A prospective study to identify preoperative serum parameters for spinal implant infection detected by sonication fluid culture.

PURPOSE: Low-virulent microorganisms identified on pedicle screws by sonication fluid culture (SFC) are an important cause of implant loosening. While sonication of explanted material improves the detection rate, the risk of contamination exists and no standardized diagnostic criteria for chronic low-grade spinal implant-related infection (CLGSII) are stablished. Besides, the role of serum C-reactive protein (CRP) and procalcitonin (PCT) in CLGSII has not been adequately investigated. METHODS: Blood samples were collected prior to implant removal. To increase sensitivity, the explanted screws were sonicated and processed separately. Patients exhibiting at least one positive SFC were classified in the infection group (loose criteria). To increase specificity, the strict criteria only considered multiple positive SFC (≥ 3 implants and/or ≥ 50% of explanted devices) as meaningful for CLGSII. Factors which might promote implant infection were also recorded. RESULTS: Thirty-six patients and 200 screws were included. Among them, 18 (50%) patients had any positive SFCs (loose criteria), whereas 11 (31%) patients fulfilled the strict criteria for CLGSII. Higher serum protein level was the most accurate marker for the preoperative detection of CLGSSI, exhibiting an area under the curve of 0.702 (loose criteria) and 0.819 (strict criteria) for the diagnosis of CLGSII. CRP only exhibited a modest accuracy, whereas PCT was not a reliable biomarker. Patient history (spinal trauma, ICU hospitalization and/or previous wound-related complications) increased the likelihood of CLGSII. CONCLUSION: Markers of systemic inflammation (serum protein level) and patient history should be employed to stratify preoperative risk of CLGSII and decide the best treatment strategy.

The Presence of PDL-1 on CD8+ Lymphocytes Is Linked to Survival in Neonatal Sepsis.

Sepsis is life-threatening organ dysfunction caused by a dysregulated host response to infection. Neonatal sepsis is the main cause of death in newborns, especially preterm infants. The pathogenesis of sepsis is based on a hyper-inflammatory syndrome combined with an immunosuppressive mechanism in sepsis. This study aimed to find critical parameters that are associated with the outcome of newborns with suspected sepsis. Understanding the association might have clinical relevance for immuno-monitoring, outcome prediction, and targeted therapy. Methods: A total of 210 newborn infants no older than 4 days with suspected sepsis at admission in Karaganda (Kazakhstan) were prospectively enrolled. Blood cultures were incubated, and pathogens in positive cultures were determined by MALDI-TOF. An immunological assay for blood cell components was conducted by flow cytometry with antibody cocktails. The diagnostic criteria for neonatal sepsis were identified by qualified neonatologists and included both clinical sepsis and/or positive blood culture. The analyzed infants were grouped into non-septic infants, surviving septic infants, and deceased septic infants. The results showed that deceased septic newborns had a lower level of CD8+ lymphocytes and higher PDL-1 expression in comparison with surviving septic newborns. PDL-1 expression on CD8+ T cells might play an immunosuppressive role during neonatal sepsis and might be used as a laboratory biomarker in the future.

Temporal Evolution of White Blood Cell Count and Differential: Reliable and Early Detection Markers for Surgical Site Infection Following Spinal Posterior Decompression Surgery.

