Volume 54, Issue 5

Rapid transmission, high morbidity, and mortality are the features of human infectious diseases caused by microorganisms, such as bacteria, fungi, and viruses. These diseases may lead within a short period of time to great personal and property losses, especially in regions where sanitation is poor. Thus, rapid diagnoses are vital for the prevention and therapeutic intervention of human infectious diseases. Several conventional methods are often used to diagnose infectious diseases, e.g. methods based on cultures or morphology, or biochemical tests based on metabonomics. Although traditional methods are considered gold standards and are used most frequently, they are laborious, time consuming, and tedious and cannot meet the demand for rapid diagnoses. Disease diagnosis using capillary electrophoresis methods has the advantages of high efficiency, high throughput, and high speed, and coupled with the different nucleic acid detection strategies overcomes the drawbacks of traditional identification methods, precluding many types of false positive and negative results. Therefore, this review focuses on the application of capillary electrophoresis based on nucleic detection to the diagnosis of human infectious diseases, and offers an introduction to the limitations, advantages, and future developments of this approach.

The postmenopausal phase of life is frequently associated in women with subjective symptoms (e.g. vasomotor) and real diseases (atherosclerosis with coronary ischemia, osteoporosis, Alzheimer-type neurodegeneration, urogenital dystrophy), which together determine the post-menopausal syndrome. Observations that oxidative damage by reactive oxygen/nitrogen species in experimental models can contribute to the pathogenesis of these disturbances stimulated research on the relationships between menopause, its endocrine deficiency, oxidative balance and the “wellness” in postmenopausal life. The connection among these events is probably due to the loss of protective actions exerted by estrogens during the fertile life. Most recent studies have revealed that estrogens exert an antioxidant action not by direct chemical neutralization of reactants as it was expected until recently but by modulating the expression of antioxidant enzymes that control levels of biological reducing agents. Also nutritional antioxidants apparently act by a similar mechanism. From this perspective it is conceivable that a cumulative control of body oxidant challenges and biological defenses could help in monitoring between “normal” and “pathological” menopause. However, as clinical studies failed to confirm this scenario in vivo, we have decided to review the existing literature to understand the causes of this discrepancy and whether this was due to methodologic reasons or to real failure of the basic hypothesis.

The selection or procurement of blood collection devices in healthcare facilities is often an underestimated issue. This is probably due to different factors including the lack of knowledge of policymakers, hospital administrators and even laboratory managers about the importance of preanalytical quality and phlebotomy process, as well as to the absence of reliable guidelines or recommendations on how to precisely assess the quality of blood collection devices around the globe. With the awareness that a gap remains between manufacturers’ and local validation of blood collection devices, the Working Group for Preanalytical Phase (WG-PRE) of the European Federation of Clinical Chemistry and Laboratory Medicine (EFLM) has drafted a consensus document aimed to provide a set of essential requisites, technical criteria (e.g. presence of physical defects, malfunctioning, safety problems) and clinical issues for supporting laboratory professionals in organization blood collection tubes tenders and validating new devices before local routine implementation. The laboratory professionals should also make sure that the tenders accurately and strictly define the responsibilities for validation experiments and the potential consequences in the case the validation outcome shows that tubes due not fulfill the expectations.

Background: Molecular technologies have allowed laboratories to detect and establish the profiles of human cancers by identifying a variety of somatic variants. In order to improve personalized patient care, we have established a next-generation sequencing (NGS) test to screen for somatic variants in primary or advanced cancers. In this study, we describe the laboratory quality management program for NGS testing, and also provide an overview of the somatic variants identified in over 1000 patient samples as well as their implications in clinical practice. Methods: Over the past one-and-a-half years, our laboratory received a total of 1028 formalin-fixed, paraffin-embedded (FFPE) tumor tissues, which consisted of non-small-cell lung carcinomas (NSCLCs), colon adenocarcinomas, glioma/glioblastomas, melanomas, breast carcinomas, and other tumor types. During this time period, we implemented a series of quality control (QC) checks that included (1) pre-DNA extraction, (2) DNA quantification, (3) DNA quality, (4) library quantification, (5) post-emulsification PCR, and (6) post-sequencing metrics. At least 10 ng of genomic DNA (gDNA) were used to prepare barcoded libraries using the AmpliSeq CHPv2. Samples were multiplexed and sequenced on Ion Torrent 318 chips using the Ion PGM System. Variants were identified using the Variant Caller Plugin, and annotation and functional predictions were performed using the Golden Helix SVS. Results: A total of 1005 samples passed QC1–3, and following additional library preparation QC checkpoints, 877 samples were sequenced. Samples were classified into two categories: wild-type (127) and positive for somatic variants (750). Somatic variants were classified into clinically actionable (60%) and non-actionable (40%). Conclusions: The use of NGS in routine clinical laboratory practice allowed for the detection of tumor profiles that are essential for the selection of targeted therapies and identification of applicable clinical trials, contributing to the improvement of personalized patient care in oncology.

