The comparison of COVID-19 vs seasonal influenza in children.

BACKGROUND: Influenza in children has been well described, whereas there has been a paucity of pediatric data regarding COVID-19. It is crucial for clinicians to differentiate cases of COVID-19 from cases of influenza because of the upcoming influenza season in the new pandemic era. METHODS: This retrospective study included pediatric patients who were diagnosed with laboratory-confirmed COVID-19 between March and September 2020, or seasonal influenza between October 2019 and March 2020. RESULTS: A total of 315 children were included in this study; 151 were diagnosed with influenza and 164 had confirmed COVID-19. The median age of patients with COVID-19 was 10 years (interquartile range [IQR]: 3-15 years), whereas the median age of patients with influenza was 4 years (IQR: 1-6 years) (p = 0.001). In the COVID-19 group, 6.3% of patients had underlying diseases, the most frequent being neurological conditions (3%). In the influenza group, 20.9% of patients had an underlying disease, the most frequent being asthma (14.5%). Fever (odds ratio [OR]: 20.476; 95% confidence interval [CI]: 2.438-171.995; p = 0.005), dyspnea/tachypnea (OR 13.950; 95% CI: 2.607-74.634; p = 0.002), and increased C-reactive protein (CRP) (OR: 7.650; 95% CI: 2.094-27.955; p = 0.002) were main predictors of influenza diagnosis in comparison to COVID-19. Lymphopenia was detected in 43.2% of patients with influenza and 19.9% of patients with COVID-19 (p = 0.001). CONCLUSIONS: The accurate differentiation between "influenza or COVID-19" seems possible by evaluating a combination of factors including cough, fever, vomiting, leucopenia, lymphopenia, pneumonia, in pediatric patients with high CRP as well as age.

Comparison of a novel antigen detection test with reverse transcription polymerase chain reaction assay for laboratory diagnosis of SARS-CoV-2 infection.

Molecular diagnosis of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) by real-time reverse transcription polymerase chain reaction (RT-PCR) in respiratory specimens is considered the gold standard method. This method is highly sensitive and specific but it has some limitations such as being expensive and requiring special laboratory equipment and skilled personnel. RapidFor™ Antigen Rapid Test Kit is a commercially available Ag-RDT which is produced in Turkey and designed to detect the nucleocapsid antigen of SARS-CoV-2 in nasopharyngeal swab samples. The aim of this study was to evaluate the performance of this novel SARS-CoV-2 antigen detection considering the RT-PCR method as the gold standard. Four hundred forty-four nasopharyngeal swab samples which were collected from the patients who met clinical criteria of COVID-19 from ten centers in Turkey between September 2020 and February 2021 were included in the study. All the nasopharyngeal swab samples were tested for SARS-CoV-2 RNA using commercial RT-PCR kits (Bioeksen and A1 Lifesciences, Istanbul, Turkey) according to the manufacturer's instructions. Viral loads were assessed according to the cycle threshold (Ct) values. RapidFor™ SARS-CoV-2 antigen test (Vitrosens Biotechnology, Istanbul, Turkey) was used to investigate the presence of SARS-CoV-2 antigen in all samples following the manufacturer's instructions. Out of 444 nasopharyngeal swab samples tested, 346 (77.9%) were positive and 98 (22.1%) were negative for SARS-CoV-2 RNA by RTPCR. Overall sensitivity of the RapidFor™. Antigen Rapid Test Kit was 80.3% whereas specificity was found to be 87.8%. Positivity rate of rapid antigen test in samples with Ct values over 25 and below 30 was 82.7%, while it increased to 95.7% in samples 20 ≤ Ct < 25 and reached 100% in samples with Ct values below 20. RapidFor™ SARS-CoV-2 Ag test might be a good choice in the screening of symptomatic and asymptomatic patients and their contacts for taking isolation measures early, with advantages over RT-PCR as being rapid, easy and being applicable in every laboratory and even at point of care.

[Comparison of the Multiplex Real Time Polymerase Chain Reaction Method Directly from Whole Blood and from Blood Culture Bottle with the Conventional Method for the Etiological Diagnosis in Patients with Pre-Diagnosis of Sepsis]. / Sepsis Ön Tanili Hastalarda Tam Kandan ve Kan Kültür Sisesinden Multipleks Gerçek Zamanli Polimeraz Zincir Reaksiyonu ile Hizli Etken Tayininin Konvansiyonel Yöntemlerle Karsilastirilmasi.