Introduction: For early detection of surgical site infection (SSI) following spinal decompression surgery, we compared temporal changes in the values of laboratory markers that are not affected by operative parameters. Methods: The study included 302 patients, which were divided into an SSI group (patients who developed deep SSI) and a non-SSI group for analysis. We reviewed data on C-reactive protein level, total white blood cell (WBC) count, and WBC differential percentage and count before spinal decompression, on postoperative day 1, and on postoperative day 4. We identified laboratory markers that are not affected by operative parameters (operating time, intraoperative blood loss, and number of operative segments). Laboratory markers with a significant difference observed between the peak or nadir value and the value in the subsequent survey day were considered as an indicator of SSI. We examined the utility of each indicator by calculating sensitivity and specificity. Furthermore, we investigated the utility of the combination of all five indicators (wherein the recognition of one marker was considered positive). Results: Temporal changes in five laboratory markers were considered indicators of SSI. The changes from postoperative day 1 to postoperative day 4 were as follows: (1) increased WBC count (42% sensitivity, 88% specificity), (2) increased neutrophil percentage (25% sensitivity, 96% specificity), (3) increased neutrophil count (25% sensitivity, 94% specificity), (4) decreased lymphocyte percentage (25% sensitivity, 95% specificity), and (5) decreased lymphocyte count (25% sensitivity, 85% specificity). The combination of these five markers showed a 50% sensitivity, 81% specificity, and 0.65 AUC. Conclusions: Five markers were found to be reliable indicators of SSI following spinal decompression surgery because they were not affected by operative parameters. The combination of all five indicators had moderate sensitivity and high specificity. Therefore, this may be reliable and useful for the early detection of SSI.

Association of Transition of Laboratory Markers with Transition of Disease Activity in Psoriasis Patients Treated with Biologics.

BACKGROUND: Three categories of biologics-tumor necrosis factor (TNF) inhibitors, interleukin (IL) -17 inhibitors, and IL-23 inhibitors-are available for treatment of refractory psoriasis. Recent studies have shown that laboratory biomarkers such as peripheral blood neutrophil-lymphocyte ratio (NLR), platelet-lymphocyte ratio (PLR), monocyte-lymphocyte ratio (MLR), and serum C-reactive protein (CRP) levels are associated with psoriasis or its severity. This study evaluated associations of transition of NLR, PLR, MLR, and CRP with transition of disease activity in psoriasis patients treated with the three categories of biologics. METHODS: Data from 67 patients were analyzed. Associations of transition of psoriasis area and severity index (PASI) score with the abovementioned laboratory markers were evaluated by using a mixed effects model with PASI as the response variable, laboratory markers as fixed effects collectively, and patients as random effects. RESULTS: In an analysis of all the patients, serum CRP and NLR were associated with PASI score (P=0.006 and P=0.001, respectively). In patients treated with TNF inhibitors, CRP and NLR were associated with PASI score (P=0.043 and P=0.002, respectively). In patients treated with IL-17 inhibitors, NLR was associated with PASI score (P=0.001). CONCLUSIONS: NLR appears to be the most reliable biomarker of the effect of treatment with biologics, especially IL-17 inhibitors.

suPAR cut-offs for stratification of low, medium, and high-risk acute medical patients in the emergency department.

BACKGROUND: Soluble urokinase plasminogen activator receptor (suPAR) levels have previously been associated with readmission and mortality in acute medical patients in the ED. However, no specific cut-offs for suPAR have been tested in this population. METHODS: Prospective observational study of consecutively included acute medical patients. Follow-up of mortality and readmission was carried out for 30- and 90 days stratified into baseline suPAR < 4, 4-6 and > 6 ng/ml. suPAR levels were measured using suPARnostic® Turbilatex assay on a Cobas c501 (Roche Diagnostics Ltd) analyser. RESULTS: A total of 1747 acute medical patients in the ED were included. Median age was 70 (IQR: 57-79) and 51.4% were men. Adjusted linear regression analysis showed that suPAR, independently of age, sex and C-reactive protein levels, predicted 30- and 90-day mortality (Odds ratio for doubling in suPAR 1.96 (95% confidence intervals: 1.42-2.70) Among patients with suPAR below 4 ng/ml (N = 804, 46.0%), 8 (1.0%) died within 90-day follow-up, resulting in a negative predictive value of 99.0% and a sensitivity of 94.6%. Altogether 514 (29.4%) patients had suPAR of 4-6 ng/ml, of whom 43 (8.4%) died during 90-day follow-up. Among patients with suPAR above 6 ng/ml (N = 429, 24.6%), 87 patients (20.3%) died within 90-day follow-up, resulting in a positive predictive value of 20.1% and a specificity of 78.7%. CONCLUSIONS: suPAR cut-offs of below 4, between 4 and 6 and above 6 ng/ml can identify acute medical patients who have low, medium or high risk of 30- and 90-day mortality. The turbidimetric assay provides suPAR results within 30 min that may aid in the decision of discharge or admission of acute medical patients.