Background: Charcot-Marie-Tooth type 1A (CMT1A) is the most common type of hereditary motor and sensory neuropathies (HMSN), caused by the duplication of the 17p11.2 region that includes the PMP22 gene. Reciprocal deletion of the same region is the main cause of hereditary neuropathy with liability to pressure palsies (HNPP). CMT1A accounts for approximately 50% of HMSN patients. Diagnostics of CMT1A and HNPP are based on quantitative analysis of the affected region or RFLP detection of breakage points. The aim of this study was to improve the sensitivity and efficiency of CMT1A and HNPP genetic diagnostics by introducing analysis of six STR markers ( D17S261-D17S122-D17S839-D17S1358-D17S955-D17S921 ) spanning the duplicated region. Methods: Forty-six CMT1A and seven HNPP patients, all genetically diagnosed by RFLP analysis, were tested for duplication or deletion using six STR markers. Results: In all CMT1A and HNPP patients, microsatellite analysis comprising six STR markers confirmed the existence of a duplication or deletion. In 89% (41/46) CMT1A patients the confirmation was based on detecting three alleles on at least one locus. In the remaining 11% (5) CMT1A patients, duplication was also confirmed based on two peaks with clear dosage difference for at least two different markers. All HNPP patients (7/7) displayed only one allele for each analyzed locus. Conclusions: Microsatellite analysis using six selected STR loci showed a high level of sensitivity and specificity for genetic diagnostics of CMT1A and HNPP. The results here strongly suggest STR marker analysis as a method of choice in PMP22 duplication/deletion testing.

Background: Haptoglobin is an acute-phase binding protein that scavenges free hemoglobin. The human haptoglobin gene ( HP ) is polymorphic with two main alleles, haptoglobin allele 1 (Hp1) and haptoglobin allele 2 (Hp2). The smaller Hp1 allele features no duplication and consists of four exons, whereas the larger Hp2 allele, containing a 1.7 kb duplication, consists of six exons, with the fifth and sixth being highly homologous to exons 3 and 4 of Hp1. Methods: We designed an exonuclease (TaqMan) assay targeting single nucleotide differences between the homologous regions of Hp1 and Hp2. The assay contained one probe specifically binding to a site in intron 4 of Hp2, and another probe binding equally to intron 4 of Hp1 and intron 6 of Hp2. Results: Measurement of post-PCR fluorescence allowed unambiguous discrimination of HP genotypes. Comparison with genotypes obtained by a method based upon allele-specific primers yielded fully corresponding results. Conclusions: The new HP genotyping method is fast, reliable, does not require real-time instruments and may be especially useful for high-throughput genotyping.

Background: Pneumatic tube transportation (PTT) may induce hemolysis (H) in blood samples. We aimed to compare the H degree before and after PTT implementation in our hospital. Methods: Hemolysis indices (HI) for all lithium-heparin plasma samples (P) drawn by the Emergency Department in 2-month periods were retrospectively collected and pre- (n=3579) and post-PTT (n=3469) results compared. The impact of PTT introduction was investigated on LDH [HI threshold (HIt), 25], conjugated bilirubin (cBIL) (HIt, 30), K (HIt, 100) and ALT (HIt, 125). In addition, HI retrieved for P and paired serum samples collected in silica clot activator tubes (S) from the same venipuncture were compared in pre- (n=501) and post-PTT (n=509) periods. Results: Median (5–95th percentile) HI in P was significantly higher in post-PTT period [7 (0–112) vs. 6 (0–82), p<0.001]. Results reported as ‘Hemolysis’ in P increased from 6.6% in pre-PTT to 9.4% in post-PTT (p<0.001). Investigated tests gave the following rejection rates (pre-PTT vs. post-PTT): LDH, 13.4% vs. 18.8%, p<0.001; cBIL, 9.4% vs. 27.0%, p<0.05; K, 3.7% vs. 5.6%, p<0.001; ALT, 2.9% vs. 4.4%, p<0.01. The slightly higher susceptibility to H of S compared to paired P found in the pre-PTT [9 (1–64) vs. 6 (0–85)] was not confirmed in the post-PTT period [7 (0–90) vs. 8 (1–72)], in which median HI in S was significantly lower (p<0.001) than in pre-PTT. Conclusions: In our setting PTT promotes H in P, increasing the rate of rejected tests. The use of S appears to protect against the hemolysing effect of PTT.

