New diagnostic tests for pneumonia: what is their role in clinical practice?

Diagnostic and Prognostic Roles of Procalcitonin and Other Tools in Community-Acquired Pneumonia: A Narrative Review

Community-acquired pneumonia (CAP) is among the most common causes of death and one of the leading healthcare concerns worldwide. It can evolve into sepsis and septic shock, which have a high mortality rate, especially in critical patients and comorbidities. The definitions of sepsis were revised in the last decade as "life-threatening organ dysfunction caused by a dysregulated host response to infection". Procalcitonin (PCT), C-reactive protein (CRP), and complete blood count, including white blood cells, are among the most commonly analyzed sepsis-specific biomarkers also used in pneumonia in a broad range of studies. It appears to be a reliable diagnostic tool to expedite care of these patients with severe infections in the acute setting. PCT was found to be superior to most other acute phase reactants and indicators, including CRP as a predictor of pneumonia, bacteremia, sepsis, and poor outcome, although conflicting results exist. In addition, PCT use is beneficial to judge timing for the cessation of antibiotic treatment in most severe infectious states. The clinicians should be aware of strengths and weaknesses of known and potential biomarkers in expedient recognition and management of severe infections. This manuscript is intended to present an overview of the definitions, complications, and outcomes of CAP and sepsis in adults, with special regard to PCT and other important markers.

Unmet needs in pneumonia research: a comprehensive approach by the CAPNETZ study group

Introduction

Despite improvements in medical science and public health, mortality of community-acquired pneumonia (CAP) has barely changed throughout the last 15 years. The current SARS-CoV-2 pandemic has once again highlighted the central importance of acute respiratory infections to human health. The “network of excellence on Community Acquired Pneumonia” (CAPNETZ) hosts the most comprehensive CAP database worldwide including more than 12,000 patients. CAPNETZ connects physicians, microbiologists, virologists, epidemiologists, and computer scientists throughout Europe. Our aim was to summarize the current situation in CAP research and identify the most pressing unmet needs in CAP research.

Methods

To identify areas of future CAP research, CAPNETZ followed a multiple-step procedure. First, research members of CAPNETZ were individually asked to identify unmet needs. Second, the top 100 experts in the field of CAP research were asked for their insights about the unmet needs in CAP (Delphi approach). Third, internal and external experts discussed unmet needs in CAP at a scientific retreat.

Results

Eleven topics for future CAP research were identified: detection of causative pathogens, next generation sequencing for antimicrobial treatment guidance, imaging diagnostics, biomarkers, risk stratification, antiviral and antibiotic treatment, adjunctive therapy, vaccines and prevention, systemic and local immune response, comorbidities, and long-term cardio-vascular complications.

Conclusion

Pneumonia is a complex disease where the interplay between pathogens, immune system and comorbidities not only impose an immediate risk of mortality but also affect the patients’ risk of developing comorbidities as well as mortality for up to a decade after pneumonia has resolved. Our review of unmet needs in CAP research has shown that there are still major shortcomings in our knowledge of CAP.

The extent of microbiological testing is associated with alteration of antibiotic therapy in adults with community-acquired pneumonia

The aim of this study was to explore the relationship between the extent of microbiological testing and the frequency of antibiotic alteration in adults hospitalised with community-acquired pneumonia (CAP). We retrospectively studied 283 immunocompetent patients hospitalised with CAP. Information on microbiological testing and prescribed antibiotics was obtained. Patients were grouped according to the number of different microbiological tests performed within the first 2 days of admission (0-5 tests). Alteration rates were compared between these groups. Antimicrobial alteration was defined as a switch at day 3 of hospital stay to (1) a narrower spectrum antibiotics, or (2) a different class of antibiotics, or (3) a switch from dual therapy to monotherapy (4) or discontinuation of antibiotic treatment because the indication for antibiotic treatment did no longer exist. For each additional test performed, a stepwise increase in percentage of patients with altered antibiotic regimen ranging from 0 to 59% (p = 0.001) was found. Multivariate logistic regression analyses showed that performing PCR assay for atypical pathogens was most strongly associated with any alteration of antibiotic treatment (OR 2.6 (95% CI 1.4-4.9)) and with changes in atypical coverage specifically (OR 3.1 (95% CI 1.6-6.0). The extent of microbiological testing was positively associated with antibiotic alteration in adults hospitalised with CAP. Antibiotic treatment was most likely to be altered in patients in whom PCR assay for atypical pathogens was performed.

Economic evaluation of procalcitonin-guided antibiotic therapy in acute respiratory infections: a Chinese hospital system perspective

Background:

Cost-impact models have indicated that in the USA, the use of antibiotic stewardship protocols based on procalcitonin (PCT) levels for patients with suspected acute respiratory tract infection results in cost savings. Our objective was to assess the cost impact of adopting PCT testing among patients with acute respiratory infections (ARI) from the perspective of a typical hospital system in urban China.

Methods:

To conduct an economic evaluation of PCT testing versus usual care we built a cost-impact model based on a previously published patient-level meta-analysis data of randomized trials including Chinese sites. The data were adapted to the China setting by applying the results to mean lengths of stay, costs, and practice patterns typically found in China. We estimated the annual ARI visit rate for the typical hospital system (assumed to be 1650 beds) and ARI diagnosis.

