COMPARISON OF THE ACCURACY OF NEUTROPHIL CD 64 VERSUS C-REACTIVE PROTEIN AS A TEST FOR THE EARLY DETECTION OF NEONATAL SEPSIS

COMPARISON OF THE ACCURACY OF NEUTROPHIL CD 64 VERSUS C-REACTIVE PROTEIN AS A TEST FOR THE EARLY DETECTION OF NEONATAL SEPSIS

By

Hassan Saad Abu Saif*, Khaled Mahmoud Zayed*,

Mosallam Hamed Yousef** and Mohamed Sobhi Abd Elaziz*

Departments of  Pediatrics* and Clinical Pathology**, Faculty of  Medicine, Al-Azhar University

ABSTRACT

Background: Early identification of neonatal infection is, however, a major diagnostic problem due to presence of non specific clinical signs and limitation of current diagnostic procedures.

Objective: Making a comparison of the accuracy of neutrophil cluster of differentiation 64 (CD 64) versus
C -  reactive  protein (CRP) as a single test for the early detection of neonatal sepsis.

Patients and Methods: A prospective study enrolled newborns with proved sepsis (n=64) and control newborn (no=32). CRP, neutrophil CD64, complete blood count and blood culture were taken at the time of suspected sepsis for proved sepsis and at the time of venipuncture for labortary tests in control newborns. Neutrophil CD64 was analyzed by flowcytometry.

Results: CD64 significantly elevated in the groups with proved sepsis  ,whereas CRP did not significantly increase in comparison with controls.  CD64 and CRP have sensitivity 85.9 % and 48.7 %, specificity 78.1% and 71.9%, positive predictive value of 88.7%and 77.5% and negative predictive value 73.5% and 41.1 % respectively.

The area under the receiver operating characteristic curves for CD64 and CRP were 0.83 and 0.48  respectively .

            Conclusion: CD64 expression on neutrophils increased significantly in neonates with neonatal sepsis. CD64 was a more specific marker for neonatal sepsis than CRP as shown by area under the curve (AUC)

Key words   : Neutrophil CD64, C-reactive protein, neonatal sepsis.

INTRODUCTION

     Infection is one of most important causes of neonatal mortality. Early identification of neonatal infection is however a major diagnostic problem particularly in preterm and low-birth weight infants due to presence of non specific clinical signs and limitation of current diagnostic procedures (Prashant et al., 2013).

    Neonatal sepsis is classified into early -onset form (EONS) within the first 72 hours of life and late – onest form (LONS) afterwards ( Stoll et al., 2011).

    The current gold standard for confirming diagnosis of neonatal sepsis is blood culture. However, blood culture results are not available for 48 hours after starting the culture, and if blood cultures are drawn after administration of antibiotics, growth of microorganisms can be suppressed. Hence, a reliable inflammatory marker or set of markers is required for prompt and accurate identification of neonatal sepsis (Icardi et al., 2009).

     C-reactive protein (CRP) is a conven-tional inflammatory marker as a kind of acute phase protein. Concentrations of CRP increase at around 24 hours after onset of infection, peak between 36 and 50 hours and remain elevated throughout infection (Batlivala et al ., 2009).

     Neutrophil CD64,  know as fc - gamma receptor 1(FcγRI),  neutrophil CD64 has high affinity to the  Fc  portion of immunoglobulin G (IgG) and is expressed and upregulated by bacterial or endotoxin interaction. Upregulation of CD64 is considered to be very early step of the host's immune response to bacterial infection, increasing approximately one hour after invasion ( Livaditi  et al ., 2010).

The present work aimed to compare between accuracy of neutrophil CD 64 and C – reactive protein as a test for the early detection of neonatal sepsis.

PATIENTS AND METHODS

     The study was carried on ninety six newborns with the approval of the ethical committee of neonatal intensive care unit and parents of the neonates. They met all inclusion and exclusion criteria for enrollment into this study. They were divided into 2 groups.

