonia post-PCV10 introduction in Mozambique. In a population of children with high antibiotic exposure, the use of PCR for culture-negative NP swabs can improve assessment of pneumococcal colonization and circulating serotypes.

Pneumococcal vaccination: Direct and herd effect on carriage of vaccine types and antibiotic resistance in Icelandic children

BACKGROUND

Since the introduction of pneumococcal conjugate vaccines, vaccine type pneumococcal carriage and disease has decreased world-wide. The aim was to monitor changes in the nasopharyngeal carriage of pneumococci, the distribution of serotypes and antimicrobial resistance in children before and after initiation of the 10-valent pneumococcal vaccination in 2011, in a previously unvaccinated population.

METHODS

Repeated cross-sectional study at 15day-care centres in greater Reykjavik area. Nasopharyngeal swabs were collected yearly in March from 2009 to 2015. The swabs were selectively cultured for pneumococci, which were serotyped using latex agglutination and/or PCR and antimicrobial susceptibility determined. Two independent studies were conducted. In study 1, on total impact, isolates from children aged <4years were included. The vaccine-eligible-cohort (birth-years: 2011-2013, sampled in 2013-2015) was compared with children at the same age born in 2005-2010 and sampled in 2009-2012. In study 2 on herd effect, isolates from older non-vaccine-eligible children (3.5-6.3years) were compared for the periods before and after the vaccination (2009-2011 vs 2013-2015. Vaccine impact was determined using 1-odds-ratio.

RESULTS

Following vaccination, the vaccine impact on vaccine type acquisition was 94% (95% CI: 91-96%) in study 1 and 56% (95% CI: 44-65%) in study 2. The impact on serotype 6A was 33% (95% CI: -9%; 59%) in study 1 and 42% (95% CI: 10-63%) in study 2 with minimal effect on 19A. The non-vaccine serotypes/groups 6C, 11, 15 and 23B were the most common serotypes/groups after vaccination. Isolates from the vaccine-eligible-cohort had lower penicillin MICs, less resistance to erythromycin and co-trimoxazole and less multi resistance than isolates from the control-group.

CONCLUSIONS

The efficacy of the vaccination on vaccine serotypes was high, and a milder effect on vaccine-associated-serotype 6A was observed for the vaccine-eligible-cohort. There was a significant herd effect on vaccine types in older non-vaccine-eligible children. Overall antimicrobial non-susceptibility was reduced.

Impact of PCV13 on community-acquired pneumonia by C-reactive protein and procalcitonin levels in children

BACKGROUND

Many countries have observed an early and strong impact of implementation of the 13-valent pneumococcal conjugate vaccine (PCV13) on community-acquired pneumonia (CAP). High levels of C-reactive protein (CRP) and procalcitonin (PCT) are considered biomarkers of bacterial infection (particularly infection due to pneumococcus); therefore, PCV13 implementation should have different effectiveness on CAP depending on the levels of these two biomarkers. To demonstrate this assumption, we analyzed the evolution of number of CAP cases seen in pediatric emergency departments in France after PCV13 implementation (in 2010) by levels of these two biomarkers.

METHODS

From June 2009 to May 2015, 8 pediatric emergency units prospectively enrolled all children (1month to 15years) with radiologically confirmed CAP.

RESULTS

A cohort of 9586 children with CAP was enrolled (median age 3years). CAP with pleural effusion (PE-CAP) and proven pneumococcal pneumonia (PP-CAP) accounted for 5.5% and 2.0% of cases. During the study period, the number of cases of overall CAP decreased by 25.4%, hospitalized CAP by 30.5%, PE-CAP by 63.4%, CAP with CRP level≥100mg/L by 50.9%, CAP with PCT level≥4ng/L by 60.4% and PP-CAP by 86.4%. We found no change in number of cases of CAP with low levels of CRP (<20 or <40mg/L) or PCT (<0.5ng/mL). The number of cases of CAP overall increased (20.0%) in the last year of the study as compared with the preceeding year but not cases with CRP level≥100mg/L and/or PCT level≥4ng/mL.

CONCLUSION

PCV13 implementation has had a strong impact on number of CAP cases with high levels of CRP and/or PCT in children but no impact on that with low levels of these two biomarkers. Five years after PCV13 implementation, a sustained reduction in CAP cases is observed.

