Diagnosis of pneumococcal pneumonia: current pitfalls and the way forward

Enhancing pneumococcal bacteraemia diagnosis: A comparative assessment of culture-independent assays (MALDI-TOF-MS Sepsityper® module and a lateral flow inmunochromatography test)

INTRODUCTION

Pneumococcal bacteraemia is a major contributor to global morbidity and mortality. Traditional culture-based methods lack sensitivity and are time-consuming. This study aimed to assess the effectiveness of two culture-independent assays, the MALDI-TOF-MS Sepsityper® module and the lateral flow inmunochromatography test (LFICT) with the Standard F® Streptococcus pneumoniae, directly from positive blood culture (BC) bottles.

METHODS

A prospective study was conducted from December 2021 to July 2022. For all BC positives for S. pneumoniae a double centrifugation protocol was implemented. The resulting pellet was subsequently processed using both techniques.

RESULTS

The LFICT showed exceptional performance with 100% sensitivity and specificity, outperforming the MALDI-TOF-MS Sepsityper® module, which achieved 85.2% sensitivity and 100% specificity. Nevertheless, the combination of these assays offers a robust and comprehensive approach to diagnosis.

CONCLUSIONS

The simultaneous use of both techniques offers a promising alternative that can be integrated into routine practices directly from BC samples.

Necrotizing Pneumonia With Extensive Lobar Cavitation

Pneumonia occupies one of the leading positions in morbidity and mortality worldwide. It is frequently categorized depending on the site of acquisition. Here, we present a case of a young woman who was admitted to the Emergency Department (ED) with cough, dyspnea, fever, and progressive worsening associated with palpitations and hypotension. An initial x-ray was followed by a computed tomography (CT) scan of the chest, which revealed signs of extensive left lung pneumonia with pleural effusion. Despite initial improvement after antibiotic treatment, the patient's condition declined. A repeat chest CT showed evidence of extensive lobar cavitations, leading to suspicion of tuberculosis.

Derivation and external validation of a prediction model for pneumococcal urinary antigen test positivity in patients with community-acquired pneumonia

Objective

Derive and externally validate a prediction model for pneumococcal urinary antigen test (pUAT) positivity.

Methods

Retrospective cohort study of adults admitted with community-acquired pneumonia (CAP) to 177 U.S. hospitals in the Premier Database (derivation and internal validation samples) or 12 Cleveland Clinic hospitals (external validation sample). We utilized multivariable logistic regression to predict pUAT positivity in the derivation dataset, followed by model performance evaluation in both validation datasets. Potential predictors included demographics, comorbidities, clinical findings, and markers of disease severity.

Results

Of 198,130 Premier patients admitted with CAP, 27,970 (14.1%) underwent pUAT; 1962 (7.0%) tested positive. The strongest predictors of pUAT positivity were history of pneumococcal infection in the previous year (OR 6.99, 95% CI 4.27-11.46), severe CAP on admission (OR 1.76, 95% CI 1.56-1.98), substance abuse (OR 1.57, 95% CI 1.27-1.93), smoking (OR 1.23, 95% CI 1.09-1.39), and hyponatremia (OR 1.35, 95% CI 1.17-1.55). Negative predictors included IV antibiotic use in past year (OR 0.65, 95% CI 0.52-0.82), congestive heart failure (OR 0.72, 95% CI 0.63-0.83), obesity (OR 0.71, 95% CI 0.60-0.85), and admission from skilled nursing facility (OR 0.60, 95% CI 0.45-0.78). Model c-statistics were 0.60 and 0.67 in the internal and external validation cohorts, respectively. Compared to guideline-recommended testing of severe CAP patients, our model would have detected 23% more cases with 5% fewer tests.

Conclusion

Readily available data can identify patients most likely to have a positive pUAT. Our model could be incorporated into automated clinical decision support to improve test efficiency and antimicrobial stewardship.

The diagnostic utility of microscopic quality assessment of sputum samples in the era of rapid syndromic PCR testing

This prospective study assessed the value of initial microscopy evaluation of sputum samples submitted for rapid syndromic PCR-based testing. Bacterial detections by the BioFire FilmArray Pneumonia Panel plus in 126 high- and 108 low-quality sputum samples, based on initial microscopy evaluation in samples from patients with lower respiratory tract infections were compared. We found that high-quality samples had a higher proportion of bacterial detections compared to low-quality samples (P = 0.013). This included a higher proportion of detections of bacteria deemed clinically relevant by predefined criteria (70% and 55%, P = 0.016), as well as a higher proportion of detections of Haemophilus influenzae (36% and 20%, P = 0.010). High-quality samples also had more detections of bacteria with high semi-quantitative values. The study found no significant difference between high- and low-quality samples in the proportions of samples with a single species of bacteria detected, samples with a bacteria treated by the clinician, samples with detection of a proven etiology of community-acquired pneumonia by predefined criteria, the number of bacterial species detected, or the detection of Streptococcus pneumoniae, Moraxella catarrhalis, or Staphylococcus aureus. The results showed that 40% (95% CI 35%-47%) of the bacterial detections would have been missed if only high-quality samples were analyzed. This included 41% (27%-56%) of detections of S. pneumoniae, 33% (23%-45%) of detections of H. influenzae, 42% (28%-58%) of detections of S. aureus, and 37% (23%-54%) of detections of M. catarrhalis. These findings suggest that all sputum samples submitted for rapid syndromic PCR testing should be analyzed, regardless of initial microscopy quality assessment. (This study has been registered at ClinicalTrials.gov under registration no. NCT04660084.) IMPORTANCE Microscopic quality assessment of sputum samples was originally designed for sputum culture, and its applicability in today's workflow, which includes syndromic PCR testing, may differ. Addressing this crucial gap, our study emphasizes the need to optimize the use and workflow of syndromic PCR panels, like the BioFire FilmArray Pneumonia plus (FAP plus), in microbiology laboratories. These advanced PCR-based tests offer rapid and comprehensive pathogen detection for respiratory infections, yet their full potential remains uncertain. By comparing bacterial detections in high- and low-quality sputum samples, we underscore the importance of including low-quality samples in testing. Our findings reveal a significant proportion of potentially clinically relevant bacterial detections that would have been missed if only high-quality samples were analyzed. These insights support the efficient implementation of syndromic PCR panels, ultimately enhancing patient care and outcomes.

Novel pneumococcal capsule type 33E results from the inactivation of glycosyltransferase WciE in vaccine type 33F

The polysaccharide (PS) capsule is essential for immune evasion and virulence of Streptococcus pneumoniae. Existing pneumococcal vaccines are designed to elicit anticapsule antibodies; however, the effectiveness of these vaccines is being challenged by the emergence of new capsule types or variants. Herein, we characterize a newly discovered capsule type, 33E, that appears to have repeatedly emerged from vaccine type 33F via an inactivation mutation in the capsule glycosyltransferase gene, wciE. Structural analysis demonstrated that 33E and 33F share an identical repeat unit backbone [→5)-β-D-Galf2Ac-(1→3)-β-D-Galp-(1→3)-α-D-Galp-(1→3)-β-D-Galf-(1→3)-β-D-Glcp-(1→], except that a galactose (α-D-Galp) branch is present in 33F but not in 33E. Though the two capsule types were indistinguishable using conventional typing methods, the monoclonal antibody Hyp33FM1 selectively bound 33F but not 33E pneumococci. Further, we confirmed that wciE encodes a glycosyltransferase that catalyzes the addition of the branching α-D-Galp and that its inactivation in 33F strains results in the expression of the 33E capsule type. Though 33F and 33E share a structural and antigenic similarity, our pilot study suggested that immunization with a 23-valent pneumococcal PS vaccine containing 33F PS did not significantly elicit cross-opsonic antibodies to 33E. New conjugate vaccines that target capsule type 33F may not necessarily protect against 33E. Therefore, studies of new conjugate vaccines require knowledge of the newly identified capsule type 33E and reliable pneumococcal typing methods capable of distinguishing it from 33F.

[Respiratory infections: Additional transmission-based precautions in healthcare facilities]

INTRODUCTION

In health care, measures against cross-transmission of microorganisms are codified by standard precautions, and if necessary, they are supplemented by additional precautions.

STATE OF THE ART

Several factors impact transmission of microorganisms via the respiratory route: size and quantity of the emitted particles, environmental conditions, nature and pathogenicity of the microorganisms, and degree of host receptivity. While some microorganisms necessitate additional airborne or droplet precautions, others do not.

PROSPECTS

For most microorganisms, transmission patterns are well-understood and transmission-based precautions are well-established. For others, measures to prevent cross-transmission in healthcare facilities remain under discussion.

CONCLUSIONS

Standard precautions are essential to the prevention of microorganism transmission. Understanding of the modalities of microorganism transmission is essential to implementation of additional transmission-based precautions, particularly in view of opting for appropriate respiratory protection.