Association study of transition of laboratory marker levels and transition of disease activity of atopic dermatitis patients treated with dupilumab.

BACKGROUND: Dupilumab, a fully human monoclonal antibody that blocks signalling pathways of interleukin (IL)-4 and IL-13, is effective in treating patients with atopic dermatitis (AD). We previously showed that transitions of serum thymus and activation-regulated chemokine (TARC) levels and eosinophil numbers were strongly associated with that of AD activity and that the transitions of serum lactate dehydrogenase (LDH) and immunoglobulin E (IgE) levels were weakly and not associated with that of AD activity, respectively, in patients treated without dupilumab. OBJECTIVES: The purpose of this study was to elucidate whether the association of the transition of laboratory marker levels and transition of disease activity in dupilumab-treated AD patients (present study) was different from that in patients who are not treated with dupilumab (previous study). METHODS: Sixty AD outpatients treated with dupilumab were included in this study. Associations between the transition of the eczema area and severity index (EASI) score and those of above-mentioned laboratory marker levels were evaluated using a mixed effects model of EASI as the response variable, laboratory markers as fixed effects and patients as random effects. RESULTS: The transitions of serum TARC and LDH levels were associated strongly with that of AD activity, but the transitions of serum IgE level and eosinophil numbers were associated with that of AD activity intermediately and weakly, respectively. CONCLUSIONS: Laboratory markers are useful for evaluating the effects of treatments for AD, but the meaning of each laboratory marker depends on the drugs used for treatment.

Utility of Symptom Duration and C-Reactive Protein, White Blood Cell Count, and Absolute Neutrophil Count in the Evaluation of Pediatric Appendicitis.

BACKGROUND: Appendicitis is a common pediatric surgical emergency, and the diagnosis may be delayed or missed because of nonspecific findings in children. Not all patients with abdominal pain need to be imaged for appendicitis, and laboratory evaluation may improve diagnostic accuracy in this population. OBJECTIVE: To determine if C-reactive protein (CRP) and symptom duration could be used to improve diagnosis of appendicitis compared with white blood cell count (WBC) and absolute neutrophil count (ANC). METHODS: This was a retrospective chart review from June 2017 to 2019 at our tertiary academic children's hospital. A consecutive sample of all children <18 years of age being evaluated for appendicitis who had magnetic resonance imaging ordered were included. The diagnostic accuracy of WBC, ANC, and CRP were compared for patients with symptom duration ≤1 day compared with symptom duration for >1 day. RESULTS: Five hundred thirty-nine patients were identified. The sensitivity and specificity of WBC (10,000 cells/µL) was 87.1% and 65.2%, respectively; ANC (7,500 cells/µL) was 86.5% and 70.8%, respectively; and CRP (0.5 mg/dL) were 73.7% and 58.1%, respectively. At >1 day of symptom duration, the specificity of WBC and ANC increased to 74.9% and 80.9%, respectively, and the sensitivity of CRP increased to 88.9%. Three patients with appendicitis (2.8%) had no laboratory abnormalities. CONCLUSIONS: No laboratory test studied has adequate characteristics to be used alone. CRP adds minimal sensitivity beyond WBC and ANC when symptoms are >1 day but with poor specificity, making it of limited utility.

[Laboratory evaluation of immunological dysfunctions in primary immunodeficiency diseases]. / Immunológiai eltérések kimutatása laboratóriumi módszerekkel primer immunhiányos betegségekben.

