Using the kinetics of C-reactive protein response to improve the differential diagnosis between acute bacterial and viral infections

Protective effect of chicken yolk antibody Y against Campylobacter jejuni induced diarrhea in cats

Campylobacter jejuni (C. jejuni) is a common pathogen that often causes diarrhea, loss of appetite, and even enteritis in domestic cats, affecting their growth and development, especially in kittens under 6 months of age. Oral passive immunization with chicken yolk antibody Y has been proved effective for the treatment of gastrointestinal pathogen infections due to its high specificity. In this study, C. jejuni was isolated from diarrheal cat feces, and the specific egg yolk antibody Y against C. jejuni was demonstrated to effectively inhibit its proliferation in vitro experiments. To evaluate the effect of anti-C. jejuni IgY, the mouse C. jejuni infection model was established and it was found that IgY could alleviate C. jejuni-induced clinical symptoms. Consistent with these results, the reduction of pro-inflammatory factors and intestinal colonization by C. jejuni in the IgY-treated groups, especially in the high dose group. We then evaluated the protective effect of IgY on young Ragdoll cats infected with C. jejuni. This specific antibody reduced the rate of feline diarrhea, protected the growth of young cats, inhibited systemic inflammatory hyperactivation, and increased fecal short-chain fatty acid concentrations. Notably, IgY may have a protective role by changing intestinal amino acid metabolism and affecting C. jejuni chemotaxis. Collectively, specific IgY is a promising therapeutic strategy for C. jejuni-induced cat diarrhea.

Protocol for the diagnostic performance of C reactive protein, procalcitonin and interleukin-6 for serious bacterial infections among children ≤36 months old presenting with fever without source: a systematic review and meta-analysis

INTRODUCTION

The management of fever without source in children ≤36 months old remains a diagnostic challenge as the underlying aetiologies can vary from self-limiting viral infections to serious bacterial infections (SBIs). Biomarkers such as C reactive protein (CRP), procalcitonin (PCT) and interleukin-6 (IL-6) have varying thresholds in the prediction of SBIs due to differences in SBI definitions, SBI prevalence, patient characteristics and timing of presentation. This protocol describes a systematic review and meta-analysis that aims to determine the thresholds at which CRP, PCT and IL-6 can perform optimally in distinguishing the presence of SBIs in children ≤36 months old, as well as to determine their performances in early detection of bacterial infections within 48 hours of fever onset.

METHODS AND ANALYSIS

We will systematically search electronic databases including MEDLINE, Cochrane Central Register of Controlled Trials, Cochrane CENTRAL, EMBASE, CINAHL (Cumulative Index to Nursing and Allied Health Literature) and Science Citation Index from 1 July 2023 to 31 July 2023. We will include studies that report the diagnostic accuracy of CRP, PCT and IL-6 in detecting SBIs in children aged ≤36 months presenting with fever without apparent source. Randomised controlled trials (RCTs) and non-randomised studies including non-RCTs and controlled before-and-after studies will be included. A meta-analysis will be performed and diagnostic performances of these biomarkers will be reported.

ETHICS AND DISSEMINATION

The results of this study will provide guidance on clinical decision-making in young children presenting with fever without source. Ethics approval will not be required for this study. The authors aim to publish the findings in a peer-reviewed journal as well as present at international conferences.

PROSPERO REGISTRATION NUMBER

CRD42023439093.

Pig Acute Phase Proteins as Non-Antibody Systemic Biomarkers of Intracellular Infections

As an alternative to traditional serological markers, that is, antibodies, for serum-based specific diagnosis of infections, circulating non-antibody markers may be used to monitor active disease. Acute phase proteins (APPs) are a prominent class of such markers widely used for diagnosing ongoing inflammation and infection. In this chapter, basic theoretical and practical considerations on developing APP assays and using APPs as markers of ongoing infection are presented with a specific focus on intracellular infections in pigs. Examples on APP-based monitoring of infection in pigs with viruses such as porcine respiratory and reproductive syndrome virus (PRRSV), porcine endemic diarrhea virus (PEDV), and influenza A virus (IAV), as well as intracellular bacteria (Lawsonia intracellularis) and the protozoan intracellular parasites Toxoplasma gondii and Cryptosporidium parvum are presented, with an emphasis on major pig APPs C-reactive protein (CRP), haptoglobin, serum amyloid A (SAA), and pig major acute phase protein (pig-MAP). The performance of these APPs as biomarkers in a range of experimental infection studies in pigs is described as examples on their use for estimating the severity of infection, vaccine efficacy, herd health characterization, and differential diagnosis.

Why C-reactive protein is one of the most requested tests in clinical laboratories?

C-reactive protein (CRP) is an acute-phase protein which is synthesized by the liver in response to the secretion of several inflammatory cytokines including interleukin 6 (IL-6), IL-1 and tumor necrosis factor (TNF). CRP was the first acute-phase protein to be described and adopted in clinical laboratories as an exquisitely sensitive systemic marker of inflammation and tissue damage. The measurement of CRP is widely used for the diagnosis and monitoring of inflammatory conditions, including sepsis, trauma, and malignancies. In the last decades, impressive advances in analytical methods (from qualitative to high-sensitivity assays), automation and availability of results in a short time, not only translated in an increasing demand for the right management of systemic inflammatory diseases, but also in evaluating subclinical inflammatory processes underlying atherothrombotic events. CRP measurement is one of the most requested laboratory tests for both the wide range of clinical conditions in which it may assure a valuable information and some analytical advantages due to the evidence that it is a "robust biomarker". Even recently, the measurement of CRP received new interest, particularly as a biomarker of severity of Coronavirus disease 2019 (COVID-19), and it deserves further concern for improving demand appropriateness and result interpretation.