Surveillance of pneumococcal colonization and invasive pneumococcal disease reveals shift in prevalent carriage serotypes in Massachusetts' children to relatively low invasiveness

BACKGROUND

Following the introduction of pneumococcal conjugate vaccines (PCV), overall nasopharyngeal colonization rates have not changed significantly, however a dramatic and sustained decline in invasive pneumococcal disease (IPD) in children was observed in every setting where the PCVs were implemented. We aimed to describe the differences in invasive disease potential of serotypes that are common colonizers in pre- and post-vaccine eras in order to provide further insight in our understanding of dynamic epidemiology of pneumococcal diseases.

METHODS

Using data from surveillance of nasopharyngeal carriage and enhanced surveillance for IPD, a serotype specific "invasive capacity (IC)" was computed by dividing the incidence of IPD due to serotype x by the carriage prevalence of that same serotype in children <7years of age in Massachusetts. We have evaluated the serotype specific invasive capacity in two periods; pre-PCV13 (2001/02, 2003/04, 2006/07, 2008/09) and post-PCV13 (2010/11 and 2013/14), and by age groups; <24monthsvs. ≥24months.

RESULTS

An approximate 50-fold variation in the point estimate was observed between the serotypes having the highest (7F, 38, 19A, 3, 33F) and the lowest (6C, 35B, 21, 11A, 23B and 23A) computed serotype specific invasive disease potential. In the post-PCV13 era (6C, 35B, 11A, 23B and 23A), 5 of the 7 most common serotypes colonizing the nasopharynx were serotypes with the lowest invasive capacity. Serotype specific invasive capacity trended down in older children for majority of the serotypes, and serotypes 3, 10A and 19A had significantly lower invasive capacity in children older than 24months of age compared to younger children.

CONCLUSION

Invasive capacity differs among serotypes and likely by age. Point estimates of IC for most of the common serotypes colonizing children in Massachusetts in post-PCV13 era were low and likely explain the continued reduction in IPD from the pre-PCV era in the absence of specific protection against these serotypes.

Streptococcus pneumoniae Serotypes and Antibiotic Susceptibility Patterns in Middle Ear Fluid Isolates During Acute Otitis Media and Nasopharyngeal Isolates During Community-acquired Alveolar Pneumonia in Central Romania

BACKGROUND

Streptococcus pneumoniae is a common cause of community-acquired alveolar pneumonia (CAAP) and acute otitis media (AOM) in children. Romania has high rates of S. pneumoniae antibiotic resistance. The pneumococcal conjugated vaccines (PCVs) are not being used routinely in this country. The aims of the study were as follows: 1) to compare pneumococcal antibiotic resistance patterns in AOM and CAAP in children from central Romania and 2) to compare differences in the distribution of pneumococcal serotypes isolated from the middle ear fluid (MEF) of children with AOM and from the nasopharynx (NP) of children with CAAP.

METHODS

Children younger than 5 years old with AOM or with radiologically confirmed CAAP were prospectively enrolled. Samples from MEF and NP were evaluated for antibiotic susceptibility and serotyping.

RESULTS

Eighty-eight children with CAAP and 68 with AOM were enrolled. Of the MEF and CAAP isolates, 64 (94.1%) and 79 (89.7%) were penicillin nonsusceptible, respectively. The pneumococcal serotypes distribution in AOM was similar to those in CAAP except for serotype 19F, which was more common in AOM. Overall, 89.7% and 85.8% of all serotypes in AOM and CAAP patients, respectively, were covered by 13-valent PCV.

CONCLUSIONS

MEF and NP-CAAP S. pneumoniae isolates were similar in regard to serotype distribution and antibiotic resistance. S. pneumoniae antibiotic resistance rates were extremely high. Thirteen-valent PCV has the potential to reduce both the burden of disease as well as the rates of antibiotic-resistant S. pneumoniae in both diseases.

Pneumococcal Colonization in the Familial Context and Implications for Anti-Pneumococcal Immunization in Adults: Results from the BINOCOLO Project in Sicily

