Neutrophil to lymphocyte count ratio as a biomarker of bacterial infections

Clinical evaluation of a fully electronic microfluidic white blood cell analyzer

The White Blood Cell (WBC) count is one of the key parameters signaling the health of the immune system. Abnormal WBC counts often signal a systemic insult to the body such as an underlying infection or an adverse side effect to medication. Typically, the blood collected is sent to a central lab for testing, and results come back within hours, which is often inconvenient and may delay time-sensitive diagnosis or treatment. Here, we present the CytoTracker, a fully electronic, microfluidic based instant WBC analyzer with the potential to be used at point-of-care. The CytoTracker is a lightweight, portable, affordable platform capable of quantifying WBCs within minutes using only 50 μl of blood (approximately one drop of blood). In this study, we clinically evaluated the accuracy and performance of CytoTracker in measuring WBC and granulocyte counts. A total of 210 adult patients were recruited in the study. We validated the CytoTracker against a standard benchtop analyzer (Horiba Point of Care Hematology Analyzer, ABX Micros 60). Linear dynamic ranges of 2.5 k/μl- 35 k/μl and 0.6 k/μl- 26 k/μl were achieved for total WBC count and granulocyte count with correlation coefficients of 0.97 and 0.98. In addition, we verified CytoTracker's capability of identifying abnormal blood counts with above 90% sensitivity and specificity. The promising results of this clinical validation study demonstrate the potential for the use of the CytoTracker as a reliable and accurate point-of-care WBC analyzer.

Neutrophil-to-lymphocyte ratio is associated with 28-day mortality in patients with severe fever with thrombocytopenia syndrome

Objectives

To determine the association of the neutrophil-to-lymphocyte ratio (NLR) with 28-day mortality in patients with severe fever with thrombocytopenia syndrome (SFTS).

Methods

A single-centre retrospective analysis was performed in an emergency department from January 01, 2018, to June 30, 2021. Univariate and multivariable Cox proportional hazards regression models were used to investigate the prognostic factors associated with 28-day mortality. Kaplan–Meier curves were analysed in patients stratified by the optimal cut-off point of the NLR determined using a receiver operating characteristic (ROC) curve.

Results

In total, 182 SFTS patients were included, and 24 (13.2%) died within 28 days. The median age of the included patients was 59.64 ± 12.74 years, and 48.4% (88/182) were male. The patients in the non-survival group had significantly higher NLRs than those in the survival group (6.91 ± 6.73 vs. 2.23 ± 1.83). The NLR was a significant predictor of 28-day mortality (adjusted HR: 1.121, 95% CI: 1.033, 1.215). The area under the ROC curve of the NLR for predicting 28-day mortality was 0.743 (95% CI: 0.624, 0.862), and the optimal cut-off value was 4.19 (sensitivity, 54.2%; specificity, 89.2%). In addition, 28-day mortality in the patients with an NLR ≥ 4.19 was notably higher than that in the patients with an NLR < 4.19 (43.3% vs. 7.2%), and Kaplan–Meier analysis showed that the patients with an NLR ≥ 4.19 had a significantly lower survival rate than those with an NLR < 4.19.

Conclusions

The NLR was a significant, independent predictor of 28-day mortality in SFTS patients.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-022-07206-8.

Neutrophil to Lymphocyte Ratio (NLR)—A Useful Tool for the Prognosis of Sepsis in the ICU

Sepsis is a life-threatening medical emergency induced by the body′s extreme response to an infection. Despite well-defined and constantly updated criteria for diagnosing sepsis, it is still underdiagnosed worldwide. Among various markers studied over time, the neutrophil to lymphocyte ratio (NLR) recently emerged as a good marker to predict sepsis severity. Our study was a single-center prospective observational study performed in our ICU and included 114 patients admitted for sepsis or septic shock. Neutrophil to lymphocyte ratio (NLR) is easy to perform, CBC being one of the standard blood tests routinely performed upon admission for all ICU patients. We found that NLR was increased in all patients with sepsis and significantly raised in those with septic shock. NLR correlates significantly with sepsis severity evaluated by the SOFA score (R = 0.65) and also with extensively studied sepsis prognosis marker presepsin (R = 0.56). Additionally, NLR showed good sensitivity (47%) and specificity (78%) with AUC = 0.631 (p < 0.05). NLR is less expensive and easier to perform compared with other specific markers and may potentially become a good alternate option for evaluation of sepsis severity. Larger studies are needed in the future to demonstrate the prognosis value of NLR.

The Dynamical Assessment of Inflammatory Biomarkers in Predicting the Outcome of Septic Patients and the Response to Antimicrobial Therapy

Aims

To evaluate the kinetics of inflammatory biomarkers in septic patients in order to identify the most reliable predictor of unfavorable outcome.

Methods

A prospective analysis of septic patients was performed. Median levels of neutrophil/lymphocyte count ratio, fibrinogen, C-reactive protein and procalcitonin were dynamically assessed and comparatively analyzed.

Results

Seventy-seven patients were included. Descendent kinetic patterns were registered for all biomarkers, except C-reactive protein. At 24 hours, neutrophil/lymphocyte count ratio significantly decreased in 42.85% of cases, procalcitonin in 37.33%, C-reactive protein in 16.12% and fibrinogen in 1.58% of cases. At 72 hours, procalcitonin decreased to one-half in 70% of cases and neutrophil/lymphocyte count ratio in 67.53% of cases.

Conclusions

Neutrophil/lymphocyte count ratio and procalcitonin significantly decreased in the first 72 hours, while C-reactive protein increased in the first 24 hours. The proportions of patients with major decrease of baseline values were higher for neutrophil/lymphocyte count ratio and procalcitonin.

Association Between Rapid Antigen Testing and Antibiotic Use and Accuracy of Peripheral Blood Parameters in Detecting Group A Streptococcus in Children With Tonsillopharyngitis

Objectives: To investigate the effect of rapid antigen testing (RAT) on the practice of antibiotic prescription as well as the accuracy of peripheral blood neutrophil-to-lymphocyte ratio (NLR) and C-reactive protein (CRP) values in detecting group A beta-hemolytic Streptococcus (GABHS) in children with tonsillopharyngitis. Methods: In a multicenter study performed in Turkey, we retrospectively analyzed data from 668 consecutive pediatric patients under 17 years of age, who presented with signs and symptoms of tonsillopharyngitis and underwent RAT. The rates of positive and negative RAT results were determined and patients' antibiotic prescriptions were examined in relation to RAT results. In addition, the accuracy of peripheral blood NLR and CRP values was examined for 212 patients whose laboratory data were available, with RAT as the reference standard. Results: Positive RAT results were observed in 190 of 668 (28.4%) patients. Antibiotics were prescribed to all 190 patients with positive RAT results and to 8 of 478 patients with negative RAT results. Overall, the rate of antibiotic prescription was 29.6%. Patients with positive and negative RAT results did not differ significantly with regard to NLR and CRP values. In ROC analysis, the area under the ROC curve (AUC) of NLR and CRP were 0.54 (95% confidence interval [CI] 0.45-0.64), and 0.55 (95% CI 0.45-0.65), respectively. Conclusion: RAT results proved highly associated with antibiotic prescribing, suggesting that RATs could be of great value in preventing unnecessary antibiotic use. Our findings also suggest that NLR and CRP are poorly accurate to identify GABHS in children with tonsillopharyngitis.