Impact of the emergence of non-vaccine pneumococcal serotypes on the clinical presentation and outcome of adults with invasive pneumococcal pneumonia

Emerging pneumococcal serotypes in Iraq: scope for improved vaccine development

Pneumococcal disease is a global public health concern as it affects the young, aged and the immunocompromised. The development of pneumococcal vaccines and their incorporation in the immunization programs has helped to reduce the global burden of disease. However, serotype replacement and the emergence of non-vaccine serotypes as well as the persistence of a few vaccine serotypes underscores the need for development of new and effective vaccines against such pneumococcal serotypes. In the Middle East, places of religious mass gatherings are a hotspot for disease transmission in addition to the global risk factors. Therefore, the periodic surveillance of pneumococcal serotypes circulating in the region to determine the effectiveness of existing prevention strategies and develop improved vaccines is warranted. Currently, there is a lack of serotype prevalence data for Iraq due to inadequate surveillance in the region. Thus, this review aims to determine the pneumococcal serotypes circulating in Iraq which may help in the development and introduction of improved pneumococcal vaccines in the country.

Community-acquired pneumonia in hospitalised patients: changes in aetiology, clinical presentation, and severity outcomes in a 10-year period

BACKGROUND AND OBJECTIVE

Community-acquired pneumonia (CAP) is a frequent cause of hospitalisation. Several factors, such as pandemics, vaccines and globalisation may lead to changes in epidemiology, clinical presentation, and outcomes of CAP, which oblige to a constant actualisation. We performed this study to analyse how these factors have evolved over a 10-year period.

MATERIALS AND METHODS

Patients diagnosed with CAP for two 1-year periods that were 10 years apart (2007-2008 and 2017-2018) were included. We compared microbiological information, clinical data and evolutive outcomes in the two periods. A mortality analysis was performed.

RESULTS

1043 patients were included: 452 during the first period (2007- 2008), and 591 during the second period (2017-2018). Bacterial aetiology did not change during the 10-year period, besides a slight increase in Staphylococcus aureus (0.9% vs 2.9%, p = 0.026). There was a decline in the proportion of bacteraemia in the second period (14.8% vs 9.6%, p = 0.012). The incidence of complicated pleural effusion and septic shock declined too (6.4% vs 3.6%, p = 0.04 and 15.5% vs 6.3%, p < 0.001). Respiratory failure and Intensive care unit (ICU) admission were similar in both periods. Variables independently associated with mortality were age and septic shock. Influenza vaccine was a protective factor against mortality in the second period.

CONCLUSIONS

We have not found relevant differences in the bacterial aetiology of CAP over this 10-year period. There has been a decline in septic complications of CAP such as septic shock, bacteraemia, and complicated pleural effusion. Influenza vaccination is an important tool to reduce mortality.KEY MESSAGESThere were no differences in the bacterial pathogens causing CAP among the 10-year study period. There has been a decline in septic complications of CAP such as septic shock, bacteraemia, and complicated pleural effusion.

Mechanistic Understanding of Lung Inflammation: Recent Advances and Emerging Techniques

Acute respiratory distress syndrome (ARDS) is a life-threatening lung injury characterized by an acute inflammatory response in the lung parenchyma. Hence, it is considered as the most appropriate clinical syndrome to study pathogenic mechanisms of lung inflammation. ARDS is associated with increased morbidity and mortality in the intensive care unit (ICU), while no effective pharmacological treatment exists. It is very important therefore to fully characterize the underlying pathobiology and the related mechanisms, in order to develop novel therapeutic approaches. In vivo and in vitro models are important pre-clinical tools in biological and medical research in the mechanistic and pathological understanding of the majority of diseases. In this review, we will present data from selected experimental models of lung injury/acute lung inflammation, which have been based on clinical disorders that can lead to the development of ARDS and related inflammatory lung processes in humans, including ventilation-induced lung injury (VILI), sepsis, ischemia/reperfusion, smoke, acid aspiration, radiation, transfusion-related acute lung injury (TRALI), influenza, Streptococcus (S.) pneumoniae and coronaviruses infection. Data from the corresponding clinical conditions will also be presented. The mechanisms related to lung inflammation that will be covered are oxidative stress, neutrophil extracellular traps, mitogen-activated protein kinase (MAPK) pathways, surfactant, and water and ion channels. Finally, we will present a brief overview of emerging techniques in the field of omics research that have been applied to ARDS research, encompassing genomics, transcriptomics, proteomics, and metabolomics, which may recognize factors to help stratify ICU patients at risk, predict their prognosis, and possibly, serve as more specific therapeutic targets.

Mortality changes for patients with pneumococcal pneumonia from 2012 to 2017 in Japan

INTRODUCTION

Pneumococcal pneumonia has a high morbidity and mortality in adults, especially those ≥65 years old. In the past decade, pneumococcal vaccination programs have been initiated worldwide, however, few data concerning mortality changes are available in pneumococcal pneumonia patients and there are no reports clarifying these current changes in Japan.

METHODS

Japanese patients ≥65 years old hospitalized with pneumococcal pneumonia between April 2012 and March 2018 were analyzed using the Diagnostic Procedure Combination database. In-hospital mortality was evaluated, and the odds ratios for this outcome in each fiscal year compared with that in 2012 was analyzed using multivariable logistic regression models.

RESULTS

Between 2012 and 2017, data of 47,375 pneumococcal pneumonia patients ≥65 years old were extracted. The incidence per 1000 person-years for in-hospital mortality was 60.4 in 2012, 56.8 in 2013, 63.2 in 2014, 56.1 in 2015, 73.0 in 2016, and 67.4 in 2017 and the odds ratios for in-hospital mortality in 2013, 2014, 2015, 2016, and 2017 compared with that in 2012 were 1.00, 1.05, 1.04, 1.06, and 0.98, respectively. There were no significant differences between 2012 and each year from 2013 to 2017. Low BMI; low ADL score; high A-DROP score; comorbid malignancy and heart failure; the coexistence of invasive pneumococcal infection; and the use of invasive mechanical ventilation were independent risk factors for in-hospital mortality.

