Host-pathogen interactions and prognosis of critically ill immunocompetent patients with pneumococcal pneumonia: the nationwide prospective observational STREPTOGENE study

Comparison of clinical characteristics and outcomes of patients with sepsis identified by the Sepsis-3 criteria by blood and urine culture results: A multicentre retrospective cohort study

Background and Aims

Blood and urine are the most common culture testing for sepsis patients. This study aimed to compare clinical characteristics and outcomes of sepsis patients by blood and urine culture positivity and to identify factors associated with positive cultures.

Methods

This retrospective study included patients aged ≥16 years with sepsis identified by the Sepsis-3 criteria presenting to the emergency department at four hospitals between 2017 and 2019 in Australia. Patient clinical outcomes were in-hospital mortality, intensive care unit (ICU) admission, hospital length of stay, and representation following discharge. Four culture groups were defined based on the positivity of blood cultures (BC) and urine cultures (UC) ordered within 24 h of triage.

Results

Of 4109 patient encounters with sepsis, 2730 (66%) were nonbacteremic, urine culture-negative (BC-UC-); 767 (19%) nonbacteremic, urine culture-positive (BC-UC+); 359 (9%) bacteremic, urine culture-negative (BC+UC-); and 253 (6%) bacteremic, urine culture-positive (BC+UC+). Compared with BC-UC- patients, BC+UC- patients had the highest risk of ICU admission (adjusted odds ratio [AOR] 95% CI: 1.60 [1.18-2.18]) while BC-UC+ patients had lowest risk (adjusted odds ratio [AOR]: 0.56 [0.41-0.76]). BC+UC- patients had the highest risk of 3-day representation (AOR: 1.51 [1.02-2.25]) and second longest hospital stay (adjusted relative risk 1.17 [1.03-1.34]). Antibiotic administration before sample collection for culture was associated with lower odds of positive blood or urine culture results (AOR: 0.38, p < 0.0001).

Conclusions

Enhanced clinical care should be beneficial for nongenitourinary sepsis patients (BC+UC-) who had the highest comparative risk of adverse clinical outcomes. Every effort needs to be made to collect relevant culture samples before antibiotic administration, to follow up on culture results, and tailor treatment accordingly.

Epidemiology of community-acquired pneumonia caused by S treptococcus pneumoniae in older adults: a narrative review

PURPOSE OF REVIEW

This review covers updated perspectives on different aspects of pneumococcal community-acquired pneumonia (pCAP), including the epidemiology, clinical presentation, risk factors, antibiotic treatment, and existing preventive strategies in older adults.

RECENT FINDINGS

pCAP remains the most prevalent condition among lower respiratory tract infections in the older adults according to Global Burden of Diseases 2019. Older adults can display atypical symptoms such as confusion, general clinical deterioration, new onset of and exacerbation of underlying illness that might trigger clinical suspicion of pCAP. Older adults with pCAP often experience increased disease severity and a higher risk of pulmonary complications compared with younger individuals, owing to age-related changes in immunity and a higher prevalence of comorbidities. Vaccination stands fundamental for prevention, emphasizing the need for effective immunization strategies, specifically tailored for older adults. There is a pressing need to reinforce efforts aimed at boosting pneumococcal vaccination rates.

SUMMARY

Despite a high morbidity and mortality, the burden of pCAP, in particular hospital admission and occurrence of invasive infections, among the elderly population is not sufficiently documented. This review findings emphasize the substantial burden of pCAP in this vulnerable population, driven by factors such as advancing age and underlying comorbidities. The emergence of antibiotic-resistant pneumococcal strains further complicates treatment decisions and highlights the importance of tailored approaches for managing pCAP in older adults.

Meningitis in critically ill patients admitted to intensive care unit for severe community-acquired pneumococcal pneumonia

BACKGROUND

Although it has been reported that patients with pneumococcal pneumonia may develop meningitis, lumbar puncture is not systematically recommended in these patients, even in patients with associated bacteremia or invasive pneumococcal disease. The aim of this study was to determine the characteristics and outcomes of patients admitted to intensive care unit (ICU) for pneumococcal community-acquired pneumonia who developed meningitis.

