The role of biomarkers in low respiratory tract infections

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.

Diagnostic value of serum neutrophil gelatinase-associated lipocalin, interleukin-6 and anti-citrullinated alpha-enolase peptide 1 for lower respiratory tract infections

OBJECTIVES

The aim of this study was to explore the auxiliary diagnostic value of neutrophil gelatinase-associated lipocalin (NGAL) and anti-citrullinated alpha-enolase peptide 1 (CEP-1) in lower respiratory tract infections (LRTIs).

METHODS

Blood samples were collected from 99 in-patients with LRTIs [62 community-acquired pneumonia (CAP), 14 acute exacerbated chronic obstructive pulmonary diseases (AECOPD), 23 other diseases] and 50 healthy subjects. NGAL, CEP-1 and IL-6 were measured and compared. IL-6 was tested by electrochemiluminescence assay kit on Roche E601 immunology analyzer, CEP-1 was assessed with enzyme-linked immunosorbent assay kit, and NGAL was detected by latex immunoturbidimetric assay kit on Beckman Coulter AU2700.

RESULTS

Compared with healthy controls, NGAL and IL-6 levels were significantly increased in the patients with LRTIs, the area under the curves (AUC) was 0.97 and 0.88 respectively (P < 0.01). The sensitivity and specificity of NGAL at a cut-off of 86 ng/ml were 93.0% and 96.0%, respectively, in which the sensitivity was consistent with IL-6 (P = 0.21) and the specificity was better than IL-6 (P < 0.01). CEP-1 slightly increases in the patient group, however the difference was not significant (P = 0.41). The levels of NGAL and IL-6 was no differences in different diseases, the P-value was 0.50 and 0.29, respectively. LRTIs with and without underlying diseases have similar NGAL and IL-6 values.

CONCLUSIONS

NGAL, rather than CEP-1, may be appealing adjuncts for diagnosis of LRTIs. NGAL proved to be a better biomarker than IL-6.

Do we need biomarkers for the follow-up and shortening of antibiotic treatment duration?

PURPOSE OF REVIEW

Clinical and laboratory parameters are useful tools for the diagnosis, follow-up and evaluation of resolution, and to predict outcomes when measured at different time-points onset and serially during follow-up in patients with hospital-acquired pneumonia and/or ventilator-associated pneumonia (HAP/VAP).

RECENT FINDINGS

Both, the 2017 ERS/ESICM/ESCMID/Asociación Latino Americana de Tórax (EEEAG) and the 2016 IDSA/ATS guidelines (IAG) for the management of HAP/VAP recommend using clinical criteria alone, rather than biomarkers for diagnosis. Several studies were conducted to assess the value of serum biomarker concentration and kinetics for predicting the outcome in HAP/VAP, including C-reactive protein and procalcitonin (PCT). Although the EEEAG do not recommend routinely performing biomarker determinations in addition to bedside clinical assessment in patients receiving antibiotic treatment for VAP or HAP to predict adverse outcomes and clinical response, the IAG recommend that routine bedside clinical assessment should be accompanied by measurements of PCT to guide antimicrobial therapy. Additionally, the 2016 Surviving Sepsis Campaign also suggests that PCT levels can be used to support the shortening of antibiotic therapy.

SUMMARY

Current evidence indicate that there is no recommendation to use biomarkers systematically to guide every decision. However, in some circumstances they might add some relevant information to our everyday practice.

Biomarkers of Community-Acquired Pneumonia: A Key to Disease Diagnosis and Management

Community-acquired pneumonia (CAP) is a dangerous disease caused by a spectrum of bacterial and viral pathogens. The choice of specific therapy and the need for hospitalization or transfer to the intensive care unit are determined by the causative agent and disease severity. The microbiological analysis of sputum largely depends on the quality of the material obtained. The prediction of severity and the duration of therapy are determined individually, and existing prognostic scales are used generally. This review examines the possibilities of using specific serological biomarkers to detect the bacterial or viral aetiology of CAP and to assess disease severity. Particular emphasis is placed on the use of biomarker signatures and the discovery of biomarker candidates for a single multiplex analysis.

Bacteria in the respiratory tract-how to treat? Or do not treat?

BACKGROUND

Acute and chronic respiratory tract infections are a common cause of inappropriate antimicrobial prescription. Antimicrobial therapy leads to the development of resistance and the emergence of opportunistic pathogens that substitute the indigenous microbiota.