CONCLUSIONS

There were no changes in in-hospital mortality in pneumococcal pneumonia patients between 2012 or each year from 2013 to 2017 and further epidemiological observations are necessary.

Streptococcus pneumoniae Serotypes Associated with Death, South Africa, 2012-2018

The Streptococcus pneumoniae polysaccharide capsule plays a role in disease severity. We assessed the association of serotype with case-fatality ratio (CFR) in invasive pneumococcal disease (IPD) and meningitis in South Africa, 2012-2018 (vaccine era), using multivariable logistic regression by manual backward elimination. The most common serotypes causing IPD were 8 and 19A. In patients <15 years of age, serotypes associated with increased CFR in IPD, compared with serotype 8 and controlling for confounding factors, were 11A, 13, 19F, 15A, and 6A. None of these serotypes were associated with increased CFR in meningitis. Among IPD patients >15 years of age, serotype 15B/C was associated with increased CFR. Among meningitis patients of all ages, serotype 1 was associated with increased CFR. PCV13 serotypes 1, 3, 6A, 19A, and 19F should be monitored, and serotypes 8, 12F, 15A, and 15B/C should be considered for inclusion in vaccines to reduce deaths caused by S. pneumoniae.

Burden of pneumococcal disease among adults in Southern Europe (Spain, Portugal, Italy, and Greece): a systematic review and meta-analysis

The aim was to summarize pneumococcal disease burden data among adults in Southern Europe and the potential impact of vaccines on epidemiology. Of 4779 identified studies, 272 were selected. Invasive pneumococcal disease (IPD) incidence was 15.08 (95% CI 11.01-20.65) in Spain versus 2.56 (95% CI 1.54-4.24) per 100,000 population in Italy. Pneumococcal pneumonia incidence was 19.59 (95% CI 10.74-35.74) in Spain versus 2.19 (95% CI 1.36-3.54) per 100,000 population in Italy. Analysis of IPD incidence in Spain comparing pre-and post- PCV7 and PCV13 periods unveiled a declining trend in vaccine-type IPD incidence (larger and statistically significant for the elderly), suggesting indirect effects of childhood vaccination programme. Data from Portugal, Greece and, to a lesser extent, Italy were sparse, thus improved surveillance is needed. Pneumococcal vaccination uptake, particularly among the elderly and adults with chronic and immunosuppressing conditions, should be improved, including shift to a higher-valency pneumococcal conjugate vaccine when available.

The potential role of pneumococcal conjugate vaccine in reducing acute respiratory inflammation in community-acquired pneumococcal pneumonia

Background

Pneumococcal conjugate vaccine (PCV) reduces both invasive pneumococcal disease (IPD) and other pneumococcal infections worldwide. We investigated the impact of stepwise implementation of childhood PCV programs on the prevalence of pneumococcal pneumonia, severity of acute inflammation, and associations between breakthrough pneumonia and pneumococcal serotypes in Taiwan.

Methods

In total, 983 children diagnosed with community-acquired pneumococcal pneumonia were enrolled between January 2010 and December 2015.

Results

Proportions of pneumococcal vaccinations increased each year in age-stratified groups with PCV7 (32.2%) as the majority, followed by PCV13 (12.2%). The proportion of pneumococcal pneumonia decreased each year in age-stratified groups, especially in 2–5 year group. Serotype 19A is the leading serotype either in vaccinated (6.4%) or unvaccinated patients (5.2%). In particular, vaccinated patients had significantly higher lowest WBC, lower neutrophils, lower lymphocytes and lower CRP values than non-vaccinated patients (p < 0.05). After stratifying patients by breakthrough infection, those with breakthrough pneumococcal infection with vaccine coverage serotypes had more severe pneumonia disease (p < 0.05).

Conclusion

Systematic childhood pneumococcal vaccination reduced the prevalence of community-acquired pneumococcal pneumonia, especially in 2–5 year group. Serotype 19A was the major serotype for all vaccine types in patients with pneumococcal pneumonia and severity of acute inflammatory response was reduced in vaccinated patients.

Epidemiology of pneumococcal diseases in Spain after the introduction of pneumococcal conjugate vaccines

In Spain, the use of pneumococcal conjugate vaccines (PCVs) has led to a decrease in the incidence of vaccine serotypes causing invasive and non-invasive disease in vaccinated and unvaccinated children and adults. Further, the coverage of most of the resistant serotypes by vaccines resulted in an overall decline in antibiotic resistance. As an undesirable effect, there was an increase in the non-vaccine serotypes causing infection, especially serotypes 1, 7F and 19A after PCV7 and serotype 8 after PCV13 approval, this making the beneficial effect of vaccination less apparent. The inclusion of PCVs in childhood vaccination schedules, its approval for use in healthy adults and the increasing number of serotypes covered by the vaccines in development are strong strategies in the fight against pneumococcal disease. Nonetheless, the epidemiology of Streptococcus pneumoniae infections must be still under surveillance to detect new changes, given the high capacity for recombination and adaptability of this always-surprising microorganism.

The shifting epidemiology and serotype distribution of invasive pneumococcal disease in Ontario, Canada, 2007-2017

Background

Ontario, Canada introduced a publicly-funded 13-valent pneumococcal conjugate vaccine (PCV13) for infants in 2010, replacing the 10-valent (PCV10, 2009–2010) and the 7-valent (PCV7, 2005–2009) conjugate vaccine programs; a 23-valent pneumococcal polysaccharide vaccine (PPV23) has been available for older adults since 1996. We examined the epidemiology and serotype distribution of invasive pneumococcal disease (IPD) in Ontario in the context of provincial immunization programs.