In primary immunodeficiencies, the malfunction of the immune system is caused by genetic alterations. The physician proposes the most probable diagnosis based on symptoms, clinical signs, the family history and the results of the pathogen identification. To confirm this clinical suspicion, it is essential that the immunological malfunction be tested using in vitro diagnostic procedures. This paper summarizes the screening, confirmatory and disease-specific laboratory methods capable of testing the antibody response, the T cells, the phagocytic function, the complement system and other components of the innate immune system. The genetic tests necessary to make the final diagnosis are beyond the scope of this publication. Orv Hetil. 2018; 159(49): 2087-2094.

Useful laboratory markers for the diagnosis of bone marrow involvement by malignant lymphoma.

INTRODUCTION: This study aimed to investigate the effect of bone marrow involvement by malignant lymphoma (BMI) on laboratory data and to determine the useful laboratory markers for diagnosing BMI. METHODS: We compared laboratory data between patients with and without BMI. We performed multivariate logistic regression and receiver operating characteristic (ROC) analyses to evaluate the diagnostic values of independent predictors. RESULTS: In the BMI group, platelets in peripheral blood (PLT) and megakaryocyte count in bone marrow (MgK) were significantly lower than those in the non-BMI group (PLT, P < .0001; MgK, P = .0384). The rate of peripheral blood involvement by malignant lymphoma (PBI), red blood cell distribution width (RDW), D-dimer (DD), soluble interleukin-2 receptor (sIL2R), aspartate aminotransferase (AST), and lactate dehydrogenase (LDH) was significantly higher in the BMI group than in the non-BMI group (PBI, P < .0001; RDW, P = .0190; DD, P = .0006; sIL2R, P < .0001; AST, P = .0256; LDH, P = .0002). In multivariate analysis, PBI, PLT, sIL2R, and MgK levels were independent predictors of BMI. CONCLUSION: PBI, PLT, sIL2R, and MgK may be the useful laboratory markers for BMI diagnosis.

The Significance of Neutrophil-to-Lymphocyte Ratio and Platelet-to-Lymphocyte Ratio as Markers for Prognosis in Idiopathic Sudden Sensorineural Hearing Loss / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: The cause of idiopathic sudden sensorineural hearing loss (ISSNHL) is still unclear, but recently, chronic inflammation and thrombosis have received attention. The neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR) are some of the markers that show the state of inflammation and ischemia, which are measured routinely in the complete blood cell count (CBC) test. The aim of this study were to investigate the relevance of NLR and PLR with ISSNHL. SUBJECTS AND METHOD: Enrolled in our retrospective analysis were 103 patients diagnosed with ISSNHL. Blood samples were taken from the patients and hearing assessments were performed. NLR and PLR were calculated using the CBC results. Then the patients were divided into 4 groups using Sigel's criteria according to their response to the treatment, which were again classified two groups, the “recovered” and “unrecovered” group. RESULTS: NLR, PLR, and neutrophil values of the unrecovered group were significantly higher than the recovered group (p=0.002, p=0.009, and p=0.038, respectively). On the other hand, lymphocyte values were significantly higher in the recovered group (p=0.007). After adjustment in a multivariate logistic regression analysis, NLR was associated with the recovery of ISSNHL (Odds ratio=1.290, p=0.042). In addition, NLR and PLR values were also significantly different between the groups classified by the Sigel's criteria (p=0.009 and p=0.029, respectively). CONCLUSION: PLR values may be useful in predicting hearing recovery after treatment in patients with ISSNH. It is also expected to be a potential marker for predicting the prognosis and determining further treatment options.

Prognostic Index Model for Progression-Free Survival in Chemotherapy-Naïve Metastatic Castration-Resistant Prostate Cancer Treated With Abiraterone Acetate Plus Prednisone.

