Renata Zrinski Topić

Interferon-γ release assay for the diagnosis of latent tuberculosis in children younger than 5 years of age.

Background: There are limited data available on interferon-&ggr; release assay (IGRA) performance in children up to 5 years of age, with documented exposure to active tuberculosis (TB). The aim of this study was to evaluate (1) the influence of infectivity of adult source cases on test results, (2) the impact of age, and (3) the level of agreement, between IGRA and tuberculin skin test (TST) results. Methods: A total of 142 Bacille Calmette-Guerin-vaccinated children up to 5 years of age were investigated because of a history of exposure to active TB. QuantiFERON-TB Gold In-Tube IGRA (QFT) and TST assays were performed. Results: Test results were significantly influenced by positive finding of cavitary lesions (QFT, odds ratio [OR] = 6.15; TST, OR = 7.48) and positive acid-fast bacilli (QFT, OR = 4.01; TST, OR = 4.47) in active TB contacts. QFT resulted in 1 indeterminate response (0.7%), attributable to low mitogen. There was no evidence for age having any effect on QFT performance. The 2 tests showed a moderate overall concordance (89%; &kgr; = 0.591) at a TST cutoff value of ≥10 mm. Conclusions: Association of positive QFT and TST results with risk factors for infection in child contacts (presence of cavitary lesions and acid-fast bacilli smear positivity in index cases) suggests that both the tests have good diagnostic accuracy. However, there was significant discord between results of the 2 tests that could not be definitively resolved. Thus, in a high-risk population of children up to 5 years of age, both tests (QFT and TST) should be performed and the child should be considered infected if either or both tests are positive.

Serial interferon‐γ release assay in children with latent tuberculosis infection and children with tuberculosis

Interferon‐γ (IFN‐γ) release assay (IGRA) is used for diagnosis of latent tuberculosis infection (LTBI), and for serial testing of active tuberculosis (TB). The aim of this study was to evaluate the results of IGRA for diagnosis and treatment monitoring of children with LTBI and children with TB. IGRA was performed in BCG vaccinated children before and six months after the beginning of treatment.

Eosinophil catonic protein – current concepts and controversies

Eosinophil cationic protein (ECP) is a heterogeneous molecule originating from activated eosinophil granulocytes. Biological activity and the cellular content of ECP are determined by genetic and posttranslational factors. Several single nucleotide polymorphisms (SNPs) in human ECP gene (RNASE3) have been described so far. ECP is a mediator in host immune response to parasites, bacteria and viruses. By its cytotoxic and non-cytotoxic activity, ECP may also cause side-effects in the hosts own tissues. The largest number of clinical studies is focused on the role of ECP in eosinophil-related disorders, particularly in asthma. Although present in numerous body fluids, difficult bioavailability of biological material, invasive sampling methods and complex sample management prior to ECP level determination are the reasons that serum is most commonly used in routine laboratory practice. As numerous biological and methodological preanalytical factors (the type of collection test-tube, temperature and duration of blood clotting, centrifugation, hemolysis) may affect test result, the sample for serum ECP determination should be collected under standardized conditions. Regarding interpretation of results, it is necessary, along with absolute ECP concentration values, to monitor changes in ECP concentration during the duration of disease or after implemented therapy, and interpret ECP test result in combination with other laboratory and clinical findings. Rational approach to selection of new tests is indeed one of important requirements that medical workers meet today. To enable them to determine the clinical significance of ECP with better certainty, further studies on a large number of specific patient groups are needed.

Indeterminate Results of QuantiFERON-TB Gold In-Tube Assay in Nonimmunosuppressed Children