Discovery and Characterization of Pneumococcal Serogroup 36 Capsule Subtypes, Serotypes 36A and 36B

Streptococcus pneumoniae can produce a wide breadth of antigenically diverse capsule types, a fact that poses a looming threat to the success of vaccines that target pneumococcal polysaccharide (PS) capsule. Yet, many pneumococcal capsule types remain undiscovered and/or uncharacterized. Prior sequence analysis of pneumococcal capsule synthesis (cps) loci suggested the existence of capsule subtypes among isolates identified as "serotype 36" according to conventional capsule typing methods. We discovered these subtypes represent two antigenically similar but distinguishable pneumococcal capsule serotypes, 36A and 36B. Biochemical analysis of their capsule PS structure reveals that both have the shared repeat unit backbone [→5)-α-d-Galf-(1→1)-d-Rib-ol-(5→P→6)-β-d-ManpNAc-(1→4)-β-d-Glcp-(1→] with two branching structures. Both serotypes have a β-d-Galp branch to Ribitol. Serotypes 36A and 36B differ by the presence of a α-d-Glcp-(1→3)-β-d-ManpNAc or α-d-Galp-(1→3)-β-d-ManpNAc branch, respectively. Comparison of the phylogenetically distant serogroup 9 and 36 cps loci, which all encode this distinguishing glycosidic bond, revealed that the incorporation of Glcp (in types 9N and 36A) versus Galp (in types 9A, 9V, 9L, and 36B) is associated with the identity of four amino acids in the cps-encoded glycosyltransferase WcjA. Identifying functional determinants of cps-encoded enzymes and their impact on capsule PS structure is key to improving the resolution and reliability of sequencing-based capsule typing methods and discovering novel capsule variants indistinguishable by conventional serotyping methods.

Prevalence of Pneumococcal Serotypes in Community-Acquired Pneumonia among Older Adults in Italy: A Multicenter Cohort Study

Pneumococcal community-acquired pneumonia (CAP) is a leading cause of mortality. Following the introduction of pneumococcal conjugate vaccines (PCVs) in children, a decrease in the burden of the disease was reported. In parallel, an increase in non-vaccine serotypes was also noted. The objective of this study was to assess the current serotype-specific epidemiology of pneumococci among Italian older adults hospitalized for CAP. A prospective study was conducted between 2017 and 2020 in four Italian regions. Subjects aged ≥65 years hospitalized with confirmed CAP were tested for pneumococci using both pneumococcal urinary antigen and serotype-specific urine antigen tests able to identify all 24 serotypes included in the available vaccines. Of the 1155 CAP cases, 13.1% were positive for pneumococci. The most prevalent serotypes were 3 (2.0%), 8 (1.7%), 22F (0.8 %) and 11A (0.7%). These serotypes are all included in the newly licensed PCV20. The serotypes included in PCV13, PCV15 and PCV20 contributed to 3.3%, 4.4% and 7.5% of the CAP cases, respectively. In the context of a low PCV13 coverage among older adults and a high PCV coverage in children, a substantial proportion of CAP is caused by PCV13 serotypes. Higher valency PCV15 and PCV20 may provide additional benefits for the prevention of CAP in vaccinated older adults.

Prevalence, Antimicrobial Resistance, and Associated Factors of Streptococcus pneumoniae Colonization Rate among Old-Age Patients with Respiratory Tract Infection Attending Sheik Hassan Yebere Referral and Karamara General Hospitals, Jigjiga, Ethiopia

Background

Streptococcus pneumoniae is part of the normal flora of the upper respiratory tract of humans. Colonization of the upper respiratory tract (carriage of pneumococcus) by S. pneumoniae is considered a prerequisite for pneumococcal infection. It is the major cause of respiratory tract infection and frequent cause of physician visits, hospitalization, and death among old-aged patients because of their low immunity status. However, data on S. pneumoniae among old-aged patients in eastern Ethiopia are limited. This study was undertaken to determine the prevalence, antimicrobial resistance, and associated factor of S. pneumoniae colonization among old-aged patients.

Method

A health facility-based cross-sectional study was conducted from 1 March to 15 April 2020, at Sheik Hassan Yebere Referral and Karamara General Hospitals, Jigjiga, eastern Ethiopia. A total of 188 individuals greater than or equal to 60 years suspected of both upper and lower respiratory tract infections were included. Sociodemographic, behavioral, living conditions, and clinical data were collected by trained data collectors. Sputum samples were collected and examined for S. pneumoniae using the culture and biochemical tests as per the standard procedures. The Kirby–Bauer disk diffusion method was used for antimicrobial susceptibility testing. The data were entered on Epi-data version 3.1, and frequencies, crude odds ratio, and adjusted odds ratio were analyzed using SPSS version 20.

Results

The prevalence of S. pneumoniae colonization rate among old-aged patients was 13.8% (26/188) (95% CI: 9.6–19.1). Smoking (AOR = 3.3; 95% CI: 1.3–8.3), upper airway problems (AOR = 4.1; 95% CI: 1.1–15), and asthma disease (AOR = 3.1; 95% CI: 1.1–8.9) were the factors associated with S. pneumoniae colonization. The isolated organisms showed high antimicrobial resistance to trimethoprim-sulphamethoxazole (n = 12, 46.2%), tetracycline (n = 11, 42.3%), and ampicillin (n = 9, 34.6%).

Conclusion

This study showed that high prevalence of S. pneumoniae and antimicrobial resistance for trimethoprim-sulphamethoxazole, tetracycline, and ampicillin when compared to similar studies. Cigarette smoking, having upper airway problem, and asthma disease were factors associated with S. pneumoniae colonization. The provision of pneumococci conjugate vaccination and avoiding smoking are highly recommended for old aged in the community.

Incidence of Hospitalisation and Emergency Department Visits for Pneumococcal Disease in Children, Adolescents, and Adults in Liguria, Italy: A Retrospective Analysis from 2012-2018

Streptococcus pneumoniae infection is responsible for significant morbidity and mortality, particularly in young children and older adults. The aim of this study was to investigate the incidence of hospitalisation and emergency department (ED) visits in relation to episodes of pneumococcal disease (PD) following the introduction of pneumococcal conjugate vaccines (PCVs) into the Liguria region of Italy. Between 2012 and 2018, episodes of all-cause pneumonia (80,152), pneumococcal-specific pneumonia (1254), unspecified pneumonia (66,293), acute otitis media (AOM; 17,040), and invasive PD (IPD; 1788) were identified from in-patient claims, ED and hospital discharge records, and the Liguria Chronic Condition Data Warehouse. In children < 15 years of age, pneumococcal pneumonia-related hospitalisations decreased from 35 to 13 per 100,000 person-years during the study period (p < 0.001); this decrease is potentially related to PCV use in children. All-cause pneumonia hospitalisations remained stable, whereas IPD hospitalisations increased and AOM hospitalisations decreased. In adults, hospitalisations for all-cause pneumonia increased from 5.00 to 7.50 per 1000 person-years (+50%; p < 0.001). Pneumococcal and unspecified pneumonia hospital admissions increased significantly during the study period, considerably affecting those ≥ 65 years of age. IPD hospitalisations varied across all age groups, but a significant change was not observed. Despite pneumococcal vaccination, substantial burden remains for PD in children and adults in Liguria, Italy.

Raman Spectroscopic Differentiation of Streptococcus pneumoniae From Other Streptococci Using Laboratory Strains and Clinical Isolates

Streptococcus pneumoniae, commonly referred to as pneumococci, can cause severe and invasive infections, which are major causes of communicable disease morbidity and mortality in Europe and globally. The differentiation of S. pneumoniae from other Streptococcus species, especially from other oral streptococci, has proved to be particularly difficult and tedious. In this work, we evaluate if Raman spectroscopy holds potential for a reliable differentiation of S. pneumoniae from other streptococci. Raman spectra of eight different S. pneumoniae strains and four other Streptococcus species (S. sanguinis, S. thermophilus, S. dysgalactiae, S. pyogenes) were recorded and their spectral features analyzed. Together with Raman spectra of 59 Streptococcus patient isolates, they were used to train and optimize binary classification models (PLS-DA). The effect of normalization on the model accuracy was compared, as one example for optimization potential for future modelling. Optimized models were used to identify S. pneumoniae from other streptococci in an independent, previously unknown data set of 28 patient isolates. For this small data set balanced accuracy of around 70% could be achieved. Improvement of the classification rate is expected with optimized model parameters and algorithms as well as with a larger spectral data base for training.

Clinical management and outcomes of acute febrile illness in children attending a tertiary hospital in southern Ethiopia

Background

The management of febrile illnesses is challenging in settings where diagnostic laboratory facilities are limited, and there are few published longitudinal data on children presenting with fever in such settings. We have previously conducted the first comprehensive study of infectious aetiologies of febrile children presenting to a tertiary care facility in Ethiopia. We now report on clinicians’ prescribing adherence with guidelines and outcomes of management in this cohort.

Methods

We consecutively enrolled febrile children aged 2 months and under 13 years, who were then managed by clinicians based on presentation and available laboratory and radiologic findings on day of enrolment. We prospectively collected outcome data on days 7 and 14, and retrospectively evaluated prescribing adherence with national clinical management guidelines.

Results

Of 433 children enrolled, the most common presenting syndromes were pneumonia and acute diarrhoea, diagnosed in 177 (40.9%) and 82 (18.9%), respectively. Antibacterial agents were prescribed to 360 (84.7%) of 425 children, including 36 (34.0%) of 106 children without an initial indication for antibacterials according to guidelines. Antimalarial drugs were prescribed to 47 (11.1%) of 425 children, including 30 (7.3%) of 411 children with negative malaria microscopy. Fever had resolved in 357 (89.7%) of 398 children assessed at day 7, and in-hospital death within 7 days occurred in 9 (5.9%) of 153 admitted patients. Among children with pneumonia, independent predictors of persisting fever or death by 7 days were young age and underweight for age. Antibacterial prescribing in the absence of a guideline-specified indication (overprescribing) was more likely among infants and those without tachypnea, while overprescribing antimalarials was associated with older age, anaemia, absence of cough, and higher fevers.

Conclusion

Our study underscores the need for improving diagnostic support to properly guide management decisions and enhance adherence by clinicians to treatment guidelines.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-022-07424-0.