The spread of Streptococcus pneumoniae within families has been scarcely investigated so far. This feasibility study aimed to estimate the prevalence of pneumococcal carriage in school-aged children and co-habiting relatives and to explore the potential link between the family environment and the sharing of pneumococcal serotypes covered by the vaccine. Oropharyngeal samples of 146 subjects belonging to 36 different family groups were molecularly tested for pneumococcal detection and serotyping. The overall prevalence of pneumococcal carriage was 65.8% (n = 96/146), whereas it was higher among schoolchildren (77.8%, n = 28/36); subjects of seven years of age had the highest odds of being colonized (odds ratio, OR = 5.176; p = 0.145). Pneumococcal serotypes included in the 13-valent conjugate vaccine formulation were largely detected in the study population and multiple serotypes colonization was considerable. Factors relating to a close proximity among people at the family level were statistically associated with pneumococcal carriage (OR = 2.121; p = 0.049), as well as active smoking habit with a clear dose-response effect (ORs = 1.017–3.326). About half of family clusters evidenced similar patterns of carried pneumococcal serotypes and the odds of sustaining a high level of intrafamilial sharing increased with household size (ORs = 1.083–5.000). This study highlighted the potential role played by the family environment in sustaining both the circulation and horizontal transmission of pneumococcus.

Pneumococcal nasopharyngeal carriage in children <5 years of age visiting the pediatric emergency room in relation to PCV7 and PCV13 introduction in southern Israel

The 7-valent and the 13-valent pneumococcal conjugate vaccines (PCV7 and PCV13, respectively) were introduced to the Israeli National Immunization plan in July 2009 and November 2010, respectively. Our aim was to assess pneumococcal conjugate vaccines (PCVs) uptake and dynamics in serotype-specific pneumococcal nasopharyngeal (NP) carriage in children <5  years old in southern Israel, during the immediate 5 y following PCV introduction. This was an ongoing, prospective, population-based, active surveillance, from July 2009 through December 2014. PCVs uptake and NP cultures were obtained daily from children seen at the Pediatric Emergency Room for any reason. Overall, 10,702 vaccine status and 7,610 NP swabs were obtained. Both PCV7 and PCV13 uptake were high, reaching ˜90% by July 2012 and December 2013, respectively. All-pneumococcal carriage rates significantly declined by 10%, from 54.3% in the early-PCV7 period, to 49.1% in the PCV13 impact period. The respective declines for PCV7, 6A and additional PCV13 serotypes carriage rates were 76%, 90% and 66%. In contrast, non-PCV13 serotypes carriage rates increased significantly throughout the study by 71%. All-pneumococcal carriage rates in children <12  months old decreased significantly by 15%, with similar trends observed in other age groups. Initially, all-pneumococcal carriage rates were 45.7%, and 61.9% in Jewish and Bedouin children, respectively (P < 0.001), with a significant 17% reduction throughout the study observed only in Bedouins. While early carriage rates were higher in unvaccinated children compared to vaccinated children, PCV impact on carriage were similar in both groups. In conclusion, a relatively moderate decline in pneumococcal carriage rates, facilitated by a substantial decrease of vaccine-serotypes and increase of non-vaccine serotypes was observed in the immediate period following PCVs introduction in southern Israel.

Using Pneumococcal Carriage Data to Monitor Postvaccination Changes in the Incidence of Pneumococcal Otitis Media

Pneumococcal conjugate vaccines (PCVs) have substantially reduced the burden of pneumococcal disease, including the incidence of otitis media (OM). However, in most countries, no surveillance exists to monitor the change in pneumococcal OM incidence after the introduction of PCVs. We explored whether measuring pneumococcal carriage was a useful surrogate for monitoring postvaccination changes in the incidence of pneumococcal OM. The 7-valent PCV was introduced to Israel's national immunization program in July 2009 and gradually replaced by the 13-valent PCV starting in November 2010. Each day since 2009, nasopharyngeal swabs have been obtained from the first 4 Bedouin children and the first 4 Jewish children who were younger than 5 years old and attended a pediatric emergency room in southern Israel. During the same time, OM surveillance in southern Israel included all children younger than 2 years of age who were diagnosed with OM and had undergone a middle-ear fluid culture. The relative change in the prevalence of vaccine-serotype (VT) pneumococcal carriage was predictive of the relative change in incidence of OM due to VT pneumococcus. However, the serotype replacement observed in non-VT carriage is not paralleled in the incidence of OM due to non-VT pneumococcus. This could indicate that there are more complex mechanisms of the immune response involved in preventing initial and consecutive episodes of OM, which has been changed through declining prevalence of the most virulent serotypes as a result of vaccination.