METHODS

This review explores the major challenges and lines of research to adequately establish the clinical role of bacteria and the indications for antimicrobial treatment, and reviews novel therapeutic approaches.

RESULTS

In patients with chronic pulmonary diseases and structural disturbances of the bronchial tree or the lung parenchyma, clinical and radiographic signs and symptoms are almost constantly present, including a basal inflammatory response. Bacterial adaptative changes and differential phenotypes are described, depending on the clinical role and niche occupied. The respiratory tract has areas that are potentially inaccessible to antimicrobials. Novel therapeutic approaches include new ways of administering antimicrobials that may allow intracellular delivery or delivery across biofilms, targeting the functions essential for infection, such as regulatory systems, or the virulence factors required to cause host damage and disease. Alternatives to antibiotics and antimicrobial adjuvants are under development.

CONCLUSIONS

Prudent treatment, novel targets, and improved drug delivery systems will contribute to reduce the emergence of antimicrobial resistance in lower respiratory tract infections.

The Diagnostic Value of Serum C-Reactive Protein for Identifying Pneumonia in Hospitalized Patients with Acute Respiratory Symptoms

Background. The clinical diagnosis of pneumonia is sometimes difficult since chest radiographs are often indeterminate. In this study, we aimed to assess whether serum C-reactive protein (CRP) could assist in identifying patients with pneumonia. Methods. For one winter, all consecutive patients with acute respiratory symptoms admitted to the emergency ward of a single center were prospectively enrolled. In addition to chest radiographs, basic laboratory tests, and microbiology, serum levels of CRP were measured at entry. Results. A total of 923 (62.3%) of 1473 patients hospitalized for acute respiratory symptoms were included. Subjects with a final diagnosis of pneumonia had higher serum CRP levels (median 187 mg/L) than those with exacerbations of chronic obstructive pulmonary disease (63 mg/L) or acute bronchitis (54 mg/L, p < 0.01). CRP was accurate in identifying pneumonia (area under the curve 0.84, 95% CI 0.82-0.87). The multilevel likelihood ratio (LR) for intervals of CRP provided useful information on the posttest probability of having pneumonia. CRP intervals above 200 mg/L were associated with LR+ > 5, for which pneumonia is likely, whereas CRP intervals below 75 mg/L were associated with LR < 0.2, for which pneumonia is unlikely. Conclusion. Serum CRP may be a useful addition for diagnosing pneumonia in hospitalized patients with acute respiratory symptoms.

Antibiotic treatment of severe exacerbations of chronic obstructive pulmonary disease with procalcitonin: a randomized noninferiority trial

Background

The duration of antibiotic treatment of exacerbations of COPD (ECOPD) is controversial. Serum procalcitonin (PCT) is a biomarker of bacterial infection used to identify the cause of ECOPD.

Methods and Findings

We investigated whether a PCT-guided plan would allow a shorter duration of antibiotic treatment in patients with severe ECOPD. For this multicenter, randomized, non-inferiority trial, we enrolled 184 patients hospitalized with ECOPD from 18 hospitals in Italy. Patients were assigned to receive antibiotics for 10 days (standard group) or for either 3 or 10 days (PCT group). The primary outcome was the rate of ECOPD at 6 months. Having planned to recruit 400 patients, we randomized only 183: 93 in the PCT group and 90 in the standard group. Thus, the completed study was underpowered. The ECOPD rate at 6 months between PCT-guided and standard antibiotic treatment was not significant (% difference, 4.04; 90% confidence interval [CI], −7.23 to 15.31), but the CI included the non-inferiority margin of 15. In the PCT-guided group, about 50% of patients were treated for 3 days, and there was no difference in primary or secondary outcomes compared to patients treated for 10 days.

Conclusions

Although the primary and secondary clinical outcomes were no different for patients treated for 3 or 10 days in the PCT group, the conclusion that antibiotics can be safely stopped after 3 days in patients with low serum PCT cannot be substantiated statistically. Thus, the results of this study are inconclusive regarding the noninferiority of the PCT-guided plan compared to the standard antibiotic treatment. The study was funded by Agenzia Italiana del Farmaco (AIFA-FARM58J2XH). Clinical trial registered with www.clinicaltrials.gov (NCT01125098).