In this study, it was aimed to evaluate the use of multiplex real time polymerase chain reaction (RtPCR) method, directly from whole blood and blood culture bottles of intensive care unit patients with a pre-diagnosis of sepsis for the determination of the causative agent by comparing it with the conventional method. The study was carried out prospectively between November 2019 and August 2020. Ninety patients hospitalized with a pre-diagnosis of sepsis were included in the study. Samples were collected simultaneously with aseptic technique as whole blood and at least two sets of blood cultures. Blood culture bottles were monitored by the BACT/ALERT 3D (bioMerieux, France) instrument. Blood culture bottles were studied both by Sepsis Pathogens Panel Kit v1 (Anatolia, Turkey) using the multiplex Rt-PCR and with the conventional culture methods. The duration of detection and reporting of the multiplex Rt-PCR methods were compared with the conventional method. In this study, a total of 90 whole blood samples and 280 blood culture bottles were collected from the patients. It was found that 73 (81%) patients had already been administered antibiotic treatment at the time of blood sampling. Conventional blood culture was accepted as the gold standard in the diagnosis of sepsis. Rt-PCR performed from blood culture bottles was found to have a sensitivity of 89.58%; specificity of 57.14%; positive predictive value of 70.49%; negative predictive value of 82.76% and accuracy of 74.44% (p= 0.019). On the basis of the bacterial species, the sensitivity of the Rt-PCR method was determined to be between 66.7-100% and the specificity was between 86.6-100%. The Rt-PCR performed from whole blood, was found to have a sensitivity of 11.67% and a specificity of 96.67%; positive predictive value of 87.50%; negative predictive value of 35.37% and accuracy of 40% (p= 1.684). In this study, the duration of reporting of blood culture results was in average 116:50 hours, that of PCR from blood culture bottles was 80:57 hours, and that of PCR from whole blood samples was 15:38 hours (p<0.001). It was determined that the PCR from whole blood shortened the reporting time by an average of 101:12 hours (approximately four days), and that the PCR from blood culture bottles shortened the reporting time by an average of 35:53 hours (1.5 days) compared to the conventional method. In this study, the results determined by the Sepsis Pathogens Panel Kit v1 (Anatolia, Turkey) performed from blood culture bottles were superior compared to the conventional method. It has been determined that improvement is required for the usage of the sepsis kit directly from whole blood. On the other hand, considering the species detected by the blood culture method and not by the assay, the species range detected by the multiplex assay panel needs to be improved.

[Evaluation of EUCAST Direct Rapid Antimicrobial Susceptibility Test Method in Blood Culture Bottles with Positive Signal]. / Pozitif Sinyal Veren Kan Kültürü Siselerinde EUCAST Dogrudan Hizli Antimikrobiyal Duyarlilik Testi Yönteminin Degerlendirilmesi.

Early reporting of the antibiotic susceptibility testing (AST) results is essential for the survival of sepsis patients. In 2019, European Committee on Antimicrobial Susceptibility Testing (EUCAST) published a proposal to detect antimicrobial susceptibility from positive blood culture bottles with a rapid antimicrobial susceptibility test (RAST) method in a maximum of eight hours. In this study, it was aimed to evaluate the EUCAST RAST method in blood culture bottles that resulted with positive signal in BacT/ALERT (bioMérieux, France) blood culture system and that showed gram-negative bacteria with single morphology with Gram stain. The study was conducted prospectively between April 2019 and November 2019. Ninety blood culture bottles that we detected single gram negative bacteria morphology by Gram stain were tested according to the EUCAST RAST method, The isolates obtained from the blood culture bottles were studied with the EUCAST disk diffusion method and the Vitek 2 Compact (bioMerieux, France) automated system. The results obtained with RAST were compared with the results of these methods. The turn around time of the RAST method was recorded. Categorical agreement of the RAST method with conventional methods and the very major error rates were determined. Of the 14 isolates not yet covered by the EUCAST HADT method, 12 were determined to be other Enterobacterales members and two as other non-fermentatives. Two isolates were detected with the same morphological characteristics in Gram stain of the blood culture bottle and the same antibiotic susceptibility profile, but with different identification results. These sixteen isolates were excluded from the study. In this study the susceptibility of 74 isolates were determined according to the EUCAST breakpoint tables, of which 31 were Klebsiella pneumoniae, 35 were Escherichia coli, four were Acinetobacter baumannii and four were Pseudomonas aeruginosa. According to the evaluation periods of EUCAST RAST; the susceptibility profile was reported for nine (12%) of E.coli at four hours, eight (11%) at six hours, 18 (24%) at eight hours; three (4%) of K.pneumoniae at four hours, 16 (21%) at six hours, 12 (16%) at eight hours; three of P.aeruginosa (4%) at six hours, one (1%) at eight hours; two of A.baumannii (2%) at six hours and two (2%) at eight hours. The categorical aggrement of the RAST method was 91.8% with the automated system and 96.8% with the disc diffusion method. Very major errors of RAST method compared to the automated system were detected for piperacillin-tazobactam (17.7%), ceftazidime (11.6%) and meropenem (5.6%); and when compared to the disc diffusion method, for cefotaxime (5.7%) and meropenem (6.7%). Our results have shown that EUCAST RAST method can practicaly be performed in routine laboratories to report early results with a low cost. Because of the very major errors it is necessary to confirm the results with the standard methods.