Differences Between Radiologically Confirmed Pneumonia With and Without Pleural Fluid in Hospitalized Children Younger Than 5 Years in Southern Israel

We compared demographic and clinical characteristics of pneumonia with and without pleural fluid (PF and Pn, respectively) in hospitalized children younger than 5 years in southern Israel, between 2002 and 2011. Overall, 108 PF and 5811 Pn episodes were recorded. Children with PF were older. Prematurity (6.6% vs 14.0%) and asthma (9.9% vs 23.5%) were less common in PF. Mean temperature and saturation were higher in PF while hemoglobin and sodium levels were lower in PF compared with Pn. Nasal washes were obtained in 30.6% and 39.9% of PF and Pn episodes, respectively, with respiratory syncytial virus identified more commonly in Pn (24.2% vs 42.3%). Streptococcus pneumoniae was identified in 5.2% and 0.9% of blood cultures in PF and Pn, respectively. In conclusion, PF differed from Pn in demographic and clinical characteristics, possibly due to differences in etiology. Although both diseases are considered bacterial, a high proportion of viral etiology was found in both, especially in Pn.

Surveillance of the impact of pneumococcal conjugate vaccines in developing countries

Infection due to Streptococcus pneumoniae is a leading cause of morbidity and mortality in young children, especially in developing countries. With the support of Gavi, the Vaccine Alliance, the majority of these countries have introduced pneumococcal conjugate vaccines (PCV) into their national immunization programs and early data demonstrate a high degree of effectiveness, translating to enormous public health benefit through both direct and indirect (herd) effects. Future vaccination strategy may be focused on maintaining herd effects rather than individual protection. Evaluation of vaccine-type carriage, particularly in pneumonia cases, may be an easy, feasible way of measuring continued vaccine impact.

Impact of PCV7/PCV13 introduction on community-acquired alveolar pneumonia in children <5 years

BACKGROUND

Alveolar community-acquired pneumonia (A-CAP) is mostly considered a bacterial disease, mainly pneumococcal. This study was conducted to document the impact of sequential 7-valent and the 13-valent pneumococcal conjugate vaccines (PCV7; PCV13) on emergency room and hospitalization for A-CAP among children <5 years of age.

METHODS

This is an ongoing prospective population-based study in southern Israel. The current analysis spans over the period July 2002 through June 2013. A-CAP was defined using the World Health Organization (WHO)'s criteria for radiologically-confirmed pneumonia. PCV7 was introduced in Israel in July 2009 and gradually replaced by PCV13 in November 2010. Pneumococcal conjugate vaccine (PCV) impact was calculated by comparing incidences during 3 pre-defined periods: pre-PCV (2002-2008), PCV7 (2010-2011) and PCV13 (2012-2013).

RESULTS

Overall, 10,142 A-CAP episodes occurred. The annual incidences (per 1,000 inhabitants) in children <5 years old declined from a mean (±standard deviation) of 13.8 ± 0.9 in the pre-PCV period to 11.2 ± 2.7 in the PCV7 period and 7.4 in the PCV13 period, representing a reduction of 13% and 47%, respectively. The overall decrease was significantly faster among outpatients than among hospitalized children (42% and -8%, respectively in the PCV7 period; 68% vs. 32% in hospitalized children in the PCV13 period). While in children 12-23 months a significant decline was observed during the PCV7 and PCV13 periods, significant declines in A-CAP rates were observed only during the PCV13 period in the <12 months and 24-59 months age groups (44% and 46%, respectively).

CONCLUSIONS

A moderate decline in hospital A-CAP visits in children <5 years old was observed after PCV7 introduction. In contrast, after PCV13 introduction a substantial reduction in all visits was evident.

Differential impact of pneumococcal conjugate vaccines on bacteremic pneumonia versus other invasive pneumococcal disease

BACKGROUND

Bacteremic pneumonia (BP) accounts for ~35% of invasive pneumococcal disease (IPD) in young children. Our aims were to compare age, seasonal and serotype distribution of BP versus non-BP IPD and to determine whether the impact of the sequential 7/13-valent pneumococcal conjugate vaccine (PCV7/PCV13) introduction on disease incidence differed between BP and non-BP IPD in children <5 years of age.

METHODS

A nationwide, prospective, population-based, active surveillance (July 2004-June 2013) was conducted. All IPD episodes were included. PCV7 was introduced to the Israeli National Immunization Plan in July 2009 and has been replaced by PCV13 since November 2010.

RESULTS

In all, 983 (36.8%) BP and 1687 (63.2%) non-BP IPD episodes were recorded. A higher proportion of BP than that of non-BP IPD episodes (42.0% vs. 20.7%; P < 0.001) occurred in children >24 months old. Seasonality differed between BP and non-BP IPD, with yearly earlier peaks of non-BP IPD. The proportion of the 5 additional PCV13 serotypes (1, 3, 5, 7F and 19A) was higher in children with BP versus non-BP IPD (39.6% vs. 23.6%; P < 0.01). Shortly after PCV7 introduction, non-BP IPD rate was significantly reduced but that of BP was not. However, PCV13 introduction resulted in rapid reduction of BP rate, with a further reduction of non-BP IPD.