Methods

We included confirmed IPD cases reported in Ontario between 2007 and 2017. We grouped serotypes according to Ontario’s current immunization program (PCV13, PPV23, and non-vaccine-preventable) and calculated incidence rates (per 100,000 population) using population data.

Results

Between 2007 and 2017, annual incidence of IPD in Ontario ranged between 7.3 and 9.7/100,000 per year. Measures of illness severity were high throughout the period of surveillance. After PCV13 program implementation in 2010, incidence due to PCV13 serotypes decreased significantly across all age groups, with the greatest reductions in children <5 years and adults ≥65 years. Conversely, incidence due to PPV23 unique serotypes increased significantly between 2007 and 2017, with the greatest increases observed in adults 50–64 years (1.4 to 3.5/100,000) and ≥65 years (2.3 to 7.2/100,000). Similar increases were observed in incidence due to non-vaccine-preventable serotypes among all age groups, except infants <1 year. Within specific serotypes, incidence due to serotypes 3 (0.42 to 0.98/100,000) and 22F (0.31 to 0.72/100,000) increased significantly between 2007 and 2017, while incidence due to serotypes 19A and 7F decreased significantly during the PCV13 period (2010–2017).

Conclusions

Eight years after PCV13 implementation in Ontario, our data suggest both direct and indirect effects on serotype-specific incidence in young children and older adults. However, overall provincial rates have remained unchanged, and IPD continues to be a severe burden on the population. The rising incidence of IPD due to PPV23 unique and non-vaccine-preventable serotypes, and the growing burden of serotypes 3 and 22F, require further study.

Factors Associated With Severe Nonmeningitis Invasive Pneumococcal Disease in Adults in France

Background

In France, pneumococcal vaccination in adults is recommended for risk groups (chronic conditions/immunosuppression). We conducted a study on invasive pneumococcal disease (IPD) in adults to identify factors associated with disease severity and death.

Methods

We included IPD cases, excluding meningitis, from 25 acute care hospitals in 6 regions. We defined severe cases as those with shock or severe sepsis or intensive care unit admission/mechanical ventilation. We included deaths occurring within 30 days of hospitalization. Infectious disease specialists collected clinical/microbiological data on cases.

Results

During 2014–2017, 908 nonmeningitis IPD cases were diagnosed; 48% were severe, 84% had comorbidities, 21% died. Ninety percent of cases with comorbidities who previously sought health care were not vaccinated against pneumococcus. Compared with previously healthy cases, the risk of severe IPD increased from 20% (adjusted risk ratio [aRR], 1.2; 95% confidence interval [CI], 1.0–1.4) in cases with 1–2 chronic diseases to 30% (aRR, 1.3; 95% CI, 1.0–7.0) in those with >2 chronic diseases. Among risk groups, 13-valent pneumococcal conjugate vaccine (PCV13) serotypes and 23-valent pneumococcal polysaccharide vaccine (PPSV23) nonPCV13 serotypes were more likely to induce severe IPD compared with nonvaccine serotypes (aRR, 1.5; 95% CI, 1.3–1.9; aRR, 1.3; 95% CI, 1.0–1.5, respectively).

Conclusions

We observed a cumulative effect of concurrent comorbidities on severe IPD. Vaccine serotypes were more likely to induce severe IPD among risk groups. The missed opportunities for vaccination underscore the need to enhance vaccination in risk groups.

What is the clinical relevance of drug-resistant pneumococcus?

PURPOSE OF REVIEW

Pneumococcal infections are a major cause of morbidity and mortality worldwide. In recent years, Streptococcus pneumoniae has shown increasing resistance to a several antibiotics, becoming a worldwide problem. The impact of antibiotic resistance of S. pneumoniae on clinical outcomes is still controversial. The principal reason for this controversy is the existence of several factors related to the patients and to the pathogen that may influence how antibiotic resistance patterns affect clinical outcomes. The aim of this review is to discuss current knowledge of the epidemiological data on antibiotic resistance; we also discuss mechanisms and risk factors for antibiotic resistance.

RECENT FINDINGS

The phenomenon of serotype replacement after the introduction of conjugate pneumococcal vaccinations and the escalation of antibiotic resistance worldwide remains an important issue in terms of their impact on clinical outcomes in pneumococcal disease. Antimicrobial resistance of pneumococcus leads to changes in the clinical presentation of pneumococcal disease, making it more difficult to diagnose and to treat. Consumption of antibiotics in the community is directly proportional to antimicrobial resistance. Carriage of S. pneumoniae and infection with antibiotic-resistant pneumococcus is associated with prior antibiotic therapy, extremes of age, presence of comorbidities (i.e. COPD), attendance at child day care centers, crowded conditions, intra-familial transmission, and nursing home residence.

SUMMARY

Antibiotic-resistant S. pneumoniae is a worldwide problem. The implementation of several strategies including vaccine campaigns, prudent use of current antibiotics, and programs for the surveillance of pneumococcal infections, could limit the increasing resistance of this pathogen to antimicrobials.

