Diagnostic system for distinguishing bacterial infection and viral infection using myxovirus resistance protein a and c-reactive protein

Abstract

A diagnostic system for distinguishing between bacterial infection and viral infection using Myxovirus resistance proteins A and C-reactive proteins, which is characterized in that a detector antibody binds to an antigen in a blood sample to form an antigen-antibody complex, and the antigen-antibody complex, while moving to a nitrocellulose matrix, is captured by other antibodies immobilized on a test strip, allowing the quantitative detection of MxA and CRP levels in the blood sample.

Description

A diagnostic system for differentiating bacterial and viral infections using myxovirus resistance protein A and C-reactive protein.

[0001] The present invention relates to a diagnostic system capable of safely distinguishing between viral infection and bacterial infection by using a combination of Myxovirus Resistance Protein A (hereinafter referred to as MxA) and C-Reactive Protein (hereinafter referred to as CRP).

[0002] More specifically, the present invention can quantitatively measure biomarkers MxA and CRP, and obtain the probability of bacterial infection using an equation including MxA and CRP values.

[0003] Viral and bacterial infections are major causes of morbidity, mortality, and healthcare costs. Approximately 80% of all antibiotics are prescribed in primary care settings, most of which are used to treat respiratory infections.

[0004] However, the majority of acute respiratory infections are viral in origin, and clinicians need tools to reinforce their belief in the cause and avoid unnecessary antibiotic prescribing when in doubt.

[0005] This tool should be point-of-care (POC) and should readily provide a potential for viral or bacterial infection.

[0006] Procalcitonin has been the biomarker of choice to avoid unnecessary antibiotic use. Procalcitonin is produced in cells and organs by proinflammatory cytokines induced by bacterial infection and is released into the bloodstream.

[0007] This has been demonstrated in randomized clinical trials. However, to properly assess patients, two or more biomarkers often need to be used together.

[0008] Ideally, at least one biomarker should indicate a possible viral infection, while the other should indicate a possible bacterial infection. This need is supported by several microbiological studies demonstrating that lower respiratory tract infections often have a mixed viral and bacterial etiology.

[0009] Domestic Patent No. 10-2515555 (announced on March 28, 2023) relates to a method for diagnosing bacterial and viral infections using biomarkers to determine whether a patient with acute inflammation has a bacterial or viral infection. (See Figure 1.)

[0010] The above patent relates to a method for providing information useful for diagnosing a patient diagnosed with an infection to determine whether the infection is a viral infection or a bacterial infection.

[0011] a) a step of measuring the expression level of two biomarkers in a biological sample of a patient, wherein the two biomarkers are transcripts selected from CTSB, ISG15, OASL, IFI27, and JUP; and

[0012] b) a step of analyzing the expression level of each biomarker along with the respective reference value range for said biomarker to calculate a metascore that identifies the patient as having a viral infection or a bacterial infection.

[0013] U.S. Patent No. 9,910,036 B2 (Mar. 6, 2018) relates to a combined detection device and method for viral and bacterial infections. (See Fig. 2)

[0014] The above patent describes a lateral flow analysis device that detects and differentiates between viral and bacterial infections. This complex diagnostic device tests for viral and bacterial infection markers on-site, effectively helping to quickly and effectively differentiate between viral and bacterial infections.

[0015] In a preferred embodiment, the bacterial marker is CRP. In another preferred embodiment, the viral marker is MxA. In some embodiments, lysing the cells in the sample prior to applying it to the device is unnecessary.

[0016] [Prior Art Literature]

[0017] (Patent Document 1) KR 10-2515555 B1 (announced on March 28, 2023)

[0018] (Patent Document 2) US 9,910,036 B2 (MAR. 6, 2018)

[0019] Examples of candidate biomarkers include myxovirus resistance protein (MxA) and C-reactive protein (CRP).

[0020] Myxovirus resistance protein (MxA) is a large interferon-inducible GTPase involved in the control of intracellular pathogens. In humans, two Mx homologs mediate antiviral activity against a wide range of viruses, including SARS-CoV-2. Elevated MxA indicates increased endogenous interferon production mediated by viral activation and can be used as a marker of viral infection.