CONCLUSION

The differences in age distribution, seasonality and serotype distribution between BP and non-BP IPD suggest that the pathogenesis of these 2 entities is not identical and resulted in different impact rate dynamics after PCV7 and PCV13 introduction.

Seasonality of both bacteremic and nonbacteremic pneumonia coincides with viral lower respiratory tract infections in early childhood, in contrast to nonpneumonia invasive pneumococcal disease, in the pre-pneumococcal conjugate vaccine era

We assessed the seasonality of viral lower respiratory tract infections (V-LRI), bacteremic pneumonia, nonbacteremic pneumonia and nonpneumonia invasive pneumococcal diseases (IPD) in the pre-PCV era. Both bacteremic and nonbacteremic pneumonia seasonality peaked in winter, coinciding with V-LRI seasonality, whereas non-pneumonia IPD peaked in autumn before V-LRI increase, suggesting different pathogenesis.

Early indication for a reduced burden of radiologically confirmed pneumonia in children following the introduction of routine vaccination against Haemophilus influenzae type b in Nha Trang, Vietnam

INTRODUCTION

Despite the global success of Hib vaccination in reducing disease and mortality, uncertainty about the disease burden and the potential impact of Hib vaccination in Southeast Asia has delayed the introduction of vaccination in some countries in the region. Hib vaccination was introduced throughout Vietnam in July 2010 without catch-up. In an observational, population based surveillance study we estimated the impact of routine Hib vaccination on all cause radiologically confirmed childhood pneumonia in Nha Trang, Vietnam.

MATERIALS AND METHODS

In 2007 active hospital based surveillance was established in Khanh Hoa General Hospital, the only hospital in Nha Trang, Khanh Hoa province. Nasopharyngeal samples and chest radiographs are taken routinely from all children diagnosed with acute respiratory illness on admission. For admissions between 02/2007 and 03/2012 chest radiographs were interpreted for the presence of WHO primary endpoint pneumonia and nasopharyngeal swabs were analysed by PCR for the presence of Influenza A or B, RSV and rhinovirus. We employed Poisson regression to estimate the impact of Hib vaccination on radiologically confirmed pneumonia (RCP) while statistically accounting for potential differences in viral circulation in the post vaccination era which could have biased the estimate.

RESULTS

Of 3151 cases admitted during the study period, 166 had RCP and major viruses were detected in 1601. The adjusted annual incidence of RCP in children younger than 5 years declined by 39% (12-58%) after introduction of Hib vaccination. This decline was most pronounced in children less than 2 years old, adjusted IRR: 0.52 (0.33-0.81), and no significant impact was observed in the 2-4 years old who were not eligible for vaccination, adjusted IRR: 0.96 (0.52-1.72).

DISCUSSION

We present early evidence that the burden of Hib associated RCP in Nha Trang before vaccination was substantial and that shortly after introduction to the routine childhood immunisation scheme vaccination has substantially reduced that burden.

Nasopharyngeal carriage of Streptococcus pneumoniae in Romanian children before the introduction of the pneumococcal conjugated vaccination into the national immunization programme: a national, multi-centre, cross-sectional observational study

OBJECTIVES

We analysed the distribution of vaccine and non-vaccine Streptococcus pneumoniae serotypes and the antimicrobial susceptibility of pneumococcal strains isolated from healthy Romanian children.

METHODS

A multi-centre cross-sectional study was performed in four counties to evaluate carried strains of S. pneumoniae isolated from 2000 children aged 0-5 years.

RESULTS

S. pneumoniae carriage was detected in 25.25% of the tested children. Carriage increased from 16.7% among infants to 29.4% in 3-5-year-old children (p<0.0001). The proportions of the serotypes included in pneumococcal conjugate vaccines PCV7, PCV10, and PCV13 among our isolates were 39.9%, 40.1%, and 58.7%, respectively. Erythromycin resistance was 72.5%, and it was significantly lower in non-vaccine serotypes compared with PCV13 serotypes: 57.3% versus 83.6% (p<10(-7)). Penicillin minimum inhibitory concentrations (MICs) >0.064mg/l were recorded in 71.6%, but the penicillin MIC was >2mg/l for only 8.4% of tested isolates.