Early signaling of bacteremia in patients who present to the Department of Emergency Medicine with relatively low C-Reactive Protein (CRP) concentrations

OBJECTIVES

Examiningthe usefulness of C-reactive protein velocity (CRPv) as an early biomarker for the presence of bacteraemia in patients presenting to the Department of Emergency Medicine with acute infection/inflammation and suspected bacteraemia.

METHODS

A retrospective study examining a cohort of patients who presented to the E.R and in whom blood cultures were taken. CRPv was calculated as the difference in mg/hour/litter between two consecutive CRP tests performed within 12 hours.

RESULTS

256 patients were included in the cohort. Using CRPv in patients who at first presented with a relatively low (17.9≤mg/L 1^stquartile) CRP concentration, we found an AUC of 0.808±0.038 (p<0.001) for the presence of positive versus negative blood cultures (what is AUC?). This was better than the AUC that was obtained when the WBC for the same purpose.

CONCLUSIONS

CRPv may be a useful biomarker in the identification of patients with suspected bacteremiaand a low CRP-a challenging situation for clinicians who may underestimate the severity of illness in this patient group.

Photonic sensor to detect rapid changes in CRP levels

One of the most important biomarkers used to determine inflammation is C-reactive protein (CRP). Its level, when it is within the range that does not define inflammation, informs about the risk of cardiovascular events. If the norm is exceeded and inflammation is detected in the body, CRP level can increase 1000 times within a few hours. The type of infection can also be determined based on the level of elevated CRP. All this makes CRP a very important element of diagnostics. A sensor based on low coherence interference is presented. Preliminary studies have shown that its sensitivity is 5.65 μg/L and the measurement time is short, <10 min. The entire system is built of commercially available components, which allow production cost minimalization. In addition, the user-friendly operation allows it to be operated by unqualified people. Due to these features, our solution is a promising alternative to commercially used enzyme-linked immunosorbent assay, which needs trained personnel to perform time-consuming measurement procedures.

Discrepancy of C-Reactive Protein, Procalcitonin and Interleukin-6 at Hospitalization: Infection in Patients with Normal C-Reactive Protein, Procalcitonin and High Interleukin-6 Values

C-reactive protein (CRP) or procalcitonin (PCT) alone has limitations in the early detection of infection or inflammation due to shortcomings in specificity and varied cut-off values. Recently, interleukin (IL)-6 has been assessed, but it is not known to what extent the three values are homogeneous in reality. This retrospective study was conducted with two large datasets (discrepancy set with results within 24 h of admission [7149 patients] and follow-up set until 2 weeks of hospital stay [5261 tests]) consisting of simultaneous examinations of CRP, PCT, and IL-6 between January 2015 and August 2021. The specific discrepant group (n = 102, 1.4%) with normal CRP (<10 mg/L) and PCT (<0.1 ng/mL) and high IL-6 (≥100 pg/mL) values was extracted from the discrepancy set. Dimensionality reduction and visualization were performed using Python. The three markers were not clearly clustered after t-distributed stochastic neighbor embedding. Pearson’s correlation coefficients between two markers were substantially low (0.23−0.55). Among the high normalized IL-6 levels (≥0.5) (n = 349), 17.8% and 38.7% of CRP and PCT levels were very low (≤0.01). 9.2% and 13.4% of normal CRP (n = 1522) had high PCT (≥0.5 ng/mL) and IL-6 (≥100 pg/mL) values, respectively. Infection and bacteremia among 102 patients occurred in 36 (35.3%) and 9 (8.8%) patients, respectively. In patients with bacteremia, IL-6 was the first to increase, followed by PCT and CRP. Our study revealed that CRP, PCT, and IL-6 levels were considerably discrepant, which could be misinterpreted if only CRP tests are performed.

Platelet-Derived Biomarkers: Potential Role in Early Pediatric Serious Bacterial Infection and Sepsis Diagnostics

Fever is the most common complaint of children who are attending a pediatric emergency department (PED). Most of the fever cases are of viral origin; however, the most common markers, such as leucocyte, neutrophil count, or C-reactive protein, are not sensitive or specific enough to distinguish the etiology of fever, especially if children present at the early phase of infection. Currently, platelets have been attributed a role as important sentinels in viral and bacterial infection pathogenesis. Thus, our aim was to analyze different platelet indices, such as PNLR (platelet-to-neutrophil/lymphocyte ratio), PNR (platelet-to-neutrophil ratio) as well as specific secreted proteins, such as sP-selectin, CXCL4, CXCL7, and serotonin. We included 68 children who were referred to PED with the early onset of fever (<12 h). All children with comorbidities, older than five years, and psychiatric diseases, who refused to participate were excluded. All the participants were divided into viral, bacterial, or serious bacterial infection (SBI) groups. All the children underwent blood sampling, and an additional sample was collected for protein analysis. Our analysis revealed statistically significant differences between leucocyte, neutrophil, and CRP levels between SBI and other groups. However, leucocyte and neutrophil counts were within the age norms. A higher PNLR value was observed in a bacterial group, PNR-in viral. As we tested CXCL7 and sP-selectin, alone and together those markers were statistically significant to discriminate SBI and sepsis from other causes of infection. Together with tachypnoe and SpO2 < 94%, it improved the prediction value of sepsis as well as SBI. CXCL4 and serotonin did not differ between the groups. Concluding, CXCL7 and sP-selectin showed promising results in early SBI and sepsis diagnosis.