Relationship between chest computed tomography findings and clinical conditions of coronavirus disease (COVID-19): A multicentre experience.

AIMS: This study aimed to investigate the clinical and chest computed tomography (CT) features associated with clinical parameters for coronavirus disease (COVID-19) in the capital of Turkey, Ankara. MATERIALS AND METHODS: Epidemiological, clinical features, laboratory findings and radiological characteristics of 1563 hospitalised patients with COVID-19 in Ankara were collected, reviewed and analysed in this study. The risk factors associated with disease severity were investigated. RESULTS: Non-severe (1214; 77.7%) and severe cases (349; 22.3%) were enrolled in the study. Compared with the non-severe group, the severe group were significantly older and had more comorbidities (ie, hypertension, diabetes mellitus, cardiovascular disease and chronic kidney disease). Smoking was more common in the severe group. Severe patients had higher respiratory rates and higher incidences of cough and dyspnoea compared with non-severe patients. Compared with the non-severe patients, the severe patients had increased C-reactive protein (CRP), procalcitonin, neutrophil to lymphocyte ratio (NLR) and CRP/albumin ratio and decreased albumin. The occurrence rates of consolidation, subpleural sparing, crazy-paving pattern, cavity, halo sign, reversed halo sign, air bronchogram, pleural thickening, micronodule, subpleural curvilinear line and multilobar and bilateral involvement in the CT finding of the severe patients were significantly higher than those of the non-severe patients. CONCLUSIONS: Many factors are related to the severity of COVID-19, which can help clinicians judge the severity of the patient and evaluate the prognosis. This cohort study revealed that male sex, age (≥55 years), patients with any comorbidities, especially those with cardiovascular disease, dyspnoea, increased CRP, D-dimer and NLR, and decreased lymphocyte count and CT findings of consolidation and multilobar involvement were predictors of severe COVID-19.

Pneumococcal carriage in children with COVID-19.

Background: SARS-CoV-2 is the new virus, and Streptococcus pneumoniae is one of the most important pathogens affecting humans. However, we do not yet know whether these microorganisms interact. Thus, we aimed to evaluate the relationship between Streptococcus pneumoniae and SARS-CoV-2 in pediatric patients.Methods: This study was conducted retrospectively by means of medical records of pediatric patients who were tested for SARS-CoV-2 between March 11 and June 04, 2020, in the University of Health Sciences, Ankara Educating and Training Hospital and Hacettepe University Faculty of Medicine.Results: We evaluated 829 pediatric patients for S. pneumoniae and SARS-CoV-2 from their nasopharyngeal specimen. Of 115 children positive for SARS-CoV-2, 32.2% had a positive S. pneumoniae test, whereas of 714 children negative for SARS-CoV-2, 14.1% had a positive S. pneumoniae test (p < .01). We compared patients with positive vs. negative SARS-CoV-2 tests according to S. pneumoniae positivity There were no statistically significant differences in terms of gender, underlying disease, fever, cough, leukocytosis, lymphopenia, increased CRP, increased procalcitonin, findings of chest x-ray, severity of disease, and treatment.Conclusion: The nasopharyngeal S. pneumoniae carriage rate in patients with COVID-19 was higher than in non-infected children, while S. pneumoniae carriage did not affect the course of COVID-19 disease. Pneumococcal vaccination is significant, such that we do not know the outcomes of increased pneumococcal carriage for the upcoming months of pandemic.

[Investigation of the diagnostic value of anti-dense fine speckled 70/lens epithelium derived growth factor p75 autoantibody for autoimmune diseases]. / Anti-dense fine speckled 70/lens epithelium derived growth factor p75 otoantikorunun otoimmün hastaliklarda klinik taniya katkisinin arastirilmasi.