[0021] C-reactive protein (CRP) is a well-known cytokine-induced acute phase protein. Rather than responding to specific infections, its blood levels increase in response to nonspecific infections caused by a variety of potential factors.

[0022] Measurement of these two proteins can be integrated into existing commercially available assays, allowing a qualitative approach to detect elevations in MxA, CRP, or both.

[0023] However, existing approaches have limitations in personalized diagnosis. Qualitative approaches ignore the individual patient's environment, and many patients are susceptible to concurrent viral and bacterial infections, requiring more accurate measurements for informed decision-making.

[0024] This patent provides a completely different approach to analyzing MxA and CRP as diagnostic tools for viral and bacterial infections to address the above problems.

[0025] Serial measurements of the two proteins are analyzed using a discovery cohort and a validation cohort. The discovery cohort consists of patients with the final infection, and the validation cohort consists of patients with a high probability of viral or bacterial etiology or co-infection. The cutoff points developed in the discovery cohort are validated in the validation cohort.

[0026] The algorithm used in the diagnostic system of the present invention provides the utility of MxA and CRP as tools for distinguishing between viral acute respiratory diseases and bacterial acute respiratory diseases in the emergency room, and the sensitivity and specificity for bacterial infections were reported to be 93.2% and 88.4%, respectively.

[0027] Using the algorithm of the present invention, antibiotic administration to patients with viral infections can be significantly reduced from 18.4% to 11.6%.

[0028] The algorithm of the present invention presents a novel approach to the interpretation of MxA and CRP for the differential diagnosis between viral and bacterial infections.

[0029] Both biomarkers MxA and CRP are quantitatively measured and then used to calculate the probability of bacterial infection, with the results interpreted taking into account the ratio of MxA to CRP.

[0030] According to the algorithm of the present invention, a combination of MxA and CRP can safely distinguish between viral infection and bacterial infection.

[0031] The algorithm of the present invention can calculate the infection probability using an equation that includes MxA and CRP values.

[0032] According to the approach of the present invention, the overall sensitivity and overall NPV for bacterial infection are greater than 90%.

[0033] Figure 1 is an example of a domestically registered patent for diagnosis of existing viral and bacterial infections.

[0034] Figure 2 is an example of a US registered patent for diagnosis of existing viral and bacterial infections.

[0035] Figure 3 is a classification diagram of patients according to the study of the present invention.

[0036] Figure 4 is a table showing the results of analyzing MxA and CRP measurements and actual patients according to the study of the present invention.

[0037] Figure 5 shows the results of blood MxA and CRP concentration analysis for viral infection (group b, 136 people) and bacterial infection (group c, 131 people) according to the study of the present invention.

[0038] Figure 6 shows the results of logistic regression analysis according to the study of the present invention.

[0039] Figure 7 is a receiver operating characteristics (ROC) curve of the probability value (p) for diagnosing bacterial infection.

[0040] Figure 8 is an ROC curve of the MxA / CRP ratio for the diagnosis of viral infection.

[0041] Figure 9 is a table that integrates the probability of bacterial infection (p) and the MxA / CRP ratio into one single diagnostic rule.

[0042] Figure 10 shows MxA and CRP values ​​for the diagnosis of bacterial and viral infections in the validation cohort.

[0043] Figure 11 is a table integrating the probability of bacterial infection (p) and the MxA / CRP ratio into a single diagnostic rule in the validation cohort.

[0044] Figure 12 shows the MxA and CRP diagnostic values ​​of patients with concurrent infection.

[0045] Figure 13 shows the MxA / CRP ratio for the diagnosis of negative outcomes.

[0046] The terminology used in this application is only used to describe specific embodiments and is not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly indicates otherwise. In this application, it should be understood that the terms "comprise" or "have" indicate the presence of a feature, number, step, operation, component, part, or combination thereof described in the specification, but do not preclude the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0047] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Terms defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and shall not be interpreted in an idealized or overly formal sense unless explicitly defined herein.