C-Reactive Protein Velocity (CRPv) as a New Biomarker for the Early Detection of Acute Infection/Inflammation

C-reactive protein (CRP) is considered a biomarker of infection/inflammation. It is a commonly used tool for early detection of infection in the emergency room or as a point-of-care test and especially for differentiating between bacterial and viral infections, affecting decisions of admission and initiation of antibiotic treatments. As C-reactive protein is part of a dynamic and continuous inflammatory process, a single CRP measurement, especially at low concentrations, may erroneously lead to a wrong classification of an infection as viral over bacterial and delay appropriate antibiotic treatment. In the present review, we introduce the concept of C-reactive protein dynamics, measuring the velocity of C-reactive protein elevation, as a tool to increase this biomarker’s diagnostic ability. We review the studies that helped define new metrics such as estimated C-reactive protein velocity (velocity of C-reactive protein elevation from symptoms’ onset to first C-reactive protein measurement) and the measured C-reactive protein velocity (velocity between sequential C-reactive protein measurements) and the use of these metrics in different clinical scenarios. We also discuss future research directions for this novel metric.

Extensive Study on Hematological, Immunological, Inflammatory Markers, and Biochemical Profile to Identify the Risk Factors in COVID-19 Patients

Background

Tissue damage caused by COVID-19 could be detected by several clinical indicators including hematological, immunological, biochemical, and inflammatory markers. This study was to detect these clinical parameters to reveal the correlation between the factors and their roles in the development of COVID-19, to explore the hazard factors in severe cases.

Materials and Methods

A total of 200 participants of both sexes were included in the study, with an age range of (25–72) years, categorized into three main groups: 50 healthy individuals, 62 mild infected patients, and 88 severe infected patients with pneumonia. Different hematological and clinical parameters were included in the analysis (Basrah city, Iraq). Serum levels of interleukin-6 (IL-6), ferritin, and high-sensitivity C-reactive protein (hs-CRP) were assessed for all participants using an enzyme-linked immunosorbent assay (ELISA). The liver, renal, and cardiac functions were assessed by clinical chemistry testing.

Results

COVID-19 patients had leukocytosis, with an increased number of neutrophils and a decreased lymphocyte count, according to our findings. In regard to inflammatory parameters, both ESR and hs-CRP showed significant differences between the two groups, whereas IL-6 was significantly higher in the total severe group compared to the other two groups. Biochemical results revealed that each lactate dehydrogenase (LDH), ferritin, alanine aminotransferase (ALT), and aspartate aminotransferase (AST) had significant changes in the total severe group. Among pneumonic with an O2 requirement and pneumonic without an O2 requirement, there were significant differences in immunological and inflammatory markers (p > 0.05). The neutrophils-lymphocytes ratio (NLR) was highly elevated in severe who required O2. Moreover, IL-6, lymphocytes, and neutrophils were possible risk factors for COVID-19 infection, with the strongest influence of IL-6 with a high odds ratio (OR: 24.138, 95% CI: 8.437–30.65, p < 0.01). Furthermore, there were significant correlations among the indicators.

Conclusion

Each of IL-6, lymphocytes, and neutrophils might represent major factors in the severity of COVID-19 and IL-6 plays the main role in inducing the inflammatory and pathophysiology process that is known as the cytokine storm.

Use of infection biomarkers in the emergency department

The use of infection biomarkers in the emergency department is discussed in terms of their possible contributions to diagnostic-prognostic uncertainties, appropriate antibiotic treatments, and triage and follow-up planning. Procalcitonin (PCT), C-reactive protein (CRP), proadrenomedullin (proADM), and presepsin are among the most discussed infection biomarkers for use in the emergency department. Due to the variable sensitivity results and cutoff values, there are insufficient data to recommend the widespread use of CRP and procalcitonin (PCT) for the diagnosis and prognosis of infection in the emergency department. However, these biomarkers can be used for appropriate antibiotic use in selected infection groups, such as community-acquired pneumonia, especially to reduce unnecessary antibiotic prescribing. With its prognostic superiority over other biomarkers and its contribution to prognostic score systems in community-acquired pneumonia (CAP), proADM can be used to predict hospitalization, preferably within the scope of clinical studies. Although presepsin has been shown to have some advantages over other biomarkers to rule out sepsis, there are insufficient data for its clinical use in the emergency department.

C-reactive protein velocity discriminates between acute viral and bacterial infections in patients who present with relatively low CRP concentrations

Background

To assess the utility of C-reactive protein (CRP) velocity to discriminate between patients with acute viral and bacterial infections who presented with relatively low CRP concentrations and were suspected of having a bacterial infection.