Background: Vitamin D deficiency is an important concern in clinical settings although there is no consensus on who should undergo 25-OH-vitamin D testing. We studied the prevalence of vitamin D deficiency before and after introducing adequacy (clinical and biochemical) criteria for testing. Methods: A total of 32,363 tests for 25-OH-vitamin D were retrospectively evaluated. Requests were unrestricted until December 2010 and justification criteria were applied from January 2011. During 6 years, 25,656 samples were analyzed (UHPLC) of which 12,315 were considered the first visit. The prevalence of deficiency was assessed for all the samples and according to the year, sex, season, age, origin of the requests, inclusion of adequacy criteria and consecutive visits. Results: A significant proportion of the requests (25%) were unjustified and less than half of the clinically or biochemically-justified tests displayed serum concentrations indicative of deficiency. Application of adequacy criteria resulted in a non-significant increase in the prevalence of deficiency, both at the first visit (36.5 vs. 41.7, p=0.17) and for all the samples analyzed (32.0 vs. 35.5, p=0.14). The percentage of deficiency decreased in consecutive visits although 2/3 and 41% of the patients remained deficient on the second and third visit, respectively. Moreover, at least 1/5 of sufficient patients at the first test became deficient in subsequent evaluations. Conclusions: A significant proportion of the requests was unjustified by clinical or biochemical criteria. Our data also indicate that clinical and biochemical criteria may be necessary (to be present) to justify vitamin D testing but not sufficient (predictive) to indicate the presence of vitamin D deficiency.

Background: Cell-derived microparticles (MPs) are important biomarkers in many facets of medicine. However, the MP detection methods used till date are costly and time consuming. The main aim of this study was to standardize an in-house clot based screening method for MP detection which would not only be specific and sensitive, but also inexpensive. Methods: Four different methods of MP assessment were performed and the results correlated. Using the flow cytometry technique as the gold standard, 25 samples with normal phosphatidylserine (PS) expressing MP levels and 25 samples with elevated levels were selected, which was cross checked by the commercial STA Procoag PPL clotting time (CT) assay. A simple recalcification time and an in-house clot assay were the remaining two tests. The in-house test measures the CT after the addition of calcium chloride to MP rich plasma, following incubation with Russell viper venom and phospholipid free plasma. Results: The CT obtained by the in-house assay significantly correlated with the results obtained by flow cytometry (R 2 =0.87, p<0.01). Conclusions: Though preliminary, the in-house assay seems to be efficient, inexpensive and promising. It could definitely be utilized routinely for procoagulant MP assessment in various clinical settings.

Background: Laboratory investigation with specific factor XIII (FXIII) assays plays a crucial role in diagnosis of FXIII deficiency. According to the International Society on Thrombosis and Hemostasis (ISTH), it is necessary a blank sample with iodoacetamide, provided by the kit or locally prepared, when the ammonia release assays are used, to avoid FXIII activity overestimation. Methods: In this study we set up a modification of the Berichrom FXIII chromogenic assay, in which iodoacetamide was added by the BCS analyzer in the reaction mixture of the blank sample, without modifications of the original reagents. We analyzed 100 plasma samples of outpatients with clinical symptoms suggestive of a bleeding diathesis (20 samples had FXIII activity <20%). Results: In all samples blank subtraction significantly reduced FXIII activity, mostly in the low activity range group (from 10.1% to 2.4%, p<0.0001). In this group correction with iodoacetamide also increased the agreement with the immunoassay and allowed FXIII activity measure up to 0%. Conclusions: Despite the low number of samples included in the study, the described automatic procedure seemed to decrease FXIII activity overestimation and, especially for low activity range samples (<20%), to improve the agreement between FXIII activity and concentration. Our data suggested that iodoacetamide correction could allow the detection of severe FXIII deficiencies (activity <5%) otherwise undiagnosed using the original method.