Factors associated with pneumococcal polysaccharide vaccination of the elderly in Spain: A cross-sectional study

Vaccination of the elderly is an important factor in limiting the impact of pneumonia in the community. The aim of this study was to investigate the factors associated with pneumococcal polysaccharide vaccination in patients aged ≥ 65 years hospitalized for causes unrelated to pneumonia, acute respiratory disease, or influenza-like illness in Spain. We made a cross-sectional study during 2013-2014. A bivariate analysis was performed comparing vaccinated and unvaccinated patients, taking into account sociodemographic variables and risk medical conditions. A multivariate analysis was performed using multilevel regression models. 921 patients were included; 403 (43.8%) had received the pneumococcal vaccine (394 received the polysaccharide vaccine). Visiting the general practitioner ≥ 3 times during the last year (OR = 1.79; 95% CI 1.25-2.57); having received the influenza vaccination in the 2013-14 season (OR = 2.57; 95% CI 1.72-3.84) or in any of the 3 previous seasons (OR = 11.70; 95% CI 7.42-18.45) were associated with receiving the pneumococcal polysaccharide vaccine. Pneumococcal vaccination coverage of hospitalized elderly people is low. The elderly need to be targeted about pneumococcal vaccination and activities that encourage healthcare workers to proactively propose vaccination might be useful. Educational campaigns aimed at the elderly could also help to increase vaccination coverages and reduce the burden of pneumococcal disease in the community.

Immunogenicity and safety of a 23-valent pneumococcal polysaccharide vaccine in Chinese healthy population aged >2 years: A randomized, double-blinded, active control, phase III trial

Streptococcus pneumoniae is an important pathogen causing invasive diseases such as sepsis, meningitis, and pneumonia. Vaccines have become the most effective way to prevent pneumococcal infections. This phase III trial was designed to evaluate the immunogenicity and safety of a 23-valent pneumococcal polysaccharide vaccine in Chinese healthy population aged >2 years. We conducted a randomized, double-blinded, active-controlled, multicenter trial in which 1660 healthy population (>2 years of age) were randomly assigned in a 1 : 1 ratio to receive 2 intramuscular doses of either the treatment vaccine or the active control vaccine, PNEUMOVAX 23. The surveillance period was 30 days. The primary end point was the 2-fold increase rate of anti-pneumococcal antibody for all 23 included serotypes in each group. In the intention-to-treat cohort, the 2-fold increase rate of anti-pneumococcal antibody for 23 included serotypes varied from 62.47% to 97.01% in the treatment group, and from 51.49% to 95.77% in the control group. According to -10% non-inferiority margin and 95% confidence intervals of rate difference, almost all included serotypes of the treatment group reached non-inferiority to control group except for serotype 6B, the lower limit of rate difference of which was -10.00%, equal to the non-inferiority margin. The 2-fold increase rates of anti-pneumococcal antibody were significantly higher in the treatment group for serotype 2, 3, 4, 10A, 11A and 20. Furthermore, for all 23 serotypes, IgG geometric mean concentrations (GMCs) at day 30 were significantly higher in treatment group for serotype 2, 3, 4, 9 V, 10A, 11A, 15 B, 18C, 19 A, 22 F and 33 F. Higher geometric mean fold increase (GMFI) were also observed in the treatment group correspondingly. Serious adverse events occurred in 3 of 830 participants in the treatment group (0.36%) and 2 of 830 participants in the control group (0.24%). No death occurred during the trial. The frequencies of both solicited and unsolicited adverse events (AEs) were small lower in the treatment group (34.34% vs 35.66% for solicited AEs, 4.34% vs 5.42% for unsolicited AEs). Both vaccines were well tolerated and most AEs were mild or moderate in intensity. The newly vaccine was well tolerated and immunologically non-inferior to the active control vaccine PNEUMOVAX 23 for all 23 vaccine serotypes in the Chinese population (>2 years of age).

Nasopharyngeal pneumococcal carriage rates among HIV-infected adults following widespread pediatric use of conjugate pneumococcal vaccine-13

BACKGROUND

Nasopharyngeal pneumococcal carriage rates among HIV-infected adults has not been described since conjugate pneumococcal vaccine-13 (PCV13) was added to the universal infant and childhood vaccination schedule in 2010.

METHODS

HIV-infected adults presenting for routine health care visits to the Designated AIDS Center in Syracuse, NY between December 2013 and June 2015 were eligible for enrollment. Demographic, medical, and social history were recorded after obtaining informed consent. Nasopharyngeal samples were collected and cultured for the presence of Streptococcus pneumoniae using standard microbiologic techniques. Antibiotic susceptibility testing was performed using E-test→.

RESULTS

707 nasopharyngeal samples were collected from 414 HIV-infected adults. 18 samples were culture positive for S. pneumoniae; 1 (6%) isolate was of vaccine-type, 9 (50%) were non-vaccine types, and 8 (44%) were non-typeable. The 18 isolates were recovered from 15 different patients (4% of those enrolled). Three patients were culture positive for pneumococcus isolated from 2 consecutive samples, with non-typeable pneumococci identified consecutively from 2 patients and serotype 35B identified consecutively from 1 patient. The most commonly identified non-vaccine serotypes were 35B and 15B/C. Identified pneumococci were penicillin and cefotaxime susceptible.

CONCLUSION

Four percent of HIV-infected adults in our study population were colonized with S. pneumoniae. The non-vaccine serotypes 35B and 15B/C predominated.

Declining mortality from adult pneumococcal infections linked to children's vaccination

OBJECTIVE

To determine changes in mortality among adults with invasive pneumococcal disease (IPD) after introducing pneumococcal conjugate vaccines (PCVs) in children.

METHODS

An active surveillance of adults with culture-proven IPD in Barcelona. Serotype-specific mortality and rates of disease and death were analysed in three periods: baseline (1994-2001), PCV7 (2002-2009) and PCV13 (2010-2013).

RESULTS

Overall, IPD caused by PCV7 serotypes was associated with increased case fatality rate (24 percent). In patients 18-64 years (baseline vs. PCV7 vs. PCV13 periods), case fatality rate from IPD decreased (22 vs.14 vs. 12 percent), and it was associated with a decline in PCV7 serotypes (3.56 vs. 2.80 vs. 1.49 cases/10(5) person-years) and in PCV7 serotypes-specific death (0.74 vs. 0.53 vs. 0.09 deaths/10(5) person-years). In patients ≥65 years, case fatality rate did not change (24 vs. 22 vs. 24 percent); however, there was a decline in PCV7 serotypes-specific death (4.94 vs. 3.58 vs. 2.45 deaths/10(5) person-years), and an increase in non-PCV serotypes-specific death (2.55 vs. 3.70 vs. 4.09 deaths/10(5) person-years).