Methods

We analyzed a retrospective cohort of patients with acute infections who presented to the emergency department (ED) with a relatively low first CRP measurement (CRP1) ≤ 31.9 mg/L and received antibiotics shortly after. We then calculated C-reactive protein velocity (CRPv), milligram per liter per hour, for each patient based on CRP1 and the second CRP value (CRP2) measured within the first 24 h since admission. Finally, we compared CRPv between patients with bacterial and viral infections.

Results

We have presently analyzed 74 patients with acute bacterial infections and 62 patients with acute viral infections at the mean age of 80 and 66 years respectively, 68 male and 68 female. CRP1 did not differ between both groups of patients (16.2 ± 8.6 and 14.8 ± 8.5 for patients with viral and bacterial infections respectively, p value = 0.336). However, the CRP2 was significantly different between the groups (30.2 ± 21.9 and 75.6 ± 51.3 for patients with viral and bacterial infections respectively, p-value < 0.001) and especially the CRPv was much higher in patients with acute bacterial infections compared to patients with acute viral infections (0.9 ± 1.2 and 4.4 ± 2.7 respectively, p-value < 0.001).

Conclusion

CRPv and CRP2 are useful biomarkers that can discriminate significantly between patients who present with acute bacterial and viral infections, and relatively low CRP concentration upon admission who were suspected of having a bacterial infection.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-021-06878-y.

The Predictive Role of Artificial Intelligence-Based Chest CT Quantification in Patients with COVID-19 Pneumonia

We sought to analyze the prognostic value of laboratory and clinical data, and an artificial intelligence (AI)-based algorithm for Coronavirus disease 2019 (COVID-19) severity scoring, on CT-scans of patients hospitalized with COVID-19. Moreover, we aimed to determine personalized probabilities of clinical deterioration. Data of symptomatic patients with COVID-19 who underwent chest-CT-examination at the time of hospital admission between April and November 2020 were analyzed. COVID-19 severity score was automatically quantified for each pulmonary lobe as the percentage of affected lung parenchyma with the AI-based algorithm. Clinical deterioration was defined as a composite of admission to the intensive care unit, need for invasive mechanical ventilation, use of vasopressors or in-hospital mortality. In total 326 consecutive patients were included in the analysis (mean age 66.7 ± 15.3 years, 52.1% male) of whom 85 (26.1%) experienced clinical deterioration. In the multivariable regression analysis prior myocardial infarction (OR = 2.81, 95% CI = 1.12–7.04, p = 0.027), immunodeficiency (OR = 2.08, 95% CI = 1.02–4.25, p = 0.043), C-reactive protein (OR = 1.73, 95% CI = 1.32–2.33, p < 0.001) and AI-based COVID-19 severity score (OR = 1.08; 95% CI = 1.02–1.15, p = 0.013) appeared to be independent predictors of clinical deterioration. Personalized probability values were determined. AI-based COVID-19 severity score assessed at hospital admission can provide additional information about the prognosis of COVID-19, possibly serving as a useful tool for individualized risk-stratification.

Potential biomarkers for the early prediction of SARS-COV-2 disease outcome

The current pandemic due to the fast spreading of SARS-CoV-2 infection has caused severe impairment in health, social, economic, scientific, and medical sectors across the globe. Owing to the not so well understood mechanism of disease pathogenesis in terms of variations in immune responses, there remains obscure why some of the patients who are infected by the novel SARS-CoV-2 develop an unpredictable clinical course that rapidly causes severe and deadly complications/manifestations. Currently, several assays are available for the confirmation of SARS-CoV-2 infection at the point of care. However, none of these assays can predict the severity of the COVID-19 disease. Thus, the identification of a prognostic biomarker that forecasts the condition of SARS-CoV-2 patients to develop a severe form of the disease could enable the clinicians for more efficient patient triage and treatment. In this regard, the present review describes the role of selected biomolecules that are crucially involved in the immune-pathogenesis of SARS-CoV-2 infection such as hyper-immune responsiveness, bradykinin storm and vascular leakage assuming these may serve as an effective prognostic biomarker in COVID-19 to understand the outcome of the disease. Based on the review, we also propose the development of a cost-effective SERS-based prognostic biosensor for the detection and quantification of biomolecules for use as a point-of-care system during a disease outbreak.

C-Reactive Protein as a Prognostic Indicator in COVID-19 Patients

While some biomolecules have been explored to identify potential biomarkers for the prognosis of COVID-19 patients, there is no reliable prognostic indicator of the disease progression and severity. We aimed to evaluate the ability of the C-reactive protein (CRP) to predict COVID-19 infection outcome. This retrospective study was conducted on 429 patients diagnosed with COVID-19 between March 30, 2020, and April 30, 2020. The study population was divided into severe (n = 175) and nonsevere cases (n = 254). Data on demographic characteristics, clinical features, and laboratory findings on admission were collected. The proportion of patients with increased CRP levels was significantly higher in severe cases than in nonsevere patients. Analysis of the receiver operating characteristic (ROC) curve found that CRP could be used as an independent factor in predicting the severity of COVID-19. Also, patients with CRP >64.75 mg/L were more likely to have severe complications. In conclusion, CRP serum levels can predict the severity and progression of illness in patients with COVID-19.

Exclusion of bacterial co-infection in COVID-19 using baseline inflammatory markers and their response to antibiotics

BACKGROUND

COVID-19 is infrequently complicated by bacterial co-infection, but antibiotic prescriptions are common. We used community-acquired pneumonia (CAP) as a benchmark to define the processes that occur in bacterial pulmonary infections, testing the hypothesis that baseline inflammatory markers and their response to antibiotic therapy could distinguish bacterial co-infection from COVID-19.

