Disease Burden and Etiologic Distribution of Community-Acquired Pneumonia in Adults: Evolving Epidemiology in the Era of Pneumococcal Conjugate Vaccines

Application of Metagenomic Next-Generation Sequencing (mNGS) Using Bronchoalveolar Lavage Fluid (BALF) in Diagnosing Pneumonia of Children

Pneumonia is the leading cause of death in children; the pathogens are often difficult to diagnose. In this study, the performance of metagenomic next-generation sequencing (mNGS) using bronchoalveolar lavage fluid (BALF) samples from 112 children with confirmed pneumonia has been evaluated. mNGS performed a significantly higher positive detection rate (91.07%, 95% confidence interval [CI] 83.80% to 95.40%) and coincidence rate against the final diagnosis (72.32%, 95% CI 62.93% to 80.15%) than that of conventional methods (70.54%, 95% CI 61.06% to 78.58% and 56.25%, 95% CI 46.57% to 65.50%, respectively) (P < 0.01 and P < 0.05, respectively). Bacteria, viruses, and their mixed infections were common in children with pneumonia. Streptococcus pneumoniae was the most common bacterial pathogen in children with pneumonia, while Haemophilus parainfluenzae and Haemophilus influenzae seemed more likely to cause nonsevere pneumonia in children. In contrast, human cytomegalovirus (CMV) infection and the simultaneous bacterial infections could cause severe pneumonia, especially in children with underlying diseases. After adjustments of antibiotics based on mNGS and conventional methods, the conditions improved in 109 (97.32%) children. mNGS of BALF samples has shown great advantages in diagnosing the pathogenic etiology of pneumonia in children, especially when considering the limited volumes of BALF and the previous use of empirical antibiotics, contributing to the timely adjustment of antibiotic treatments, which can potentially improve the prognosis and decrease the mortality. IMPORTANCE Our study indicates high efficiency of mNGS using BALF for the detection of causative pathogens that cause pneumonia in children. mNGS can be a potential diagnostic tool to supplement conventional methods for children's pneumonia.

Pneumonia and Related Conditions in Critically Ill Patients—Insights from Basic and Experimental Studies

Pneumonia is an acute infectious disease with high morbidity and mortality rates. Pneumonia’s development, severity and outcome depend on age, comorbidities and the host immune response. In this study, we combined theoretical and experimental investigations to characterize pneumonia and its comorbidities as well as to assess the host immune response measured by TREC/KREC levels in patients with pneumonia. The theoretical study was carried out using the Columbia Open Health Data (COHD) resource, which provides access to clinical concept prevalence and co-occurrence from electronic health records. The experimental study included TREC/KREC assays in young adults (18–40 years) with community-acquired (CAP) (n = 164) or nosocomial (NP) (n = 99) pneumonia and healthy controls (n = 170). Co-occurring rates between pneumonia, sepsis, acute respiratory distress syndrome (ARDS) and some other related conditions common in intensive care units were the top among 4170, 3382 and 963 comorbidities in pneumonia, sepsis and ARDS, respectively. CAP patients had higher TREC levels, while NP patients had lower TREC/KREC levels compared to controls. Low TREC and KREC levels were predictive for the development of NP, ARDS, sepsis and lethal outcome (AUC_TREC in the range 0.71–0.82, AUC_KREC in the range 0.67–0.74). TREC/KREC analysis can be considered as a potential prognostic test in patients with pneumonia.

Socioeconomic burden of pneumonia due to multidrug-resistant Acinetobacter baumannii and Pseudomonas aeruginosa in Korea

