Radiographically confirmed community-acquired pneumonia in hospitalized adults due to pneumococcal vaccine serotypes in Sweden, 2016-2018-The ECAPS study

Global distribution and characteristics of pneumococcal serotypes in adults

The introduction of pneumococcal conjugate vaccines (PCVs) into pediatric national immunization programs (NIP) has significantly reduced invasive pneumococcal diseases and pneumococcal pneumonia caused by PCV serotypes in adults due to herd immunity. However, diseases caused by PCV13 serotypes persist, mainly serotype 3, known for its severity. With the reduction in PCV13 serotypes, diseases caused by non-PCV13 serotypes increased. Residual and emerging serotypes vary regionally; serotype 8 in Europe and South Africa, and serotype 4 in the US and Canada. PCV20 and PCV21 were recently developed, which can prevent residual and emerging pneumococcal diseases where herd immunity is well-established. In countries that have not introduced PCV into pediatric NIP, the pneumococcal disease burden due to PCV serotypes is still marked. Given that serotype distribution varies by region and evolves over time, this review aimed to discuss serotype distribution and disease severity in adults across countries to support future pneumococcal vaccine strategies.

Changes in the incidence, viral coinfection pattern and outcomes of pneumococcal hospitalizations during and after the COVID-19 pandemic

BACKGROUND

The incidence of pneumococcal pneumonia in the context of the Coronavirus Disease 2019 (COVID-19) pandemic, along with the real-world data on the ratio of non-invasive to invasive pneumococcal pneumonia, is an area that has not been thoroughly studied. The outcomes associated with coinfection of influenza and COVID-19 remain unknown. This study examined the incidence, demographics, coinfection with influenza and/or COVID-19, and clinical outcomes of pneumococcal hospitalizations in Hong Kong during the baseline, pandemic, and post-pandemic periods.

METHODS

Hospitalization records of individuals aged 18 years and above with pneumococcal disease from January 2015 to August 2024 were extracted from the territory-wide electronic medical record database. Pneumococcal disease was categorized into invasive pneumococcal pneumonia (IPP), invasive pneumococcal disease without pneumonia (IPDWP), and non-invasive pneumococcal pneumonia (NIPP), followed by univariate and multivariate analyses. Effects of coinfection with influenza and COVID-19 were analyzed.

RESULTS

The incidence of pneumococcal disease decreased during the COVID-19 pandemic but rebounded in the post-pandemic period. There were no significant changes in the distribution of pneumococcal serotypes across the three periods. The study revealed a strong positive correlation between monthly pneumococcal hospitalizations and the indicator of influenza activity, while the correlation with the COVID-19 indicator was weak. Additionally, strong positive correlations were observed between the indicator of influenza activity and influenza coinfections, as well as between the indicator of COVID-19 activity and COVID-19 coinfections. Multivariate analyses identified male gender, a higher comorbidity index, older age, invasive pneumococcal disease (IPP and IPDWP), coinfection with influenza and COVID-19, and hospitalization during the pandemic period as factors associated with adverse outcomes.

CONCLUSIONS

The study showcases changes in the epidemiology of pneumococcal disease during and after the COVID-19 pandemic. It highlights the adverse effects of influenza and COVID-19 coinfections on the outcomes of patients with pneumococcal disease and emphasizes the need to vaccinate vulnerable populations against these infections.

Profiling the nasopharyngeal Microbiome in patients with community-acquired pneumonia caused by Streptococcus pneumoniae: diagnostic challenges and ecological insights