CONCLUSIONS

In Romanian children, the majority of carried S. pneumoniae isolates are vaccine serotypes. The isolates with MICs defining macrolide resistance were very frequent, as well as the isolates with MICs defining penicillin resistance in the case of meningitis or penicillin dose-dependent susceptibility for other infections, mainly for the strains belonging to PCV13 serotypes. The implementation of PCV13 within the Romanian national immunization programme could reduce the circulation of these strains with higher macrolide and/or penicillin MICs.

Emergence of serogroup 15 Streptococcus pneumoniae of diverse genetic backgrounds following the introduction of pneumococcal conjugate vaccines in Hong Kong

Serogroup 15 pneumococcal isolates from nasopharyngeal carriage of hospitalized children admitted to a teaching hospital in Hong Kong from April 2009 to September 2013 were characterized by pulse-field gel electrophoresis (PFGE), multilocus sequence typing, and antimicrobial non-susceptibility testing. The overall proportion of serogroup 15 isolates in the pre-PCV7 and post-PCV13 periods rose from 5.7% to 20.0%. The increase in trend for serotype 15B/C was statistically significant among children presented with pneumonia; bronchiolitis; upper respiratory tract infection; and febrile, non-respiratory diseases and for serotype 15A/F, among children with bronchiolitis and febrile, non-respiratory diseases. The predominant PFGE cluster of serotype 15B/C belonged to sequence type (ST) 199. Replacement of this more susceptible cluster (Ery and Tet non-susceptibilities of 32.2% and 25.4%) with the non-susceptible cluster, ST8859 (Ery and Tet non-susceptibilities of 91.7% and 87.5%) was noted. ST63 was the predominant serotype 15A cluster (Ery and Tet non-susceptibilities of 97.4% and 92.3%). Serogroup 15 subtypes have emerged in the post-PCV13 era, and these non-susceptible clusters warrant closer monitoring as candidates for incorporation to future pneumococcal vaccines.

Pneumococcal colonisation density: a new marker for disease severity in HIV-infected adults with pneumonia

OBJECTIVE

A high genomic load of Pneumococcus from blood or cerebrospinal fluid has been associated with increased mortality. We aimed to analyse whether nasopharyngeal colonisation density in HIV-infected patients with community-acquired pneumonia (CAP) is associated with markers of disease severity or poor outcome.

METHODS

Quantitative lytA real-time PCR was performed on nasopharyngeal swabs in HIV-infected South African adults hospitalised for acute CAP at Chris Hani Baragwanath Hospital, Soweto, South Africa. Pneumonia aetiology was considered pneumococcal if any sputum culture or Gram stain, urinary pneumococcal C-polysaccharide-based antigen, blood culture or whole blood lytA real-time PCR revealed pneumococci.

RESULTS

There was a moderate correlation between the mean nasopharyngeal colonisation densities and increasing CURB65 scores among all-cause patients with pneumonia (Spearman correlation coefficient r=0.15, p=0.06) or with the Pitt bacteraemia score among patients with pneumococcal bacteraemia (p=0.63). In patients with pneumococcal pneumonia, nasopharyngeal pneumococcal colonisation density was higher among non-survivors than survivors (7.7 vs 6.1 log10 copies/mL, respectively, p=0.02) and among those who had pneumococci identified from blood cultures and/or by whole blood lytA real-time PCR than those with non-bacteraemic pneumococcal pneumonia (6.6 vs 5.6 log10 copies/mL, p=0.03). Nasopharyngeal colonisation density correlated positively with the biomarkers procalcitonin (Spearman correlation coefficient r=0.37, p<0.0001), proadrenomedullin (r=0.39, p=0.008) and copeptin (r=0.30, p=0.01).

CONCLUSIONS

In addition to its previously reported role as a diagnostic tool for pneumococcal pneumonia, quantitative nasopharyngeal colonisation density also correlates with mortality and prognostic biomarkers. It may also be useful as a severity marker for pneumococcal pneumonia in HIV-infected adults.