We aimed to estimate the socioeconomic burden of pneumonia due to multidrug-resistant Acinetobacter baumannii (MRAB) and Pseudomonas aeruginosa (MRPA). We prospectively searched for MRAB and MRPA pneumonia cases and matched them with susceptible-organism pneumonia and non-infected patients from 10 hospitals. The matching criteria were: same principal diagnosis, same surgery or intervention during hospitalisation, age, sex, and admission date within 60 days. We calculated the economic burden by using the difference in hospital costs, the difference in caregiver costs, and the sum of productivity loss from an unexpected death. We identified 108 MRAB pneumonia [MRAB-P] and 28 MRPA pneumonia [MRPA-P] cases. The estimated number of annual MRAB-P and MRPA-P cases in South Korea were 1309–2483 and 339–644, with 485–920 and 133–253 deaths, respectively. The annual socioeconomic burden of MRAB-P and MRPA-P in South Korea was $64,549,723–122,533,585 and $15,241,883–28,994,008, respectively. The results revealed that MRAB-P and MRPA-P occurred in 1648–3127 patients, resulted in 618–1173 deaths, and caused a nationwide socioeconomic burden of $79,791,606–151,527,593. Multidrug-resistant organisms (MDRO) impose a great clinical and economic burden at a national level. Therefore, controlling the spread of MDRO will be an effective measure to reduce this burden.

Introductory Chapter: Pneumonia

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Classification and Drug Resistance Analysis of Pathogenic Bacteria in Patients with Bacterial Pneumonia in Emergency Intensive Care Unit

OBJECTIVE

This study aimed to compare the identification efficiency of metagenome next generation sequencing (mNGS) and traditional methods in detecting pathogens in patients with severe bacterial pneumonia (BP) and further analyze the drug resistance of common pathogens.

METHODS

A total of 180 patients with severe BP who were admitted to our hospital from June 2017 to July 2020 were selected as the research objects. Alveolar lavage fluid from the patients were collected, and pathogens were detected by the mNGS technology and traditional etiological detection technology. Common pathogens detected by mNGS were tested for the drug sensitivity test. The difference between mNGS and traditional detection method in the identification of pathogenic bacteria in severe BP patients was compared, and the distribution characteristics and drug resistance of pathogenic bacteria were analyzed.

RESULTS

The positive rate of mNGS detection was 92.22%, which was significantly higher than that of the traditional culture method (58.33%, P < 0.05). 347 strains of pathogenic bacteria were detected by mNGS, including 256 strains of Gram-negative bacteria (G^-), 89 strains of Gram-positive bacteria (G⁺), and 2 strains of fungi. Among G^- bacteria, Acinetobacter baumannii had higher resistance to piperacillin/tazobactam, ceftazidime, imipenem, levofloxacin, amikacin, ciprofloxacin, gentamicin, and the lowest resistance to tigecycline. The resistance of Klebsiella pneumoniae to piperacillin/tazobactam and ceftazidime was higher. Pseudomonas aeruginosa had low resistance to all the drugs. Escherichia coli had high drug resistance to most drugs, and the drug resistant rates to cefoperazone/sulbactam, piperacillin/tazobactam, ceftazidime, imipenem, and gentamicin were all more than 50.00%. G⁺ bacteria had high resistance to penicillin, azithromycin, amoxicillin and levofloxacin, and amoxicillin and levofloxacin had high resistance, up to 100.00%.

CONCLUSION

mNGS has high sensitivity for the identification of pathogenic bacteria in patients with BP. G^- bacteria were the main pathogens of BP, but both G^- and G⁺ bacteria had high resistance to a variety of antibacterial drugs.

All-cause community acquired pneumonia cost by age and risk in real-world conditions of care in Spain

BACKGROUND

: Economic burden of Community-acquired pneumonia (CAP) is recognized. Few studies have documented such burden in adults stratified by age, risk status, and by care setting. Spanish data available is scarce.

METHOD

: A retrospective, multicenter study in seven regions of Spain (2017-2019) was conducted. Patients ≥18 years with a primary all-cause CAP episode diagnosis were identified. Episode-level variables included risk-stratum based on presence of an immunocompromising/chronic condition, age, number and length of hospitalized and outpatient episodes, and CAP-related healthcare costs/sick leaves were included.

RESULTS

: 7,108 episodes [mean age (SD): 59.2 (19.6), 50.42% male, 31.0% hospitalized] were analyzed. Low-risk group accounted for 47.7% of all CAP episodes, 31.5% moderate-risk and 20.8% high-risk. Pneumococcus was identified in 42.2% of cases. Mean CAP episode length was 22.9 days for hospitalized and 13.7 days for outpatient episode. Total healthcare cost for episode was higher in inpatient vs. outpatient: €3,955 vs. €511, p<0.001, with higher sick leave cost (€3,281 vs. €2,632, p<0.001), respectively.

