The paradox in pneumococcal serotypes: highly invasive does not mean highly lethal

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.

Serotype 1 pneumococcus: epidemiology, genomics, and disease mechanisms

Streptococcus pneumoniae (the 'pneumococcus') is a significant cause of morbidity and mortality worldwide, causing life-threatening diseases such as pneumonia, bacteraemia, and meningitis, with an annual death burden of over one million. Discovered over a century ago, pneumococcal serotype 1 (S1) is a significant cause of these life-threatening diseases. Our understanding of the epidemiology and biology of pneumococcal S1 has significantly improved over the past two decades, informing the development of preventative and surveillance strategies. However, many questions remain unanswered. Here, we review the current state of knowledge of pneumococcal S1, with a special emphasis on clinical epidemiology, genomics, and disease mechanisms.

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.

Vaccines against major ICU pathogens: where do we stand?

PURPOSE OF REVIEW

Multidrug resistance of bacterial pathogens has confronted physicians around the world with the threat of inefficacy of the antibiotic regime, which is particularly important for patients with sepsis. Antibiotic resistance has revived search for alternative nonantibiotic strategies. Among them, prophylaxis by vaccination is an appealing concept.

RECENT FINDINGS

This review provides a compact overview on available vaccines against community-acquired pathogens such as pneumococci (in synergy with influenza) and meningococci and provides an overview on the ongoing developments of vaccines targeting typical nosocomial pathogens such as Clostridium difficile, Staphylococcus aureus, Acintetobacter baumannii, Klebsiella pneumonia, and Pseudomonas aeruginosa.

SUMMARY

The effects achieved by some conjugated vaccines (e.g. against Haemophilus influenzae B and Streptococcus pneumoniae) are encouraging. Their widespread use has resulted in a decrease or almost elimination of invasive diseases by the covered pneumococcal serotypes or Haemophilus influenzae B, respectively. These vaccines confer not only individual protection but also exploit herd protection effects. However, a multitude of failures reflects the obstacles on the way to effective and well tolerated bacterial vaccines. Regional differences in strain prevalence and variability of antigens that limit cross-protectivity remain major obstacles. However, promising candidates are in clinical development.

Impact of pneumococcal vaccination in children on serotype distribution in adult community-acquired pneumonia using the serotype-specific multiplex urinary antigen detection assay

The aim of the study was to compare the distribution of the vaccine-serotypes covered by pneumococcal conjugate vaccines (PCV7 and PCV13) in adult patients with pneumococcal community-acquired pneumonia in Germany between the periods 2002-2006 and 2007-2011 using a novel serotype-specific multiplex urinary antigen detection assay (SSUA). Vaccination of children started with PCV7 in 2007, which was replaced by PCV13 in 2010. Following confirmation of the accuracy of SSUA in long-term stored urine samples from 112 patients with confirmed pneumonia and known pneumococcal serotype, urine samples of 391 CAPNETZ patients with documented pneumococcal pneumonia (i.e. positive BinaxNOW) Streptococcus pneumoniae urine antigen test) but unknown serotype were tested for the 13 vaccine-serotypes using SSUA. The proportion of PCV7-serotypes significantly decreased in adult patients with pneumonia from 30.6% (2002-6) to 13.3% (2007-11, p < 0.001); in bacteremic pneumonia, PCV7-serotypes completely disappeared (3/14 versus 0/19, p = 0.058). Conversely, pneumococcal serotypes included by PCV13 remained stable during study period with a coverage of 61.5% (2002-06) and 59.7% (2007-11) in non-bacteremic pneumonia and 79% (for both periods) in bacteremic pneumonia, mainly due to an increase in pneumococcal serotypes 1, 3 and 7F during the second period. Thus, implementation of PCV7 in children in Germany in 2007 was associated with a significant decrease in vaccine-serotypes covered by PCV7 in adult patients with non-bacteremic pneumococcal pneumonia and with an elimination of PCV7 vaccine-serotypes in bacteremic pneumococcal pneumonia. PCV13 coverage remained high up to 2011, mainly due to an increase in serotypes 1, 3 and 7F.