Evolving role of 13-valent pneumococcal conjugate vaccine in clinical practice

Since the introduction of 7-valent pneumococcal conjugate vaccine (PCV7), PCVs with extended coverage have become available, and there is emerging global evidence that these vaccines, in particular PCV13, have further reduced rates of invasive pneumococcal disease compared with PCV7. The present article aims to address emerging topics related to PCV13 use in routine clinical practice; specifically: (1) the potential role of high-valent PCVs in reducing pneumococcal disease burden; (2) the impact of PCVs on nasopharyngeal carriage and how this may contribute to reductions in otitis media and pneumonia, as well as the prevalence of resistant pneumococcal strains; (3) new PCV13 indications and (4) importance of schedule adherence for PCV in the prevention of cases of vaccine serotype-specific invasive pneumococcal disease. The beneficial effects of PCVs in protecting individuals from a wide spectrum of pneumococcal diseases can be increased by improving the vaccine coverage and adhering to the recommended vaccination schedules. There is increasing evidence that PCV13 has reduced much of the post-PCV7 burden of pneumococcal diseases in the pediatric community, including reducing pneumococcal colonization and the incidence of invasive pneumococcal disease and mucosal diseases. This has also led to a reduction in antibiotic-resistant pneumococcal diseases. The role of PCV13 in clinical practice is evolving, with PCV13 now available for children and adolescents between the ages of 6 weeks and 17 years, thus ensuring that children in all age groups can be protected against vaccine-serotype pneumococcal diseases. Continued surveillance is warranted to monitor the impact of PCV13 on disease burden.

Standard method for detecting upper respiratory carriage of Streptococcus pneumoniae: updated recommendations from the World Health Organization Pneumococcal Carriage Working Group

In 2003 the World Health Organization (WHO) convened a working group and published a set of standard methods for studies measuring nasopharyngeal carriage of Streptococcus pneumoniae (the pneumococcus). The working group recently reconvened under the auspices of the WHO and updated the consensus standard methods. These methods describe the collection, transport and storage of nasopharyngeal samples, as well as provide recommendations for the identification and serotyping of pneumococci using culture and non-culture based approaches. We outline the consensus position of the working group, the evidence supporting this position, areas worthy of future research, and the epidemiological role of carriage studies. Adherence to these methods will reduce variability in the conduct of pneumococcal carriage studies undertaken in the context of pneumococcal vaccine trials, implementation studies, and epidemiology studies more generally so variability in methodology does not confound the interpretation of study findings.

Increased risk for respiratory syncytial virus-associated, community-acquired alveolar pneumonia in infants born at 31-36 weeks of gestation

BACKGROUND

We compared hospitalization and pediatric intensive care unit (PICU) admission rates for community-acquired alveolar pneumonia (CAAP) and respiratory syncytial virus (RSV)-associated CAAP (RSV-CAAP) in non-RSV-immunized children <24-month-old born at 31-36 weeks gestational age (GA) versus those born at term (>36 weeks GA).

METHODS

Nasopharyngeal samples for RSV were obtained prospectively (2004-2011) during RSV season, from hospitalized children with radiographic-diagnosed CAAP. Soroka University Medical Center is the only hospital in the region, enabling population-based rate calculation. Relative risks (RR) and 95% confidence intervals (95% CI) were calculated comparing RSV-CAAP incidence in 31-36 weeks GA with >36 weeks GA children.

RESULTS

CAAP hospitalization incidences (per 1000 population) were 23.6 and 9.4 (RR: 2.52; 95% CI: 2.13-2.68), respectively; the respective incidences of PICU admission for overall CAAP were 1.8 and 0.2 (RR: 7.88; 95% CI: 4.59-11.83). The RRs (and 95% CI) for RSV-CAAP hospitalizations and PICU admission rates were (after extrapolation) 15.2 and 5.8 (RR: 2.79; 95% CI: 2.31-3.06) and 1.1 and 0.1 (RR: 9.14; 95% CI: 4.93-16.96), respectively. In a multiregression analysis in patients with RSV-CAAP versus CAAP, 31-36 weeks GA was an independent risk factor for hospitalization (RR: 1.485; 95% CI: 1.03-2.14).

CONCLUSIONS

Children <24-month-old born at 31-36 weeks GA are at increased risk for hospitalization and PICU admission for both overall CAAP and RSV-associated CAAP compared with those born at >36 weeks GA. Moreover, in late premature children, RSV represented a 50% increased risk for CAAP compared with infants born at term.

Short-course antibiotic treatment for community-acquired alveolar pneumonia in ambulatory children: a double-blind, randomized, placebo-controlled trial

BACKGROUND

Studies on short-course treatment of childhood pneumonia in the developed world are lacking. We compared clinical and laboratory outcomes of a 3-day or a 5-day to a 10-day treatment in young children with community-acquired alveolar pneumonia.