[0048] [Research Design]

[0049] This patent is based on a study conducted in the Department of Internal Medicine at a public hospital in Greece from July 2022 to February 2023.

[0050] This study is a substudy of the ACCESS and ImmunoSep clinical trials, which were approved by the Greek National Ethics Committee (1912 122 / 20 and 2 / 21) and the Greek National Agency for Medicines (1912 IS113 / 20 and IS008 / 21). Patients or their legal representatives provided written informed consent, and all patients who were screened for eligibility for both trials participated.

[0051] Enrolled patients must meet all inclusion criteria: a) male or female adult aged 18 years or older and b) clinical signs of infection; fever, cough, dyspnea, sore throat, headache, nasal congestion, or diarrhea.

[0052] Exclusion criteria included age <18 years, chronic oral or intravenous use of corticosteroids, known infection with human immunodeficiency virus, neutropenia, chronic anticytokine therapy, pregnancy, or breastfeeding.

[0053] Forty patients who did not meet any of the exclusion criteria and did not show signs of active infection were enrolled as a control group.

[0054] [Testing and Data Collection]

[0055] All study participants underwent a physical examination, including a review of current and past medical history.

[0056] Complete blood count (CBC), biochemistry, blood gases, and procalcitonin tests; chest X-ray, and high-resolution chest computed tomography if indicated; nasopharyngeal swab for SARS-COV-2 PCR testing, and upper and lower respiratory tract examinations using BioFire's FilmArray panels if indicated; urinalysis for Streptococcus pneumoniae and Legionella antigens using the BinaxNow assay, and stool toxin assay for Clostridioides difficile; and blood, sputum, or urine cultures.

[0057]

[0058] The Sequential Organ Failure Assessment (SOFA) score and Carlson's Coexistence Index (CCI) were calculated. Patients were followed for 28 days to assess their survival.

[0059] In parallel with routine blood sampling, 4 ml of venous whole blood was collected into one EDTA-coated tube (Vacutainer, Becton Dickinson, Cockeysville Md) and subjected to MxA / CRP test analysis.

[0060]

[0061] [MxA / CRP Test]

[0062] The MxA / CRP test uses a fluorescence lateral flow immunoassay system for the quantitative measurement of MxA and CRP in human blood.

[0063] The above immunoassay system is characterized in that a detector antibody binds to an antigen in a sample blood to form an antigen-antibody complex, which migrates to a nitrocellulose matrix and is captured by other antibodies immobilized on a test strip.

[0064] More antigens contained in a blood sample form more antigen-antibody complexes, which generate stronger fluorescent signals by the detector antibody, and the blood concentrations of MxA and CRP in the blood sample are quantitatively detected.

[0065] The above immunoassay system comprises a plurality of cartridge packages, each cartridge package comprising three components: a cartridge, a detector, and a dilution unit.

[0066] The above cartridge is composed of a membrane called a test strip, wherein the test line of the membrane contains anti-MxA antibodies and anti-CRP antibodies, the antigen line contains CRP Ag, and the control line contains chicken IgY.

[0067] The detector comprises microparticles comprising an anti-MxA-fluorescent complex, an anti-CRP-fluorescent binding pair, an anti-chicken Igy-fluorescent binding pair, and sodium azide as a preservative in phosphate buffered saline (PBS).

[0068] The above dilution also contains sodium azide as a preservative in phosphate buffered saline (PBS).

[0069] Preferably, the above-described immunoassay system can quantitatively measure MxA and CRP in a blood sample and display the blood concentrations of MxA and CRP in units of ng / ml and mg / L, respectively.

[0070] The detection range of the above immune measurement system is 10.0 to 300.0 ng / ml for MxA and 1.0 to 200.0 mg / L for CRP.

[0071]

[0072] [Clinical Assessment]

[0073] According to this patent, the patient's infection status can be determined as follows based on the blood concentration results of MxA and CRP.