CONCLUSION

: CAP required hospitalization cost is high regardless of age or comorbidities for the Spanish NHS. Given that almost half of the patients in this study did not have traditional risk factors for CAP, better preventative strategies should seriously be considered.

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.

Community-acquired bacterial pneumonia in adults: An update

Community-acquired pneumonia (CAP) is the prominent cause of mortality and morbidity with important clinical impact across the globe. India accounts for 23 per cent of global pneumonia burden with case fatality rates between 14 and 30 per cent, and Streptococcus pneumoniae is considered a major bacterial aetiology. Emerging pathogens like Burkholderia pseudomallei is increasingly recognized as an important cause of CAP in Southeast Asian countries. Initial management in the primary care depends on clinical assessment while the hospitalized patients require combinations of clinical scores, chest radiography and various microbiological and biomarker assays. This comprehensive diagnostic approach together with additional sampling and molecular tests in selected high-risk patients should be practiced. Inappropriate therapy in CAP in hospitalized patients lengthens hospital stay and increases cost and mortality. In addition, emergence of multidrug-resistant organisms poses tough challenges in deciding empirical as well as definitive therapy. Developing local evidence on the cause and management should be a priority to improve health outcomes in CAP.

Pneumonia

Pneumonia is a common acute respiratory infection that affects the alveoli and distal airways; it is a major health problem and associated with high morbidity and short-term and long-term mortality in all age groups worldwide. Pneumonia is broadly divided into community-acquired pneumonia or hospital-acquired pneumonia. A large variety of microorganisms can cause pneumonia, including bacteria, respiratory viruses and fungi, and there are great geographical variations in their prevalence. Pneumonia occurs more commonly in susceptible individuals, including children of <5 years of age and older adults with prior chronic conditions. Development of the disease largely depends on the host immune response, with pathogen characteristics having a less prominent role. Individuals with pneumonia often present with respiratory and systemic symptoms, and diagnosis is based on both clinical presentation and radiological findings. It is crucial to identify the causative pathogens, as delayed and inadequate antimicrobial therapy can lead to poor outcomes. New antibiotic and non-antibiotic therapies, in addition to rapid and accurate diagnostic tests that can detect pathogens and antibiotic resistance will improve the management of pneumonia.

Persistent Lung Inflammation After Clinical Resolution of Community-Acquired Pneumonia as Measured by 18FDG-PET/CT Imaging

BACKGROUND

Survivors of community-acquired pneumonia (CAP) are at increased risk of cardiovascular disease, cognitive and functional decline, and death, but the mechanisms remain unknown.

RESEARCH QUESTION

Do CAP survivors have evidence of increased inflammatory activity in their lung parenchyma on 2-deoxy-2-[¹⁸F]fluoro-d-glucose (¹⁸FDG)-PET/CT imaging after clinical resolution of infection?

STUDY DESIGN AND METHODS

We obtained ¹⁸FDG-PET/CT scans from 22 CAP survivors during their hospitalization with pneumonia (acute CAP) and 30 to 45 days after hospital discharge (post-CAP). In each set of scans, we assessed the lungs for foci of increased ¹⁸FDG uptake by visual interpretation and by total pulmonary glycolytic activity (tPGA), a background-corrected measure of total metabolic activity (as measured by ¹⁸FDG uptake). We also measured, post-CAP, the glycolytic activity of CAP survivor lung areas with volumes similar to the areas in 28 matched historical control subjects without pneumonia.

RESULTS

Overall, 68% of CAP survivors (95% CI, 45%-85%) had distinct residual areas of increased ¹⁸FDG uptake in their post-CAP studies. tPGA decreased from 821.5 (SD, 1,140.2) in the acute CAP period to 80.0 (SD, 81.4) in the post-CAP period (P = .006). The tPGA post-CAP was significantly higher than that in lung areas of similar volume in control subjects (80.0 [SD, 81.4] vs -19.4 [SD, 5.9]; P < .001).