METHODS

Retrospective cohort study of CAP (lobar consolidation on chest radiograph) and COVID-19 (PCR detection of SARS-CoV-2) patients admitted to Royal Free Hospital (RFH) and Barnet Hospital (BH), serving as independent discovery and validation cohorts. All CAP and >90% COVID-19 patients received antibiotics on hospital admission.

RESULTS

We identified 106 CAP and 619 COVID-19 patients at RFH. Compared with COVID-19, CAP was characterized by elevated baseline white cell count (WCC) [median 12.48 (IQR 8.2-15.3) versus 6.78 (IQR 5.2-9.5) ×106 cells/mL, P < 0.0001], C-reactive protein (CRP) [median 133.5 (IQR 65-221) versus 86.0 (IQR 42-160) mg/L, P < 0.0001], and greater reduction in CRP 48-72 h into admission [median ΔCRP -33 (IQR -112 to +3.5) versus +14 (IQR -15.5 to +70.5) mg/L, P < 0.0001]. These observations were recapitulated in the independent validation cohort at BH (169 CAP and 181 COVID-19 patients). A multivariate logistic regression model incorporating WCC and ΔCRP discriminated CAP from COVID-19 with AUC 0.88 (95% CI 0.83-0.94). Baseline WCC >8.2 × 106 cells/mL or falling CRP identified 94% of CAP cases, and excluded bacterial co-infection in 46% of COVID-19 patients.

CONCLUSIONS

We propose that in COVID-19, absence of both elevated baseline WCC and antibiotic-related decrease in CRP can exclude bacterial co-infection and facilitate antibiotic stewardship efforts.

COVID-19 Pandemic: What about the Safety of Anti-Coronavirus Nanoparticles?

Every day, new information is presented with respect to how to best combat the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). This manuscript sheds light on such recent findings, including new co-factors (i.e., neuropilin-1) and routes (i.e., olfactory transmucosal) allowing cell entry of SARS-CoV-2 and induction of neurological symptoms, as well as the new SARS-CoV-2 variants. We highlight the SARS-CoV-2 human-animal interfaces and elaborate containment strategies using the same vaccination (i.e., nanoparticle "NP" formulations of the BNT162b2 and mRNA-1273 vaccines) for humans, minks, raccoon dogs, cats, and zoo animals. We investigate the toxicity issues of anti-CoV NPs (i.e., plasmonic NPs and quantum dots) on different levels. Namely, nano-bio interfaces (i.e., protein corona), in vitro (i.e., lung cells) and in vivo (i.e., zebrafish embryos) assessments, and impacts on humans are discussed in a narrative supported by original figures. Ultimately, we express our skeptical opinion on the comprehensive administration of such antiviral nanotheranostics, even when integrated into facemasks, because of their reported toxicities and the different NP parameters (e.g., size, shape, surface charge, and purity and chemical composition of NPs) that govern their end toxicity. We believe that more toxicity studies should be performed and be presented, clarifying the odds of the safe administration of nanotoxocological solutions and the relief of a worried public.

Early identification of patients with severe COVID-19 at increased risk of in-hospital death: a multicenter case-control study in Wuhan

Background

Most evidence regarding the risk factors for early in-hospital mortality in patients with severe COVID-19 focused on laboratory data at the time of hospital admission without adequate adjustment for confounding variables. A multicenter, age-matched, case-control study was therefore designed to explore the dynamic changes in laboratory parameters during the first 10 days after admission and identify early risk indicators for in-hospital mortality in this patient cohort.

Methods

Demographics and clinical data were extracted from the medical records of 93 pairs of patients who had been admitted to hospital with severe COVID-19. These patients had either been discharged or were deceased by March 3, 2020. Data from days 1, 4, 7, and 10 of hospital admission were compared between survivors and non-survivors. Univariate and multivariate conditional logistic regression analyses were employed to identify early risk indicators of in-hospital death in this cohort.

Results

On admission, in-hospital mortality was associated with five risk indicators (ORs in descending order): aspartate aminotransferase (AST, >32 U/L) 43.20 (95% CI: 2.63, 710.04); C-reactive protein (CRP) greater than 100 mg/L 13.61 (1.78, 103.941); lymphocyte count lower than 0.6×10⁹/L 9.95 (1.30, 76.42); oxygen index (OI) less than 200 8.23 (1.04, 65.15); and D-dimer over 1 mg/L 8.16 (1.23, 54.34). Sharp increases in D-dimer at day 4, accompanied by decreasing lymphocyte counts, deteriorating OI, and persistent remarkably high CRP concentration were observed among non-survivors during the early stages of hospital admission.

Conclusions

The potential risk factors of high D-dimer, CRP, AST, low lymphocyte count and OI could help clinicians identify patients at high risk of death early in the hospital admission. This might assist with rationalization of health care resources.

Host Diagnostic Biomarkers of Infection in the ICU: Where Are We and Where Are We Going?

