Markers of acute inflammation in assessing and managing lower respiratory tract infections: focus on procalcitonin

Procalcitonin-Guided Antibiotic Prescription in Patients With COVID-19: A Multicenter Observational Cohort Study

BACKGROUND

Despite the low rate of bacterial coinfection, antibiotics are very commonly prescribed in hospitalized patients with COVID-19.

RESEARCH QUESTION

Does the use of a procalcitonin (PCT)-guided antibiotic protocol safely reduce the use of antibiotics in patients with a COVID-19 infection?

STUDY DESIGN AND METHODS

In this multicenter cohort, three groups of patients with COVID-19 were compared in terms of antibiotic consumption, namely one group treated based on a PCT-algorithm in one hospital (n = 216) and two control groups, consisting of patients from the same hospital (n = 57) and of patients from three similar hospitals (n = 486) without PCT measurements during the same period. The primary end point was antibiotic prescription in the first week of admission.

RESULTS

Antibiotic prescription during the first 7 days was 26.8% in the PCT group, 43.9% in the non-PCT group in the same hospital, and 44.7% in the non-PCT group in other hospitals. Patients in the PCT group had lower odds of receiving antibiotics in the first 7 days of admission (OR, 0.33; 95% CI, 0.16-0.66 compared with the same hospital; OR, 0.42; 95% CI, 0.28-0.62 compared with the other hospitals). The proportion of patients receiving antibiotic prescription during the total admission was 35.2%, 43.9%, and 54.5%, respectively. The PCT group had lower odds of receiving antibiotics during the total admission only when compared with the other hospitals (OR, 0.23; 95% CI, 0.08-0.63). There were no significant differences in other secondary end points, except for readmission in the PCT group vs the other hospitals group.

INTERPRETATION

PCT-guided antibiotic prescription reduces antibiotic prescription rates in hospitalized patients with COVID-19, without major safety concerns.

Procalcitonin as a diagnostic marker for infection in sickle cell disease

Background: Patients with sickle cell disease (SCD) are at increased risk of infection. Fever often occurs with vaso-occlusive crisis (VOC), posing a diagnostic challenge in SCD. Procalcitonin (PCT) is an infectious biomarker validated in the general population but with limited data on use in SCD.Methods: We performed a retrospective single-center study (n=145) with primary objective of assessing ability of PCT to differentiate infection from VOC in SCD presenting with fever. Subgroups included confirmed bacterial infection (CBI), suspected bacterial infection, viral infection and VOC. A secondary objective examined association of PCT with acute chest syndrome. Clinical characteristics and data were collected and analyzed to assess diagnostic performance of PCT and associated variables.Results: The majority of patients were male with HbSS genotype, age ranging 18-73 years and mean of 34 years. Of the cohort, 16% had CBI and 8% had viral infection. PCT was able to discriminate CBI from viral infection [AUC=0.89 (95%CI, 0.78-0.99)] and VOC [AUC=0.87 (95%CI, 0.78-0.97)]. PCT had association with ACS but poor diagnostic performance [AUC=0.69 (95% CI, 0.54-0.84)].Conclusion: PCT has utility in distinguishing confirmed bacterial infection from VOC or viral infection and is a promising biomarker when investigating fever in SCD.

Procalcitonin and C-reactive protein as markers of infection in systemic lupus erythematosus: the controversy continues

OBJECTIVE

The objective of this paper is to investigate the utility of serum procalcitonin (PCT) and C-reactive protein (CRP) as markers of infection in systemic lupus erythematosus (SLE) patients.

PATIENTS AND METHODS

Sixty-nine SLE patients with symptoms and signs of infection proved by culture and/or a favorable response to antibiotics and 69 SLE patients without infection were included. Serum PCT and plasma high-sensitivity CRP were assessed by an enzyme-linked immunosorbent assay.

RESULTS

SLE patients with infection had a significantly higher level of CRP than those without infection ((median (IQR) 104.5 (25.5-100.9) and 10.3 (5.4-23.1) mg/l, respectively), p<0.001).

CONCLUSION

Serum PCT could not differentiate SLE patients with or without bacterial infection in this study, while the utility of CRP as a marker of infection has been confirmed.

Correlation of inflammatory and cardiovascular biomarkers with pneumonia severity scores

PURPOSE

To assess the correlation of procalcitonin (PCT), C-reactive protein (CRP), neopterin, mid-regional pro-atrial natriuretic peptide (MR-proANP), and mid-regional pro-adrenomedullin (MR-proADM) with severity risk scores: severe CAP (SCAP) and SMART-COP in patients with community-acquired pneumonia (CAP), as well as short term prognosis and to determine the correlation with mortality risk scores.

METHODS

Eighty-five patients with a final diagnosis of pneumonia were consecutively included during a two month period. Epidemiological, clinical, microbiological, and radiological data were recorded. Patients were stratified according to the PSI, CURB-65, SCAP and SMART-COP. Complications were defined as respiratory failure/shock, need of ICU, and death. Plasma samples were collected at admission.