METHODS

A double-blind, randomized, placebo-controlled trial was conducted in 2 stages: (1) 3 days versus 10 days and (2) 5 days versus 10 days. Amoxicillin (80 mg/kg/d; divided into 3 daily doses) was used for all arms. Case definition was: age 6-59 months; radiologically confirmed community-acquired alveolar pneumonia; temperature ≥38.5°C; peripheral white blood cell count ≥15,000/mm³; status permitting outpatient treatment. Scheduled visits were on days 4-5 and 10-14 with daily telephone interviews for 30 days. Treatment failure was defined by the need for a rescue treatment or hospitalization. Secondary outcomes were: duration of fever and symptoms and white blood cell and C-reactive protein responses.

RESULTS

During Stage 1, 4/10 (40%) and 0/12 (0%) evaluable patients failed in the 3-day and 10-day arms, respectively (P = 0.16). Therefore, the 3-day arm was replaced by a 5-day arm (Stage 2). No failures occurred in the 5-day (n = 56) and 10-day (n = 59) arms. Overall, 4/10 (0%), 0/56 and 0/42 (0%) children failed in the 3-day, 5-day and 10-day arms, respectively (P < 0.001, 3-day versus 5-day or 10-day). Secondary outcomes were similar in the 5-day and 10-day arms.

CONCLUSION

In 6- to 59-month-old outpatients with community-acquired alveolar pneumonia, a 5-day course with high-dose oral amoxicillin was not inferior to a 10-day course. The 3-day regimen may be associated with an unacceptable failure rate.

Influence of pneumococcal vaccines and respiratory syncytial virus on alveolar pneumonia, Israel

Postlicensure surveillance of pneumonia incidence can be used to estimate whether pneumococcal conjugate vaccines (PCVs) affect incidence. We used Poisson regression models that control for baseline seasonality to determine the impact of PCVs and the possible effects of variations in virus activity in Israel on these surveillance estimates. PCV was associated with significant declines in radiologically confirmed alveolar pneumonia (RCAP) among patients <6 months, 6–17 months, and 18–35 months of age (–31% [95% CI –51% to –15%], –41% [95% CI –52 to –32%], and –34% [95% CI –42% to –25%], respectively). Respiratory syncytial virus (RSV) activity was associated with strong increases in RCAP incidence, with up to 44% of cases attributable to RSV among infants <6 months of age and lower but significant impacts in older children. Seasonal variations, particularly in RSV activity, masked the impact of 7-valent PCVs, especially for young children in the first 2 years after vaccine introduction.

Safety and immunogenicity of 10-valent pneumococcal nontypeable Haemophilus influenzae protein D conjugate vaccine (PHiD-CV) in Nigerian children: Booster dose and 2-dose catch-up regimens in the second year of life

In a previous study, 3-dose primary vaccination of Nigerian infants with the 10-valent pneumococcal nontypeable Haemophilus influenzae protein D conjugate vaccine (PHiD-CV) was immunogenic for vaccine pneumococcal serotypes, with comparable tolerability between PHiD-CV and control groups. In an open-label study (ClinicalTrials.gov, NCT01153893), 68 primed children received a PHiD-CV booster dose co-administered with a diphtheria-tetanus-acellular pertussis (DTPa) booster dose at 15–21 months and 36 children unprimed for pneumococcal vaccination received two PHiD-CV catch-up doses (first dose co-administered with DTPa booster dose) at 15–21 and 17–23 months. Adverse events were recorded and immune responses were measured before and one month after vaccination. In both groups, pain was the most frequent solicited local symptom and fever was the most frequent solicited general symptom after the booster dose and each catch-up dose. Few grade 3 solicited symptoms and no vaccine-related serious adverse events were reported. After booster vaccination, for each vaccine serotype, at least 98.5% of children had an antibody concentration ≥0.2 µg/ml and at least 94.0% had an opsonophagocytic activity (OPA) titer ≥8. After 2-dose catch-up, for each vaccine serotype, at least 97.1% had an antibody concentration ≥0.2 µg/ml, except for serotypes 6B (82.9%) and 23F (88.6%), and at least 91.4% had an OPA titer ≥8, except for serotypes 6B (77.4%) and 19F (85.3%). PHiD-CV induced antibody responses against protein D in both groups. In conclusion, PHiD-CV administered to Nigerian toddlers as a booster dose or 2-dose catch-up was well tolerated and immunogenic for vaccine pneumococcal serotypes and protein D.