[Characterization of patients who died of invasive pneumococcal disease in the child population of Bogota, Colombia]

INTRODUCTION

Streptococcus pneumoniae (S. pneumoniae), also known as pneumococcus, is one of the main bacteria associated with mortality in children under 2 years of age, with a morbidity and mortality incidence that varies according to demographics and exposure to risk, or protective factors.

OBJECTIVE

To describe the child mortality due to invasive pneumococcal disease (IPD) between 2008 -2014 (6 years), in 8 Medical Centres in Bogotá, Colombia.

PATIENTS AND METHOD

Descriptive observational case series of patients who died of IPD, aged 28 days to 18 years, in 8 tertiary care institutions in Bogota, Colombia. The study period was from 1 January 2008 to 15 January 2014.

SAMPLE SIZE

239 patients.

RESULTS

A total of 239 registered cases of IPD were reviewed, showing a mortality of 8% (n 18). The mean age of patients that died was 43.7 months, with an age range from 2 to 176 months (14 years), with 66% of the cases being male. Serotypes were identified in 8 patients, finding: 6A, 6B, 10A, 14, 18C, 23B, 23F, and 35B. The most common clinical presentation of the cases was meningitis with mortality of 33% (6 cases), followed by bacteraemia without focus in 28% (5 cases), and pneumonia with 27% (5 cases). Combined clinical situations were presented, such as pneumonia and meningitis in 11% (2 cases). Two of the patients had clearly documented risk factors for IPD (asplenia and chronic respiratory disease).

CONCLUSIONS

IPD mortality is particularly high in children under 2 years in male patients, especially when presented with a meningeal focus (44%). Serotyping was not possible in all patients who died, since no strain isolated was sent to the National Institute of Health. Continuous and systematic vigilance is required to evaluate the impact of vaccination and possible changes in the pattern of presentation of disease.

Risk factors for death from invasive pneumococcal disease, Europe, 2010

Risk varies by Streptococcus pneumoniae serotype.

We studied the possible association between patient age and sex, clinical presentation, Streptococcus pneumoniae serotype, antimicrobial resistance, and death in invasive pneumococcal disease cases reported by 17 European countries during 2010. The study sample comprised 2,921 patients, of whom 56.8% were men and 38.2% were >65 years of age. Meningitis occurred in 18.5% of cases. Death was reported in 264 (9.0%) cases. Older age, meningitis, and nonsusceptibility to penicillin were significantly associated with death. Non–pneumococcal conjugate vaccine (PCV) serotypes among children <5 years of age and 7-valent PCV serotypes among persons 5–64 years of age were associated with increased risk for death; among adults >65 years of age, risk did not differ by serotype. These findings highlight differences in case-fatality rates between serotypes and age; thus, continued epidemiologic surveillance across all ages is crucial to monitor the long-term effects of PCVs.

[Streptococcus pneumoniae: serotype distribution, antimicrobial susceptibility, risk factors and mortality in Galicia over a two year-period]

INTRODUCTION

To examine the epidemiology of pneumococcal infection in Galicia (Spain) after the incorporation of the pneumococcal conjugate vaccine, and to determine serotype distribution, antibiotic susceptibility, risk factors and associated mortality in cases of invasive pneumococcal disease (IPD) during 2011 and 2012.

METHODS

All strains causing IPD in Galicia were studied. Serotyping was performed by agglutination and Quellung reaction. Antibiotic sensitivity to penicillin, cefotaxime, erythromycin, vancomycin, and levofloxacin was determined. The risk factors considered were chronic respiratory disease, heart disease, liver disease, kidney disease, diabetes mellitus, and HIV and non-HIV immunodeficiency.