Background: Dysregulation of the adrenal cortex has been assessed with measurement of salivary cortisol. So far salivary cortisol is routinely measured with immunoassay (IA). However, liquid chromatography-tandem mass spectrometry (MS) is known to offer better specificity. We compared the concentrations of salivary cortisol measured by MS and IA at basal and stress induced conditions and evaluated reasons for the difference in method-dependent cortisol results. Methods: Saliva samples (n=2703) were collected from 169 children (age range: 8–14 years; 81 healthy children; 55 with internalizing and 33 with externalizing disorders) under circadian conditions and during the Trier Social Stress Test for Children (TSST-C). Biochemical analyses were performed with MS for cortisol and cortisone, IA (IBL, RE62011) for cortisol, and enzyme kinetic assay for α-amylase. Results: MS and IA showed mostly comparable results for circadian activity and TSST-C response with similar statistical power. However, IA measured cortisol concentrations about 2.39-fold higher than MS. We found that this difference in measured values between MS and IA was mainly due to different standardization of IA compared to MS. In addition, at cortisol IA concentration below 5 nmol/L, cross-reactivity with cortisone was found to contribute to the lower concordance between MS and IA. Conclusions: Immunoassay and LC-MS/MS were largely comparable in the interpretation of salivary cortisol dynamics in stress research. But the IA method revealed a restricted accuracy in the measuring range below 5 nmol/L.

Background: Monitoring of plasma drug levels is mandatory in patients receiving high-dose methotrexate. This study evaluated the analytical performance of the novel Architect and the established ARK™ methotrexate immunoassay (running on the Roche Cobas © c502 analyzer) in comparison with liquid chromatography-mass spectrometry (LC-MS) and the TDx/TDxFLx Methotrexate II assay. Methods: Imprecision and linearity were verified for the Architect and ARK assay according to CLSI EP15-A3 and EP6-A guidelines, respectively. The reported limit of quantitation (0.04 μmol/L) was tested for both assays according to the CLSI EP17-A2 guideline. Correlation and agreement between the different assays were evaluated using residual plasma samples (n=153). Results: Total imprecision was <6.3% and <9.5% for the Architect and ARK assay, respectively. The claimed linearity and limit of quantitation were confirmed for the Architect assay. For the ARK assay, imprecision at the limit of quantitation was <18% with a positive bias resulting in a high total error up to 58%, and hence the linearity could not be confirmed. Both assays showed strong correlations with the TDX assay and LC-MS but a positive bias of 12.2% and 20.5% in comparison to LC-MS for the Architect and ARK assay, respectively. For the ARK assay this bias increased dramatically for samples with concentrations towards the limit of quantitation. Conclusions: The Architect assay is suitable for monitoring plasma methotrexate, but the ARK assay showed unsatisfactory performance in the analysis of low concentrated samples. Unlike the TDX assay, both assays require manual dilution of samples at higher concentrations, which delays sample processing in clinical routine.

Background: Traumatic brain injury management is a tricky issue in children and pregnant women (due to adverse effects of computer tomography). To facilitate management, we report the main analytical performances and reference ranges for blood tests for the well-established S100B biomarker in under-16 children on a DiaSorin ® Liaison XL analyzer and in pregnant women on DiaSorin ® Liaison XL and Roche Diagnostics ® Cobas e411 analyzers. Methods: Serum S100B concentrations were determined by chemiluminescent immunoassay on a DiaSorin ® analyzer in a population of 409 healthy children aged 0–16 years and on DiaSorin ® /Roche Diagnostics ® instruments in a population of 50 pregnant women (one blood sample for each trimester). The analytical performances of both instruments and the influence of blood cells and skin pigmentation on the assay were also studied. Results: For children, four age-groups emerged, i.e. 0–3 months (mean: 0.97 μg/L; standard deviation (SD): 0.36; 95th percentile: 1.55), 4–9 months (mean: 0.58 μg/L; SD: 0.30; 95th: 1.18), 10–24 months (mean: 0.31 μg/L; SD: 0.12; 95th: 0.54) and 2–16 years (mean: 0.20 μg/L; SD: 0.07; 95th: 0.32). For pregnant women, serum S100B concentrations were similar to defined ranges for adults and not significantly different between trimesters on DiaSorin ® (p=0.652)/Roche Diagnostics ® (p=0.877) analyzers. We also found S100B expression (protein, total mRNA) in lymphocytes, an influence of skin pigmentation, and good analytical performances for both instruments. Conclusions: Data provided here is useful for interpreting serum S100B test results, in terms of preanalytical conditions, analytical performances, pediatric and pregnancy’ environment.