Results:

In the inpatient setting, the costs of PCT-guided care compared to usual care for a cohort of 16,405 confirmed ARI patients was almost 1.1 million Chinese yuan (CNY), compared to almost 1.8 million CNY for usual care, resulting in net savings of 721,563 CNY to a typical urban Chinese hospital system for 2015. In the ICU and outpatient settings, savings were 250,699 CNY and 2.4 million CNY, respectively. The overall annual net savings of PCT-guided care was nearly 3.4 million CNY.

Conclusions:

Substantial savings are associated with PCT protocols of ARI across common China hospital treatment settings mainly by direct reduction in unnecessary antibiotic utilization.

Lower Respiratory Tract Infections

This review will focus on the infectious etiologies and more common noninfectious causes of lower respiratory tract syndromes among major immunosuppressed populations. The changing epidemiology of infections in the era of highly active antiretroviral therapy (HAART) in the case of HIV-positive patients and the impacts of both newer immune-suppressant therapies and anti-infective prophylaxis for other immunocompromised hosts will be discussed, with emphasis on diagnostic approaches and practice algorithms.

Etiology of community-acquired pneumonia and diagnostic yields of microbiological methods: a 3-year prospective study in Norway

Background

Despite recent advances in microbiological techniques, the etiology of community-acquired pneumonia (CAP) is still not well described. We applied polymerase chain reaction (PCR) and conventional methods to describe etiology of CAP in hospitalized adults and evaluated their respective diagnostic yields.

Methods

267 CAP patients were enrolled consecutively over our 3-year prospective study. Conventional methods (i.e., bacterial cultures, urinary antigen assays, serology) were combined with nasopharyngeal (NP) and oropharyngeal (OP) swab samples analyzed by real-time quantitative PCR (qPCR) for Streptococcus pneumoniae, and by real-time PCR for Mycoplasma pneumoniae, Chlamydophila pneumoniae, Bordetella pertussis and 12 types of respiratory viruses.

Results

Etiology was established in 167 (63%) patients with 69 (26%) patients having ≥1 copathogen. There were 75 (28%) pure bacterial and 41 (15%) pure viral infections, and 51 (19%) viral–bacterial coinfections, resulting in 126 (47%) patients with bacterial and 92 (34%) patients with viral etiology. S. pneumoniae (30%), influenza (15%) and rhinovirus (12%) were most commonly identified, typically with ≥1 copathogen. During winter and spring, viruses were detected more frequently (45%, P=.01) and usually in combination with bacteria (39%). PCR improved diagnostic yield by 8% in 64 cases with complete sampling (and by 15% in all patients); 5% for detection of bacteria; 19% for viruses (P=.04); and 16% for detection of ≥1 copathogen. Etiology was established in 79% of 43 antibiotic-naive patients with complete sampling. S. pneumoniae qPCR positive rate was significantly higher for OP swab compared to NP swab (P<.001). Positive rates for serology were significantly higher than for real-time PCR in detecting B. pertussis (P=.001) and influenza viruses (P<.001).

Conclusions

Etiology could be established in 4 out of 5 CAP patients with the aid of PCR, particularly in diagnosing viral infections. S. pneumoniae and viruses were most frequently identified, usually with copathogens. Viral–bacterial coinfections were more common than pure infections during winter and spring; a finding we consider important in the proper management of CAP. When swabbing for qPCR detection of S. pneumoniae in adult CAP, OP appeared superior to NP, but this finding needs further confirmation.

Trial registration

ClinicalTrials.gov Identifier: NCT01563315.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-015-0803-5) contains supplementary material, which is available to authorized users.

Health promotion, risk stratification, and treatment options to decrease hospitalization rates for community-acquired pneumonia in adults

PURPOSE

Community-acquired pneumonia (CAP) is a serious illness and hospitalization for this illness is expensive. There is much the nurse practitioner (NP) can do to prevent and manage this illness.

DATA SOURCES

Review of current literature, medical/nursing references, and data from the healthcare utilization project (HCUP).

CONCLUSIONS

The use of health promotion, risk stratification, and current evidence-based treatment guidelines can help to decrease hospitalization rates for CAP for adults.

IMPLICATIONS FOR PRACTICE

NPs are experts at health promotion and evidence-based practice. Adhering to these practices and using risk stratification, NPs can help to further decrease hospitalization rates for CAP lowering healthcare costs related to this serious illness.

Does empiric therapy for atypical pathogens improve outcomes for patients with CAP?

The present controversy regarding the need to cover atypical pathogens in the empiric therapy of community-acquired pneumonia is related to several issues, including the relevance of terminology, imprecise diagnostic methods, and perceived contradictory results of published evidence. Studies evaluating the time to clinical recovery and the use of earlier endpoints for evaluation suggest that appropriate therapy provides a benefit if an atypical pathogen is a pathogen. Because recent surveillance studies suggest these pathogens are common and until there is the availability of accurate, cost-effective, and easily interpreted laboratory tests to provide the etiologic diagnosis at the time of point of care, empiric therapy of atypical pathogens is supported.

What is the role of newer molecular tests in the management of CAP?

Community-acquired pneumonia (CAP) accounts for major morbidity and mortality in the United States. With improved broad-spectrum antibiotics, the implementation of diagnostic studies has declined and most patients do not have an etiologic pathogen of CAP identified. To enhance the appropriate use of antiviral agents and prevent overuse of antibiotics, the successful management of CAP requires rapid and accurate diagnosis of the etiologic agent of CAP. This article provides an overview of the new rapid molecular tests for the diagnosis of influenza, other respiratory viruses, and bacteria compared with nonmolecular tests and how their use for directed therapy can enhance and improve the management of CAP.