Purpose of Review

Early identification of infection in the critically ill patient and initiation of appropriate treatment is key to reducing morbidity and mortality. On the other hand, the indiscriminate use of antimicrobials leads to harms, many of which may be exaggerated in the critically ill population. The current method of diagnosing infection in the intensive care unit relies heavily on clinical gestalt; however, this approach is plagued by biases. Therefore, a reliable, independent biomarker holds promise in the accurate determination of infection. We discuss currently used host biomarkers used in the intensive care unit and review new and emerging approaches to biomarker discovery.

Recent Findings

White cell count (including total white cell count, left shift, and the neutrophil-leucocyte ratio), C-reactive protein, and procalcitonin are the most common host diagnostic biomarkers for sepsis used in current clinical practice. However, their utility in the initial diagnosis of infection, and their role in the subsequent decision to commence treatment, remains limited. Novel approaches to biomarker discovery that are currently being investigated include combination biomarkers, host 'sepsis signatures' based on differential gene expression, site-specific biomarkers, biomechanical assays, and incorporation of new and pre-existing host biomarkers into machine learning algorithms.

Summary

To date, no single reliable independent biomarker of infection exists. Whilst new approaches to biomarker discovery hold promise, their clinical utility may be limited if previous mistakes that have afflicted sepsis biomarker research continue to be repeated.

The potential role of neopterin in Covid-19: a new perspective

Neopterin (NPT) is a member of pteridines group, synthesized by macrophages when stimulated by interferon gamma (INF-γ). NPT is regarded as a macrophage stimulation indicator, marker of cellular immune activation and T helper 1 (Th1) type 1 immune response. Here, we aimed to provide a view point on the NPT features and role in Covid-19. Serum NPT level is regarded as an independent prognostic factor for Covid-19 severity, with levels starting to increase from the 3rd day of SARS-CoV-2 infection, being associated with severe dyspnea, longer hospitalization period and complications. Also, early raise of NPT reflects monocytes/macrophages activation before antibody immune response, despite the NPT level may also remain high in Covid-19 patients or at the end of incubation period before the onset of clinical symptoms. On the other hand, NPT attenuates the activity of macrophage foam cells and is linked to endothelial inflammation through inhibition of adhesion molecules and monocytes migration. However, NPT also exerts anti-inflammatory and antioxidant effects by suppressing NF-κB signaling and NLRP3 inflammasomes. NPT can be viewed as a protective compensatory mechanism to counterpoise hyper-inflammation, oxidative stress, and associated organ damage.

A second C-reactive protein (CRP) test to detect inflammatory burst in patients with acute bacterial infections presenting with a first relatively low CRP

A first C-reactive protein (CRP) test, as often performed by clinicians during the presentation of patients with an acute bacterial infection, might be misleading. The aim of our study was to explore the dynamic between a second CRP test taken within 12 hours from admission CRP test in a cohort of patients diagnosed with acute bacterial infection in comparison to CRP in a control group of apparently healthy individuals.This was a historical cohort study comprised of all patients admitted to the Sourasky Tel-Aviv Medical Center, Israel, between July 2007 and March 2016. The study cohort included adult patients who were diagnosed as having an infection, assumed to be of bacterial etiology (cellulitis and erysipelas, pneumonia, cholecystitis, pyelonephritis, or septicemia), who had a CRP test during the first 6 hours of hospital admission (baseline CRP), and a successive CRP test up to 12 hours from the first one (recurrent CRP). The control group was of healthy subjects who attended our medical center for a routine annual check-up.The study included 950 patients. Baseline CRP ranged from 0.04 to 454 mg/L. The median CRP velocity was 0.53 mg/L/h. Patients were grouped by baseline CRP into 4 groups (CRP < 10, 10-74.9, 75-199.9, ≥200). There was an increase in median CRP velocity between the first (0.48 mg/L/h) and the second (0.93 mg/L/h) groups, which then was decreased in the next 2 groups (0.46 and -2.58 mg/L/h, respectively). In 45 of 103 (44%) patients of the group of baseline CRP concentration less than 10 mg/dL with bacterial diagnosis, there was a complete overlap with CRP values of apparently healthy individuals during their routine annual checkup.A first single low CRP result cannot exclude the presence of a significant bacterial infection. Patients with acute bacterial infection might present with a relatively low CRP value that at times correspond to normal limit CRP concentrations. A second test, obtained within 12 hours of admission, might serve as an important tool to identify patient with an evolving inflammatory burst commonly seen during acute bacterial infection.

The plasma level of mCRP is linked to cardiovascular disease in antineutrophil cytoplasmic antibody-associated vasculitis

BACKGROUND

C-reactive protein (CRP) has two natural isomers: C-reactive protein pentamer (pCRP) and C-reactive protein monomer (mCRP). The levels of CRP are significantly elevated in patients with anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV). mCRP not only activates the endothelial cells, platelets, leukocytes, and complements, but also has a proinflammatory structural subtype that can localize and deposit in inflammatory tissues. Thus, it regulates a variety of clinical diseases, such as ischemia/reperfusion (I/R) injury, Alzheimer's disease, age-related macular degeneration, and cardiovascular disease. We hypothesized that plasma mCRP levels are related to cardiovascular disease in AAV.