METHODS

We retrospectively included all consecutive patients admitted to our ICU from January 2006 to December 2020 for severe pneumococcal community-acquired pneumonia according to American Thoracic Society criteria. Meningitis was defined as pleocytosis > 5 cells/mm3 or a positive culture of cerebrospinal fluid for Streptococcus pneumoniae in lumbar puncture. The primary endpoint was the proportion of patients with meningitis during their ICU stay.

RESULTS

Overall, 262 patients [64(52-75) years old] were included: 154(59%) were male, 80(30%) had chronic respiratory disease, 105(39%) were immunocompromised and 6(2%) were vaccinated against S. pneumoniae. A lumbar puncture was performed in 88(34%) patients with a delay from ICU admission to puncture lumbar of 10.5 (2.8-24.1) h and after the initiation of pneumococcal antibiotherapy in 81(92%) patients. Meningitis was diagnosed in 14 patients: 16% of patients with lumbar puncture and 5% of patients in the whole population. Patients with meningitis had more frequently human immunodeficiency virus positive status (29 vs. 5%, p = 0.02), neurological deficits on ICU admission (43 vs. 16%, p = 0.03) and pneumococcal bacteremia (71 vs. 30%, p < 0.01) than those without. The ICU mortality rate (14 vs. 13%, p = 0.73) and the mortality rate at Day-90 (21 vs. 15%, p = 0.83) did not differ between patients with and without meningitis. The proportion of patients with neurological disorders at ICU discharge was higher in patients with meningitis (64 vs. 23%, p < 0.001) than in those without. The other outcomes did not differ at ICU discharge, Day-30 and Day-90 between the two groups of patients.

CONCLUSION

Meningitis was diagnosed in 16% of patients with severe pneumococcal community-acquired pneumonia in whom a lumbar puncture was performed, was more frequent in patients with pneumococcal bacteremia and was associated with more frequent neurological disorders at ICU discharge. Further studies are needed to confirm these results.

Systematic Literature Review of the Epidemiological Characteristics of Pneumococcal Disease Caused by the Additional Serotypes Covered by the 20-Valent Pneumococcal Conjugate Vaccine

Higher valency pneumococcal conjugate vaccines (PCV15 and PCV20) have been developed to address the disease burden of current non-vaccine serotypes. This review describes the epidemiological characteristics of serotypes beyond PCV13 (serotypes 8, 10A, 11A, 12F, 15B/C, 22F, and 33F; PCV20nonPCV13 serotypes). Peer-reviewed studies published between 1 January 2010 (the year PCV13 became available) and 18 August 2020 were systematically reviewed (PROSPERO number: CRD42021212875). Data describing serotype-specific outcomes on disease proportions, incidence, severity, and antimicrobial non-susceptibility were summarized for individual and aggregate PCV20nonPCV13 serotypes by age group and by type and duration of pediatric PCV immunization program. Of 1168 studies, 127 (11%) were included in the analysis. PCV20nonPCV13 serotypes accounted for 28% of invasive pneumococcal disease (IPD), although the most frequent serotypes differed between children (10A, 15B/C) and adults (8, 12F, 22F). In children, serotype 15B/C tended to be more frequently associated with pneumococcal meningitis and acute otitis media; in adults, serotype 8 was more frequently associated with pneumonia and serotype 12F with meningitis. Serotypes 10A and 15B/C in children and 11A and 15B/C in adults were often associated with severe IPD. Serotype 15B/C was also among the most frequently identified penicillin/macrolide non-susceptible PCV20nonPCV13 serotypes. These results could inform decision making about higher valency PCV choice and use.

Association of admission lactate with mortality in adult patients with severe community-acquired pneumonia

PURPOSE

The present study was conducted to investigate the association of admission lactate with mortality in severe community-acquired pneumonia (SCAP).

METHODS

We performed a retrospective, observational, cohort study on adult SCAP patients admitted to intensive care unit (ICU) in West China Hospital of Sichuan University between December 2011 and December 2018. The primary outcome was hospital mortality. Univariate and then multivariate analysis were performed to identify independent risk factors for hospital mortality. The association of admission lactate categories with hospital mortality was examined in three logistic regression models and Kaplan-Meier plots. We also applied restricted cubic splines to estimate the potential non-linear associations.