RESULTS

MR-proANP and MR-proADM showed significantly higher levels in high risk SCAP group in comparison to low risk. When considering SMART-COP none of the biomarkers showed statistical differences. MR-proADM levels were high in patients with high risk of needing intensive respiratory or vasopressor support according to SMRT-CO. Neopterin and MR-proADM were significantly higher in patients that developed complications. PCT and MR-proADM showed significantly higher levels in cases of a definite bacterial diagnosis in comparison to probable bacterial, and unknown origin. MR-proANP and MR-proADM levels increased statistically according to PSI and CURB-65.

CONCLUSIONS

Biomarker levels are higher in pneumonia patients with a poorer prognosis according to SCAP and SMART-COP indexes, and to the development of complications.

Usefulness of consecutive biomarkers measurement in the management of community-acquired pneumonia

The aim of this study was to investigate whether procalcitonin (PCT), neopterin, C-reactive protein (CRP), and mid regional pro-atrial natriuretic peptide (MR-proANP) levels at admission and during the clinical course can be useful for the management of patients with pneumonia. The study population consisted of 75 patients with clinical and radiological diagnosis of pneumonia. Serum samples were collected at admission and during hospitalization. Complications were defined as intensive care unit (ICU) admission or death. The levels of PCT were significantly higher in pneumonia of definite bacterial origin in comparison to probable bacterial or unknown origin. The PCT levels were higher in pneumococcal pneumonia. The PCT and MR-proANP levels increased significantly according to the Pneumonia Severity Index (PSI). All biomarkers levels are higher in patients developing complications and who were dying. The serial levels of MR-proANP remain significantly elevated in patients developing complications and in patients classified in PSI and CURB-65 risk groups. In patients not developing complications, there is a significant decrease in the PCT levels. PCT can be useful for identifying pneumonia etiology. PCT and MR-proANP levels correlate with pneumonia severity rules. PCT and MR-proANP serial measurements can be useful for predicting short-term prognosis. Systemic biomarkers can provide additional information regarding clinical evolution, because these are dynamic and can be measured daily.

Usefulness of mid regional pro-atrial natriuretic peptide in the exacerbations of chronic obstructive pulmonary disease

BACKGROUND

A recent approach for the management of chronic obstructive pulmonary disease (COPD) is the measurement of systemic biomarkers. The aim of this study was to evaluate the usefulness of mid regional pro-atrial natriuretic peptide (MR-proANP) to predict short and long term prognosis.

METHODS

We included 318 COPD patients: 46 in a stable phase, 217 undergoing an exacerbation and 55 with pneumonia. Serum samples were collected at admission. For 20 exacerbated patients, we also collected a second sample one month later. MR-proANP was measured by an inmunofluorescent assay.

RESULTS

Statistically higher levels of MR-proANP were found in patients with pneumonia when comparing to patients in the stable state (p=0.031). For those patients with paired samples, MR-proANP decreased statistically one month later (p=0.027). MR-proANP showed significant lower levels in exacerbations with isolation of pathogenic bacteria (p=0.011). MR-proANP levels were higher in patients that died within one month, decreasing as long as the moment of death occurred later on (p=0.163).

CONCLUSIONS

The identification of exacerbation etiology by means of MR-proANP is not clinically reliable. Levels of MR-proANP vary depending on the clinical status, being higher during pneumonia in comparison to the stable state. MR-proANP levels were higher in patients that died within one month after the exacerbation episode.

Procalcitonin and pneumonia: is it a useful marker?

An ideal biomarker for pneumonia should allow an early diagnosis and differential diagnosis from noninfectious conditions and should inform about the course and prognosis of the disease. Procalcitonin (PCT) covers these features better as compared to more commonly used biomarkers like C-reactive protein or leukocyte count. PCT complements and improves the assessment of pneumonia based on careful patient history, dedicated physical examination, and appropriate cultures. Importantly, a PCT-based therapeutic strategy can safely and markedly reduce antibiotic courses in community-acquired pneumonia. However, as is the cast with all diagnostic surrogate markers, PCT can be increased in noninfectious conditions and may remain low in bacterial infections, especially localized infections. This stresses the importance of follow-up measurements, because PCT levels in these patients often show a gradual increase during follow-up. Although PCT is -better than more common biomarkers for the prognosis of pneumonia and to predict survival and outcome, novel biomarkers show an even better prognostic accuracy.

Markers of infection in inpatients and outpatients with acute Q-fever

BACKGROUND

Query-fever (Q-fever) is a zoonotic infection caused by the intracellular Gram-negative coccobacillus Coxiella burnetii. A large ongoing outbreak of Q-fever has been reported in the Netherlands. We studied various markers of infection in inpatients (hospitalised) and outpatients (treated by a general physician) with acute Q-fever in relation to disease severity.