Trial Registration

ClinicalTrials.gov NCT01125098

A pilot study on the diagnostic accuracy of proadrenomedullin and proatrial natriuretic Peptide in lower respiratory tract infections

Background :

Pneumonia is the leading cause of death among infectious diseases in developed countries. However, the severity of pneumonia requiring hospitalization often makes the initial diagnosis difficult because of an equivocal clinical picture or interpretation of the chest film. The objective of the present study was to assess the usefulness of the plasma levels of mid-regional proadrenomedullin (MR-proADM) and mid-regional proatrial natriuretic peptide (MR-proANP) in differentiating pneumonia from other lower respiratory tract infections (LRTIs).

Methods :

A retrospective study was conducted. The plasma levels of MR-proADM and MR-proANP were measured in 85 patients hospitalized for LRTIs, 56 of whom with diagnosis of pneumonia and 29 with other LRTIs.

Results :

The patients with pneumonia had increased MR-proADM levels (median 1.46 nmol/L [IQR 25-75, 0.82-2.02 nmol/L]) compared with the patients with other LRTIs (median 0.88 nmol/mL [0.71-1.39 nmol/L]) (p= 0.04). However, the MR-proANP levels did not show differences between the groups. The optimal threshold of MR-proADM to predict pneumonia was 1.5 nmol/L, which yielded a sensitivity of 51.7% (95% CI, 38.0-65.3), a 79.3% specificity (95% CI, 60.3-92.0), and an odds ratio of 6.64 (95% CI, 1.32-32.85). The combination of this parameter with C-reactive protein in an “and” rule increased the specificity for detecting pneumonia significantly.

Conclusion :

MR-proADM levels (but not MR-proANP levels) are increased in patients with pneumonia although its discriminatory power is moderate.

Community-acquired pneumonia

PURPOSE OF REVIEW

Community-acquired pneumonia (CAP) contributes significantly to morbidity and mortality, especially in the elderly. Recent advances aimed at improving outcomes and reducing CAP disease burden are summarized.

RECENT FINDINGS

Emerging data suggests that newer CAP risk stratification indices based on disease severity hold promise in predicting intensive care need. Additional evidence supports a role of procalcitonin and pro-adrenomedullin as biomarkers of disease severity and for guiding antimicrobial therapy. New diagnostic tools have greatly contributed to early diagnosis and better-targeted therapy. There is increasing recognition of the role of coinfections in CAP. In patients with severe disease, therefore, current guidelines advise against monotherapy. Although inclusion of coverage for atypical pathogens in nonsevere CAP has been challenged, evidence suggests that such coverage is beneficial in patients with severe disease. Use of steroids as adjunctive therapy for CAP, however, is associated with complications and prolonged hospitalization. Updated prevention strategies include approval of pneumococcal conjugate vaccine (PCV13) for adults at risk.

SUMMARY

Despite these developments research aimed at further reducing CAP-related morbidity and mortality is required. Increasing global life expectancy is likely to expand the at-risk population; therefore, research directed at CAP prevention in view of changing demography is essential.

The neutrophil-lymphocyte count ratio in patients with community-acquired pneumonia

Study Objective

The neutrophil-lymphocyte count ratio (NLCR) has been identified as a predictor of bacteremia in medical emergencies. The aim of this study was to investigate the value of the NLCR in patients with community-acquired pneumonia (CAP).

Methods and Results

Consecutive adult patients were prospectively studied. Pneumonia severity (CURB-65 score), clinical characteristics, complications and outcomes were related to the NLCR and compared with C-reactive protein (CRP), neutrophil count, white blood cell (WBC) count. The study cohort consisted of 395 patients diagnosed with CAP. The mean age of the patients was 63.4±16.0 years. 87.6% (346/395) of the patients required hospital admission, 7.8% (31/395) patients were admitted to the Intensive Care Unit (ICU) and 5.8% (23/395) patients of the study cohort died. The NLCR was increased in all patients, predicted adverse medical outcome and consistently increased as the CURB-65 score advanced. NLCR levels (mean ± SD) were significantly higher in non-survivors (23.3±16.8) than in survivors (13.0±11.4). The receiver-operating characteristic (ROC) curve for NLCR predicting mortality showed an area under the curve (AUC) of 0.701. This was better than the AUC for the neutrophil count, WBC count, lymphocyte count and CRP level (0.681, 0.672, 0.630 and 0.565, respectively).

Conclusion

Admission NLCR at the emergency department predicts severity and outcome of CAP with a higher prognostic accuracy as compared with traditional infection markers.