RESULTS

A total of 555 strains were collected, with 43 different serotypes being found. The most frequently isolated ones were: serotype3 (17.5%), serotype7F (12.6%), serotype19A (9.4%), serotype14 (4.1%), serotype6C (4.1%), serotype11A (4%) and serotype22F (3.8%). 57.1% of isolates were serotypes included in VNC-13V. Two non-penicillin-sensitive strains and two others were not sensitive to cefotaxime, and 24.7% of the strains were not susceptible to erythromycin (26.9% in 2011 and 22.5% in 2012). The case fatality rate was 16.5%, reaching 23.3% in patients over 75years. Diseases with a statistically significant risk of mortality were: liver, kidney and immunodeficiency without HIV.

CONCLUSIONS

Serotype3 was the most frequent in Galicia. Very few strains were not susceptible to penicillin. Erythromycin resistance decreased from 2011 to 2012. It is highlighted that mortality increases with age. Liver disease, renal disease and non-HIV immunodeficiency increases the mortality risk.

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 serotypes before and after introduction of conjugate vaccines, United States, 1999-2011(1.)

Serotyping data for pneumococci causing invasive and noninvasive disease in 2008-2009 and 2010-2011 from >43 US centers were compared with data from preconjugate vaccine (1999-2000) and postconjugate vaccine (2004-2005) periods. Prevalence of 7-valent pneumococcal conjugate vaccine serotypes decreased from 64% of invasive and 50% of noninvasive isolates in 1999-2000 to 3.8% and 4.2%, respectively, in 2010-2011. Increases in serotype 19A stopped after introduction of 13-valent pneumococcal vaccine (PCV13) in 2010. Prevalences of other predominant serotypes included in or related to PCV13 (3, 6C, 7F) also remained similar for 2008-2009 and 2010-2011. The only major serotype that increased from 2008-2009 to 2010-2011 was nonvaccine serotype 35B. These data show that introduction of the 7-valent vaccine has dramatically decreased prevalence of its serotypes and that addition of serotypes in PCV13 could provide coverage of 39% of isolates that continue to cause disease.

Pneumococcal polysaccharide vaccination for adults: new perspectives for Europe

Vaccination is the only public-health measure likely to reduce the burden of pneumococcal diseases. In 2010, a group of European experts reviewed evidence on the burden of pneumococcal disease and the immunogenicity, clinical effectiveness and cost-effectiveness of vaccination with 23-valent pneumococcal polysaccharide vaccine (PPV23). They also considered issues affecting the future use of PPV23 and pneumococcal conjugate vaccines in the elderly and adults at high risk of pneumococcal disease. PPV23 covers 80-90% of the serotypes responsible for invasive pneumococcal disease in Europe. Primary vaccination and revaccination with PPV23 are well tolerated, induce robust, long-lasting immune responses in elderly adults and are cost effective. Ensuring protection against pneumococcal disease requires monitoring of the changing epidemiology of pneumococcal serotypes causing invasive pneumococcal disease and improving vaccine coverage. In the future, it will be critically important for pneumococcal vaccination recommendations for elderly adults to be based on comparative evaluations of PPV23 and newer pneumococcal conjugate vaccines with regard to their long-term immunogenicity, clinical effectiveness and cost-effectiveness.

Invasive pneumococcal disease: association between serotype, clinical presentation and lethality

To ascertain the factors linked to invasive pneumococcal disease (IPD) caused by the different serotypes in the period 2007-2009, following the conjugate vaccine's inclusion in the childhood vaccination schedule, a total of 2013 IPD cases were reviewed. The mean annual incidence in this period was 10.74 cases per 100,000 inhabitans and the lethality was 8.8%. Overall serotype distribution displayed certain peculiarities, such as the high frequency of serotype 5. Serotype 3, male gender, sepsis and presence of risk factors were significantly associated with lethality. Vaccinated children under 5 years of age had a higher risk of disease due to serotype 19A. Serotype 8 was associated with the presence of underlying risk factors.