Urinary Antigen Testing for Respiratory Infections: Current Perspectives on Utility and Limitations

Pneumonia is a leading cause of hospitalization and death due to infection worldwide. Streptococcus pneumoniae and Legionella pneumophila remain among the most commonly identified bacterial pathogens. Unfortunately, more than half of all pneumonia cases today lack an etiologic diagnosis due to limitations in traditional microbiological methods like blood and sputum cultures, which are affected by poor sample collection, prior antibiotic administration, and delayed processing. Urinary antigen tests (UATs) for S. pneumoniae and L. pneumophila have emerged as powerful tools for improving the diagnosis of bacterial respiratory infections, enabling physicians to administer early directed therapy and improve antimicrobial stewardship. UATs are simple, rapid, and non-invasive diagnostic tests with high specificity (>90%) and moderate sensitivity (<80%). The potential impact of urinary antigen testing is especially significant for respiratory infections caused by Legionella. While all recommended community-acquired pneumonia (CAP) therapies are adequate for treating pneumococcal pneumonia, only certain antibiotics are effective against Legionella. Delayed therapy for Legionella is associated with worse clinical outcomes, which underscores the importance of rapid diagnostic methods like UATs. Despite their potential impact, current American Thoracic Society and Infectious Diseases Society of America (ATS/IDSA) guidelines argue against the routine use of urinary antigen testing for S. pneumoniae and L. pneumophila, except in patients with severe CAP and those with epidemiological risk factors for Legionella. Further research is necessary to evaluate the impact of early targeted treatment due to positive UAT results, as well as optimal strategies for UAT utilization. The purpose of this review is to summarize the UATs available for bacterial respiratory infections, describe current guidelines on their usage, and assess their impact on clinical outcomes and targeted therapy.

Non-invasive pneumococcal pneumonia due to vaccine serotypes: A systematic review and meta-analysis

BACKGROUND

Non-invasive pneumococcal pneumonia causes significant morbidity and mortality in older adults. Understanding pneumococcal sero-epidemiology in adults ≥50 years is necessary to inform vaccination policies and the updating of pneumococcal vaccines.

METHODS

We conducted a systematic review and random-effects meta-analysis to determine the proportion of community-acquired pneumonia (CAP) in people ≥50 years due to pneumococcus and the proportion caused by pneumococcal vaccine serotypes. We searched MEDLINE, EMBASE and PubMed from 1 January 1990 to 30 March 2021. Heterogeneity was explored by subgroup analysis according to a) patient group (stratified versus age) and depth of testing, b) detection/serotyping method, and c) continent. The protocol is registered with PROSPERO (CRD42020192002).

FINDINGS

Twenty-eight studies were included (34,216 patients). In the period 1-5 years after introduction of childhood PCV10/13 immunisation, 18% of CAP cases (95% CI 13-24%) were attributable to pneumococcus, with 49% (43-54%) of pneumococcal CAP due to PCV13 serotypes. The estimated proportion of pneumococcal CAP was highest in one study that used 24-valent serotype-specific urinary-antigen detection (ss-UAD)(30% [28-31%]), followed by studies based on diagnostic serology (28% [24-33%]), PCR (26% [15-37%]), ss-UAD14 (17% [13-22%]), and culture alone (14% [10-19%]). A higher estimate was observed in Europe (26% [21-30%] than North America (11% [9-12%](p<0·001). PCV13-serotype estimates were also influenced by serotyping methods.

INTERPRETATION

Non-invasive pneumococcal CAP and vaccine-type pneumococcal CAP remains a burden in older adults despite widespread introduction of pneumococcal infant immunisation. Studies heavily reliant on ss-UADs restricted to vaccine-type serotypes may overestimate the proportion of potentially vaccine-preventable pneumococcal pneumonia. Sero-epidemiological data from low-income countries are lacking.

Viruses and Mycoplasma pneumoniae are the main etiological agents of community-acquired pneumonia in hospitalized pediatric patients in Spain

OBJECTIVES

To describe the etiology of community-acquired pneumonia (CAP) in hospitalized children in Spain and analyze the predictors of the etiology.

HYPOTHESIS

The different etiological groups of pediatric CAP are associated with different clinical, radiographic, and analytical data.

DESIGN

Observational, multicenter, and prospective study.

PATIENT SELECTION

This study included children aged 1 month to 17 years with CAP, who were hospitalized between April 2012 and May 2019.

METHODS

An extensive microbiological workup was performed. The clinical, radiographic, and analytical parameters were analyzed for three etiological groups.

RESULTS

Among the 495 children included, at least one causative pathogen was identified in 262 (52.9%): pathogenic viruses in 155/262 (59.2%); atypical bacteria (AB), mainly Mycoplasma pneumonia, in 84/262 (32.1%); and typical bacteria (TyB) in 40/262 (15.3%). Consolidation was observed in 89/138 (64.5%) patients with viral CAP, 74/84 (88.1%) with CAP caused by AB, and 40/40 (100%) with CAP caused by TyB. Para-pneumonic pleural effusion (PPE) was observed in 112/495 (22.6%) patients, of which 61/112 (54.5%) presented a likely causative pathogen: viruses in 12/61 (19.7%); AB in 23/61 (37.7%); and TyB in 26/61 (42.6%). Viral etiology was significantly frequent in young patients and in those with low oxygen saturation, wheezing, no consolidation, and high lymphocyte counts. CAP patients with AB as the etiological agent had a significantly longer and less serious course as compared to those with other causative pathogens.

CONCLUSIONS

Viruses and M. pneumoniae are the main causes of pediatric CAP in Spain. Wheezing, young age, and no consolidation on radiographs are indicative of viral etiology. Viruses and AB can also cause PPE. Since only a few cases can be directly attributed to TyB, the indications for antibiotics must be carefully considered in each patient.

Pediatric Invasive Pneumococcal Disease (IPD) in Yogyakarta, Indonesia: A Case Series

Given the fact that invasive pneumococcal disease (IPD) has a high clinical burden, particularly among children in developing countries, data on its occurrence and clinical profile in Indonesia is still insufficient. We presented 3 cases of IPD in children who were admitted to Dr. Sardjito General Hospital, Yogyakarta, Indonesia between 2016 and 2019. While our first 2 patients had milder course of disease, our third patient who presented with meningoencephalitis had poor outcome. Risk factors shown in our cases were young age and malignancy history. Multiple antibiotic resistance was observed in our isolates. The fact that none of our patients have received pneumococcal vaccination marks the necessity of this vaccine especially for at-risk children.

Pooled Microbiological Findings and Efficacy Outcomes by Pathogen in Adults With Community-Acquired Bacterial Pneumonia from the Lefamulin Evaluation Against Pneumonia (LEAP) 1 and LEAP 2 Phase 3 Trials of Lefamulin Versus Moxifloxacin

BACKGROUND

Lefamulin, a pleuromutilin antibiotic approved for community-acquired bacterial pneumonia (CABP), was evaluated for microbiological efficacy in a prespecified pooled analysis of LEAP 1 and 2 phase 3 clinical trial data in patients with CABP.

METHODS

In LEAP 1, adults (Pneumonia Outcomes Research Team [PORT] risk class III‒V) received intravenous (IV) lefamulin 150 mg every 12 hours (q12h; 5‒7 days) or moxifloxacin 400 mg every 24 hours (q24h; 7 days), with optional IV-to-oral switch. In LEAP 2, adults (PORT II‒IV) received oral lefamulin 600 mg q12h (5 days) or moxifloxacin 400 mg q24h (7 days). Primary outcomes were early clinical response (ECR) 96±24 hours after treatment start and investigator assessment of clinical response (IACR) 5‒10 days after last dose. Secondary outcomes included ECR and IACR in patients with a baseline CABP pathogen (detected via culture, urinary antigen test, serology, and/or real-time PCR).

RESULTS

Baseline CABP pathogens were detected in 709/1289 patients (55.0% [microbiological intent-to-treat population]). The most frequently identified pathogens in this population were Streptococcus pneumoniae (61.9% of patients) and Haemophilus influenzae (29.9%); 25.1% had atypical pathogens and 33.1% had polymicrobial infections. Pathogens were identified most frequently by PCR from sputum, followed by culture from respiratory specimens. In patients with baseline CABP pathogens, ECR rates were 89.3% (lefamulin) and 93.0% (moxifloxacin); IACR success rates were 83.2% and 86.7%, respectively. Results were consistent across CABP pathogens, including drug-resistant isolates and polymicrobial infections.

CONCLUSIONS

Lefamulin is a valuable IV and oral monotherapy option for empiric and directed CABP treatment in adults.

Associations of Serum Resistin With the Severity and Prognosis in Patients With Community-Acquired Pneumonia

Background

Resistin is an endogenous ligand of Toll-like receptor 4 that activates several inflammatory signals. But the physiological function of resistin in community-acquired pneumonia (CAP) remains unknown. The goal of this research was to explore the associations between serum resistin and the severity and prognosis in CAP patients through a retrospective cohort study.

Methods

All 212 CAP patients and 106 healthy cases were enrolled. Demographic characteristics were extracted. Serum resistin was determined via enzyme-linked immunosorbent assay. The prognosis was tracked in CAP patients.

Results

Serum resistin on admission was raised in CAP patients compared with control cases. The level of resistin was gradually increased in parallel with CAP severity scores in CAP patients. Pearson and Spearman analyses revealed that serum resistin was positively correlated with CAP severity scores, white blood cells, urea nitrogen, creatinine, and inflammatory cytokines among CAP patients. There were negative relationships between resistin and hematocrit and albumin in CAP patients. Besides, linear and logistic regression analyses further indicated that serum resistin on admission was positively associated with CAP severity scores among CAP patients. Follow-up research revealed that serum resistin elevation on admission prolonged hospital stay in CAP patients.

Conclusion

Serum resistin on admission is positively correlated with the severity and hospital stay in CAP patients, indicating that resistin may be involved in the physiological process of CAP. Serum resistin may be a potential biomarker in the diagnosis and prognosis for CAP.