[0074] (1) MxA ≥ 15.00 ng / mL

[0075] ① CRP < 10.00 mg / L: Viral infection

[0076] ② 10.00 < CRP < 20.00 mg / L: Low possibility of viral or bacterial infection

[0077] ③ 20.00 < CRP < 100.00 mg / L: Possibility of simultaneous infection with virus and bacteria

[0078] ④ CRP ≥ 100.00 mg / L: Very high possibility of viral and bacterial co-infection

[0079] (2) MxA < 15.00 ng / mL

[0080] ① 10.00 < CRP < 20.00 mg / L: Possible bacterial infection

[0081] ② 20.00 < CRP < 100.00 mg / L: Possible bacterial infection

[0082] ③ CRP ≥ 100.00 mg / L: High possibility of bacterial infection

[0083] ④ CRP < 10.00 mg / L: Non-infection

[0084]

[0085] According to the above judgment method, patients can be classified into the following seven categories.

[0086] a) Non-infected; Patients without infection

[0087] b) Viral-limited infection: Infection is limited to viruses, and no bacterial pathogens are found.

[0088] c) Bacterial-limited infection: Infection is limited to bacteria, and no viral pathogens are found.

[0089] d) Viral / bacterial co-infection: infection by both viruses and bacteria

[0090] e) High probability of viral infection: No viral pathogen has been found, but there is a high probability of viral infection.

[0091] f) High probability of bacterial infection: No bacterial pathogen was found, but there is a high probability of bacterial infection.

[0092] g) Limited viral infection and high possibility of bacterial co-infection: The infection is limited to a virus, and no bacterial pathogens are found, but there is a high possibility of bacterial co-infection.

[0093]

[0094] The main objective of this patent is to develop an algorithm that accurately classifies patients as having a viral infection, a bacterial infection or a co-infection using the blood levels and their ratios of two biomarkers MxA and CRP.

[0095]

[0096] Additionally, a secondary objective of this patent is to develop cutoffs for MxA, CRP and their ratios to provide early prognosis of adverse outcomes after 28 days from onset.

[0097]

[0098] [Statistical Analysis]

[0099] Qualitative variables are presented as frequencies and their 95% confidence intervals (CIs), and medians and their 95% CIs. Comparisons of qualitative variables between groups are performed using Fisher's test. Comparisons of quantitative variables between groups are performed using the Mann-Whitney U test after Bonferroni correction for multiple testing.

[0100]

[0101] Patients with viral and bacterial co-infection are the discovery cohort.

[0102] In these patients, two new approaches are followed: the probability of infection (p) and the MxA / CRP ratio.

[0103]

[0104] a) Diagnostic performance is determined by combining diagnostic cutoff values ​​for two biomarkers, MxA and CRP.

[0105] According to the embodiments of the present patent, the diagnostic cutoff values ​​are MxA (>15ng / ml) and CRP (>10mg / l).

[0106] b) Perform logistic regression analysis to generate an equation that defines the probability of bacterial infection (p).

[0107] c) Perform receiver operator characteristic (ROC) curve analysis using the Youden index to define the cutoff for the probability of having an optimal trade-off.

[0108] d) The area under the curve (AUC) and 95% Cls are calculated.

[0109] e) Calculate the ratio of MxA to CRP and display it as a ROC curve that provides the best trade-off for diagnosing viral infection.

[0110] f) Combine the two cutoffs for the probability of infection (p) and the MxA / CRP ratio into a final diagnostic rule for separating bacterial and viral infections.

[0111]

[0112] The final diagnostic rule is validated in a validation cohort.

[0113] In addition, the above cutoff applies to patients with viral / bacterial co-infection; and patients with a high probability of viral and bacterial co-infection.

[0114] Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) are calculated.

[0115] A p-value less than 0.05 is considered statistically significant.

[0116]

[0117] [Research Group]

[0118] A total of 537 patients were enrolled, and 40 uninfected patients (group a) were included in the control group.

[0119] The discovery cohort included 267 patients. 136 patients had a final viral infection, and 131 patients had a final bacterial infection (see Figure 3).

[0120] The remaining patients were studied in a validation cohort.

[0121] Overall, the mean age of patients was 68.1 years; 60.7% were male.

[0122] The average SOFA is 3.27 and the average CCI is 3.9.

[0123] Overall, the mortality rate after 28 days was 19.0%.