Background: This study is a part of the IFCC-global study to derive reference intervals (RIs) for 28 chemistry analytes in Saudis. Method: Healthy individuals (n=826) aged ≥18 years were recruited using the global study protocol. All specimens were measured using an Architect analyzer. RIs were derived by both parametric and non-parametric methods for comparative purpose. The need for secondary exclusion of reference values based on latent abnormal values exclusion (LAVE) method was examined. The magnitude of variation attributable to gender, ages and regions was calculated by the standard deviation ratio (SDR). Sources of variations: age, BMI, physical exercise and smoking levels were investigated by using the multiple regression analysis. Results: SDRs for gender, age and regional differences were significant for 14, 8 and 2 analytes, respectively. BMI-related changes in test results were noted conspicuously for CRP. For some metabolic related parameters the ranges of RIs by non-parametric method were wider than by the parametric method and RIs derived using the LAVE method were significantly different than those without it. RIs were derived with and without gender partition (BMI, drugs and supplements were considered). Conclusions: RIs applicable to Saudis were established for the majority of chemistry analytes, whereas gender, regional and age RI partitioning was required for some analytes. The elevated upper limits of metabolic analytes reflects the existence of high prevalence of metabolic syndrome in Saudi population.

Background: Most of the factors causing preanalytical and analytical variation in ammonia measurement have been identified. Biological variation data for ammonia is still lacking. We therefore estimated the components of biological variation (within-subject=CV I and between-subject=CV G ), reference change value (RCV) and quality specifications for ammonia in a group of healthy individuals using fresh and frozen plasma samples. Methods: Blood samples from 20 healthy subjects were collected in K2EDTA tubes daily over a period of 4 consecutive days from each subject. Each plasma sample was split into two aliquots; one was immediately analyzed as the samples were collected and the other was stored –80 °C until testing at the end of the collection period and analyzed at once in one analytical run. All samples were analyzed in duplicate. Estimations were calculated according to Fraser and Harris methods. Results: CV I value for fresh samples (13.78%) was significantly lower than that in frozen samples (18.91%) (p<0.001). However, there was no statistically significant difference in CV G values between fresh (16.91%) and frozen (18.43%) samples (p=0.570). The index of individuality did not exceed 1.4 for fresh and frozen samples. The estimated RCVs were high for both fresh and frozen samples (43.37% and 56.85%, respectively). Quality specifications were established. Conclusions: The present study for the first time described the components of biological variation for ammonia in healthy individuals. These data regarding biological variation of ammonia could be useful for a better evaluation of ammonia test results in clinical interpretation and for determining quality specifications based on biological variation.

Background: Hypermethylation of DLX4 (distal-less homeobox 4) has been disclosed in a variety of cancers. Our work was aimed to examine the pattern of DLX4 methylation and further investigate its clinical relevance in patients with myelodysplastic syndrome (MDS). Methods: Real-time quantitative methylation-specific PCR and bisulfite sequencing PCR were carried out to detect the level of DLX4 methylation. Clinical significance of DLX4 methylation was analyzed between the DLX4 hypermethylated and non-hypermethylated patients. Results: DLX4 was significantly hypermethylated in MDS patients than controls (p<0.001). No significant differences were observed between the hypermethylated and non-hypermethylated MDS patients in white blood cells, platelets, age, WHO classifications, FAB classifications, IPSS risks, and common gene mutations (p>0.05). However, DLX4 hypermethylated patients tended to have higher hemoglobin (HB) than DLX4 non-hypermethylated patients (p=0.079). Moreover, there was a trend that male patients, poor karyotype patients, and IPSS Int-2/High patients had a higher frequency of DLX4 hypermethylation (p=0.067, 0.065, and 0.068). DLX4 hypermethylated patients had significantly shorter overall survival than DLX4 non-hypermethylated patients (p=0.004). Multivariate analysis confirmed the prognostic value of DLX4 methylation in MDS patients (p<0.001). Conclusions: Our study indicated that DLX4 hypermethylation was a frequent event and acted as an independent prognostic biomarker in de novo MDS patients.