Evaluation of the impact of childhood 13-valent pneumococcal conjugate vaccine introduction on adult pneumonia in Ulaanbaatar, Mongolia: study protocol for an observational study

BACKGROUND

Community-acquired pneumonia is an important cause of morbidity and mortality in adults. Approximately one-third of pneumonia cases can be attributed to the pneumococcus. Pneumococcal conjugate vaccines (PCVs) protect against colonisation with vaccine-type serotypes. The resulting decrease in transmission of vaccine serotypes leads to large indirect effects. There are limited data from developing countries demonstrating the impact of childhood PCV immunisation on adult pneumonia. There are also insufficient data available on the burden and severity of all-cause pneumonia and respiratory syncytial virus (RSV) in adults from low resource countries. There is currently no recommendation for adult pneumococcal vaccination with either pneumococcal polysaccharide vaccine or PCVs in Mongolia. We describe the protocol developed to evaluate the association between childhood 13-valent PCV (PCV13) vaccination and trends in adult pneumonia.

METHODS

PCV13 was introduced into the routine childhood immunisation schedule in Mongolia in a phased manner from 2016. In March 2019 we initiated active hospital-based surveillance for adult pneumonia, with the primary objective of evaluating trends in severe hospitalised clinical pneumonia incidence in adults 18 years and older in four districts of Ulaanbaatar. Secondary objectives include measuring the association between PCV13 introduction and trends in all clinically-defined pneumonia, radiologically-confirmed pneumonia, nasopharyngeal carriage of S. pneumoniae and pneumonia associated with RSV or influenza. Clinical questionnaires, nasopharyngeal swabs, urine samples and chest radiographs were collected from enrolled patients. Retrospective administrative and clinical data were collected for all respiratory disease-related admissions from January 2015 to February 2019.

DISCUSSION

Establishing a robust adult surveillance system may be an important component of monitoring the indirect impact of PCVs within a country. Monitoring indirect impact of childhood PCV13 vaccination on adult pneumonia provides additional data on the full public health impact of the vaccine, which has implications for vaccine efficiency and cost-effectiveness. Adult surveillance in Mongolia will contribute to the limited evidence available on the burden of pneumococcal pneumonia among adults in low- and middle-income countries, particularly in the Asia-Pacific region. In addition, it is one of the few examples of implementing prospective, population-based pneumonia surveillance to evaluate the indirect impact of PCVs in a resource-limited setting.

Effectiveness of Pneumococcal Vaccination Against Hospitalized Pneumococcal Pneumonia in Older Adults: A Prospective, Test-Negative Study

BACKGROUND

Despite use of the 13-valent pneumococcal conjugate vaccine (PCV13) and 23-valent pneumococcal polysaccharide vaccine (PPSV23) over the last decade, the disease burden of pneumococcal pneumonia is still high. We evaluated the field effectiveness of PCV13, PPSV23, and sequential vaccination against pneumococcal pneumonia in older adults.

METHODS

This prospective multicenter study was conducted in adults aged ≥ 65 years with hospitalized community-acquired pneumonia (CAP) between September 2015 and August 2017. The case-control test-negative design was used to estimate vaccine effectiveness (VE) against pneumococcal CAP.

RESULTS

Of 1,525 cases with hospitalized CAP, 167 (11.0%) were identified as pneumococcal CAP. In the elderly aged ≥65 years, the adjusted VE of pneumococcal vaccines against pneumococcal CAP was statistically insignificant: 40.0% (95% CI -10.8% to 67.5%) for PCV13 and 11.0% (95% CI, -26.4% to 37.3%) for PPSV23. However, in the younger subgroup (aged 65-74 years), sequential PCV13/PPSV23 vaccination showed the highest adjusted VE of 80.3% (95% CI 15.9% to 95.4%), followed by single-dose PCV13 (adjusted VE 66.4%; 95% CI 0.8% to 88.6%) and PPSV23 (adjusted VE 18.5%; 95% CI -38.6% to 52.0%).

CONCLUSIONS

Sequential PCV13/PPSV23 vaccination is most effective for preventing pneumococcal CAP among the elderly aged 65-74 years.

Structural, Genetic, and Serological Elucidation of Streptococcus pneumoniae Serogroup 24 Serotypes: Discovery of a New Serotype, 24C, with a Variable Capsule Structure

Pneumococcal capsules are important in pneumococcal pathogenesis and vaccine development. Although conjugate vaccines have brought about a significant reduction in invasive pneumococcal disease (IPD) caused by vaccine serotypes, the relative serotype prevalence has shifted with the dramatic emergence of serotype 24F in some countries. Here, we describe 14 isolates (13 IPD and 1 non-IPD) expressing a new capsule type, 24C, which resembles 24F but has a novel serological profile. We also describe the antigenic, biochemical, and genetic basis of 24F and 24C and the related serotypes 24A and 24B. Structural studies show that 24B, 24C, and 24F have identical polysaccharide backbones [β-Ribf-(1→4)-α-Rhap-(1→3)-β-GlcpNAc-(1→4)-β-Rhap-(1→4)-β-Glcp] but with different side chains, as follows: 24F has arabinitol-phosphate and 24B has ribitol-phosphate. 24C has a mixture of 24F and 24B repeating units, with the ratio of ribitol to arabinitol being strain dependent. In contrast, the 24A capsule has a backbone without β-Ribf but with arabinitol-phosphate and phosphocholine side chains. These structures indicate that factor-sera 24d and 24e recognize arabinitol and ribitol, respectively, which explains the serology of serogroup 24, including those of 24C. The structures can be genetically described by the bispecificity of wcxG, which is capable of transferring arabinitol or ribitol when arabinitol is limiting. Arabinitol is likely not produced in 24B but is produced in reduced amounts in 24C due to various mutations in abpA or abpB genes. Our findings demonstrate how pneumococci modulate their capsule structure and immunologic properties with small genetic changes, thereby evading host immune responses. Our findings also suggest a potential for new capsule types within serogroup 24.

Improvement of pneumococcal pneumonia diagnosis using quantitative real-time PCR targeting lytA in adult patients: a prospective cohort study

OBJECTIVES

The aim of the study was to assess the performance of real-time PCR targeting the lytA gene (rtPCR-lytA) in plasma, urine and nasopharyngeal (NP) samples for the diagnosis of pneumococcal community-acquired pneumonia (P-CAP).

METHODS

Prospective observational study including all consecutive adults with CAP from November 2015 to May 2017. P-CAP was defined if pneumococcus was identified using conventional methods (CM) and/or a positive rtPCR-lytA was detected in blood, urine or NP samples (NP cut-off ≥8000 copies/mL). Diagnostic performance of each test was calculated.

RESULTS

A total of 133 individuals with CAP were included. Of these, P-CAP was diagnosed in 62 (46.6%). The proportion of P-CAP diagnosed by rtPCR-lytA methods was significantly higher than that diagnosed by CM (87.1% versus 59.7%, p 0.005). The rtPCR-lytA identified Streptococcus pneumoniae in 25 patients (40.3% of all individuals with P-CAP) whose diagnosis would have been missed by CM. NP-rtPCR-lytA allowed diagnosis of 62.3% of P-CAP. A nasopharyngeal colonization density ≥2351 copies/mL predicted P-CAP diagnosis (area under the curve = 0.82, sensitivity 83.3%, specificity 80.9%). There was a positive correlation between increasing bacterial load in blood and CURB-65 score (Spearman correlation coefficient r = 0.4, p 0.001), pneumonia severity index (r = 0.3, p 0.02) and time to clinical stability (r = 0.33, p 0.01). Median bacterial load in blood was higher in P-CAP patients with bacteraemia (0.65 × 10³ versus 0 × 10³ copies/mL, p 0.002), intensive care unit admission (0.68 × 10³ versus 0 × 10³ copies/mL, p 0.04) or mechanical ventilation (7.45 × 10³ versus 0 × 10³ copies/mL, p 0.04).

CONCLUSIONS

The use of rtPCR-lytA methods significantly increased the diagnosis of P-CAP compared with CM. Nasopharyngeal swabs rtPCR-lytA detection, with an accurate cut-off value, was the most promising among molecular methods for the diagnosis of P-CAP.

Acute Respiratory Tract Infections among Hospitalized Palestinian Patients (2011-2016): A Retrospective Study

Respiratory tract infections (RTIs) are a major public health concern. This study aims to investigate the profiles and epidemiological characteristics of acute RTIs and respiratory pathogens in Palestinian hospitalized patients. Clinical samples from hospitalized patients with symptoms of acute RTIs admitted between January 2011 and December 2016 were referred to the Palestinian Central Public Health Laboratory (PHCL) to identify the causative pathogen. Patients' demographic information and the results of the molecular identification were retrieved from the electronic database at the PHCL. A total of 15413 patients with acute RTIs were hospitalized during the study period. The causal agent was identified only in 28.7% of the patients. Overall, influenza viruses were the most common cause of RTIs among hospitalized Palestinian patients in the West Bank. Children and elderlies were the most affected with RTIs. The elderly population (≥60 years old) had the highest rates. After influenza A virus, respiratory syncytial virus (RSV), and Bordetella pertussis (B. pertussis) were the most common causes of acute RTIs among hospitalized Palestinian patients. Children showed the highest hospitalization rates for RSV, B. pertussis, adenovirus, enterovirus, and Streptococcus pneumoniae. On the other hand, elderlies had the highest rates of influenza. Outbreaks of RTIs occurred mainly during winter (between December and March). The resurgence of B. pertussis in spite of vaccination is alarming and requires further investigation.