CONCLUSIONS

The use of PCVs for children was associated with a reduction of mortality from IPD in adults 18-64 years, through the indirect effect of herd protection. In older adults, age-related factors could play a role in IPD mortality.

The potential role of 13-valent pneumococcal conjugate vaccine in preventing respiratory complications in bacteraemic pneumococcal community-acquired pneumonia

INTRODUCTION

Pneumococcal 13-valent vaccine (PCV-13) has a potential role in preventing bacteraemic pneumococcal pneumonia and its complications, but little is known about its ability to specifically prevent respiratory complications. Our aim were to analyse the pneumococcal serotypes associated with the development of respiratory complications and the potential role of PCV-13 in preventing respiratory complications in bacteraemic pneumococcal pneumonia.

MATERIAL AND METHODS

We analysed demographic characteristics, comorbidities, antibiotic resistances and the outcomes of a cohort of 65 vaccine-naïve bacteraemic pneumococcal pneumonias, stratified by the pneumococcal serotypes included in PCV13 vs. those not included. Complications were clustered as follows: respiratory complications (hypoxemic respiratory failure; mechanical ventilation), systemic complications (septic shock; multiorgan failure), suppurative complications (empyema; pleural effusion; lung abscess).

RESULTS

From a population of 65 CAP-SP, 47.7% of the isolates belonged to PCV-13 serotypes group. No differences in comorbidities or clinical manifestations were found between groups. With regard to biochemical parameters, we found more profound hypoxemia levels in PCV-13 serotypes group comparing to non-vaccine group [PaO2/FiO2 209 (63) vs. 268 (57); p=0.007]. Global complications were identified in 69.2% (45 patients), and the most frequent were respiratory complications, found in 47.7%. Respiratory complications were detected more frequently in PCV-13 groups compared to non-vaccine groups (61.3% vs. 35.3%; p=0.036). Overall 30-day mortality was 30.8%. Mortality was similar between both groups (25.8% vs. 35.3%; p=0.408).

CONCLUSIONS

Pneumococcal 13-valent conjugate vaccine includes the serotypes which cause more respiratory complications in our series; these serotypes were not associated with higher mortality in our series. PCV-13 may have a potential role in preventing respiratory complications due to bacteraemic pneumonoccal pneumonia.

Invasive pneumococcal disease: Clinical outcomes and patient characteristics 2-6 years after introduction of 7-valent pneumococcal conjugate vaccine compared to the pre-vaccine period, the Netherlands

BACKGROUND

Implementation of 7-valent pneumococcal conjugate vaccine (PCV7) in the Dutch national immunization program for infants led to a shift from vaccine to non-vaccine serotypes in invasive pneumococcal disease (IPD) in all age groups. We studied the impact of the serotype shift on clinical syndromes and outcomes.

METHODS

Pneumococcal isolates from hospitalized IPD patients obtained from nine sentinel microbiology laboratories, covering 25% of the Dutch population, were serotyped. Clinical syndromes, outcomes and patient characteristics in the post-PCV7 (2008-2012) period were compared with the pre-PCV7 period (2004-2006). Serotype specific propensity of the association with empyema, meningitis and death was calculated.

RESULTS

Invasive pneumonia incidence significantly decreased in children <5 years and elderly ≥65 years, but increased in 5-64 years old from 4.92 to 5.58 cases/100.000/year (RR 1.13 95% CI 0.99-1.29). Empyema incidence significantly increased in elderly 65 years and older from 0.61 to 2.60 cases/100.000/year (RR 4.28 95% CI 1.97-9.33), mainly due to serotype 1. The incidence of meningitis only declined significantly in children <5 years. IPD case-fatality decreased in children <5 years from 5% to 3%, in 5-64 years old from 9% to 7% and in elderly ≥65 years significantly from 22% to 17%, due to lower case-fatality rates for most emerging non-PCV7 serotypes.

CONCLUSIONS

An increase in empyema incidence was observed in persons ≥65 years old in the post-PCV7 era, mainly due to the emergence of serotype 1, although overall IPD case-fatality decreased. Extended conjugate vaccines that target serotype 1 or serotypes with high case-fatality may offer further reduction of pneumococcal disease burden.

Isolation site influences virulence phenotype of serotype 14 Streptococcus pneumoniae strains belonging to multilocus sequence type 15

Streptococcus pneumoniae is a diverse species causing invasive as well as localized infections that result in massive global morbidity and mortality. Strains vary markedly in pathogenic potential, but the molecular basis is obscured by the diversity and plasticity of the pneumococcal genome. We have previously reported that S. pneumoniae serotype 3 isolates belonging to the same multilocus sequence type (MLST) differed markedly in in vitro and in vivo phenotypes, in accordance with the clinical site of isolation, suggesting stable niche adaptation within a clonal lineage. In the present study, we have extended our analysis to serotype 14 clinical isolates from cases of sepsis or otitis media that belong to the same MLST (ST15). In a murine intranasal challenge model, five ST15 isolates (three from blood and two from ears) colonized the nasopharynx to similar extents. However, blood and ear isolates exhibited significant differences in bacterial loads in other host niches (lungs, ear, and brain) at both 24 and 72 h postchallenge. In spite of these differences, blood and ear isolates were present in the lungs at similar levels at 6 h postchallenge, suggesting that early immune responses may underpin the distinct virulence phenotypes. Transcriptional analysis of lung tissue from mice infected for 6 h with blood isolates versus ear isolates revealed 8 differentially expressed genes. Two of these were exclusively expressed in response to infection with the ear isolate. These results suggest a link between the differential capacities to elicit early innate immune responses and the distinct virulence phenotypes of clonally related S. pneumoniae strains.