METHODS

In this cross-sectional study, 37 patients with AAV were assessed. Brain natriuretic peptide (BNP) and mCRP in plasma were assessed by enzyme-linked immunosorbent assay (ELISA). The acute ST-segment elevation myocardial infarction (STEMI) was diagnosed by coronary angiography, and the Gensini score calculated. Echocardiography evaluated the ejection fraction (EF%), left ventricular end-diastolic volume (LVEDV), left ventricular end-systolic volume (LVESV), and left ventricular mass index (LVMI). Estimated glomerular filtration rate (eGFR) was calculated based on serum creatinine, age, and gender.

RESULTS

The plasma level of mCRP in AAV was significantly higher than that in healthy volunteers (P < 0.001). Then, mCRP and CRP levels were compared with and without STEMI complications in AAV. The plasma level of mCRP was higher, but that of CRP was lower in STEMI. The plasma level of mCRP was correlated with Birmingham vasculitis activity score (BVAS), eGFR, BNP, EF%, LVEDV, LVESV, LVMI, and STEMI complications' Gensini score in AAV; however, CRP did not correlate with BNP, EF%, LVEDV, LVESV, LVMI, and Gensini score.

CONCLUSIONS

The plasma level of mCRP was related to cardiovascular diseases in AAV patients.

Clinical Characteristics and Outcome of Hospitalized COVID-19 Patients in a MERS-CoV Endemic Area

Background: The Kingdom of Saudi Arabia (KSA) reported 170,639 cases and 1430 deaths from COVID-19 since the first case emerged in the country on March 2 through June 25, 2020. The objective of this report is to describe the characteristics and outcome observed among 99 hospitalized COVID-19 patients in the largest academic hospital in KSA, and assess co-infection with the Middle East Respiratory Syndrome Coronavirus (MERS-CoV).

Methods: This single-center case series data included select epidemiological, clinical, radiological features and laboratory findings of all confirmed hospitalized cases of COVID-19 in King Saud University Medical City (KSUMC), Riyadh, KSA, from March 22 until May 31, 2020, followed through June 6, 2020. We conducted retrospective analysis of listed data from 99 hospitalized patients and present characteristics and factors associated with severity in percentages and univariate odds ratios. Cases were confirmed using nasopharyngeal or throat swab by real-time Reverse Transcriptase Polymerase Chain Reaction (RT-PCR) for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), and MERS-CoV by RT-PCR.

Results: The 99 hospitalized COVID-19 patients included in this analysis constitute 16% of 632 positive SARS-CoV-2 among 6633 persons who were tested at the KSUMC (positivity rate, 9.4%). MERS-CoV PCR was negative in all 99 patients tested. The majority of these 99 hospitalized patients were males (66%), had a mean age of 44 years (range, 19–87), and a quarter (25.3%) were health care workers. Patients with comorbid conditions accounted for 52.5% of patients including the 8.1% who were asymptomatic; diabetes mellitus being the most frequent (31.3%), followed by hypertension (22.2%). The most common presenting symptoms were fever (67.7%), cough (60.6%), dyspnea (43.4%), upper respiratory symptoms (27.3%), fatigue (26.3%), diarrhea (19.2%) and loss of smell (9.1%). The clinical conditions among these 99 patients included upper respiratory tract infection (47.5%), abnormal chest X-ray, lymphopenia, high inflammatory markers a fifth (21%) of patients had moderate pneumonia, while 7% had severe pneumonia with 22.2% requiring admission to the intensive care unit and 12.1% died. Late presentation with severe disease, an abnormal chest X-ray, lymphopenia, high inflammatory markers (C-reactive protein, ferritin, and procalcitonin), and end organ damage (high creatinine or high aspartate aminotransferase) were predictors for admission to critical care unit or died.

Conclusion: We observed no MERS-CoV co-infection in this early cohort of hospitalized COVID-19 patients who were relatively young, more than half had comorbid conditions, presented with fever and/or cough, an abnormal chest X-ray, lymphopenia, and high inflammatory markers. Given MERS-CoV endemicity in the country, co-monitoring of MERS-CoV and SARS-CoV-2 coinfection is critical.

Sustained Postoperative Fever Without Evident Cause After Spine Instrumentation as an Indicator of Surgical Site Infection

BACKGROUND

Surgical site infection after spinal instrumentation increases morbidity and mortality as well as medical costs and is a burden to both patients and surgeons. Late-onset or sustained fever increases the suspicion for comorbid conditions. This retrospective, exploratory cohort study was conducted to identify the rate of and risk factors for sustained or late-onset postoperative fever after spinal instrumentation operations and to determine its relationship with surgical site infection.

METHODS

Five hundred and ninety-eight patients who underwent lumbar or thoracic spinal instrumentation were retrospectively reviewed. The patients were divided according to (1) whether or not they had had a sustained fever (SF[+] or SF[-]) and (2) whether or not they had had a surgical site infection (SSI[+] or SSI[-]). Clinical characteristics, surgical factors, prophylactic antibiotic usage, fever pattern, and laboratory/imaging findings were recorded for all patients by electronic medical chart review.

RESULTS

In total, 68 patients (11.4%) had a sustained fever. The rate of surgical site infection was significantly higher when the patient had sustained fever (13.2% [9 of 68] compared with 0.9% [5 of 530]; p < 0.001). Comparison of the patients who had a sustained fever but no surgical site infection (SF[+], SSI[-]) and those with both a sustained fever and surgical site infection (SF[+], SSI[+]) showed that continuous fever, an increasing or stationary pattern of inflammatory markers, and a C-reactive protein (CRP) level of >4 mg/dL on postoperative days 7 to 10 were diagnostic clues for surgical site infection. The sensitivity and specificity of postoperative magnetic resonance imaging (MRI) for the detection of surgical site infection were 40.0% and 90.9%, respectively, when MRI was performed within 1 month after surgery.