Pneumococcal Urinary Antigen Testing in United States Hospitals: A Missed Opportunity for Antimicrobial Stewardship

BACKGROUND

The Infectious Diseases Society of America recommends pneumococcal urinary antigen testing (UAT) when identifying pneumococcal infection would allow for antibiotic de-escalation. However, the frequencies of UAT and subsequent antibiotic de-escalation are unknown.

METHODS

We conducted a retrospective cohort study of adult patients admitted with community-acquired or healthcare-associated pneumonia to 170 US hospitals in the Premier database from 2010 to 2015, to describe variation in UAT use, associations of UAT results with antibiotic de-escalation, and associations of de-escalation with outcomes.

RESULTS

Among 159 894 eligible admissions, 24 757 (15.5%) included UAT performed (18.4% of intensive care unit [ICU] and 15.3% of non-ICU patients). Among hospitals with ≥100 eligible patients, UAT proportions ranged from 0% to 69%. Compared to patients with negative UAT, 7.2% with positive UAT more often had a positive Streptococcus pneumoniae culture (25.4% vs 1.9%, P < .001) and less often had resistant bacteria (5.2% vs 6.8%, P < .05). Of patients initially treated with broad-spectrum antibiotics, most were still receiving broad-spectrum therapy 3 days later, but UAT-positive patients more often had coverage narrowed (38.4% vs 17.0% UAT-negative and 14.6% untested patients, P < .001). Hospital rate of UAT was strongly correlated with de-escalation following a positive test. Only 3 patients de-escalated after a positive UAT result were subsequently admitted to ICU.

CONCLUSIONS

UAT is not ordered routinely in pneumonia, even in ICU. A positive UAT result was associated with less frequent resistant organisms, but usually did not lead to antibiotic de-escalation. Increasing UAT and narrowing therapy after a positive UAT result are opportunities for improved antimicrobial stewardship.

Thermostable Heptaplex PCR Assay for the Detection of Six Respiratory Bacterial Pathogens

A thermostabilized, multiplex polymerase chain reaction (mPCR) assay was developed in this study for the detection of six respiratory bacterial pathogens. Specific primers were designed for an internal amplification control (IAC) and six target sequences from Klebsiella pneumoniae, Staphylococcus aureus, Streptococcus pneumoniae, Pseudomonas aeruginosa, Mycobacterium tuberculosis, and Haemophilus influenzae. The resultant seven-band positive amplification control (PAC) of this heptaplex PCR assay corresponded to 105 base pairs (bp) of IAC, 202 bp of K. pneumoniae, 293 bp of S. aureus, 349 bp of S. pneumoniae, 444 bp of P. aeruginosa, 505 bp of M. tuberculosis, and 582 bp of H. influenzae. Results found that 6% (w/v) of the stabilizer was optimum to preserve the functional conformation of Taq DNA polymerase enzyme. This assay was stable at ambient temperature for at least 6 months. The sensitivity and specificity of this assay were both 100% when testing on the intended target organisms (n = 119) and non-intended species (n = 57). The mPCR assay developed in this study enabled accurate, rapid, and simple detection of six respiratory bacteria.

Invasive Pneumococcal Disease in Latvia in PCV10 Vaccination Era, 2012-2018

In 2010 in Latvia, invasive pneumococcal disease (IPD) became a cause for concern and vaccination of infants with four doses of 7-valent pneumococcal conjugate vaccine (PCV7) commenced. In 2012, 10-valent pneumococcal conjugate vaccine (PCV10) (three doses at 2, 4, and 12-15 month of age) vaccination was introduced. We described incidence and serotype distribution of IPD in Latvia and investigated serotypes associated with death from IPD based on surveillance data. Adult vaccination against pneumococcal infection is not included in the national immunization program. Laboratory confirmed IPD cases are passively notified to the Center for Disease Prevention and Control of Latvia (CDPC) by laboratories and clinicians. We calculated incidence by age, sex, case fatality, and trend in serotypes by conducting a retrospective population-based cross-sectional study based on national IPD surveillance data. From 2012 to 2018 466 cases of IPD were reported. The highest notified incidence was in 2015 at 4.4/100,000, which fell to 3.9 in 2018. The highest mean annual IPD incidence was in infants (4.8) and in the elderly (6.0). PCV10 vaccine serotypes were the most prevalent in IPD cases up to 2015 with a decreasing trend from 50% (20/40) in 2012 to 19% (14/74) in 2018 (chi2 test for trend of odds = 0.000). PCV23nonPCV13 vaccine serotypes had an increasing trend and rose from 18% (7/40) to 34% (25/74) (chi2 test for trend of odds = 0.000). Non-Vaccine serotypes had an increasing trend and rose from 13% (5/40) to 27% (20/74) (chi2 test for trend of odds = 0.038). Reported total case fatality was 19% (87/466). The highest, at 36% (20/56), was reported in 2013. After adjusting for age, Streptococcus pneumoniae serotype 3 was associated with death from IPD (adjusted OR 2.3 95%CI 1.25-4.12 p 0.007). Surveillance data indicate evidence of serotype replacement with an increasing trend of serotype 19A and PPV23nonPCV13 and Non-Vaccine serotypes. Serotype 3 and age were associated with fatal IPD outcome. Further studies of S. pneumoniae carriage would be useful in providing more evidence to characterize serotypes' circulation.

Sugar-Coated Killer: Serotype 3 Pneumococcal Disease

Capsular polysaccharide (CPS), which surrounds the bacteria, is one of the most significant and multifaceted contributors to Streptococcus pneumoniae virulence. Capsule prevents entrapment in mucus during colonization, traps water to protect against desiccation, can serve as an energy reserve, and protects the bacterium against complement-mediated opsonization and immune cell phagocytosis. To date, 100 biochemically and serologically distinct capsule types have been identified for S. pneumoniae; 20 to 30 of which have well-defined propensity to cause opportunistic human infection. Among these, serotype 3 is perhaps the most problematic as serotype 3 infections are characterized as having severe clinical manifestations including empyema, bacteremia, cardiotoxicity, and meningitis; consequently, with a fatality rate of 30%–47%. Moreover, serotype 3 resists antibody-mediated clearance despite its inclusion in the current 13-valent conjugate vaccine formulation. This review covers the role of capsule in pneumococcal pathogenesis and the importance of serotype 3 on human disease. We discuss how serotype 3 capsule synthesis and presentation on the bacterial surface is distinct from other serotypes, the biochemical and physiological properties of this capsule type that facilitate its ability to cause disease, and why existing vaccines are unable to confer protection. We conclude with discussion of the clonal properties of serotype 3 and how these have changed since introduction of the 13-valent vaccine in 2000.

Hyperglycemia, Insulin, and Insulin Resistance in Sepsis

Critically ill patients frequently have hyperglycemia. This event may reflect severe stress with an imbalance between anabolic hormones and catabolic hormones. Alternatively, it may reflect alterations in either insulin levels or insulin function. Insulin is a pleiotropic hormone with multiple important metabolic effects. In patients with sepsis, insulin levels are increased but insulin sensitivity is decreased. However, there is variability in insulin sensitivity, and this creates variability in glucose levels and insulin requirements and increases the frequency of hypo- and hyperglycemia. The factors that influence insulin sensitivity are complex and include inhibition of tyrosine kinase activity of the beta subunit, increased proteolytic activity resulting in loss of receptors from the plasma membrane, and possibly the transfer of insulin receptors into the nucleus where they bind to gene promoters. Better understanding of the role of insulin in critically ill patients requires prospective studies measuring insulin levels in various patient groups and the development of a simple measure of insulin sensitivity.

Discovery of Species-unique Peptide Biomarkers of Bacterial Pathogens by Tandem Mass Spectrometry-based Proteotyping

Mass spectrometry (MS) and proteomics offer comprehensive characterization and identification of microorganisms and discovery of protein biomarkers that are applicable for diagnostics of infectious diseases. The use of biomarkers for diagnostics is widely applied in the clinic and the use of peptide biomarkers is increasingly being investigated for applications in the clinical laboratory. Respiratory-tract infections are a predominant cause for medical treatment, although, clinical assessments and standard clinical laboratory protocols are time-consuming and often inadequate for reliable diagnoses. Novel methods, preferably applied directly to clinical samples, excluding cultivation steps, are needed to improve diagnostics of infectious diseases, provide adequate treatment and reduce the use of antibiotics and associated development of antibiotic resistance. This study applied nano-liquid chromatography (LC) coupled with tandem MS, with a bioinformatics pipeline and an in-house database of curated high-quality reference genome sequences to identify species-unique peptides as potential biomarkers for four bacterial pathogens commonly found in respiratory tract infections (RTIs): Staphylococcus aureus; Moraxella catarrhalis; Haemophilus influenzae and Streptococcus pneumoniae The species-unique peptides were initially identified in pure cultures of bacterial reference strains, reflecting the genomic variation in the four species and, furthermore, in clinical respiratory tract samples, without prior cultivation, elucidating proteins expressed in clinical conditions of infection. For each of the four bacterial pathogens, the peptide biomarker candidates most predominantly found in clinical samples, are presented. Data are available via ProteomeXchange with identifier PXD014522. As proof-of-principle, the most promising species-unique peptides were applied in targeted tandem MS-analyses of clinical samples and their relevance for identifications of the pathogens, i.e. proteotyping, was validated, thus demonstrating their potential as peptide biomarker candidates for diagnostics of infectious diseases.

Pneumococcal pneumonia prevalence among adults with severe acute respiratory illness in Thailand - comparison of Bayesian latent class modeling and conventional analysis

BACKGROUND

Determining the etiology of pneumonia is essential to guide public health interventions. Diagnostic test results, including from polymerase chain reaction (PCR) assays of upper respiratory tract specimens, have been used to estimate prevalence of pneumococcal pneumonia. However limitations in test sensitivity and specificity and the specimen types available make establishing a definitive diagnosis challenging. Prevalence estimates for pneumococcal pneumonia could be biased in the absence of a true gold standard reference test for detecting Streptococcus pneumoniae.