     Group 1 included 64 neonates with proved sepsis

    Group 2 included 32 apparent healthy neonates

Inclusion criteria: Gestational age (30-42) weeks, and birth weight > 1. 2 kg

Exclusion  criteria: Presence of any congenital anomaly and presence of  surgical  problem 

      All newborns were subjected tocomprehensive history taking, clinical examination and laboratory  investigations  (CBC and analysis of neutrophil CD64)

Statistical analysis: Data were collected and tabulated. Mean and standard deviation (SD) or median and interquartile range (IQR) were estimates of quantitative data, while frequency and percentage were estimates of qualitative data. Differences in clinical and biochemical characteristics were tested by Student’s t test for quantitative data and by chi-square test for non-parametric (qualitative) data. A two-sided P value <0.05 was considered statistically significant.

RESULTS

    There was a highly significant difference between case and control as regard prematurity and low birth weight. No significant difference between case and control as regard sex and mode of the delivery (Table 1).

Table (1): Distribution of the studied groups according to sex, gestational age, birth weight and mode of delivery.

      There was a significant comparison between neutrophil CD64 and CRP with gestational age and birth weight. No significant comparison between CD64 and CRP with sex (Table 2).

Table(2): Comparison between CD64 and CRP with sex, gestational age and birth weight in our studied cases.

There was a highly significant comparison between CD64 and CRP with staff  % , I: T ratio, lymphocyte, monocyte and  platelet . No significant comparison between CD64 and CRP with WBCs, mature and esinophils (Table 3).

Table(3): Comparison between CD64 and CRP with complete blood count in our studied cases.

     There were  significant higher levels of CD64 and CRP than control group (Table 4).

Table (4):  Differences between   cases and control group in the mean level CD64 and CRP

     There was a highly significant higher sensitivity and specificity of CD64 than CRP (Table 5).

Table (5): Sensitivity and specificity of CD64 and CRP

DISCUSSION

     The diagnosis of sepsis remains one of the most difficult tasks for physicians and other medical staff. Blood cultures often remain negative in the presence of pneumonia, meningitis and even fulminant blood born septicemia. A rapid laboratory test with high specificity for neonatal sepsis would be a valuable tool in therapeutic decision making (Baranda et al., 2010).

    This rapid  upregulation of CD64 expression on the PMNs  is a true indication of the current status of neonatal sepsis. Thus, neutrophil CD64 expression should provide improved diagnostic detection of sepsis compared with the standard diagnostic tests (Dilli and Dilmen, 2010).

    In this work, ninty six cases of neonates were admitted to the NICU of Al Glaa teaching Hospital and subgrouped into sixty four cases proven as neonatal sepsis and thirty two cases as a control group. All neonatal sepsis patients were diagnosed according to clinical signs, laboratory and radiological criteria.

     Prematurity and PROM more than 18 hours, were the most important risk factor of neonatal sepsis in which study accounted for (79.5%) and (45.3%) of studied cases. This agreed with ( Ng et al,. 2009) who have reported that PROM more than 18 hours is a strong risk factor for neonatal sepsis.

     In this study, we found that positive history of maternal fever was present in about 10.9% of studied cases due to maternal infections. This agreed with (Fjaertoft et al., 2010) who had noted that maternal fever due to maternal infections like chorioamnionitis and urinary tract infection accounts for 20% of neonatal sepsis cases.

     In this study, the most common organisms isolated from proven septic neonates were staph. auerus (46.88%), E.coli (28.13%), strept epidermidis (6.25%), pseudomonus (12.5%), and Klebsilla (6.25%). Stoll et al. (2011) showed that 25% of all episodes of EONS were caused by Klebsiella and E coli (17.5%), Staphylococcus aureus (18%), GBS (7%), Acinetobacter and  pseudomo-nas (12%).

     Abd El Haleim et al. (2012) found that the most commonly isolated micro-organisms from blood were CONS (45%), where gram negative bacilli including E.coli, Klebsiella and Enterobacterspp represented 18% of isolated microorga-nisms.

     In this study, about 90.6% of cases were preterm with GA less than 37 weeks, and about 82.8% of cases were LBW with birth weight < 2500 grams. This was agreement  with (Stoll, 2010) who stated that the majority of cases of early onset sepsis had a gestational age < 30 weeks, and a birth weight < 1500 g.