BACKGROUND AND AIMS QuantiFERON-TB Gold In-Tube (QFT-IT) assay is a highly sensitive and specific test for the diagnosis of latent tuberculosis infection. Data on the use of QFT-IT assay in children are scarce and contradictory. The aim of the study was to assess the rate of indeterminate test results and to identify factors contributing to indeterminate results on routine use of QFT-IT assay in nonimmunosuppressed children. METHODS This retrospective study included 2173 children with ages ranging from 1 month to 18 years. Determination of interferon-gamma (IFN-γ) in peripheral blood was performed by commercial QFT-IT assay. RESULTS Indeterminate test results were recorded in ten (0.46%) subjects with ages ranging from 15 months to 15 years. The value of negative control was >8.0 kIU/L in one subject, whereas in the remaining nine subjects indeterminate results were consequential to positive control (<0.50 kIU/L). None of these subjects had any history data on congenital or acquired immunodeficiency disorders. Bacterial infection (with elevated body temperature and therapy with β-lactam antibiotics) was present in eight subjects with indeterminate results, one subject had exacerbation of asthma (therapy with inhalation corticosteroids), and one subject was clinically healthy. Repeat IFN-γ determination performed in seven subjects did not yield indeterminate results. CONCLUSIONS Study results showed the rate of indeterminate QFT-IT results in nonimmunosuppressed children of all age groups to be very low. QFT-IT should preferably be performed upon resolution of acute inflammation in order to avoid repeat testing of indeterminate results in a new blood sample and to reduce the cost of testing.

Urates in exhaled breath condensate of children with obstructive sleep apnea

BACKGROUND Urate levels may be a marker of oxidative stress. The aim of the present study was to find out are there any differences in urate concentrations in exhaled breath condensate (EBC) between children with obstructive sleep apnea (OSA) and healthy children. MATERIALS AND METHODS EBC was collected in children with obstructive sleep apnea (OSA) and clinically healthy children. Urate measurements in EBC and serum were performed by enzymatic color test. RESULTS The higher concentration of urates in EBC of children with OSA than clinically healthy children indicate the oxidative stress in their airways. Since there was no significant difference in serum concentration of urates between children with OSA and healthy children, it could be considered that urates are sintetized in the airways of children with OSA. CONCLUSIONS The present study indicated that urates in EBC (but not in serum) may be used as a marker of local synthesis of antioxidant compounds, but definitive conclusion must be supported by investigations involving larger number of participants.

Hepatitis during respiratory syncytial virus infection – a case report

Introduction: Respiratory syncytial virus (RSV) infection is the most common cause of hospitalization in infants and small children. The aim was to present a 13-months old boy diagnosed with acute airway infection, acute otitis media (AOM) and hepatitis during the RSV-infection. Material and methods: Serum catalytic activities of alkaline phosphatase (ALP), aspartate aminotranspherase (AST), alanine aminotranspherase (ALT), gamma glutamyl transpherase (GGT), lactate dehydrogenase (LD), and concentrations of bilirubin were monitored during hospitalization and at control examination. Results: The child had clinical signs and symptoms of respiratory failure, AOM, and laboratory findings of virus infection and liver disease. On admission, catalytic activities of enzymes were markedly increased, especially the activity of ALP (10333 U/L, i.e. 24-fold increase in comparison with the upper reference limit). The highest increased in AST (339 U/L, 4.5-fold), ALT (475 U/L, 10.3-fold) and LD (545 U/L, 1.5-fold) were registered on the 3rd day, and the highest increase in GGT (68 U/L, 3.1-fold) occurred on the 11th day. Seven weeks after discharge AST, ALT, GGT and LD decreased into reference range, and ALP remain mildly increased (478 U/L, 1.1 fold increase). RSV was confirmed in nasal lavage fluid. Conclusion: Laboratory results in patient with RSV infection needs to be interpreted in the light of both, respiratory and extrapulmonary manifestations of the infection, respectively.

Urates in Exhaled Breath Condensate of Children with Asthma

Background: To determine whether urates as a marker of oxidative stress could be determined in exhaled breath condensate (EBC), and if there are any differences in urate concentrations between asthmatic and healthy children. Methods: Exhaled breath condensate was collected using an EcoScreen condenser (Erich Jaeger GmbH, Hoechberg, Germany). Urate measurements were performed by enzymatic color test. Asthmatic children were divided into 2 groups: children with controlled asthma and children with acute exacerbation of asthma. Results: Exhaled breath condensate urate concentration was statistically significantly higher in children with controlled asthma compared with control group and acute exacerbation group. Seven children with acute exacerbation of asthma had unmeasurable urate concentrations. Conclusion: Study results showed EBC to contain a measurable urate concentration, which was significantly higher in children with controlled asthma compared with clinically healthy children and children with acute exacerbation of asthma.