METHODS

We conducted a case control study to identify etiologies of community acquired pneumonia (CAP) from April 2014 through August 2015 in Thailand. We estimated the prevalence of pneumococcal pneumonia among adults hospitalized for CAP using Bayesian latent class models (BLCMs) incorporating results of real-time polymerase chain reaction (qPCR) testing of upper respiratory tract specimens and a urine antigen test (UAT) from cases and controls. We compared the prevalence estimate to conventional analyses using only UAT as a reference test.

RESULTS

The estimated prevalence of pneumococcal pneumonia was 8% (95% CI: 5-11%) by conventional analyses. By BLCM, we estimated the prevalence to be 10% (95% CrI: 7-16%) using binary qPCR and UAT results, and 11% (95% CrI: 7-17%) using binary UAT results and qPCR cycle threshold (Ct) values.

CONCLUSIONS

BLCM suggests a > 25% higher prevalence of pneumococcal pneumonia than estimated by a conventional approach assuming UAT as a gold standard reference test. Higher quantities of pneumococcal DNA in the upper respiratory tract were associated with pneumococcal pneumonia in adults but the addition of a second specific pneumococcal test was required to accurately estimate disease status and prevalence. By incorporating the inherent uncertainty of diagnostic tests, BLCM can obtain more reliable estimates of disease status and improve understanding of underlying etiology.

Metabolomics Reveals Anaerobic Bacterial Fermentation and Hypoxanthine Accumulation for Fibrinous Pleural Effusions in Children with Pneumonia

Fibrin formation in infectious parapneumonic effusion (IPE) characterizes complicated parapneumonic effusion and is important for providing guidelines for the management of IPEs that require aggressive interventions. We aim to identify metabolic mechanisms associated with bacterial invasion, inflammatory cytokines, and biochemical markers in cases of fibrinous infectious pleural effusions in children with pneumonia. Pleural fluid metabolites were determined by ¹H nuclear magnetic resonance spectroscopy. Metabolites that contributed to the separation between fibrinous and nonfibrinous IPEs were identified using supervised partial least squares discriminant analysis ( Q²/ R² = 0.84; P_permutation < 0.01). IL-1β in the inflammatory cytokines and glucose in the biochemical markers were significantly correlated with 11 and 9 pleural fluid metabolites, respectively, and exhibited significant overlaps. Four metabolites, including glucose, lactic acid, 3-hydroxybutyric acid, and hypoxanthine, were significantly correlated with plasminogen activator inhibitor type 1 in the fibrinolytic system enzymes. Metabolic pathway analysis revealed that anaerobic bacterial fermentation with increased lactic acid and butyric acid via glucose consumption and adenosine triphosphate hydrolysis with increased hypoxanthine appeared to be associated with fibrinous IPE. Our results demonstrate that an increase in lactic acid anaerobic fermentation and hypoxanthine accumulation under hypoxic conditions are associated with fibrin formation in IPE, representing advanced pleural inflammatory progress in children with pneumonia.

Structure-Function Relationships of C-Reactive Protein in Bacterial Infection

One host defense function of C-reactive protein (CRP) is to protect against Streptococcus pneumoniae infection as shown by experiments employing murine models of pneumococcal infection. The protective effect of CRP is due to reduction in bacteremia. There is a distinct relationship between the structure of CRP and its anti-pneumococcal function. CRP is functional in both native and non-native pentameric structural conformations. In the native conformation, CRP binds to pneumococci through the phosphocholine molecules present on the C-polysaccharide of the pneumococcus and the anti-pneumococcal function probably involves the known ability of ligand-complexed CRP to activate the complement system. In the native structure-function relationship, CRP is protective only when given to mice within a few hours of the administration of pneumococci. The non-native pentameric conformation of CRP is created when CRP is exposed to conditions mimicking inflammatory microenvironments, such as acidic pH and redox conditions. In the non-native conformation, CRP binds to immobilized complement inhibitor factor H in addition to being able to bind to phosphocholine. Recent data using CRP mutants suggest that the factor H-binding function of non-native CRP is beneficial: in the non-native structure-function relationship, CRP can be given to mice any time after the administration of pneumococci irrespective of whether the pneumococci became complement-resistant or not. In conclusion, while native CRP is protective only against early stage infection, non-native CRP is protective against both early stage and late stage infections. Because non-native CRP displays phosphocholine-independent anti-pneumococcal activity, it is quite possible that CRP functions as a general anti-bacterial molecule.

Effectiveness of pneumococcal conjugate vaccines against invasive pneumococcal disease among children under five years of age in Africa: A systematic review

BACKGROUND

Despite the widespread implementation of the pneumococcal conjugate vaccine, Streptococcus pneumoniae remains the leading cause of severe pneumonia associated with mortality among children less than 5 years of age worldwide, with the highest mortality rates recorded in Africa and Asia. However, information on the effectiveness and prevalence of vaccine serotypes post-roll out remains scarce in most African countries. Hence, this systematic review aimed to describe what is known about the decline of childhood invasive pneumococcal disease post-introduction of the pneumococcal conjugate vaccine in Africa.

METHODS

This systematic review included articles published between 2009 and 2018 on the implementation of the pneumococcal conjugate vaccine in Africa. We searched PubMed, Scopus and African Index Medicus for articles in English. Studies on implementation programmes of pneumococcal conjugate vaccine 10/13, with before and after data from different African countries, were considered eligible. The review followed the procedures published in PROSPERO (ID = CRD42016049192).

RESULTS

In total, 2,280 studies were identified through electronic database research, and only 8 studies were eligible for inclusion in the final analysis. Approximately half (n = 3) of these studies were from South Africa. The overall decline in invasive pneumococcal disease ranged from 31.7 to 80.1%. Invasive pneumococcal diseases caused by vaccine serotypes declined significantly, the decline ranged from 35.0 to 92.0%. A much higher decline (55.0-89.0%) was found in children below 24 months of age. Of all vaccine serotypes, the relative proportions of serotypes 1, 5 and 19A doubled following vaccine roll out.

INTERPRETATION

Following the introduction of the pneumococcal conjugate vaccine, a significant decline was observed in invasive pneumococcal disease caused by vaccine serotypes. However, data on the effectiveness in this region remain scarce, meriting continued surveillance to assess the effectiveness of pneumococcal vaccination to improve protection against invasive pneumococcal disease.

Proteotyping bacteria: Characterization, differentiation and identification of pneumococcus and other species within the Mitis Group of the genus Streptococcus by tandem mass spectrometry proteomics

A range of methodologies may be used for analyzing bacteria, depending on the purpose and the level of resolution needed. The capability for recognition of species distinctions within the complex spectrum of bacterial diversity is necessary for progress in microbiological research. In clinical settings, accurate, rapid and cost-effective methods are essential for early and efficient treatment of infections. Characterization and identification of microorganisms, using, bottom-up proteomics, or "proteotyping", relies on recognition of species-unique or associated peptides, by tandem mass spectrometry analyses, dependent upon an accurate and comprehensive foundation of genome sequence data, allowing for differentiation of species, at amino acid-level resolution. In this study, the high resolution and accuracy of MS/MS-based proteotyping was demonstrated, through analyses of the three phylogenetically and taxonomically most closely-related species of the Mitis Group of the genus Streptococcus: i.e., the pathogenic species, Streptococcus pneumoniae (pneumococcus), and the commensal species, Streptococcus pseudopneumoniae and Streptococcus mitis. To achieve high accuracy, a genome sequence database used for matching peptides was created and carefully curated. Here, MS-based, bottom-up proteotyping was observed and confirmed to attain the level of resolution necessary for differentiating and identifying the most-closely related bacterial species, as demonstrated by analyses of species of the Streptococcus Mitis Group, even when S. pneumoniae were mixed with S. pseudopneumoniae and S. mitis, by matching and identifying more than 200 unique peptides for each species.

Pneumococcal urinary antigen test: A tool for pneumococcal aortitis diagnosis?

Introduction

Aortitis is rare. The etiological diagnosis is difficult but essential for treatment. Even with appropriate treatment mortality remains high. We present a case of pneumococcal aortitis followed by a brief review of the literature.

Presentation of Case

In this case, the aortic disease was characterized by multiple inflammatory aneurysms. Blood cultures were negative but urine was tested for the presence of pneumococcal urinary antigen postoperatively was positive. Treatment consisted of antibacterial therapy and both surgical and endovascular procedures. The patient was discharged and is well.

Discussion

Preoperative determination of etiology is crucial in implementing a specific treatment. Pneumococcus is a common bacterium in infectious aortitis. Identification of the causative microbe is necessary to guide antimicrobial therapy. Blood cultures are frequently sterile. The pneumococcal urinary antigen test may be more sensitive than blood cultures, as is the case in pneumococcal pneumonia.

Conclusions

The pneumococcal urinary antigen test may was a useful diagnostic tool in establishing the cause for aortitis in this case. Its potential value should be assessed in furthers studies.