BACKGROUND: Radiographic progression-free survival (rPFS) is associated with overall survival (OS) in chemotherapy-naïve metastatic castration-resistant prostate cancer (mCRPC) patients. Using readily assessable baseline clinical and laboratory parameters, we developed a prognostic index model for rPFS in chemotherapy-naïve mCRPC patients without visceral disease who were treated with abiraterone acetate plus prednisone. METHODS: Data from the abiraterone acetate plus prednisone arm of COU-AA-302 were used. rPFS was defined based on modified Prostate Cancer Working Group 2 criteria. Baseline variables were assessed for association with rPFS through univariate Cox modeling. The lower (LLN) and upper (ULN) limits of laboratory normal were used to dichotomize most laboratory parameters; baseline median was used to dichotomize prostate-specific antigen (PSA). Prognostic factors for rPFS were identified by multivariate Cox modeling. Model accuracy was estimated by the C-index. RESULTS: Presence of lymph node metastasis (hazard ratio [HR] = 1.76, P < .0001), lactate dehydrogenase > ULN (234 IU/L) (HR = 1.71, P = .0001), ≥ 10 bone metastases (HR = 1.71, P = .0015), hemoglobin ≤ LLN (12.7 g/dL) (HR = 1.47, P = .0030) and PSA > 39.5 ng/mL (HR = 1.42, P = .0078) were associated with poor outcome. Patients were categorized into 3 prognostic groups (good, n = 230; intermediate, n = 152; poor, n = 164) based on number of risk factors. Median rPFS was calculated (27.6, 16.6, and 8.3 months for good, intermediate, and poor, respectively). The C-index was 0.83 (95% confidence interval = 0.73-0.91). CONCLUSIONS: The prognostic index model for rPFS reveals differential outcomes based on factors readily available in clinical practice. If validated, this model can be integrated into clinical practice and design of risk-stratified trials.

Lymphopenia and Elevated Blood C-Reactive Protein Levels at Four Days Postoperatively Are Useful Markers for Early Detection of Surgical Site Infection Following Posterior Lumbar Instrumentation Surgery.

STUDY DESIGN: Case-control study. PURPOSE: To identify the characteristics of candidate indexes for early detection of surgical site infection (SSI). OVERVIEW OF LITERATURE: SSI is a serious complication of spinal instrumentation surgery. Early diagnosis and treatment are crucial for the welfare of the patient postoperation. METHODS: We retrospectively reviewed laboratory data of patients who underwent posterior lumbar instrumentation surgery for degenerative spine disease. The sensitivity and specificity of six laboratory markers for early detection of SSI were calculated: greater elevation of the white blood cell count at day 7 than at day 4 postoperatively, greater elevation of the C-reactive protein (CRP) level at day 7 than at day 4 postoperatively, a CRP level of >10 mg/dL at 4 days postoperatively, neutrophil percentage of >75% at 4 days postoperatively, a lymphocyte percentage of <10% at 4 days postoperatively, and a lymphocyte count of <1,000/µL at 4 days postoperatively. Statistical analysis was via Fisher's exact test and a p-value of <0.05 was considered significant. RESULTS: In total, 85 patients were enrolled. Of these, five patients developed deep SSI. The sensitivity and specificity of each index were as follows: index 1, 20.0% and 77.5%; index 2, 20.0% and 83.8%; index 3, 40.0% and 97.5%; index 4, 40.0% and 86.3%; index 5, 0% and 96.3%; and index 6, 80.0% and 80.0%. A significant difference was noted for indexes 3 and 6. CONCLUSIONS: A CRP level of >10 mg/dL at 4 days postoperatively would be useful for definitive diagnosis of SSI, and a lymphocyte count of <1,000/µL at 4 days postoperatively would be a useful screening test for SSI. Although laboratory markers for early detection of SSI have been frequently reported, we believe that it is important to understand the characteristics of each index for a precise diagnosis.

Activated factor VII-antithrombin complex predicts mortality in patients with stable coronary artery disease: a cohort study.