RESULTS

In total, 2275 SCAP patients were included. Admission lactate remained a significant factor for mortality after multivariate regression (OR: 1.085; 95% CI: 1.033,1.141; by continuous variable). After lactate was categorized into quartiles and the confounders were fully adjusted, compared with the quartile 1, ORs (95% CIs) of hospital mortality for quartile 2, quartile 3 and quartile 4 were 1.001 (0.759-1.321), 1.153 (0.877-1.516) and 1.593 (1.202-2.109), respectively (P for trend =0.001). Survival curves indicated that elevated lactate was associated with poor prognosis (P < 0.001). Moreover, this association was non-linear, indicating that increased lactate has the most notable impact on mortality within the range of 1.5 to 4 mmol/L (P non-linear: 0.029 for hospital mortality; 0.004 for ICU mortality).

CONCLUSION

Elevated admission lactate has a significant, independent, and potentially non-linear association with increased mortality in SCAP patients.

Clustering ICU patients with sepsis based on the patterns of their circulating biomarkers: A secondary analysis of the CAPTAIN prospective multicenter cohort study

BACKGROUND

Although sepsis is a life-threatening condition, its heterogeneous presentation likely explains the negative results of most trials on adjunctive therapy. This study in patients with sepsis aimed to identify subgroups with similar immune profiles and their clinical and outcome correlates.

METHODS

A secondary analysis used data of a prospective multicenter cohort that included patients with early assessment of sepsis. They were described using Predisposition, Insult, Response, Organ failure sepsis (PIRO) staging system. Thirty-eight circulating biomarkers (27 proteins, 11 mRNAs) were assessed at sepsis diagnosis, and their patterns were determined through principal component analysis (PCA). Hierarchical clustering was used to group the patients and k-means algorithm was applied to assess the internal validity of the clusters.

RESULTS

Two hundred and three patients were assessed, of median age 64.5 [52.0-77.0] years and SAPS2 score 55 [49-61] points. Five main patterns of biomarkers and six clusters of patients (including 42%, 21%, 17%, 9%, 5% and 5% of the patients) were evidenced. Clusters were distinguished according to the certainty of the causal infection, inflammation, use of organ support, pro- and anti-inflammatory activity, and adaptive profile markers.

CONCLUSIONS

In this cohort of patients with suspected sepsis, we individualized clusters which may be described with criteria used to stage sepsis. As these clusters are based on the patterns of circulating biomarkers, whether they might help to predict treatment responsiveness should be addressed in further studies.

TRIAL REGISTRATION

The CAPTAIN study was registered on clinicaltrials.gov on June 22, 2011, # NCT01378169.

Comparison of prognostic factors between bacteraemic and non-bacteraemic critically ill immunocompetent patients in community-acquired severe pneumococcal pneumonia: a STREPTOGENE sub-study

Background

The presence of bacteraemia in pneumococcal pneumonia in critically ill patients does not appear to be a strong independent prognostic factor in the existing literature. However, there may be a specific pattern of factors associated with mortality for ICU patients with bacteraemic pneumococcal community-acquired pneumonia (CAP). We aimed to compare the factors associated with mortality, according to the presence of bacteraemia or not on admission, for patients hospitalised in intensive care for severe pneumococcal CAP.

Methods

This was a post hoc analysis of data from the prospective, observational, multicentre STREPTOGENE study in immunocompetent Caucasian adults admitted to intensive care in France between 2008 and 2012 for pneumococcal CAP. Patients were divided into two groups based on initial blood culture (positive vs. negative) for Streptococcus pneumoniae. The primary outcome was hospital mortality, which was compared between the two groups using odds ratios according to predefined variables to search for a prognostic interaction present in bacterial patients but not non-bacteraemic patients. Potential differences in the distribution of serotypes between the two groups were assessed. The prognostic consequences of the presence or not of initial bi-antibiotic therapy were assessed, specifically in bacteraemic patients.