INTERPRETATION

An important proportion of CAP survivors have persistent pulmonary foci of increased inflammatory activity beyond resolution of their infection. As inflammation contributes to cardiovascular disease, cognitive decline, functional waning, and mortality risk in the general population, this finding provides a plausible mechanism for the increased morbidity and mortality that have been observed post-CAP.

Epidemiology of community-acquired pneumonia in the era of extended serotype-covering multivalent pneumococcal conjugate vaccines

BACKGROUND

South Korea has been providing 10-valent pneumococcal conjugate vaccine/(PCV10)/13-valent pneumococcal conjugate vaccine (PCV13) to children and 23-valent pneumococcal polysaccharide vaccine (PPSV23) to older adults as part of a national immunization program.

METHODS

From September 2015 to August 2017, a prospective cohort study was conducted for adults aged ≥19 years with community-acquired pneumonia (CAP) at four university hospitals. All-cause and pneumococcal CAP incidence and mortality rates were evaluated on the basis of hospital catchment population. Serotype distribution of pneumococcal CAP was also evaluated.

RESULTS

Among 2669 patients with CAP, 252 cases (9.4%) were pneumococcal CAP cases. The annual incidences of all-cause and pneumococcal CAP were 194.3 cases and 18.3 cases respectively, per 100,000 persons. Serotyped Streptococcus pneumoniae was identified in 107 cases (42.5%) through culture or a serotype-specific urinary antigen detection assay. Pneumococcal CAP caused by the PCV13 and PPSV23 serotypes were 50 cases (46.7% of serotyped pneumococcal CAP and 19.8% of pneumococcal CAP), and 83 cases (77.6% of serotyped pneumococcal CAP and 32.9% of pneumococcal CAP), respectively. The most prevalent serotype was 3 (n = 21, 19.6% of serotyped pneumococcal CAP), followed by 19A (n = 10, 9.3% of serotyped pneumococcal CAP) and 11A (n = 10, 9.3% of serotyped pneumococcal CAP). Compared with non-pneumococcal CAP patients, pneumococcal CAP patients were more likely to have a higher CURB-65 scores (P = 0.002). The overall 30-day mortality rate of pneumococcal CAP was higher than that of non-pneumococcal CAP (6.3% versus 5.6%; odds ratio [OR], 1.15; 95% confidence interval [CI], 0.67-1.96), but this trend was reversed in patients aged 65-74 years (4.2% versus 8.6%; OR, 0.47; 95% CI, 0.14-1.54).

CONCLUSIONS

The disease burden of PCV13-serotype pneumococcal CAP remains significantly high in Korean adults, particularly among elderly people, even after a high uptake of pediatric PCVs.

Burden of Community-Acquired Pneumonia and Unmet Clinical Needs

Community-acquired pneumonia (CAP) is the leading cause of death among infectious diseases and an important health problem, having considerable implications for healthcare systems worldwide. Despite important advances in prevention through vaccines, new rapid diagnostic tests and antibiotics, CAP management still has significant drawbacks. Mortality remains very high in severely ill patients presenting with respiratory failure or shock but is also high in the elderly. Even after a CAP episode, higher risk of death remains during a long period, a risk mainly driven by inflammation and patient-related co-morbidities. CAP microbiology has been altered by new molecular diagnostic tests that have turned viruses into the most identified pathogens, notwithstanding uncertainties about the specific role of each virus in CAP pathogenesis. Pneumococcal vaccines also impacted CAP etiology and thus had changed Streptococcus pneumoniae circulating serotypes. Pathogens from specific regions should also be kept in mind when treating CAP. New antibiotics for CAP treatment were not tested in severely ill patients and focused on multidrug-resistant pathogens that are unrelated to CAP, limiting their general use and indications for intensive care unit (ICU) patients. Similarly, CAP management could be personalized through the use of adjunctive therapies that showed outcome improvements in particular patient groups. Although pneumococcal vaccination was only convincingly shown to reduce invasive pneumococcal disease, with a less significant effect in pneumococcal CAP, it remains the best therapeutic intervention to prevent bacterial CAP. Further research in CAP is needed to reduce its population impact and improve individual outcomes.