     A high statistical significant difference was shown between studied cases and controls as regards staff cell, I/T ratio, CRP and platelets count. This agreed with a study done by Khair et al. (2010)  who found that sepsis episodes were characterized by significantly higher white blood cell counts, and immature/total neutrophil ratios, compared with nonseptic episodes, as well as lower platelet counts.

     In this study, the mean CD64 expression in neonates with sepsis was significantly higher than those in the control group. These findings were in agreement with a previous study done by Dilli and Dilmen (2010) and a study by Streimish et al. (2013) who showed raised percentages of CD64+ cells in proven sepsis groups.

     In this work, ROC curve showed area under the curve (accuracy) for CD64 greater than area under the curve (accuracy) for CRP, AUC for CD64 =0.83, while for CRP =0.48. This implied the greater discriminating power for CD64 over CRP for early detection of neonatal sepsis.

     In this study, we found 85.9% sensitivity and 78.1% specificity for CD64 expression. On the other hand, Ng and his Colleagues (2009) showed very high sensitivity and specificity for CD64 in neonatal sepsis (about 97% and 89%, respectively).

REFERENCES

1. Abd El Haleim M, Nawar N and Abd Al Rahman M (2012): Epidemiologic and Micro-bacteriologic Study of Neonatal Septicaemia in Cairo University Neonatal Intensive Care Units. Research Journal of Medicine and Medical Sciences, 4(1): 67-77.

2. Baranda L, Layseca-Espinosa E, Perez-Gonzalez LF and Rosenstein Y (2010): Expression of CD64 as a potential marker of neonatal sepsis. Pediatr Allergy Immunol., 13:319-27.

3. Batlivala SP and Focus on diagnosis (2009): The erythrocyte sedimentation rate and the C-reactive protein test. Pediatr Rev., 30:72–74.

4. Dilli D and Dilmen U (2010): CD64 expression compared with CRP in early diagnosis of neonatal sepsis. J Clin Lab Anal., 24(6):363-70.

5. Fjaertoft G, Pauksen K, Hankansson L, Xu S and Venge P (2010): Cell surface expression of CD64 on neutrophils and monocytes in patients with influenza A with or without complications. Scand J Infect Dis., 37 (11-12): 882-9.

6. Icardi M, Erickson Y, Kilborn S, Stewart B, Grief B and Scharnweber G (2009): CD64 index provides simple and predictive testing for detection and monitoring of sepsis and bacterial infection in hospital patients. J Clin Microbiol., 47:3914–3919.

7. Khair K, Rahman M and Sultan T (2010):  Hematologic profile in Early Diagnosis of Neonatal Septicemia. BSMMU J., 3(2): 62-67.

8. Livaditi O, Kotanidou A,  Psarra A, Dimopoulou I, Sotiropoulou C and Augustatou K  (2010): Neutrophil CD64 expression and serum IL-8: sensitive early markers of severity and outcome in sepsis. Cytokine, 36 (5-6): 283-90.

9. Ng PC, Li G, Chui KM, Chu WC, Li K and Wong RP (2009): Neutrophil CD64 is a sensitive diagnostic marker for early-onset neonatal infection. Pediatr Res., 56 (5): 796-803.

10. Prashant A, Vishwanath P and Kulkarni P (2013): Diagnostic markers for neonatal sepsis. Curr Opin Pediatr., 18(2):125-31.

11. Stoll BJ (2010): Neonatal infections. A global  perspective. In: Infectious diseases of the fetus and newborn infant. By: Remington JS, Klein JO (eds), 3rd edition, Pbiladelphia, WB Saunders, PP. 27-57.

12. Stoll BJ, Hansen NI and Sanchez PJ (2011): early onset neonatal sepsis: the burden of group B streptococcal and E. coli disease continues.  Pediatrics, 127(5): 817-826.

13. Streimish I, Bizzaro M, Northrup V and Wang C (2013): Neutrophil CD64 with hematologic Criteria for Diagnosis of Neonatal Sepsis. Am J Perinatol., 119 (3):45-49.