Streptococcus pneumoniae's Virulence and Host Immunity: Aging, Diagnostics, and Prevention

Streptococcus pneumoniae is an infectious pathogen responsible for millions of deaths worldwide. Diseases caused by this bacterium are classified as pneumococcal diseases. This pathogen colonizes the nasopharynx of its host asymptomatically, but overtime can migrate to sterile tissues and organs and cause infections. Pneumonia is currently the most common pneumococcal disease. Pneumococcal pneumonia is a global health concern and vastly affects children under the age of five as well as the elderly and individuals with pre-existing health conditions. S. pneumoniae has a large selection of virulence factors that promote adherence, invasion of host tissues, and allows it to escape host immune defenses. A clear understanding of S. pneumoniae's virulence factors, host immune responses, and examining the current techniques available for diagnosis, treatment, and disease prevention will allow for better regulation of the pathogen and its diseases. In terms of disease prevention, other considerations must include the effects of age on responses to vaccines and vaccine efficacy. Ongoing work aims to improve on current vaccination paradigms by including the use of serotype-independent vaccines, such as protein and whole cell vaccines. Extending our knowledge of the biology of, and associated host immune response to S. pneumoniae is paramount for our improvement of pneumococcal disease diagnosis, treatment, and improvement of patient outlook.

Incidence and case fatality rates of community-acquired pneumonia and pneumococcal diseases among Korean adults: Catchment population-based analysis

Background

Pneumonia is a leading infectious cause of morbidity and mortality among adults. Pneumococcal pneumonia (PP) is the most common vaccine-preventable bacterial etiology of pneumonia. In this study, we estimated the incidence of community-acquired pneumonia (CAP) and pneumococcal diseases among Korean adults.

Methods

Clinical and microbiological databases from three hospitals were retrospectively reviewed to determine the incidence and case fatality rates of CAP and pneumococcal diseases in Korean adults aged ≥19 years from 2011 to 2014. Incidence and case fatality rates of CAP, PP and invasive pneumococcal diseases (IPD) were evaluated based on the catchment population. Catchment population was calculated using national health insurance data, estimating the proportion of patients with pneumonia that were medically attended at each hospital.

Results

Among 5,783 patients with medically attended CAP, 833 (14.4%) had PP. For IPD, a total of 91 culture-confirmed cases were identified. The overall incidence of CAP was 307.7 cases per 100,000 persons per year with an in-hospital mortality rate of 6.2%. The estimated annual incidence of pneumococcal pneumonia was 42.2–49.4 cases per 100,000 persons per year, increasing with age to >280 per 100,000 persons per year in older patients over 70 years. The annual incidence of IPD had a range of 4.1–6.5 cases per 100,000 persons per year. The overall case fatality rate for invasive pneumococcal diseases was 30.8% with the highest rate of 66.7% in patients over 80 years.

Conclusion

Over the study period, incidences of CAP, PP and IPD were consistently high, particularly in older people. These results provide baseline data to establish healthcare strategies and estimate their impact among Korean adults.

Evaluation of Pneumococcal Load in Blood by Polymerase Chain Reaction for the Diagnosis of Pneumococcal Pneumonia in Young Children in the PERCH Study

Background.

Detection of pneumococcus by lytA polymerase chain reaction (PCR) in blood had poor diagnostic accuracy for diagnosing pneumococcal pneumonia in children in 9 African and Asian sites. We assessed the value of blood lytA quantification in diagnosing pneumococcal pneumonia.

Methods.

The Pneumonia Etiology Research for Child Health (PERCH) case-control study tested whole blood by PCR for pneumococcus in children aged 1–59 months hospitalized with signs of pneumonia and in age–frequency matched community controls. The distribution of load among PCR-positive participants was compared between microbiologically confirmed pneumococcal pneumonia (MCPP) cases, cases confirmed for nonpneumococcal pathogens, nonconfirmed cases, and controls. Receiver operating characteristic analyses determined the “optimal threshold” that distinguished MCPP cases from controls.

Results.

Load was available for 290 of 291 cases with pneumococcal PCR detected in blood and 273 of 273 controls. Load was higher in MCPP cases than controls (median, 4.0 × 10³ vs 0.19 × 10³ copies/mL), but overlapped substantially (range, 0.16–989.9 × 10³ copies/mL and 0.01–551.9 × 10³ copies/mL, respectively). The proportion with high load (≥2.2 log₁₀ copies/mL) was 62.5% among MCPP cases, 4.3% among nonconfirmed cases, 9.3% among cases confirmed for a nonpneumococcal pathogen, and 3.1% among controls. Pneumococcal load in blood was not associated with respiratory tract illness in controls (P = .32). High blood pneumococcal load was associated with alveolar consolidation on chest radiograph in nonconfirmed cases, and with high (>6.9 log₁₀ copies/mL) nasopharyngeal/oropharyngeal load and C-reactive protein ≥40 mg/L (both P < .01) in nonconfirmed cases but not controls.

Conclusions.

Quantitative pneumococcal PCR in blood has limited diagnostic utility for identifying pneumococcal pneumonia in individual children, but may be informative in epidemiological studies.

Proportion of adult community-acquired pneumonia cases attributable to Streptococcus pneumoniae among Hajj pilgrims in 2016

•

The study evaluated the burden of pneumococcal community-acquired pneumonia (CAP) during Hajj 2016.

•

The majority of CAP cases (70.6%) were admitted to hospitals in Mecca, and 53% were admitted after Hajj.

•

A large proportion of cases were older adult males and 45.4% of cases were treated in the intensive care unit (ICU).

•

The overall case-fatality rate was 10.1%, but was higher among those treated in the ICU and in those with invasive disease.

•

The proportion of CAP cases positive for Streptococcus pneumoniae was 18.0%.

Background

The Hajj mass gathering is a risk for pneumococcal disease. This study was performed to evaluate the proportion of adult community-acquired pneumonia (CAP) cases attributable to Streptococcus pneumoniae among Hajj pilgrims in 2016. To add sensitivity to etiological attribution, a urine antigen test was used in addition to culture-based methods.

Methods

Adult subjects hospitalized with X-ray-confirmed CAP were enrolled prospectively from all general hospitals designated to treat Hajj pilgrims in the holy cities of Mecca and Medina. Patients were treated according to local standard of care and administered the BinaxNow S. pneumoniae urine antigen test.

Results

From August 23 to September 23, 2016, a total of 266 patients with CAP were enrolled in the study, 70.6% of whom were admitted to hospitals in Mecca; 53% of the cases were admitted after the peak of Hajj. Patients originated from 43 countries. Their mean age was 65.3 years and the male to female ratio was 2:1. Just over 36% of the cases had diabetes, 10% declared that they were smokers, and 45.4% of cases were treated in the intensive care unit (ICU). The overall case-fatality rate was 10.1%, but was higher among those treated in the ICU and in those with invasive disease. The proportion of CAP cases positive for S. pneumoniae, based on culture or urine antigen test, was 18.0% (95% confidence interval 13.9–23.1%).

Conclusions

CAP during Hajj has an important clinical impact. A proportion of CAP cases among Hajj pilgrims were attributable to S. pneumoniae, a pathogen for which vaccines are available. Additional studies to determine the serotypes causing pneumococcal disease could further inform vaccine policy for Hajj pilgrims.

The Metabolic Sensor GPR43 Receptor Plays a Role in the Control of Klebsiella pneumoniae Infection in the Lung

Pneumonia is one of the leading causes of death and mortality worldwide. The inflammatory responses that follow respiratory infections are protective leading to pathogen clearance but can also be deleterious if unregulated. The microbiota is known to be an important protective barrier against infections, mediating both direct inhibitory effects against the potential pathogen and also regulating the immune responses contributing to a proper clearance of the pathogen and return to homeostasis. GPR43 is one receptor for acetate, a microbiota metabolite shown to induce and to regulate important immune functions. Here, we addressed the role of GPR43 signaling during pulmonary bacterial infections. We have shown for the first time that the absence of GPR43 leads to increased susceptibility to Klebsiella pneumoniae infection, which was associated to both uncontrolled proliferation of bacteria and to increased inflammatory response. Mechanistically, we showed that GPR43 expression especially in neutrophils and alveolar macrophages is important for bacterial phagocytosis and killing. In addition, treatment with the GPR43 ligand, acetate, is protective during bacterial lung infection. This was associated to reduction in the number of bacteria in the airways and to the control of the inflammatory responses. Altogether, GPR43 plays an important role in the “gut–lung axis” as a sensor of the host gut microbiota activity through acetate binding promoting a proper immune response in the lungs.

The Alere BinaxNOW Pneumococcal Urinary Antigen Test: Diagnostic Sensitivity for Adult Pneumococcal Pneumonia and Relationship to Specific Serotypes

Little is known about the sensitivity of the BinaxNOW pneumococcal urinary antigen (PUA) test for adult pneumococcal pneumonia caused by different serotypes. In this study, we aimed to analyze the trends in the sensitivity of the PUA test over a 15-year period (2001 to 2015) and to analyze its sensitivity for pneumococcal pneumonia caused by different serotypes. In total, we analyzed 1,096 pneumococcal isolates from adults with pneumococcal pneumonia who had a PUA test performed at the onset of the episode. Three periods were analyzed: 2001 to 2005 (early use of the seven-valent pneumococcal conjugate vaccine [early PCV7]), 2006 to 2010 (late PCV7), and 2011 to 2015 (early PCV13). The sensitivity of the PUA test varied from 76.4% (95% confidence interval [CI], 70.5% to 82.4%) in the period from 2001 to 2005 to 77.9% in 2006 to 2010 (95% CI, 74.4% to 81.4%) and decreased to 60.5% (95% CI, 55.4% to 65.6%) in 2011 to 2015. This decrease was observed in 560 proven (83.2% in 2001 to 2005, 86.5% in 2006 to 2010, and 78.1%) and 536 probable (70.0% in 2001 to 2005, 68.7% in 2006 to 2010, and 41.5% in 2011 to 2015) episodes of pneumococcal pneumonia. Differences were observed in the sensitivity of the PUA test for diagnosing pneumonia caused by certain serotypes, being highest for the 9V (90.6%), 14 (86.8%), 18C (100%), and 20 (100%) serotypes and lowest for the 8 (55.2%), 9L/N (39.1%), 11A (48.8%), 23B (33.3%), and nontypeable (47.8%) serotypes. Comparing 2001 to 2005, 2006 to 2010, and 2011 to 2015, the prevalence of serotypes 9V (3.1%, 3.7%, and 1.7%, respectively) and 14 (7.2%, 5.1%, and 3.1%, respectively) decreased, while the prevalence of serotypes 23B (0%, 0.7%, and 1.4%, respectively), 9L/N (1.0%, 1.6%, and 3.4%, respectively), 11A (2.6%, 4.2%, and 3.7%, respectively), and 8 (1.5%, 1.5%, and 5.1%, respectively) increased. The PUA test sensitivity varied by pneumococcal pneumonia serotype, and these differences and the changes in serotype distribution were associated with an overall decrease in the sensitivity of the PUA test.