Community-acquired pneumonia (CAP) is a significant health threat for adults. Although conjugate vaccines have reduced pneumococcal CAP incidence in children, Streptococcus pneumoniae-related CAP remains prevalent among older adults. The nasopharynx acts as a reservoir for S. pneumoniae, yet the interplay between this pathogen and the nasopharyngeal microbiome during and after pneumonia remains poorly understood. This study included 61 adult patients diagnosed with pneumococcal CAP and 61 matched healthy controls. An S. pneumoniae-specific PCR, urine antigen tests and bacterial cultures were performed. Nasopharyngeal swabs collected at admission and three months post-infection were analyzed for microbiome dynamics through 16 S rRNA gene amplicon sequencing. 16 S rRNA gene amplicon sequencing revealed Streptococcus spp. in the majority of all nasopharyngeal samples during infection compared to the other diagnostic test performed. While overall bacterial biomass did not differ between groups, patients exhibited higher alpha diversity (p = 0.012) and lower microbiome stability post-infection. Beta diversity analysis distinguished infection from healthy status (p = 0.002). Taxonomic analysis showed similar core microbiota across groups, but Streptococcus spp. was significantly more abundant during infection, particularly in those patients with viral co-infections. Notably, unique significant bacterial interactions were identified both during and after infection, as well as in healthy states. A negative correlation was observed between Corynebacterium and Streptococcus spp. in infected patients, suggesting a potential antagonistic interaction between these taxa. The nasopharyngeal microbiome in patients with pneumococcal CAP demonstrates persistent disruption post-infection, characterized by lower resilience three months after acute illness. Additionally, we identified specific bacterial interplays during and after infection that differed from those in healthy donors. These bacterial dynamics might play critical roles in pathogen colonization resistance and infection prevention. Thus, our findings highlight the need for further investigation into microbial interactions and potential microbiome-based therapies for respiratory infections, particularly in vulnerable populations.

The incidence of radiologically verified community-acquired pneumonia requiring hospitalisation in adults living in southern Sweden, 2016-2018: a population-based study

BACKGROUND

Community-acquired pneumonia (CAP) was one of the most common causes of death in the European Union in 2017. Severity and mortality of CAP increase with age and an aging European population will require increased planning for prevention, control, and management of CAP. The purpose of this study was to provide an updated population-based estimate of the incidence of CAP requiring hospitalization in Northern Europe.

METHOD

We conducted a retrospective cohort study estimating the population-based incidence of CAP requiring hospitalization. Adults residing in Southern Sweden admitted between September 2016 and September 2018 with radiographically confirmed CAP and a primary discharge diagnosis consistent with pneumonia were identified by retrospective medical chart review. Incidence rates were stratified by age and sex.

RESULTS

We identified 1,575 episodes of CAP in 1,471 unique individuals, accounting for 45% of the total eligible patient population. The crude incidence rate of CAP requiring hospitalization was 259 (95% CI: 246-272) and age-standardized rate was 294 (95% CI: 280-309) per 100,000 person-years. Among those aged 80 years and older, hospitalization rate was 17 times higher vs those aged 18-64 years, yielding an IRR 17.4 (95% CI: 15.4-19.7). Males aged ≥ 80 years had a 57% increased risk of CAP requiring hospitalization compared to women ≥ 80 years, resulting in an IRR of 1.57 (95% CI: 1.33-1.85). The lowest in-hospital case-fatality risk was among the 18-64 years group 3.4% (n = 16), and highest among those ≥ 80 years 8.1% (n = 46).

CONCLUSION

We found that the incidence and mortality of CAP requiring hospitalization in adults are considerable. Preventive measures are needed that target older adults and those at increased risk of CAP.

Radiographically confirmed pneumonia in Malawian children and associated pneumococcal carriage after introduction of the 13-valent pneumococcal conjugate vaccine

BACKGROUND

The 13-valent pneumococcal conjugate vaccine (PCV-13) was introduced in Malawi in 2011 with an expected impact of reducing pneumococcal pneumonia in children. We aimed to describe clinical characteristics and nasopharyngeal (NP) carriage of pneumococcus by serotype in children hospitalized with primary end-point pneumonia (PEP) between 2013 and 19 after the introduction of PCV-13.

METHODS

We conducted a secondary analysis of children aged under-5-years hospitalized with acute respiratory illness (ARI) in Malawi. Chest radiographs conducted at admission were read by two independent clinicians according to WHO criteria for PEP, and a third reviewer resolved discordant diagnoses. NP swab specimens were processed and Streptococcus pneumoniae growth was serotyped. Multivariable regression analysis was conducted to assess the association between clinical characteristics, NP serotypes, and PEP.

RESULTS

We had complete radiographic and NP serotype data for 500 children, of which 54 isolates were vaccine-type (VT) (10.8%), 165 were non-VT (NVT; 33.0%), and 281 had no pneumococcal growth (56.2%). Among these, 176 (35.2%) had PEP on chest x-ray. Among those with PEP, pneumococcal carriage was documented in 43.8% of cases, and VT serotypes accounted for 10.8%. For children with PEP, we found no association between clinical characteristics and carrying either VT, NVT, or no pneumococcus.