[0124]

[0125] Diagnostic Performance Using Biomarker Cutoffs for MxA and CRP

[0126]

[0127] In this patent, the diagnostic analysis of MxA and CRP is analyzed by a cartridge consisting of a test strip having anti-MxA antibody and anti-CRP antibody in the test line, CRP Ag in the antigen line, and chicken Igy in the test line.

[0128] The diagnostic performance of MxA and CRP is determined from all enrolled patients using the cutoff values ​​of the diagnostic kit analysis equipment.

[0129] The diagnostic performance of this patent for two biomarkers with diagnostic cutoff values ​​of MxA (>15ng / ml) and CRP (>10mg / l) is as follows.

[0130]

[0131] Among 189 patients with MxA blood levels above the cutoff value (≥15 ng / mL), 181 patients actually had limited viral infection, resulting in a PPV of 95.8%.

[0132] On the other hand, among the 78 patients with MxA blood levels below the cutoff value (<15 ng / mL), 32 were non-infected, resulting in an NPV of 41.0%.

[0133] And among the 227 patients who were actually positive, 181 were diagnosed positive in the test, so the sensitivity was 79.7%.

[0134] On the other hand, among the 40 patients who were actually negative, 32 patients were judged negative in the test, resulting in a specificity of 80.0% (see Figure 4A).

[0135] Among 160 patients with CRP blood levels above the cutoff value (≥10 mg / l), 146 patients actually had limited bacterial infection, resulting in a PPV of 91.3%.

[0136] On the other hand, among the 31 patients whose MxA blood levels were below the cutoff value (<10 mg / l), 26 were non-infected, resulting in an NPV of 83.9%.

[0137] And among the 151 patients who were actually positive, 146 were diagnosed positive in the test, so the sensitivity was 96.7%.

[0138] On the other hand, among the 40 patients who were actually negative, 26 patients were judged negative in the test, resulting in a specificity of 65.0% (see Figure 4B).

[0139]

[0140] [Analysis of primary endpoints]

[0141] Finally, a comparison was performed on 267 patients from the discovery cohort, defined as having a viral infection (group b, n=136) and a bacterial infection (group c, n=131).

[0142] MxA concentrations are very high in viral infections, and CRP shows high results in bacterial infections (Figure 5).

[0143] After logistic regression analysis, the following equation is generated to derive the probability of bacterial infection (p) value by taking the absolute values ​​of MxA and CRP.

[0144]

[0145] Figure 6 shows the results of a logistic regression analysis on the extent to which MxA and CRP affect the diagnosis of bacterial infection.

[0146] From the above analysis results, it can be seen that an increase in CRP indicates a bacterial infection, and an increase in MxA indicates a viral infection.

[0147]

[0148] The applicant generates the following equation from the above analysis results.

[0149] (Formula 1)

[0150]

[0151] P is the calculated probability of bacterial infection, and when (Equation 1) is transformed, another equation is derived as follows.

[0152] (Formula 2)

[0153]

[0154] Figure 7 is a receiver operating characteristics (ROC) curve of the probability value (p) for diagnosing bacterial infection.

[0155] The analysis is based on 267 patients with limited viral infections (n=136) and limited bacterial infections (n=131).

[0156]

[0157] The AUC (area under the curve) of the ROC curve is 0.92, and the 95% CIs (confidence intervals) are 0.88 to 0.95, which allows the diagnosis of bacterial infection to be established by clearly separating bacterial infection and viral infection with a value of ≥ 0.5 for the probability of bacterial infection (p).

[0158]

[0159] Figure 8 is an ROC curve of the MxA / CRP ratio for the diagnosis of viral infection.

[0160] The analysis is based on 267 patients with limited viral infections (n=136) and limited bacterial infections (n=131).

[0161]

[0162] The AUC (area under the curve) of the ROC curve is 0.90, and the 95% CIs (confidence intervals) are 0.87 to 0.94, allowing for a diagnosis by clearly separating bacterial and viral infections with a MxA / CRP ratio < 2 for viral infection.

[0163]

[0164] Then, the above bacterial infection probability (p) and the MxA / CRP ratio are integrated into a single diagnostic rule (see Figure 9).