Impact of vaccination on invasive pneumococcal disease in adults with focus on the immunosuppressed

Pneumococcal conjugate vaccine (PCV13) has been recently added to the vaccine recommendations for immunosuppressed adults (ISP). We conducted a multicenter observational prospective study aimed to assess the evolving epidemiology of invasive pneumococcal disease (IPD) in adults, with especial focus on ISP. All IPD cases admitted from 1999 to 2014 were included. ISP was defined as patients on current cancer chemotherapy, immunosuppressive therapy for autoimmune disease, biological therapy, chronic systemic steroid use, hemodialysis, neutropenia or HIV infection. A total of 799 IPD episodes were analyzed, 198 were considered ISP. IPD incidence decreased from 20 to 8/100,000-population year (p < 0.004) over the study period. No changes in mortality were observed. Penicillin resistance experienced a significant decline. In 694 episodes the serotype was known. Global vaccine coverage considering the whole study period, was for PCV7 21.6% vs. 28.8% in general and in immunosuppressed population (p = 0.04) and for PCV13 64.5% and 56.6% respectively (p = 0.05). The proportion of IPD isolates included in PCV7 and PCV13 significantly decreased over time. A reduction in the incidence of IPD in adults was seen late after the vaccine licensure, both in general population and in ISP. Coverage of PCV13 vaccine might be suboptimal for ISP in the coming years.

A Bivalent Vaccine Based on a PB2-Knockout Influenza Virus Protects Mice From Secondary Pneumococcal Pneumonia

BACKGROUND

Secondary bacterial infections after influenza can be a serious problem, especially in young children and the elderly, yet the efficacy of current vaccines is limited. Earlier work demonstrated that a replication-incompetent PB2-knockout (PB2-KO) influenza virus possessing a foreign gene in the coding region of its PB2 segment can serve as a platform for a bivalent vaccine.

METHODS

In the current study, we generated the PB2-KO virus expressing pneumococcal surface protein A (PspA), PB2-KO-PspA virus, the replication of which is restricted to PB2-expressing cells. We then examined the protective efficacy of intranasal immunization with this virus as a bivalent vaccine in a mouse model.

RESULTS

High levels of influenza virus-specific and PspA-specific antibodies were induced in the serum and airways of immunized mice. The intranasally immunized mice were protected from lethal doses of influenza virus or Streptococcus pneumoniae. These mice were also completely protected from secondary pneumococcal pneumonia after influenza virus infection.

CONCLUSIONS

These findings indicate that our recombinant influenza virus serves as a novel and powerful bivalent vaccine against primary and secondary pneumococcal pneumonia as well as influenza.

Blood culture fluorescence rates predict severity and mortality of invasive pneumococcal pneumonia

Invasive pneumococcal pneumonia is associated with high rates of mortality. Clinical assessment tools have poor sensitivity for predicting clinical outcomes. Molecular measurements of bacterial load correlate closely with clinical outcome but require specialist facilities and expertise. This study describes how routine blood culture testing can estimate bacterial load and predict clinical outcome for invasive pneumococcal pneumonia. Between December 2009 to March 2014, clinical and laboratory data were collected for 50 patients with Streptococcus pneumoniae bacteraemia secondary to community-acquired pneumonia. Fluorescence rates (FR) were calculated from growth curves generated by BACTEC blood culture analysers by dividing change in fluorescence units (FU), measured at the first point of detectable fluorescence and at the point of automated BACTEC positivity, by time in hours. The mean age of the patients was 70.6 years (49.6–86.3). Forty patients survived invasive pneumococcal disease and ten patients died. These two groups did not significantly differ by demographic or clinical characteristics. The mean FR for the non-survival group (3.62 × 10⁻³ FU/h) was significantly higher (p < 0.001) than that of the survival group (1.73 × 10⁻³ FU/h). FR did not vary by serotype. We determined that an FR of 2.59 × 10⁻³ FU/h might represent a useful threshold for predicting high mortality risk with a sensitivity of 91 % and a specificity of 97 %. Our FR calculation uses cheap and accessible routine blood culture techniques to predict mortality in a small retrospective cohort study. In patients admitted to hospital with pneumococcal bacteraemia and, potentially, other organisms, this single tool could guide early escalation of clinical care.

Bacteraemic and non-bacteraemic/urinary antigen-positive pneumococcal community-acquired pneumonia compared

The diagnosis of invasive pneumococcal pneumonia is based mainly on bacteraemia. Episodes without bacteraemia, but with a positive urinary antigen test (UAT), are considered non-invasive. We determined differences in outcome between patients with bacteraemic and non-bacteraemic/UAT-positive pneumococcal community-acquired pneumonia (CAP). Adult patients with clinical and radiological evidence of CAP with blood cultures and UAT tests performed at presentation in three Dutch laboratories between June 2008 and May 2010 were included. Clinical characteristics were retrospectively extracted from hospital records. Overall, 168 patients had non-bacteraemic/UAT-positive pneumococcal CAP and 123 had bacteraemic pneumococcal CAP. The day-30 mortality was 9% and 13% for non-bacteraemic/UAT-positive and bacteraemic pneumococcal CAP patients, respectively [risk difference -4%, 95% confidence interval (CI) -11% to +3%, p = 0.28]. In a multivariable logistic regression model, age ≥ 65 years, admission to the intensive care unit/coronary care unit (ICU/CCU) and presence of an immunocompromising condition were associated with day-30 mortality. A non-significant association with mortality was found for bacteraemia [odds ratio (OR) 2.21, 95% CI 0.94-5.21, p = 0.07). No such trend was found for UAT positivity. The median lengths of hospital stay were 8 [interquartile range (IQR) 5-14] and 10 (IQR 6-18) days for non-bacteraemic/UAT-positive and bacteraemic pneumococcal CAP patients, respectively (p = 0.05). As compared to non-bacteraemic/UAT-positive pneumococcal CAP, bacteraemic pneumococcal CAP has a stronger association with day-30 mortality.

