Slavica Dodig

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.

Inflammatory markers in childhood asthma.

Abstract The major characteristic of asthma is persistent airway inflammation that fails to resolve spontaneously. Dysregulation of pro- and anti-inflammatory mechanisms is responsible for the development of chronic inflammation. The inflammatory reaction is mediated by numerous cells and their mediators. Detection and quantification of airway inflammation in children are subject to many requirements, e.g., use of biologic samples obtained in a non-invasive way; use of standardized analytical methods to determine biomarkers that can identify inflammation processes (inflammation itself, oxidative stress, apoptosis and remodelling); determining the role of systemic inflammation; assessment of correlation of various biomarkers of inflammation with clinical parameters and their diagnostic efficacy; providing a tool(s) to monitor diseases, and to evaluate adequacy of therapy; and predicting the clinical course of inflammation and prognosis of asthma. Using standardized analyses, it is now possible to determine direct markers of local inflammation, i.e., fractional nitric oxide (marker of oxidative stress) in exhaled breath, pH (marker of acid stress) in breath condensate, and indirect markers in blood/serum, i.e., eosinophil granulocytes (indicating migration), eosinophil cationic protein (marker of activated eosinophil granulocytes) and C-reactive protein (marker of systemic inflammation). However, none of these biomarkers are specific for asthma. Further standardization of the known pulmonary biomarkers of local inflammation and identification of new ones will allow for longitudinal follow-up of inflammation in children with asthma.

Exhaled breath condensate: a new method for lung disease diagnosis

Abstract Analysis of exhaled breath composition in lung disease patients can indirectly point to biochemical changes that occur in the fluid lining airway surfaces. The parameters of redox and acid-base changes, and of inflammatory changes relevant in the pathogenesis of most pulmonary diseases are currently most widely determined in exhaled breath condensate. The collection of exhaled breath condensate is a safe, non-invasive, easy and simple diagnostic procedure that is suitable for longitudinal studies and applicable in patients of all age groups, irrespective of the disease severity. In spite of many scientific studies involving lung disease patients, methodology for exhaled breath condensate collection and analysis has not yet been realized for daily utilization. Additional studies of the exact origin of condensate constituents and standardization of the overall analytical process, including collection, storage, analysis and result interpretation, are needed. Irrespective of these limitations, further investigation of this sample type is fully justified by the fact that classical specimens used in the management of pulmonary disease are either obtained by invasive procedures (e.g., induced sputum, biopsy, bronchoalveolar lavage) or cannot provide appropriate information (e.g., urine, serum). Analysis of exhaled breath condensate in the future might contribute significantly to our understanding of the physiological and pathophysiological processes in lungs, to early detection, diagnosis and follow up of disease progression, and to evaluation of therapeutic response. Clin Chem Lab Med 2007;45:945–52.

Cut-off values for total serum immunoglobulin E between non-atopic and atopic children in north-west Croatia

Abstract Background: The aim of this study was to determine cut-off values for total serum immunoglobulin E (IgE) between non-atopic and atopic children with respiratory symptoms. Children of 0–16years of age were evaluated for respiratory symptoms of >4-week duration. Methods: Children were divided into two groups: non-atopic children (n=3355) who were non-IgE-sensitized with undetectable allergen-specific IgE (<0.35kIUA/L), and atopic children (n=4620) who were sensitized to ≥1 allergens (specific IgE ≥0.35 kIUA/L). Upper and lower centiles were determined and cut-off values calculated using receiver operating characteristic (ROC) analysis. Results: Serum total IgE increased with age in both groups, although at a variable level and rate, and reached a plateau at 9 and 10years in non-atopic and atopic children, respectively. Atopic children had on average 14-fold higher serum total IgE compared to non-atopic children. In both groups, the median was lower than the corresponding mean and the distribution skewness was always positive (group I, 0.87; group II, 0.91). In almost all age groups, the 95th percentile for non-atopic children corresponded to the calculated cut-off values, whereas the 10th percentile for atopic children corresponded to the respective cut-off values only until the age of 8years, after which greater differences between the cut-off values and the 10th percentile were recorded. Cut-off values for total serum IgE in children up to 16years were determined with diagnostic sensitivity, specificity and area under the ROC curve of 96%, 91% and 0.950, respectively. Conclusions: The 95th percentile for total IgE in non-atopic children and the 10th percentile in atopic children could be taken as cut-off values in children up to 8years of age, after which significant percentile discrepancies between non-atopic and atopic children were recorded. Since atopic subjects show a more irregular centile distribution, cut-off values are best determined by ROC analysis.

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.

Exhaled breath condensate – from an analytical point of view

Over the past three decades, the goal of many researchers is analysis of exhaled breath condensate (EBC) as noninvasively obtained sample. A total quality in laboratory diagnostic processes in EBC analysis was investigated: pre-analytical (formation, collection, storage of EBC), analytical (sensitivity of applied methods, standardization) and post-analytical (interpretation of results) phases. EBC analysis is still used as a research tool. Limitations referred to pre-analytical, analytical, and post-analytical phases of EBC analysis are numerous, e.g. low concentrations of EBC constituents, single-analyte methods lack in sensitivity, and multi-analyte has not been fully explored, and reference values are not established. When all, pre-analytical, analytical and post-analytical requirements are met, EBC biomarkers as well as biomarker patterns can be selected and EBC analysis can hopefully be used in clinical practice, in both, the diagnosis and in the longitudinal follow-up of patients, resulting in better outcome of disease.

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.