Results

Among 614 included patients, 274 had a blood culture positive for S. pneumoniae at admission and 340 did not. The baseline difference between the groups was more frequent leukopaenia (26% vs. 14%, p = 0.0002) and less frequent pre-hospital antibiotic therapy (10% vs. 16.3%, p = 0.024) for the bacteraemic patients. Hospital mortality was not significantly different between the two groups (p = 0.11). We did not observe any prognostic factors specific to the bacteraemic patient population, as the statistical comparison of the odds ratios, as an indication of the association between the predefined prognostic parameters and mortality, showed them to be similar for the two groups. Bacteraemic patients more often had invasive serotypes but less often serotypes associated with high case fatality rates (p = 0.003). The antibiotic regimens were similar for the two groups. There was no difference in mortality for patients in either group given a beta-lactam alone vs. a beta-lactam combined with a macrolide or fluoroquinolone.

Conclusion

Bacteraemia had no influence on the mortality of immunocompetent Caucasian adults admitted to intensive care for severe pneumococcal CAP, regardless of the profile of the associated prognostic factors.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13613-021-00936-z.

Development and characterization of a new swine model of invasive pneumococcal pneumonia

Streptococcus pneumoniae is the most common microbial cause of community-acquired pneumonia. Currently, there are no available models of severe pneumococcal pneumonia in mechanically ventilated animals to mimic clinical conditions of critically ill patients. We studied endogenous pulmonary flora in 4 healthy pigs and in an additional 10 pigs in which we intra-bronchially instilled S. pneumoniae serotype 19 A, characterized by its resistance to penicillin, macrolides and tetracyclines. The pigs underwent ventilation for 72 h. All pigs that were not challenged with S. pneumoniae completed the 72-h study, whereas 30% of infected pigs did not. At 24 h, we clinically confirmed pneumonia in the infected pigs; upon necropsy, we sampled lung tissue for microbiological/histological confirmation of pneumococcal pneumonia. In control pigs, Streptococcus suis and Staphylococcus aureus were the most commonly encountered pathogens, and their lung tissue mean ± s.e.m. concentration was 7.94 ± 20 c.f.u./g. In infected pigs, S. pneumoniae was found in the lungs of all pigs (mean ± s.e.m. pulmonary concentration of 1.26 × 10⁵ ± 2 × 10² c.f.u./g). Bacteremia was found in 50% of infected pigs. Pneumococcal pneumonia was confirmed in all infected pigs at 24 h. Pneumonia was associated with thrombocytopenia, an increase in prothrombin time, cardiac output and vasopressor dependency index and a decrease in systemic vascular resistance. Upon necropsy, microbiological/histological pneumococcal pneumonia was confirmed in 8 of 10 pigs. We have therefore developed a novel model of penicillin- and macrolide-resistant pneumococcal pneumonia in mechanically ventilated pigs with bacteremia and severe hemodynamic compromise. The model could prove valuable for appraising the pathogenesis of pneumococcal pneumonia, the effects associated with macrolide resistance and the outcomes related to the use of new diagnostic strategies and antibiotic or complementary therapies.

Understanding the Host in the Management of Pneumonia. An Official American Thoracic Society Workshop Report

Pneumonia causes a significant burden of disease worldwide. Although all populations are at risk of pneumonia, those at extremes of age and those with immunosuppressive disorders, underlying respiratory disease, and critical illness are particularly vulnerable. Although clinical practice guidelines addressing the management and treatment of pneumonia exist, few of the supporting studies focus on the crucial contributions of the host in pneumonia pathogenesis and recovery. Such essential considerations include the host risk factors that lead to susceptibility to lung infections; biomarkers reflecting the host response and the means to pursue host-directed pneumonia therapy; systemic effects of pneumonia on the host; and long-term health outcomes after pneumonia. To address these gaps, the Pneumonia Working Group of the Assembly on Pulmonary Infection and Tuberculosis led a workshop held at the American Thoracic Society meeting in May 2018 with overarching objectives to foster attention, stimulate research, and promote funding for short-term and long-term investigations into the host contributions to pneumonia. The workshop involved participants from various disciplines with expertise in lung infection, pneumonia, sepsis, immunocompromised patients, translational biology, data science, genomics, systems biology, and clinical trials. This workshop report summarizes the presentations and discussions and important recommendations for future clinical pneumonia studies. These recommendations include establishing consensus disease and outcome definitions, improved phenotyping, development of clinical study networks, standardized data and biospecimen collection and protocols, and development of innovative trial designs.