Differences in serious clinical outcomes of infection caused by specific pneumococcal serotypes among adults

BACKGROUND

Infections due to Streptococcus pneumoniae serotypes differ in clinical manifestations among adults, varying in propensity for severity, invasiveness, and lethality. To characterize differences in serious outcomes between pneumococcal serotypes, we systematically reviewed the literature.

METHODS

After distilling 676 hits to 28 relevant articles, statistically significant differences in individual serotypes associated with serious clinical outcomes were assessed. Serotypes associated with elevated risk of serious clinical outcomes were evaluated in terms of serotypes included in licensed adult pneumococcal vaccines (i.e., 23-valent pneumococcal polysaccharide vaccine (PPSV23) and 13-valent pneumococcal conjugate vaccine (PCV13)). Repeated findings were considered a measure of robustness.

RESULTS

Among adult studies evaluating serious clinical outcomes, the following serotypes were associated with elevated risk: Empyema (serotypes 1, 3, 5, 7F, 8, 19A), necrotizing pneumonia (serotype 3), septic shock (serotypes 3, 19A), meningitis (repeatedly serotypes 10A, 15B, 19F, 23F), reduced quality-adjusted life years (QALYs, serotypes 15B, 3, 10A, 9N, 19F, 11A, 31), and increased case-fatality rates (repeatedly serotypes 3, 6B, 9N, 11A, 16F, 19F, 19A).

CONCLUSION

Both vaccine formulations include multiple pneumococcal serotypes associated with increased risk for serious clinical outcomes. Three studies found elevated risk from serotype 6A (unique to PCV13). Fourteen studies found elevated risk from nine serotypes unique to PPSV23 (repeatedly: case-fatality-11A & 9N, meningitis-10A & 15B). Seven studies found elevated risk from serotypes not represented in either vaccine formulation (notably 16F). The pneumococcal serotypes repeatedly associated with elevated risk of serious outcomes in adults are an important consideration for vaccine policy making.

Pneumococcal empyema and complicated pneumonias: global trends in incidence, prevalence, and serotype epidemiology

This review evaluates the serotype epidemiology of complicated pneumococcal pneumonia (CPP) during the period 1990–2012. PubMed and EMBASE were searched using the terms “empyema”, “complicated pneumonia”, “pleural infection”, “necrotizing pneumonia”, “pleural effusion”, “parapneumonic effusion”, “pneumatocele”, or “lung abscess”; “pneumococcal” or “Streptococcus pneumoniae”; and “serotype” for studies on the epidemiology of complicated pneumonias published from January 1, 1990 to October 1, 2013. Studies with data on incidence and serotypes were included; reviews, case reports, and conference abstracts were excluded. Of 152 papers, 84 fitted the inclusion criteria. A few pneumococcal serotypes were predominant causes of CPP, particularly serotypes 1, 19A, 3, 14, and 7F. CPP was a more common manifestation of pneumococcal disease among older (>2 years old) than younger children. The data support increases in both reported incidence rates and proportions of CPP in children and adults during the period 1990–2012; specific increases varied by geographic region. The proportions of serotype 3 and, particularly in Asia, serotype 19A CPP have increased, whereas most studies show declines in serotype 14. Serotype 1 has been a predominant cause of CPP since 1990, while antibiotic resistance was infrequent among serotype 1 isolates. The reported incidence and proportions of CPP among pneumonia cases steadily increased from 1990 to 2012. Several factors might account for these increases, including enhanced disease detection due to a higher index of suspicion, more sophisticated diagnostic assays, and changes in the prevalence of serotypes with capacity to invade the pleural space that were not targeted by the 7-valent pneumococcal conjugate vaccine (PCV7).

Can the success of pneumococcal conjugate vaccines for the prevention of pneumococcal diseases in children be extrapolated to adults?

Before conjugate pneumococcal vaccines (PCVs) were introduced it was estimated that Streptococcus pneumoniae caused 500,000 cases of pneumonia, 50,000 cases of bacteremia and 3000 cases of meningitis annually in the United States in both children and adults. After 10 years of routine use of the 7-valent pneumococcal conjugate vaccine (PCV7) the incidence of vaccine-type pneumococcal diseases (PDs) had significantly decreased in vaccinated children (direct effect) and unvaccinated subjects of all ages (indirect effect). Second generation, higher-valent PCVs, especially 13-valent (PCV13), routinely implemented since 2010, have reduced the incidence of PDs caused by the six additional non-PCV7 serotypes, in both vaccinated and unvaccinated subjects. The licence for this vaccine has recently been extended to include adults aged 18 to 49 in Europe. Although PCV13 has an indirect effect on IPD in adults, this will probably not achieve the same level of disease control in adults and the elderly (especially those at high risk) as that obtained in vaccinated children. As highlighted in this paper, differences exist between children and adults for PD manifestations (incidence, morbidity and mortality) and serotypes isolated in nasopharyngeal carriage and diseases, so benefits from adult vaccination must be considered in this light. PCV13 induces an immune response in adults that is non-inferior for all serotypes common with the 23-valent plain polysaccharide vaccine that is currently recommended for adults and even superior for many serotypes. Although there is no evidence that this immune response translates to clinical efficacy in adults as seen in children, the results from a randomised trial in The Netherlands, expected in 2014, should provide the missing evidence. This evidence and efficient surveillance systems should provide the necessary data, essential for policy makers in their decisions on adult pneumococcal vaccination policies.