METHODS

Leukocyte counts, C-reactive protein (CRP) and procalcitonin (PCT) concentrations were measured in 25 inpatients and 40 outpatients upon presentation with acute Q-fever. Chest X-rays, if available, were analysed and confusion, urea, respiratory rate, blood pressure-age 65 (CURB-65) scores, indicating severity of pneumonia, were calculated.

RESULTS

CRP was the only marker that significantly differentiated between inpatients and outpatients. It was increased in all patients from both groups. Leukocyte counts and PCT concentrations did not differ between inpatients and outpatients. Overall, only 13/65 patients had an increased leukocyte count and only 11/65 patients presented with PCT concentrations indicative of possible bacterial respiratory tract infection. Infiltrative changes on the chest X-ray were observed in the majority of patients. CURB-65 score was 0+/-1 (mean+/-SD).

CONCLUSIONS

Acute Q-fever, a relatively mild pneumonia with low CURB-65 scores, specifically induces a response in CRP, while PCT concentrations and leukocytes are within the normal range or increased only marginally.

Circulating biomarkers as surrogates for bloodstream infections

The use of biomarkers provides a novel approach to diagnosing infection, its severity and treatment response. Biomarkers, especially procalcitonin and, to a lesser extent, C-reactive protein and interleukin 8, can improve the diagnostic and prognostic assessment of bloodstream infections. Both strengths and weaknesses of biomarkers must be recognized for rational and safe use in clinical settings. Cut-off ranges must be chosen within the specific clinical context. Ultrasensitive assays for procalcitonin, capable of measuring low levels in healthy individuals, may help to identify even 'subclinical' inflammatory states before the development of clinically evident sepsis. For immunocompromised patients, the use of biomarkers could lead to an earlier and more targeted antimicrobial therapy for patients at risk of sepsis, whereas those patients with viral illness or a non-infectious aetiology of inflammation who maintain low levels of procalcitonin over time can be withheld from antibiotic exposure. The time has arrived to move beyond the observational reporting of 'promising' biomarkers. Specific cut-off ranges must be proposed and intervention studies conducted to tackle the existing vicious cycle of diagnostic uncertainty, antibiotic overuse and emerging multi-resistance.

Midregional pro-atrial natriuretic peptide as a prognostic marker in pneumonia

OBJECTIVE

To evaluate the usefulness of midregional pro-atrial natriuretic peptide (MR-proANP) measurement in the stratification of severity in community-acquired pneumonia.

METHODS

The population studied was three hundred patients admitted to Emergency Department of a tertiary university hospital presenting clinical signs of lower respiratory tract infection, a new infiltrate on the chest radiograph and a confirmed pneumonia by clinical evolution. Patients were stratified by the Pneumonia Severity Index (PSI), by CURB-65 score and by the development of complications. Serum samples were obtained at the moment of admission and prior to antibiotic therapy, and stored until analysis. MR-proANP was measured by B.R.A.H.M.S MR-proANP KRYPTOR.

RESULTS

Serum levels of MR-proANP increased with the severity of pneumonia, according to PSI score and CURB-65 score. Median MR-proANP levels were significantly higher (p<0.0001) in patients with high PSI risk class (IV-V) than in those with low PSI risk class (I-III). MR-proANP levels were also significantly higher (p=0.029) in those patients that developed complications or died. There was no association between MR-proANP and etiology of pneumonia and the radiographic extent.

CONCLUSION

We can conclude that MR-proANP measurement was helpful for individual risk assessment in patients with pneumonia admitted to the emergency department.

Biomarkers to improve diagnostic and prognostic accuracy in systemic infections

PURPOSE OF REVIEW

We review the advantages and drawbacks of biomarkers in the diagnostic and prognostic assessment of systemic infections.

RECENT FINDINGS

Since the signs and symptoms of severe infections can be ambiguous, biomarkers provide a more reliable tool in ascertaining the presence of a relevant bacterial infection, its severity and treatment response. Procalcitonin and, to a lesser extent, C-reactive protein and interleukin-8 can improve the diagnostic assessment of infections and guide antibiotic therapy. Promising prognostic biomarkers include cortisol, proadrenomedullin, copeptin and natriuretic peptides. The strengths and weaknesses of biomarkers must be recognized in order to use them rationally and safely. Cutoff ranges of biomarkers must be chosen according to the specific clinical context and they should be used as a complementary tool, to reinforce the clinical diagnostic workup. Biomarkers cannot determine the causative organisms and associated patterns of antibiotic susceptibility.

SUMMARY

If used in the proper setting, serial measurements of diagnostic biomarkers may allow treatments to be adjusted at an early stage in patients with severe infections. This may involve either intensifying treatment when infection levels stay high or avoiding unnecessary prolonged courses of antibiotics when levels rapidly decrease, thereby improving the allocation of healthcare resources.