Heparin-based blood purification attenuates organ injury in baboons with Streptococcus pneumoniae pneumonia

Bacterial pneumonia is a major cause of morbidity and mortality worldwide despite the use of antibiotics, and novel therapies are urgently needed. Building on previous work, we aimed to 1) develop a baboon model of severe pneumococcal pneumonia and sepsis with organ dysfunction and 2) test the safety and efficacy of a novel extracorporeal blood filter to remove proinflammatory molecules and improve organ function. After a dose-finding pilot study, 12 animals were inoculated with Streptococcus pneumoniae [5 × 10⁹ colony-forming units (CFU)], given ceftriaxone at 24 h after inoculation, and randomized to extracorporeal blood purification using a filter coated with surface-immobilized heparin sulfate (n = 6) or sham treatment (n = 6) for 4 h at 30 h after inoculation. For safety analysis, four uninfected animals also underwent purification. At 48 h, necropsy was performed. Inoculated animals developed severe pneumonia and septic shock. Compared with sham-treated animals, septic animals treated with purification displayed significantly less kidney injury, metabolic acidosis, hypoglycemia, and shock (P < 0.05). Purification blocked the rise in peripheral blood S. pneumoniae DNA, attenuated bronchoalveolar lavage (BAL) CCL4, CCL2, and IL-18 levels, and reduced renal oxidative injury and classical NLRP3 inflammasome activation. Purification was safe in both uninfected and infected animals and produced no adverse effects. We demonstrate that heparin-based blood purification significantly attenuates levels of circulating S. pneumoniae DNA and BAL cytokines and is renal protective in baboons with severe pneumococcal pneumonia and septic shock. Purification was associated with less severe acute kidney injury, metabolic derangements, and shock. These results support future clinical studies in critically ill septic patients.

Burden of pneumococcal pneumonia requiring ICU admission in France: 1-year prognosis, resources use, and costs

Background

Community-acquired pneumonia (CAP), especially pneumococcal CAP (P-CAP), is associated with a heavy burden of illness as evidenced by high rates of intensive care unit (ICU) admission, mortality, and costs. Although well-defined acutely, determinants influencing long-term burden are less known. This study assessed determinants of 28-day and 1-year mortality and costs among P-CAP patients admitted in ICUs.

Methods

Data regarding all hospital and ICU stays in France in 2014 were extracted from the French healthcare administrative database. All patients admitted in the ICU with a pneumonia diagnosis were included, except those hospitalized for pneumonia within the previous 3 months. The pneumococcal etiology and comorbidities were captured. All hospital stays were included in the cost analysis. Comorbidities and other factors effect on the 28-day and 1-year mortality were assessed using a Cox regression model. Factors associated with increased costs were identified using log-linear regression models.

Results

Among 182,858 patients hospitalized for CAP in France for 1 year, 10,587 (5.8%) had a P-CAP, among whom 1665 (15.7%) required ICU admission. The in-hospital mortality reached 22.8% at day 28 and 32.3% at 1 year. The mortality risk increased with age > 54 years, malignancies (hazard ratio (HR) 1.54, 95% CI [1.23–1.94], p = 0.0002), liver diseases (HR 2.08, 95% CI [1.61–2.69], p < 0.0001), and the illness severity at ICU admission. Compared with non-ICU-admitted patients, ICU survivors remained at higher risk of 1-year mortality. Within the following year, 38.2% (516/1350) of the 28-day survivors required at least another hospital stay, mostly for respiratory diseases. The mean cost of the initial stay was €19,008 for all patients and €11,637 for subsequent hospital stays within 1 year. One-year costs were influenced by age (lower in patients > 75 years old, p = 0.008), chronic cardiac (+ 11% [0.02–0.19], p = 0.019), and respiratory diseases (+ 11% [0.03–0.18], p = 0.006).

Conclusions

P-CAP in ICU-admitted patients was associated with a heavy burden of mortality and costs at one year. Older age was associated with both early and 1-year increased mortality. Malignant and chronic liver diseases were associated with increased mortality, whereas chronic cardiac failure and chronic respiratory disease with increased costs.