Clinical features of adults with seven-valent-conjugated-vaccine-serotype pneumococcal pneumonia

BACKGROUND

Despite the reduction in adult invasive pneumococcal disease through 'herd protection' consequent to the introduction of childhood pneumococcal conjugate vaccination (PCV), a significant proportion of adults continue to develop pneumococcal pneumonia caused by one of the seven serotypes included in the seven-valent conjugated pneumococcal vaccine (PCV7). The clinical features and outcomes of these adults have not been previously reported.

METHODS

Adults recruited over a three year period to a large prospective cohort study of community acquired pneumonia (CAP) were investigated for pneumococcal serotypes using a validated multiplex immunoassay (Bio-plex). The baseline characteristics and outcomes of adults with PCV7-serotype CAP in comparison to those with non-PCV7-serotype CAP were established.

RESULTS

Pneumococcal aetiology was identified in 415 of 1166 (35.6%) individuals, and a serotype determined in 287 (69.2%). Following exclusion of three individuals with both a PCV7 and non-PCV7 serotype, 77 of the remaining 284 (27.1%) adults had CAP due to PCV7 serotypes. Adults with PCV7-serotype CAP were older (median years (inter-quartile range) 73.3 (60.8-84.4) versus 65.0 (46.1-78.0); p=0.001) and were more likely to have a World Health Organisation performance status ≥1 (odds ratio (OR) 2.05, 95% confidence interval (CI) 1.21-3.50).The presence of stroke (adjusted OR 2.84, 95% CI 1.36-5.95) and dementia (adjusted OR 3.55, 95% CI 1.26-9.94) as underlying co-morbid illnesses were independently associated with PCV7-serotype CAP; 30-day mortality was significantly greater in adults with PCV7-serotype CAP (adjusted OR 4.38, 95% CI 1.85-10.34).

CONCLUSION

A significant proportion of adults continue to develop PCV7-serotype CAP in the era of childhood pneumococcal conjugate vaccination. These adults are more likely to have stroke and dementia as underlying co-morbid illnesses, and have a higher 30-day mortality. A combination of pneumococcal transmission factors, host factors and pneumococcal serotype specific characteristics are likely to explain these findings.

Pneumococcal infection in adults: burden of disease

To overview the present global burden of pneumococcal disease is important because new preventive measures such as the pneumococcal conjugate vaccine 13 are currently being evaluated. Pneumococcal disease is roughly divided into non-invasive and invasive disease. The burden of non-invasive pneumococcal disease in adults is mainly determined by community-acquired pneumonia. Pneumococcal pneumonia has high incidence rates and carries a high mortality risk, especially in the elderly. Within the cluster of invasive pneumococcal diseases, pneumonia also represents the most common infectious source. Incidence and mortality rates of both non-invasive and invasive disease have changed as a result of pneumococcal vaccination in children. However, especially elderly patients with comorbidities remain vulnerable to morbidity and mortality caused by pneumococcal disease. The current review summarizes the current knowledge on the epidemiology including outcome of the main clinical forms of pneumococcal disease, with a special focus on elderly patients. Furthermore, the economic burden and future vaccine strategies are briefly discussed.

Compared effectiveness of the 7-valent pneumococcal conjugate vaccine in children with the 13-valent vaccine in adults

13-valent-pneumococcal conjugated vaccine was recently approved in the USA and Europe for adults 50 years of age or more. But this approval was followed by recommendations limiting its use to immunocompromised and asplenic patients. The extension of indications to adults was based on the well-demonstrated clinical effectiveness in infants less than 2 years of age, and on a better immune response either quantitatively or qualitatively with conjugated vaccines compared to the immunogenicity of plain polysaccharide vaccines. Nevertheless, the issue was to know whether results observed with the 7-valent pneumococcal conjugate vaccine in children are reproducible in adults with the 13-valent. The answer was given by comparing the epidemiological and physiopathological data, and the immunological response of the two populations. Very few clinical effectiveness studies in adults are available. We had for aim to assess these various issues in infants and adults. A lot of questions remain, such as the unknown impact of serotype replacement with the 13-valent pneumococcal conjugated vaccine on the clinical epidemiology and emergent Streptococcus pneumoniae pathogenicity, while waiting for the CAPITA study results expected in 2014.

Clinical implications of pneumococcal serotypes: invasive disease potential, clinical presentations, and antibiotic resistance

Streptococcus pneumoniae can asymptomatically colonize the nasopharynx and cause a diverse range of illnesses. This clinical spectrum from colonization to invasive pneumococcal disease (IPD) appears to depend on the pneumococcal capsular serotype rather than the genetic background. According to a literature review, serotypes 1, 4, 5, 7F, 8, 12F, 14, 18C, and 19A are more likely to cause IPD. Although serotypes 1 and 19A are the predominant causes of invasive pneumococcal pneumonia, serotype 14 remains one of the most common etiologic agents of non-bacteremic pneumonia in adults, even after 7-valent pneumococcal conjugate vaccine (PCV7) introduction. Serotypes 1, 3, and 19A pneumococci are likely to cause empyema and hemolytic uremic syndrome. Serotype 1 pneumococcal meningitis is prevalent in the African meningitis belt, with a high fatality rate. In contrast to the capsule type, genotype is more closely associated with antibiotic resistance. CC320/271 strains expressing serotype 19A are multidrug-resistant (MDR) and prevalent worldwide in the era of PCV7. Several clones of MDR serotype 6C pneumococci emerged, and a MDR 6D clone (ST282) has been identified in Korea. Since the pneumococcal epidemiology of capsule types varies geographically and temporally, a nationwide serosurveillance system is vital to establishing appropriate vaccination strategies for each country.