Comparison of interferon-gamma whole blood assay with tuberculin skin test for the diagnosis of tuberculosis infection in tuberculosis contacts

WOS: 000246913000004PubMed ID: 17682705Tuberculin skin test which is used for the detection of latent tuberculosis (TB), has many disadvantages such as false positivities due to cross reactions between environmental mycobacteria and BCG strain, false negativities due to immunosuppression and malpractice, and also difficulties in application and evaluation. Recently a new diagnostic test which measures the production of interferon (IFN)gamma in whole blood upon stimulation with specific ESAT-6 and CFP-10 antigens of Mycobacterium tuberculosis has been introduced. Since most of the mycobacteria other than tuberculosis and BCG strain do not contain these antigens, the detection of IFN-gamma levels indicates the specific T-cell response against M.tuberculosis. The aim of the study was to compare the tuberculin skin test and whole blood IFN-gamma assay (QuantiFERON (R)-TB Gold, Cellestis Ltd, Carnegie, Victoria, Australia) for the identification of latent TB infection in the contacts with active TB patients. The tests results were evaluated by using Kappa (K) analysis, and K coefficients of 0.75 were accepted as poor, moderate and excellent agreements, respectively. A total of 233 subjects from three risk groups were included to the study. Group 1 included the household members (n=133) who had contact with smear positive index cases, Group 2 included the subjects from community (n=46) who had contact with smear positive index cases, and Group 3 included health care workers (n=74) who had contact with TB patients or their specimens. The positivity rates of tuberculin skin test and IFN-gamma assay in the cases were found as 37% and 42%, respectively. There were no significant differences among the three patient groups with regard to the results of the tuberculin skin test (p > 0.05). However, the positive result of the IFN-gamma assay in Group 1 was found statistically higher than the other groups (51.3%, p=0.013). A poor agreement between the two tests was detected in the results taken from 233 subjects (65.7%, K=0.28), while agreement was moderate in unvaccinated group (72.7%, K=0.44). Evaluation of agreement rates of the tests according to the risk groups yielded 64.6% (K=0.3) for Group 1, 71.7% (K=0.32) for Group 2, and 63.5% (K=0.21) for Group 3, which all coefficients showed poor agreement. Although IFN-gamma blood assay has many advantages such as objective and quantitative results, no interference with vaccination due to the use of specific antigens and being practical, the high cost and the need for well-equipped laboratory are its disadvantages. As a result it was concluded that, IFN-gamma blood assay has limited value for the detection of latent TB infection in our country, since the prevalence of TB infection and BCG vaccination rates are high in Turkey

The Evaluation of the Diagnostic Performance of the BioFire FilmArray Meningitis/Encephalitis Panel in Children: A Retrospective Multicenter Study

Objective Acute bacterial meningitis (ABM) declined after implementing conjugate Haemophilus influenzae type B and the pneumococcal vaccines worldwide. However, it still contributes to significant morbidity and mortality. The Biofire FilmArray Meningitis Encephalitis (FAME) panel can rapidly diagnose common bacterial and viral pathogens. Several studies suggested that the use of FAME may accelerate diagnosis and decrease the time to pathogen-specific therapy. However, the clinical utility is still controversial due to scarce data and relatively high costs. Therefore, we aimed to evaluate the diagnostic performance of FAME in children. Methods A retrospective multicenter cross-sectional study was conducted to evaluate FAME in diagnosing ABM in children with a suspected central nervous system infection between January 2017 and May 2021. Results This study consisted of 179 children diagnosed with central nervous system infection who had parallel testing done using FAME and traditional microbiological diagnostic methods. Twenty-two FAME results were positive; 8 (36.3%) were bacterial pathogens and 14 (53.7%) were viral pathogens . The most common viral pathogen was human herpesvirus 6 (n =6; 27.2%), followed by herpes simplex virus 1 (n =4; 18.1%), Enterovirus spp. (n = 2; 9%), Parechovirus (n = 2; 9%), and Cytomegalovirus (n = 1; 4.5%). Bacterial pathogens included S. pneumoniae (n = 3; 13.6%), H. influenzae (n = 3; 13.6%), Neisseria meningitidis (n = 1; 4.5%), and Streptococcus agalactiae (n = 1; 4.5%). Bacterial culture confirmed S. pneumoniae infection in only 1 of 8 (12.5%) patients, while 7 of 8 bacterial meningitis were only detected by FAME. Conclusion FAME may also help with diagnosis and pathogen identification in patients who have already had antibiotics before cerebrospinal fluid collection. The use of FAME to detect infections quickly may minimize the improper use of medications, treatment duration, and the cost of hospitalization

Investigation of Bacterial and Viral Etiology in Community Acquired Central Nervous System Infections with Molecular Methods

WOS: 000408311400008PubMed ID: 28929964In this multicenter prospective cohort study, it was aimed to evaluate the bacterial and viral etiology in community-acquired central nervous system infections by standart bacteriological culture and multiplex polymerase chain reaction (PCR) methods. Patients hospitalized with central nervous system infections between April 2012 and February 2014 were enrolled in the study. Demographic and clinical information of the patients were collected prospectively. Cerebrospinal fluid (CSF) samples of the patients were examined by standart bacteriological culture methods, bacterial multiplex PCR (Seeplex meningitis-B ACE Detection (Streptococcus pneumoniae, Neisseria meningitidis, Haemophilus influenzae, Listeria monocytogenes, Group B streptococci) and viral multiplex PCR (Seeplex meningitis-V1 ACE Detection kits herpes simplex virus-1 (HSV1), herpes simplex virus-2 (HSV2), varicella zoster virus (VZV), cytomegalovirus (CMV), Epstein Barr virus (EBV) and human herpes virus 6 (HHV6)) (Seeplex meningitis-V2 ACE Detection kit (enteroviruses)). Patients were classified as purulent meningitis, aseptic meningitis and encephalitis according to their clinical, CSF (leukocyte level, predominant cell type, protein and glucose (blood/CSF) levels) and cranial imaging results. Patients who were infected with a pathogen other than the detection of the kit or diagnosed as chronic meningitis and other diseases during the follow up, were excluded from the study. A total of 79 patients (28 female, 51 male, aged 42.1 +/- 18.5) fulfilled the study inclusion criteria. A total of 46 patients were classified in purulent meningitis group whereas 33 were in aseptic meningitis/encephalitis group. Pathogens were detected by multiplex PCR in 41 patients. CSF cultures were positive in 10 (21.7%) patients (nine S.pneumoniae, one H.influenzae) and PCR were positive for 27 (58.6%) patients in purulent meningitis group. In this group one type of bacteria were detected in 18 patients (14 S.pneumoniae, two N.meningitidis, one H.influenzae, one L.monocytogenes). Besides, it is noteworthy that multiple pathogens were detected such as bacteria-virus combination in eight patients and two different bacteria in one patient. In the aseptic meningitis/encephalitis group, pathogens were detected in 14 out of 33 patients; single type of viruses in 11 patients (seven enterovirus, two HSV1, one HSV2, one VZV) and two different viruses were determined in three patients. These data suggest that multiplex PCR methods may increase the isolation rate of pathogens in central nervous system infections. Existence of mixed pathogen growth is remarkable in our study. Further studies are needed for the clinical relevance of this result