CONCLUSION

Carriage of S. pneumoniae remains high among children hospitalized with ARI in Malawi, but children with VT carriage were no more likely to have PEP than children carrying no pneumococcus or those with NVT carriage. There were no differences in clinical characteristics between those carrying VT, NVT, or no pneumococcus.

The importance of Haemophilus influenzae in community-acquired pneumonia: an emerging pathogen in the elderly regardless of comorbidities compared to Streptococcus pneumoniae

BACKGROUND

Haemophilus influenzae community-acquired pneumonia (CAP) is common, and it is equally common to Streptococcus pneumoniae in some settings. The purpose of this study was to provide additional data on patients affected by H. influenzae CAP and their outcomes.

METHODS

Streptococcus pneumoniae-caused CAP (111 cases) was compared to CAP with H. influenzae (53 cases). Patients were adults (≥ 18 years) from the prospective study "Etiology of community acquired pneumonia in Sweden" (ECAPS), which was established during the years 2016-2018.

RESULTS

Cases with H. influenzae CAP were significantly older compared to S. pneumoniae CAP (median 77 vs 70 years, p = 0.037) albeit similar comorbidities. Haemophilus influenzae was generally absent in the bloodstream compared to S. pneumoniae (18% vs 2%, p = 0.01) but clinical presentations were comparable. Only a minority of patients, 34% with H. influenzae and 41% with S. pneumoniae CAP had underlying lung disease.

CONCLUSION

In the light of childhood immunization campaigns against S. pneumoniae and the increasing numbers of pneumococcal vaccinations among the elderly, coupled with an aging population, the incidence of CAP caused by H. influenzae may increase. Further research is needed to understand the impact of H. influenzae CAP and to a development of a vaccine against this emerging microbe.

Hospital Burden of All-Cause Pneumonia and Nonbacteremic Pneumococcal Pneumonia in Adults in France Between 2013 and 2019

Background

Community-acquired pneumonia (CAP) is associated with significant morbidity and mortality. The study objective was to describe the hospital burden of pneumonia in the adult population in France.

Methods

This retrospective study was conducted from the National Health Insurance Database. All hospitalizations for pneumonia (all-cause) between 2013 and 2019 were included. Different risk categories for patients were established based on pneumococcal vaccine recommendations by French health authorities.

Results

A total of 2 199 240 episodes of CAP were registered over the study period (annual mean, 314 177 [standard deviation, 17 818.6]); 75% occurred in patients aged ≥65 years, among whom 47% were not classified in the moderate- or high-risk categories recommended for French pneumococcal vaccination. The incidence of CAP increased with age (117.9, 395.3, and 1916.7 per 100 000 for the age groups 18-49, 50-64, and ≥65 years, respectively, in 2019). Furthermore, being at risk of pneumococcal disease resulted in more severe outcomes, including longer episode duration (mean, 14 days in low-risk vs 17 days in high-risk patients) and higher risk of referral to critical care units (from 20% to 27%), of rehospitalization up to 180 days (from 39% to 67%), of in-hospital death (from 12% to 19%), and of 1-year mortality (from 26% to 49%).

Conclusions

This study establishes the incidence of CAP in adults in France, describes the significant burden of disease, and highlights the need for better prevention policies.

Pneumococcal serotypes and risk factors in adult community-acquired pneumonia 2018-20; a multicentre UK cohort study

Background

Higher-valency pneumococcal vaccines are anticipated. We aimed to describe serotype distribution and risk factors for vaccine-serotype community-acquired pneumonia (CAP) in the two years pre-SARS-CoV-2 pandemic.

Methods

We conducted a prospective cohort study of adults hospitalised with CAP at three UK sites between 2018 and 2020. Pneumococcal serotypes were identified using a 24-valent urinary-antigen assay and blood cultures. Risk factors associated with vaccine-type pneumonia caused by serotypes in the 13-, 15- and 20-valent pneumococcal conjugate vaccines (PCV13, PCV15, PCV20) and 23-valent pneumococcal polysaccharide vaccine (PPV23) were determined from multivariable analysis.