[0165] Among 153 patients with a probability of bacterial infection (p) ≥ 0.5 and / or MxA / CRP < 2, 120 patients actually had a bacterial infection, resulting in a PPV of 78.4%.

[0166] In contrast, among 114 patients with a probability of bacterial infection (p) < 0.5 and / or MxA / CRP ≥ 2, 103 patients actually had a viral infection, resulting in an NPV of 90.4%.

[0167] And in fact, among the 131 patients with bacterial infection, 120 patients were judged to have a probability of infection (p) ≥ 0.5 and / or MxA / CRP < 2 in the test, so the sensitivity was 91.6%.

[0168] On the other hand, among the 136 patients with actual viral infection, 103 patients had probability (p) < 0.5 and / or MxA / CRP ≥ 2, resulting in a specificity of 75.7%.

[0169]

[0170] In the above diagnostic rule, an NPV of 90% or more is a very important result to not miss patients who need antibiotics.

[0171] In the validation cohort, MxA was higher in patients with a higher probability of viral infection, and CRP was higher in patients with a higher probability of bacterial infection.

[0172] Figure 10 shows MxA and CRP for the diagnosis of bacterial and viral infections in the validation cohort.

[0173] Blood concentrations of MxA and CRP in patients with a high probability of viral infection (n=11) and patients with a high probability of bacterial infection (n=128).

[0174]

[0175] When applying the cutoff developed in the discovery cohort, the sensitivity for bacterial infection was 89.1%, and the PPV for bacterial infection was 97.4%. However, the NPV for bacterial infection was 36.4%, which was lower than that in the discovery cohort (see Figure 11).

[0176]

[0177] Both MxA and CRP were elevated in patients with concurrent infection (Fig. 12).

[0178] Among 71 patients (group g) classified as having a clear viral infection and a high probability of bacterial co-infection, 46 (64.8%) were tested positive by the integrated diagnostic tool using probability (p) and MxA / CRP ratio.

[0179] This corresponds to 14 of 20 patients (70%) with confirmed viral / bacterial co-infection.

[0180]

[0181] Figure 13 shows the MxA / CRP ratio for the diagnosis of negative outcomes.

[0182] A) Comparison of MxA between survivors and non-survivors at 28 days. (p values ​​for comparisons are provided) MxA is lower in non-survivors than in survivors (A).

[0183] B) Comparison of CRP between survivors and non-survivors at 28 days. (p values ​​for comparisons are provided) CRP is higher in non-survivors (B).

[0184] C) ROC curve of MxA for predicting negative outcome, MxA / CRP ratio

[0185] The MxA / CRP ratio has a higher AUC of the ROC curve for predicting adverse outcome after 28 days (C).

[0186] D) Prognostic significance of an MxA / CRP ratio less than 0.15 in non-survivors after 28 days, analysis of 537 patients, 95% confidence interval for non-survivors with an MxA / CRP ratio less than 0.15 (odds ratio = 2.55)

[0187] An MxA / CRP ratio value less than 0.15 was associated with an NPV of 85.4% for the exclusion of mortality risk (D).

[0188] This patent can be used to accurately classify patients as having a viral infection, a bacterial infection or a co-infection using the blood levels and ratios of two biomarkers, MxA and CRP.

Claims

1. A diagnostic system for distinguishing between bacterial and viral infections using myxovirus resistance protein A and C-reactive protein, characterized in that a detector antibody binds to an antigen in a blood sample to form an antigen-antibody complex, and the antigen-antibody complex migrates to a nitrocellulose matrix and is captured by other antibodies fixed on a test strip, thereby quantitatively detecting the blood concentration of MxA and CRP in the blood sample.

2. In paragraph 1, A diagnostic system for distinguishing bacterial infection and viral infection using myxovirus resistance protein A and C-reactive protein, characterized in that the above-mentioned immune assay system comprises a plurality of cartridge packages, each cartridge package including a cartridge, a detector, and a dilution unit.