Trial registration

N/A (study on existing database)

Gender differences in community-acquired pneumonia

INTRODUCTION

Community-acquired pneumonia (CAP) is the most common type of lower respiratory tract infection and a major cause of morbidity and mortality in adults worldwide. Sex and gender play an active role in the incidence and outcomes of major infectious diseases, including CAP.

EVIDENCE ACQUISITION

We searched the following electronic databases from January 2001 to December 2018: MEDLINE, EMBASE, CINHAIL, CENTRAL (Cochrane Central register of Controlled Trials), DARE (Database of Abstracts of Reviews of Effectiveness), Cochrane Database of Systematic Reviews and ACP Journal Club database.

EVIDENCE SYNTHESIS

Several studies have reported higher male susceptibility to pulmonary infections and higher risk of death due to sepsis. Biological differences (e.g. hormonal cycles and cellular immune-mediated responses) together with cultural, behavioral and socio-economic differences are important determinants of the course and outcome of CAP. However, gender-related bias in the provision of care and use of hospital resources has been reported among women, resulting in delayed hospital admission and consequently necessary care.

CONCLUSIONS

CAP is more severe in males than in females, leading to higher mortality in males, especially in older age. To identify gender differences in CAP can guide patient's prognostication and management.

Community Acquired Pneumonia

Early identification of patients with severe community-acquired pneumonia (SCAP) who require ICU care is important as delayed transfer is associated with increased mortality. In such patients, aggressive diagnostic testing is warranted given the increased probability of detecting a pathogen resistant to usual empirical therapy. Despite aggressive culture and other routine diagnostic testing, the majority of cases of SCAP remain without a definitive etiology. Early coverage of S. pneumoniae, methicillin-susceptible S. aureus, and L. pneumophila is crucial and adequate in the absence of risk factors for drug-resistant pathogens. Combination antibiotics with a beta-lactam and either a macrolide or fluoroquinolone are strongly recommended. When methicillin-resistant Staphylococcus aureus is suspected, linezolid is superior to vancomycin.

Several aspects of managing severe CAP remain without consensus, including risk factors for multidrug resistant pathogens, need for suppression of exotoxin production, the role of procalcitonin, and adjunctive treatment with corticosteroids and extracorporeal membrane oxygenation.

Interleukin-22 (IL-22) Binding Protein Constrains IL-22 Activity, Host Defense, and Oxidative Phosphorylation Genes during Pneumococcal Pneumonia

Streptococcus pneumoniae is the most common cause of community-acquired pneumonia worldwide, and interleukin-22 (IL-22) helps contain pneumococcal burden in lungs and extrapulmonary tissues. Administration of IL-22 increases hepatic complement 3 and complement deposition on bacteria and improves phagocytosis by neutrophils. The effects of IL-22 can be tempered by a secreted natural antagonist, known as IL-22 binding protein (IL-22BP), encoded by Il22ra2 To date, the degree to which IL-22BP controls IL-22 in pulmonary infection is not well defined. Here, we show that Il22ra2 inhibits IL-22 during S. pneumoniae lung infection and that Il22ra2 deficiency favors downregulation of oxidative phosphorylation (OXPHOS) genes in an IL-22-dependent manner. Il22ra2-/- mice are more resistant to S. pneumoniae infection, have increased IL-22 in lung tissues, and sustain longer survival upon infection than control mice. Transcriptome sequencing (RNA-seq) analysis of infected Il22ra2-/- mouse lungs revealed downregulation of genes involved in OXPHOS. Downregulation of this metabolic process is necessary for increased glycolysis, a crucial step for transitioning to a proinflammatory phenotype, in particular macrophages and dendritic cells (DCs). Accordingly, we saw that macrophages from Il22ra2-/- mice displayed reduced OXPHOS gene expression upon infection with S. pneumoniae, changes that were IL-22 dependent. Furthermore, we showed that macrophages express IL-22 receptor subunit alpha-1 (IL-22Ra1) during pneumococcal infection and that Il22ra2-/- macrophages rely more on the glycolytic pathway than wild-type (WT) controls. Together, these data indicate that IL-22BP deficiency enhances IL-22 signaling in the lung, thus contributing to resistance to pneumococcal pneumonia by downregulating OXPHOS genes and increasing glycolysis in macrophages.