Findings

Of 1921 adults hospitalised with CAP, 781 (40.7%, 95% confidence intervals (CI) 38.5-42.9%) had pneumococcal pneumonia. A single PCV13-serotype was detected in 242 (31.0%, 95% CI 27.8-34.3%) pneumococcal CAP patients, mostly serotype 3 (171/242, 70.7%, 95% CI 64.5-76.0%). The additional two PCV15-serotypes were detected in 31 patients (4%, 95% CI 2.8-5.6%), and PCV20-non13-serotypes in 192 (24.6%), with serotype 8 most prevalent (123/192, 64.1%, 95% CI 57.1-70.5%). Compared to PCV13-serotype CAP, people with PCV20-non13 CAP were younger (median age 62 versus 72 years, p < 0.001) and less likely to be male (44% versus 61%, p = 0.01). PPV23-non13-serotypes were found in 252 (32.3%, 95% CI 29.1-35.6%) pneumococcal CAP patients.

Interpretation

Despite mature infant pneumococcal programmes, the burden of PCV13-serotype pneumonia remains high in older adults, mainly due to serotype 3. PCV20-non13-serotype pneumonia is more likely in younger people with fewer pneumococcal risk factors.

Funding

Unrestricted investigator-initiated research grant from Pfizer, United Kingdom; support from National Institute for Health Research (NIHR) Biomedical Research Centre, Nottingham.

Exploring the microbial landscape: uncovering the pathogens associated with community-acquired pneumonia in hospitalized patients

Objectives

This study aimed to investigate the etiology, clinical features, and outcomes of community-acquired pneumonia (CAP) in adults. Understanding the causative pathogens is essential for effective treatment and prevention.

Design

Between 2016-2018, 518 hospitalized adults with CAP and 241 controls without symptoms were prospectively enrolled. Urine samples were collected for pneumococcal urinary antigen tests and nasopharyngeal swabs for viral and bacterial analysis, combined with routine diagnostic care.

Results

Among the included CAP patients, Streptococcus pneumoniae was the most common pathogen, detected in 28% of patients, followed by Haemophilus influenzae in 16%. Viruses were identified in 28%, and concurrent viruses and bacteria were detected in 15%. There was no difference in mortality, length of stay, or symptoms at hospitalization when comparing patients with bacterial, viral, or mixed etiologies. Among the control subjects without respiratory symptoms, S. pneumoniae, H. influenzae, or Moraxella catarrhalis were detected in 5-7%, and viruses in 7%.

Conclusion

Streptococcus pneumoniae emerged as the predominant cause of CAP, followed closely by viruses and H. influenzae. Intriguingly, symptoms and outcome were similar regardless of etiology. These findings highlight the complexity of this respiratory infection and emphasize the importance of comprehensive diagnostic and treatment strategies.Clinical Trial Registration: ClinicalTrials.gov, identifier [NCT03606135].

Epidemiology of Pneumococcal Pneumonia in Louisville, Kentucky, and Its Estimated Burden of Disease in the United States

Streptococcus pneumoniae remains a primary pathogen in hospitalized patients with community-acquired pneumonia (CAP). The objective of this study was to define the epidemiology of pneumococcal pneumonia in Louisville, Kentucky, and to estimate the burden of pneumococcal pneumonia in the United States (US). This study was nested in a prospective population-based cohort study of all adult residents in Louisville, Kentucky, who were hospitalized with CAP from 1 June 2014 to 31 May 2016. In hospitalized patients with CAP, urinary antigen detection of 24 S. pneumoniae serotypes (UAD-24) was performed. The annual population-based pneumococcal pneumonia incidence was calculated. The distribution of S. pneumoniae serotypes was characterized. Ecological associations between pneumococcal pneumonia and income level, race, and age were defined. Mortality was evaluated during hospitalization and at 30 days, 6 months, and 1 year after hospitalization. Among the 5402 CAP patients with a UAD-24 test performed, 708 (13%) patients had pneumococcal pneumonia. The annual cumulative incidence was 93 pneumococcal pneumonia hospitalizations per 100,000 adults (95% CI = 91-95), corresponding to an estimated 226,696 annual pneumococcal pneumonia hospitalizations in the US. The most frequent serotypes were 19A (12%), 3 (11%), and 22F (11%). Clusters of cases were found in areas with low incomes and a higher proportion of Black or African American population. Pneumococcal pneumonia mortality was 3.7% during hospitalization, 8.2% at 30 days, 17.6% at 6 months, and 25.4% at 1 year after hospitalization. The burden of pneumococcal pneumonia in the US remains significant, with an estimate of more than 225,000 adults hospitalized annually, and approximately 1 out of 4 hospitalized adult patients dies within 1 year after hospitalization.