3. In paragraph 2, The above cartridge is composed of a membrane called a test strip, and the test line of the membrane contains anti-MxA antibody and anti-CRP antibody, the antigen line contains CRP Ag, and the control line contains chicken Igy. A diagnostic system for distinguishing between bacterial infection and viral infection using myxovirus resistance protein A and C-reactive protein.

4. In paragraph 2, A diagnostic system for distinguishing bacterial infection and viral infection using myxovirus resistance protein A and C-reactive protein, characterized in that the detector comprises microparticles comprising anti-MxA-fluorescent complex, anti-CRP-fluorescent binding pair, anti-chicken Igy-fluorescent binding pair, and sodium azide as a preservative in phosphate buffered saline (PBS).

5. In paragraph 2, A diagnostic system for distinguishing bacterial infection and viral infection using myxovirus resistance protein A and C-reactive protein, characterized in that the dilution portion contains sodium azide as a preservative in phosphate buffered saline (PBS).

6. In paragraph 1, A diagnostic system for distinguishing between bacterial and viral infections using myxovirus resistance protein A and C-reactive protein, characterized in that the blood concentrations of MxA and CRP in the blood sample are displayed as unit values ​​of ng / ml and mg / L, respectively.

7. In paragraph 1, A diagnostic system for distinguishing bacterial and viral infections using myxovirus resistance protein A and C-reactive protein, characterized by a detection range of 10.0 to 300.0 ng / ml for MxA and 1.0 to 200.0 mg / L for CRP.

8. In paragraph 1, A diagnostic system for distinguishing bacterial and viral infections using myxovirus resistance protein A and C-reactive protein, characterized by diagnostic cutoff values ​​of biomarkers MxA and CRP of 15 ng / ml and 10 mg / l, respectively.

9. In paragraph 1, A diagnostic system for distinguishing between bacterial and viral infections using myxovirus resistance protein A and C-reactive protein, characterized in that the absolute values ​​of biomarkers MxA and CRP can be used to derive the probability (p) value of bacterial infection through the following equation (1). (Formula 1) 10. In paragraph 1, A diagnostic system for distinguishing between bacterial and viral infections using myxovirus resistance protein A and C-reactive protein, characterized in that the absolute values ​​of biomarkers MxA and CRP can be used to derive the probability (p) value of bacterial infection through the following equation (2). (Formula 2) 11.a) A step of determining diagnostic performance by combining diagnostic cutoff values ​​for biomarkers MxA and CRP; b) performing logistic regression analysis to generate an equation that can define the probability of bacterial infection (p); c) performing receiver operator characteristic (ROC) curve analysis using the Youden index to define a probability cutoff with an optimal trade-off; d) Steps to calculate the area under the curve (AUC) and 95% Cls; e) calculating the MxA ratio for CRP and displaying it as a ROC curve providing the best trade-off for diagnosing viral infection; f) a step of combining the cutoff for the probability of bacterial infection (p) and the MxA / CRP ratio into a final diagnostic rule for separating between bacterial and viral infections; a diagnostic method for distinguishing between bacterial and viral infections using myxovirus resistance protein A and C-reactive protein; 12. In paragraph 11, A diagnostic method for distinguishing bacterial infection from viral infection using myxovirus resistance protein A and C-reactive protein, characterized in that the diagnostic cutoff values ​​for biomarkers MxA and CRP in step a) above are 15 ng / ml and 10 mg / l, respectively.

13. In paragraph 11, The equation generated in step b) above is a diagnostic method for distinguishing between bacterial infection and viral infection using myxovirus resistance protein A and C-reactive protein, characterized by the equation as shown below (Equation 1). (Formula 1) 14. In paragraph 11, The equation generated in step b) above is a diagnostic method for distinguishing between bacterial infection and viral infection using myxovirus resistance protein A and C-reactive protein, characterized by the equation as shown below (Equation 2). (Formula 2) 15. In paragraph 11, A diagnostic method for distinguishing between bacterial and viral infections using myxovirus resistance protein A and C-reactive protein, characterized in that the cutoff values ​​for the probability of bacterial infection (p) and the MxA / CRP ratio in step f) are 0.5 and 2.0, respectively.

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