Association of Polymorphisms in Coagulation Factor Genes and Enzymes of Homocysteine Metabolism With Arterial Ischemic Stroke in Children

Despite the identification of a wide range of inherited and acquired risk factors for arterial ischemic stroke (AIS) in children, genetic risk factors are incompletely characterized and may vary among different populations. We investigated the role of individual and combined inherited prothrombotic and intermediate-risk factors in 73 children with perinatal (n = 35) and childhood AIS (n = 38) and 100 age- and sex-matched controls. Ten polymorphisms in 8 candidate genes encoding coagulation and fibrinolytic proteins (factor V [FV] Leiden, FV HR2, factor II [FII] G20210A, β-fibrinogen [β-FBG]-455G>A, factor XIII [FXIII]-A p.Val34Leu, plasminogen activator inhibitor 1 4G/5G), homocysteine metabolism (methylenetetrahydrofolate reductase [MTHFR] C677T, MTHFR A1298C), and intermediate-risk factors (angiotensin-converting enzyme I/D, apoE ∊2-4) were detected using a multilocus genotyping assay. Allele-specific polymerase chain reaction was used for the determination of human platelet alloantigens (HPA-1, HPA-2, HPA-3, and HPA-5). Factor V Leiden was associated with an increased risk of AIS (odds ratio [OR]: 4.72, 95% confidence interval [CI]: 1.22-18.27) and perinatal AIS (OR: 8.29, 95% CI: 1.95-35.24). Human platelet antigen-3b allele carriers had a 2-fold lower risk of AIS (OR: 0.51, 95% CI: 0.26-0.98) and perinatal AIS (OR: 0.40, 95% CI: 0.18-0.92). A 2.21-fold increased risk of childhood AIS (95% CI: 1.03-4.73) was identified in FXIII-A Leu34 allele carriers. Combined FV Leiden/FV HR2, FV Leiden/MTHFR A1298C, FV Leiden/MTHFR C677T/MTHFR A1298C, and FV Leiden/FV HR2/MTHFR A1298C heterozygosity was identified in children with AIS but not in controls, which revealed a statistically significant difference. This case–control study shows that besides already documented association between FV Leiden and AIS, other previously unreported polymorphisms (FXIII-A p.Val34Leu, HPA-3) and several genotype combinations that always include heterozygous FV Leiden can be related to AIS in Croatian population.

Eosinophil Cationic Protein in Children With Respiratory Allergies - When Is It Useful?

Background: To assess the differences in serum eosinophilic cationic protein (ECP) concentrations between treated and untreated children with asthma, children with rhinitis, and children with both and possible influence of seasonal exposure to sensitizing allergens on ECP levels. Methods: The study included treated (n=156) and untreated (n=55) children with asthma, children with rhinitis, and children with asthma and rhinitis. Serum ECP was measured in serum collected between 8 am and 12 pm under standardized pre-analytical conditions (regarding the type of blood collection tube, time, and incubation temperature during blood clotting). Results: Untreated children had significantly higher ( P <0.0001) concentrations of ECP (M[IQR]=35.1 [29.5–50.9] μg/L) than treated children (M[IQR]=11.3 [7.1–16.1] μg/L). Eosinophilic cationic protein was significantly higher during the allergen exposure season (M[IQR]=23.9 [17.6–40] μg/L) than out of season (M[IQR]=8.3 [5.4–17.2]) μg/L, P =0.0001. Conclusions: To make ECP measurements useful in clinical practices, it is necessary to meet standardized pre-analytical conditions. * ECP : eosinophilic cationic protein IL-2 : interleukin-2 ARIA : Allergic Rhinitis and its Impact on Asthma GINA : Global Initiative for Asthma IgE : immunoglobulin E FeNO : fraction of exhaled nitric oxide

Troponin i B-tip natrijuretskog peptida : laboratorijska dijagnostika i klinička upotreba u pedijatriji

Troponin i B-tip natrijuretskog peptida su dva srčana biljega koja se u općoj odrasloj populaciji već dugi niz godina rutinski primjenjuju u dijagnostici srčanih bolesti, no malo je spoznaja o njihovoj korisnoj upotrebi u pedijatrijskoj praksi. Ovaj pregledni rad obuhvaća svu problematiku određivanja, tumačenja nalaza i korisnost troponina i B-tipa natrijuretskog peptida u pedijatriji na temelju podataka iz literature i vlastitog iskustva. Namijenjen je liječnicima pedijatrima i laboratorijskim stručnjacima koji se u svom radu susreću s dječjom populacijom.