CONCLUSIONS

Although most patients with sustained fever did not have surgical site infection, fever was significantly related to surgical site infection. Continuous fever, increasing patterns of inflammatory markers, and high CRP on postoperative days 7 to 10 were diagnostic clues for surgical site infection. This study demonstrated provisional results for factors that can discriminate febrile patients with surgical site infection from febrile patients without infection. Further investigation with a larger sample size is warranted for clarification.

LEVEL OF EVIDENCE

Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

The potential benefit of a second C-reactive protein measurement in patients with gram-negative bacteraemia presenting to the emergency medicine department

BACKGROUND

Low C-reactive protein in acute bacterial infections could convey the erroneous impression of a mild infection. We focussed on gram-negative bacteraemia, a phenomenon frequently seen at the emergency room.

METHODS

Of 2200 patients with gram-negative bacteraemia, 460 patients with first C-reactive protein <30 mg/L and 460 patients with C-reactive protein >187 mg/L were reviewed. Following exclusions, we finally investigated 229 and 289 patients with low and high C-reactive protein concentrations, respectively.

RESULTS

The cohort was divided into low and high C-reactive protein groups. Median first C-reactive protein was 13.6 and 219.9 mg/L, respectively (interquartile range 6.4-21.6 and 195-270.1). Compared to patients with first high C-reactive protein, patients with first low C-reactive protein concentrations had a significant five-fold higher C-reactive protein level with their second test.

CONCLUSIONS

Patients with gram-negative bacteraemia can present with C-reactive protein within the range of apparently healthy individuals. A second C-reactive protein might help to avoid an erroneous decision regarding the severity of the infection.

C-Reactive Protein Level May Predict the Risk of COVID-19 Aggravation

BACKGROUND

Clinical findings indicated that a fraction of coronavirus disease 2019 (COVID-19) patients diagnosed as mild early may progress to severe cases. However, it is difficult to distinguish these patients in the early stage. The present study aimed to describe the clinical characteristics of these patients, analyze related factors, and explore predictive markers of the disease aggravation.

METHODS

Clinical and laboratory data of nonsevere adult COVID-19 patients in Changsha, China, were collected and analyzed on admission. A logistic regression model was adopted to analyze the association between the disease aggravation and related factors. The receiver operating characteristic curve (ROC) was utilized to analyze the prognostic ability of C-reactive protein (CRP).

RESULTS

About 7.7% (16/209) of nonsevere adult COVID-19 patients progressed to severe cases after admission. Compared with nonsevere patients, the aggravated patients had much higher levels of CRP (median [range], 43.8 [12.3-101.9] mg/L vs 12.1 [0.1-91.4] mg/L; P = .000). A regression analysis showed that CRP was significantly associated with aggravation of nonsevere COVID-19 patients, with an area under the curve of 0.844 (95% confidence interval, 0.761-0.926) and an optimal threshold value of 26.9 mg/L.

CONCLUSIONS

CRP could be a valuable marker to anticipate the possibility of aggravation of nonsevere adult COVID-19 patients, with an optimal threshold value of 26.9 mg/L.

Biosensors for detecting viral and bacterial infections using host biomarkers: a review

A schematic diagram showing multiple modes of biosensing platforms for the diagnosis of bacterial or viral infections.

C-reactive protein as an early predictor of COVID-19 severity

Background

Data for predicting severity of patients with COVID-19 infection are sparse and still under investigation. We retrospectively studied whether the admission serum C-reactive protein level (CRP) can serve as nearly predictor of disease severity during COVID-19 infection in comparison with other hematologic and inflammatory markers.

Methods

We included all consecutive patients who were admitted in Cheikh Khalifa International University Hospital, Casablanca, Morocco, between February to April 2020, with a confirmed diagnosis of COVID-19 infection using SARS-CoV-2 viral nucleic acid via RT-PCR. The complete blood count and serum CRP level were routinely measured on admission. All clinical and laboratory data of patients were collected and analyzed. The classification of the disease severity was in accordance with the clinical classification of the WHO interim guidance, and the management of patients were adapted to the national management guideline. We estimated receiver operating characteristic (ROC) curves of blood routine parameters as well as their association with COVID-19 disease severity.

Results

145 COVID-19 patients were included in the study. The median age (range) was 50 (32-63) years, and 75 (51.7%) were men. 101 patients were classified in the non-severe group and 44 patients in the severe group. Based on disease severity, significant differences were observed in the age, gender, comorbidities, and respiratory symptom. Similarly, the biological analysis found significant differences for the neutrophil count, lymphocyte count, eosinophil count, and CRP level. However, according to ROC curves of these laboratory biomarkers, the AUC of CRP at 0.872 was significantly higher than all other parameters. Further, CRP was independently associated with severity of COVID-19 disease (OR = 1.11, 95% IC (1.01-1.22) and or = 1.13, 95% IC (1.04-1.23)).

Conclusions

This study found that the CRP level at admission represent a simple and independent factor that can be useful for early detection of severity during COVID-19 and the easy guidance of primary care.