BACKGROUND: Plasma concentration of activated factor VII (FVIIa)-antithrombin (AT) complex has been proposed as an indicator of intravascular exposure of tissue factor. OBJECTIVES: The aims of this observational study were to evaluate (i) FVIIa-AT plasma concentration in subjects with or without coronary artery disease (CAD) and (ii) its association with mortality in a prospective cohort of patients with CAD. METHODS: FVIIa-AT levels were measured by elisa in 686 subjects with (n = 546) or without (n = 140) angiographically proven CAD. Subjects with acute coronary syndromes and those taking anticoagulant drugs at the time of enrollment were excluded. CAD patients were followed for total and cardiovascular mortality. RESULTS: There was no difference in FVIIa-AT levels between CAD (84.8 with 95% confidence interval [CI] 80.6-88.2 pmol L(-1) ) and CAD-free subjects (83.9 with 95% CI 76.7-92.8 pmol L(-1) ). Within the CAD population, during a 64-month median follow-up, patients with FVIIa-AT levels higher than the median value at baseline (≥ 79 pmol L(-1) ) had a two-fold greater risk of both total and cardiovascular mortality. Results were confirmed after adjustment for sex, age, the other predictors of mortality (hazard ratio for total mortality: 2.05 with 95% CI 1.22-3.45, hazard ratio for cardiovascular mortality 1.94 with 95% CI 1.01-3.73, with a slight improvement of C-statistic over traditional risk factors), FVIIa levels, drug therapy at discharge, and even patients using all the usual medications for CAD treatment. High FVIIa-AT levels also correlated with increased thrombin generation. CONCLUSIONS: This preliminary study suggests that plasma concentration of FVIIa-AT is a thrombophilic marker of total and cardiovascular mortality risk in patients with clinically stable CAD.

Diagnostic accuracy and prognostic utility of D Dimer in acute appendicitis in children.

UNLABELLED: The objective was to determine the uselfulness of D Dimer (DD) as a diagnostic or prognostic marker in acute appendicitis (AA) in children using a prospective observational study in the pediatric emergency department of a tertiary hospital. We enrolled 135 patients aged 1-16 years presenting with abdominal pain consistent with AA, who required laboratory studies. We analyzed clinical, analytical variables and histopathology findings (when they underwent surgery). Statistical analysis was conducted using SPSS. 38.5% of the children were clinically diagnosed with AA (n = 52), confirmed by pathology in 51 patients. 55.8% were gangrenous appendicitis. Leucocyte count, C-reactive protein (CRP), and DD were higher in the AA group and in the gangrenous appendicitis group (p < 0.05), with highest values of DD in the gangrenous group. The area under the receiving operating characteristics (ROC) curve for DD in the diagnosis of AA is 0.66 (95% CI 0.56-0.75). For DD cut-off point of 230 ng/mL, sensitivity (Se) was 0.40, specificity (Sp) 0.80, positive predictive value (PPV) 0.57, and negative predictive value (NPV) 0.66. The area under the ROC curve for DD in children with gangrenous appendicitis is 0.93 (95% CI 0.87-1). A DD cut-off point of 230 ng/mL exhibited: Se = 0.69, Sp = 1, PPV = 1 and NPV = 0.72. CONCLUSION: DD levels increase in patients with AA. Although it does not constitute a useful diagnostic marker, it could be a good prognostic marker.