A Simple Approach to Pneumococcal Vaccination in Adults

Streptococcus pneumoniae is a bacterium responsible for a spectrum of diseases including lobar pneumonia, meningitis, otitis media, and sinusitis. Invasive pneumococcal disease is responsible for significant morbidity and mortality across the world. Concerted efforts led to the development of two vaccinations, Pneumova × 23 and Prevnar 13, for the prevention of pneumococcal disease. The Advisory Committee on Immunization Practices of the US Centers for Disease Control and Prevention provides vaccination schedules for predisposed adults, but the proposed schedules remain a challenge to health-care providers. We performed a systematic review in PubMed and these specialty group websites to present the pathophysiology of pneumococcal disease, outline different pneumococcal vaccinations, and condense recommendations for vaccination administration.

[Description and role of bacteriological techniques in the management of lung infections]

Les pneumopathies aiguës recouvrent des contextes cliniques variés et les étiologies bactériennes impliquées le sont tout autant. Aucun outil microbiologique n’est 100 % sensible ni 100 % spécifique et malgré les investigations, plus de 30 % des pneumopathies restent sans étiologie identifiée. Si aucun prélèvement n’est indiqué pour les patients traités en ambulatoire, les prélèvements respiratoires non invasifs sont à privilégier pour les pneumopathies aiguës hospitalisées (communautaires ou associées aux soins), tandis que les prélèvements invasifs sont indiqués en seconde ligne pour les pneumopathies aiguës communautaires en réanimation, et en première ligne pour les pneumopathies aiguës de l’immunodéprimé. La culture microbiologique garde une place importante, à condition que le malade soit prélevé avant instauration de l’antibiothérapie. Certains contextes peuvent justifier le recours aux hémocultures, à la recherche d’antigènes urinaires ou aux sérologies. Les PCR rendent déjà service au quotidien mais l’avenir à court terme appartient probablement aux panels moléculaires multiplex capables de détecter de nombreux micro-organismes en quelques heures, surtout dans les pneumopathies communautaires sévères de réanimation et les pneumopathies aiguës de l’immunodéprimé. Le séquençage nucléotidique haut débit révolutionnera bientôt le diagnostic microbiologique, en pneumologie comme dans les autres domaines de l’infectiologie.

Inhibition of Phosphodiesterase-4 during Pneumococcal Pneumonia Reduces Inflammation and Lung Injury in Mice

Pneumococcal pneumonia is a leading cause of mortality worldwide. The inflammatory response to bacteria is necessary to control infection, but it may also contribute to tissue damage. Phosphodiesterase-4 inhibitors, such as rolipram (ROL), effectively reduce inflammation. Here, we examined the impact of ROL in a pneumococcal pneumonia murine model. Mice were infected intranasally with 10(5)-10(6) CFU of Streptococcus pneumoniae, treated with ROL in a prophylactic or therapeutic schedule in combination, or not, with the antibiotic ceftriaxone. Inflammation and bacteria counts were assessed, and ex vivo phagocytosis assays were performed. ROL treatment during S. pneumoniae infection decreased neutrophil recruitment into lungs and airways and reduced lung injury. Prophylactic ROL treatment also decreased cytokine levels in the airways. Although modulation of inflammation by ROL ameliorated pneumonia, bacteria burden was not reduced. On the other hand, antibiotic therapy reduced bacteria without reducing neutrophil infiltration, cytokine level, or lung injury. Combined ROL and ceftriaxone treatment decreased lethality rates and was more efficient in reducing inflammation, by increasing proresolving protein annexin A1 (AnxA1) expression, and bacterial burden by enhancing phagocytosis. Lack of AnxA1 increased inflammation and lethality induced by pneumococcal infection. These data show that immunomodulatory effects of phosphodiesterase-4 inhibitors are useful during severe pneumococcal pneumonia and suggest their potential benefit as adjunctive therapy during infectious diseases.

A case report of septic shock syndrome caused by S. pneumoniae in an immunocompromised patient despite of vaccination

BACKGROUND AND CASE PRESENTATION

We report a case of septic shock syndrome caused by Streptococcus pneumoniae in a patient who had undergone splenectomy due to an autoimmune lymphoproliferative syndrome (ALPS), which is characterized as a dysfunction of immunoregulation. Although the patient was vaccinated with a conjugated polysaccharide vaccine after the splenectomy, he was still susceptible to S. pneumoniae infection, because the isolated serovar (24F), a serovar long thought to be apathogenic, is not covered by any vaccine currently approved, neither a conjugated nor an unconjugated polysaccharide one.

CONCLUSIONS

This case demonstrates that, due to presence of different serovars, also infections with bacteria against which patients are vaccinated have to be considered as differential diagnosis. Although vaccine development has extended the coverage of S. pneumoniae from 7 to 23 serovars within recent years, there is still demand for novel vaccines which can provide broader protection also against so-thought "apathogenic" strains, especially for groups at high risk.

Assessing the diagnostic accuracy of PCR-based detection of Streptococcus pneumoniae from nasopharyngeal swabs collected for viral studies in Canadian adults hospitalised with community-acquired pneumonia: a Serious Outcomes Surveillance (SOS) Network of the Canadian Immunization Research (CIRN) study

STUDY DESIGN

Detection and serotyping of Streptococcus pneumoniae are important to assess the impact of pneumococcal vaccines. This study describes the diagnostic accuracy of PCR-based detection of S. pneumoniae directly from nasopharyngeal (NP) swabs collected for respiratory virus studies.

METHODS

Active surveillance for community-acquired pneumonia (CAP) in hospitalised adults was performed from December 2010 to 2013. Detection of pneumococcal CAP (CAPSpn) was performed by urine antigen detection (UAD), identification of S. pneumoniae in sputum or blood cultures. S. pneumoniae was detected in NP swabs using lytA and cpsA real-time PCR, and serotyping was performed using conventional and real-time multiplex PCRs. For serotyping, the Quellung reaction, PCR-based serotyping or a serotype-specific UAD was used.

RESULTS

NP swab results were compared against CAP cases where all pneumococcal tests were performed (n=434), or where at least one test was performed (n=1616). CAPSpn was identified in 22.1% (96/434) and 14.9% (240/1616), respectively. The sensitivity of NP swab PCR for the detection of S. pneumoniae was poor for CAPSpn (35.4% (34/96) and 34.17% (82/240)), but high specificity was observed (99.4% (336/338) and 97.89% (1347/1376)). Of the positive NP swabs, a serotype could be deduced by PCR in 88.2% (30/34) and 93.9% (77/82), respectively.

CONCLUSIONS

While further optimisation may be needed to increase the sensitivity of PCR-based detection, its high specificity suggests there is a value for pneumococcal surveillance. With many laboratories archiving specimens for influenza virus surveillance, this specimen type could provide a non-culture-based method for pneumococcal surveillance.

Cost-effectiveness of pneumococcal vaccination strategies for the elderly in Korea

Background

Although the 13-valent pneumococcal conjugate vaccine (PCV13) showed good efficacy against pneumococcal disease in the the CAPiTA trial, the 23-valent pneumococcal polysaccharide vaccination (PPSV23) program has been ongoing for older adults aged ≥ 65 years in Korea since May of 2013. This study aimed to evaluate the cost-effectiveness of the current vaccination strategy (a single-dose PPSV23 vaccination) compared to a single-dose PCV13 vaccination and sequential PCV13-PPSV23 vaccinations in the elderly population aged ≥ 65 years.

Methods

Using a Markov model, the incremental cost-effectiveness ratios (ICERs) of three vaccination strategies were assessed in a societal context. The transition probabilities, utility weights to estimate quality adjusted life year (QALY), and disease treatment costs were either calculated or cited from published data and the Health Insurance Review and Assessment Service. Simulations were performed in hypothetical cohorts of Korean adults aged ≥ 19 years. The vaccine effectiveness of PPSV23 was cited from a Cochrane Review report, while PCV13 effectiveness data were gathered from the CAPiTA trial.

Results

Current PPSV23 vaccination strategies were cost-effective (ICER, $25,786 per QALY). However, the administration of PCV13 as a substitute for PPSV23 was shown to be more cost-effective than PPSV23 vaccination (ICER, $797 per QALY). Sequential PCV13-PPSV23 vaccination was also more cost-effective than PPSV23 for elderly people aged ≥ 65 years. In sensitivity analysis assuming significant PPSV23 effectiveness (50%) against non-bacteremic pneumococcal pneumonia, the PCV13 vaccination strategy was superior to the PPSV23 vaccination strategy in terms of cost-effectiveness.

Conclusion

The results suggest that PCV13 vaccination is more cost-effective in elderly subjects aged ≥ 65 years compared to the current PPSV23 vaccination strategy. When complete data is obtained in 2018 on the maximal herd effects of childhood PCV13 immunization, the incidence of pneumococcal pneumonia and the cost-effectiveness of vaccination strategies need to be reassessed.