Background: Individuals who reach exceptional longevity (100+ years of age) free of common chronic age diseases (i.e. ‘dodgers’) arguably represent the paradigm of successful aging in humans. As such, identification of potential biomarkers associated with this phenomenon is of medical interest. Methods: We measured serum levels of galectin-3 and osteopontin, both of which have been shown to be linked with major chronic or aging-related disorders in younger populations, in centenarian ‘dodgers’ (n=81; 40 men; 100–104 years) and healthy controls (n=41; 24 men, 70–80 years). Results: Both biomarkers showed significantly lower values (p<0.001) in the former (galectin-3: 2.4±1.7 vs. 4.8±2.8 ng/mL; osteopontin: 38.1±27.7 vs. 72.6±33.1 μg/mL). Logistic regression analysis identified the combination of these two biomarkers as a significant predictor variable associated with successful aging regardless of sex (p<0.001). The area under the curve (AUC) classified the ability of galectin-3 and osteopontin to predict the likelihood of successful aging as ‘fair’ (AUC=0.75) and ‘good’ (AUC=0.80), respectively. Particularly, the combination of the two biomarkers showed good discriminatory power for successful aging (AUC=0.86), with sensitivity=83% and specificity=74%. Conclusions: Lower levels of both galectin-3 and osteopontin are associated with successful aging, representing potential biomarkers of this condition. Our cross-sectional data must be however approached with caution. Further research is necessary to replicate the present preliminary results in other cohorts and to identify the potential use of galectin-3 and osteopontin as potential targets (or at least predictors) in future personalized anti-aging therapies.

Background: Platelet volume indices (PVI), an easy and inexpensive surrogate measure of platelet function, have been associated with cardiovascular diseases (CVD) and their risk factors. However, results are conflicting because of the lack of standardized procedures. The purpose of this study is to investigate the relationship of PVI with the Framingham risk score (FRS). Methods: Baseline data (2008–2010) of 3115 participants enrolled in the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil) were used. PVI measurements were strictly controlled. The cohort was distributed according to risk factors and the general FRS was estimated. Multiple linear regression analysis was used to estimate the association between PVI and FRS. Results: Mean platelet volume (MPV), platelet distribution width (PDW) and platelet large cell ratio (P-LCR) independently correlated (p≤0.01) with FRS after adjustment for confounding variables. One unit increase in MPV, PDW, or P-LCR increased the FRS by 0.59%, 0.40%, and 0.08%, respectively. Diabetics had higher (p≤0.004) MPV, PDW, and P-LCR, and hypertensive individuals had higher (p≤0.045) PDW and P-LCR. Conclusions: Increased PVI was independently correlated with higher CVD risk based on the FRS, diabetes, and systolic hypertension. Prospective follow up of this cohort is warranted to confirm that PVI is associated with the development of CVD.

Background: Ventilator-associated pneumonia (VAP) is one of the most common nosocomial infections; however, its diagnosis remains difficult to establish in the critical care setting. We investigated the potential role of neutrophil CD64 (nCD64) expression as an early marker for the diagnosis of VAP. Methods: Forty-nine consecutive patients with clinically suspected VAP were prospectively included in a single-center study. The levels of nCD64, C-reactive protein (CRP), and serum procalcitonin (PCT) were analyzed for diagnostic evaluation at the time of intubation (baseline), at day 0 (time of diagnosis), and at day 3. The receiver operating characteristic curves were analyzed to identify the ideal cutoff values. Results: VAP was confirmed in 36 of 49 cases. In patients with and without VAP, the median levels (interquartile range, IQR) of nCD64 did not differ either at baseline [2.4 (IQR, 1.8–3.1) and 2.6 (IQR, 2.3–3.2), respectively; p=0.3] or at day 0 [2 (IQR, 2.5–3.0) and 2.6 (IQR, 2.4–2.9), respectively; p=0.8]. CRP showed the largest area under the curve (AUC) at day 3. The optimum cutoff value for CRP according to the maximum Youden index was 133 mg/dL. This cutoff value had 69% sensitivity and 76% specificity for predicting VAP; the AUC was 0.73 (95% CI, 0.59–0.85). The nCD64 and PCT values could not discriminate between the VAP and non-VAP groups either at day 0 or day 3. Conclusions: The results of this pilot study suggest that neutrophil CD64 measurement has a poor role in facilitating the diagnosis of VAP and thus may not be practically recommended to guide the administration of antibiotics when VAP is suspected.