Lymphopenia and Elevated Blood C-Reactive Protein Levels at Four Days Postoperatively Are Useful Markers for Early Detection of Surgical Site Infection Following Posterior Lumbar Instrumentation Surgery

STUDY DESIGN: Case-control study. PURPOSE: To identify the characteristics of candidate indexes for early detection of surgical site infection (SSI). OVERVIEW OF LITERATURE: SSI is a serious complication of spinal instrumentation surgery. Early diagnosis and treatment are crucial for the welfare of the patient postoperation. METHODS: We retrospectively reviewed laboratory data of patients who underwent posterior lumbar instrumentation surgery for degenerative spine disease. The sensitivity and specificity of six laboratory markers for early detection of SSI were calculated: greater elevation of the white blood cell count at day 7 than at day 4 postoperatively, greater elevation of the C-reactive protein (CRP) level at day 7 than at day 4 postoperatively, a CRP level of >10 mg/dL at 4 days postoperatively, neutrophil percentage of >75% at 4 days postoperatively, a lymphocyte percentage of 10 mg/dL at 4 days postoperatively would be useful for definitive diagnosis of SSI, and a lymphocyte count of <1,000/µL at 4 days postoperatively would be a useful screening test for SSI. Although laboratory markers for early detection of SSI have been frequently reported, we believe that it is important to understand the characteristics of each index for a precise diagnosis.

Lymphopenia and Elevated Blood C-Reactive Protein Levels at Four Days Postoperatively Are Useful Markers for Early Detection of Surgical Site Infection Following Posterior Lumbar Instrumentation Surgery

STUDY DESIGN: Case-control study. PURPOSE: To identify the characteristics of candidate indexes for early detection of surgical site infection (SSI). OVERVIEW OF LITERATURE: SSI is a serious complication of spinal instrumentation surgery. Early diagnosis and treatment are crucial for the welfare of the patient postoperation. METHODS: We retrospectively reviewed laboratory data of patients who underwent posterior lumbar instrumentation surgery for degenerative spine disease. The sensitivity and specificity of six laboratory markers for early detection of SSI were calculated: greater elevation of the white blood cell count at day 7 than at day 4 postoperatively, greater elevation of the C-reactive protein (CRP) level at day 7 than at day 4 postoperatively, a CRP level of >10 mg/dL at 4 days postoperatively, neutrophil percentage of >75% at 4 days postoperatively, a lymphocyte percentage of 10 mg/dL at 4 days postoperatively would be useful for definitive diagnosis of SSI, and a lymphocyte count of <1,000/µL at 4 days postoperatively would be a useful screening test for SSI. Although laboratory markers for early detection of SSI have been frequently reported, we believe that it is important to understand the characteristics of each index for a precise diagnosis.

Serum interleukin 8 level as a diagnostic marker in late neonatal sepsis.

OBJECTIVE: Late-onset sepsis is responsible for high morbidity and mortality in newborn infants in the world and in particular in developing countries. In this study, we evaluated whether clinical characteristics, laboratory parameters and measurements of serum interleukin-8 (IL-8) are able to discriminate between late neonatal sepsis and normal baby. METHODS: This was a prospective (case-control) study conducted between March 2007 and April 2008, at the neonatal intensive care unit, Ghaem Hospital, Mashhad, Iran. The study comprised 93 neonates ≥72 hours of life. The infants were categorized in two groups based on the clinical presentation, and biochemical markers including complete blood count, C-reactive protein (CRP) and blood culture: 1) Control group including 42 infants with routine screening and 2) Case group consisting of 38 infants with definitive infection (positive blood and/or cerebrospinal fluid culture) or clinical sepsis (clinical and laboratory signs of infection without positive blood or CSF culture). Receiver-operating characteristic curves were used for the determination of thresholds for the infection group versus healthy neonate group. FINDINGS: Eighty infants were enrolled in this study. IL-8 and CRP decreased in order of definitive infection, clinical sepsis and healthy subjects respectively (P<0.001). Sensitivity, specificity, positive predictive value, negative predictive value for serum levels were 0.95, 0.1, 0.97, 0.1 for IL-8 and 0.83, 0.86, 0.83, 0.69 for CRP respectively (cut-off point for IL-8 >60pg/ml and for CRP>6mg/dl). CONCLUSION: IL-8 may be a valid and early predictive marker of neonatal infection. Also, IL-8 is associated with severity of infection.