Antinuclear antibodies (ANA) are the autoantibodies that are produced against nuclear antigens in the cell nucleus and/or cytoplasm, and are one of the important diagnostic criteria in systemic autoimmune rheumatic diseases (SARD). Until today, several methods have been developed for detecting ANA's. However, indirect immunofluorescence (IIF) technique, that is also known as one of the oldest methods, is still the most commonly used one. Typically, anti-dense fine speckled 70/Lens epithelium derived growth factor p75 (anti-DFS70/LEDGF p75) autoantibody can be detected via IIF method where in HEp-2 (human larynx carcinoma) cells are used. The dense fine speckled (DFS) pattern method can be masked and remain unnoticed by the IIF method when it exists with the other ANA. Anti-DFS70 autoantibodies seldomly appear in SARD patients compared to healthy individuals. Moreover, these antibodies may appear in different chronic inflammatory conditions like interstitial cystitis, chronic fatigue syndrome, atopic dermatitis and Vogt-Koyanagi-Harada syndrome. The aim of this study was to determine the frequency of anti-DFS70 autoantibodies by immunblot (IB) method in patients sera with and without DFS70 staining pattern by IIF and to determine if the presence of anti-DFS70 has a clinical impact when included in ANA testing algorithm. In our study, a total of 60 patients' sera in which DFS pattern was defined by IIF method and 67 patients' sera in which other patterns observed were included in the study and anti-DFS70 autoantibody was investigated by IB method in these sera. In 67 patient samples which have shown the other patterns three (4.5%) samples were determined to be anti-DFS70 positive by IB. In 55 patients who were determined to have IIF-DFS pattern (+)/IB anti-DFS70 (+), 6 (11%) were diagnosed as SARD and the other antinuclear antibodies (ANA) were found as negative by IB. In the other group with the other ANA patterns detected, none of the SARD-diagnosed 22 patients had shown anti-DFS70 by IB method. Sixteen (26.6%) samples in the group that was positive for the IIF-DFS pattern were obtained from rheumatology and physical therapy and rehabilitation clinics, 32 (47.7%) samples were from the group in which other patterns observed and were also obtained from those clinics. DFS pattern was detected significantly more frequent in the samples from other clinics in comparison to the samples from rheumatology and physical therapy and rehabilitation clinics (p= 0.018). In our study, it was concluded that DFS pattern can be defined by IIF method by only specialists, however, since homogeneous-like and mixed patterns can be confused especially in low titers, there is a need for a second well-validated immunological test that could detect anti-DFS70 auto-antibody.

[Results of a multicenter study investigating plasmid mediated colistin resistance genes (mcr-1 and mcr-2) in clinical Enterobacteriaceae isolates from Turkey]. / Ülkemizde klinik Enterobacteriaceae izolatlarinda plazmit aracili kolistin direnç genlerini (mcr-1 ve mcr-2) arastiran çok merkezli çalismaya ait sonuçlar.

Colistin is a polymyxin antibiotic which is considered as one of the last line agents against infections due to multidrug resistant or carbapenem resistant gram-negative pathogens. Colistin resistance is associated with chromosomal alterations which can usually cause mutations in genes coding specific two component regulator systems. The first plasmid-mediated colistin resistance gene, mcr-1 was described in Escherichia coli and Klebsiella pneumoniae isolates in December 2015 and followed by another plasmid-mediated colistin resistance gene mcr-2 in 2016. The rapid and interspecies dissemination of plasmid-mediated resistance mechanisms through horizontal gene transfer, have made these genes considerably threatening. After the first reports, although mcr-1/mcr-2 producing Enterobacteriaceae isolates have been reported from many countries, there have been no reports from Turkey. Thus, the aim of this study was to investigate the presence of mcr-1/mcr-2 in clinical Enterobacteriaceae isolates from different parts of our country. A total of 329 Enterobacteriaceae isolates from 22 laboratories were collected which were isolated between March, 2015 and February, 2016. mcr-1/mcr-2 were investigated by polymerase chain reaction during February-March, 2016. Two hundred and seventeen of Klebsiella pneumoniae (66%), 75 of Salmonella spp. (22.8%), 31 of Esherichia coli (9.4%), 3 of Enterobacter cloacae (0.9%), 2 of Klebsiella oxytoca (0.6%) and 1 of Enterobacter aerogenes (0.3%) isolates were included to the study. Agarose gel electrophoresis results of PCR studies have shown expected band sizes for positive control isolates as 309 bp for mcr-1 and 567 bp for mcr-2. However, the presence of mcr-1/mcr-2 genes was not detected among the tested study isolates of Enterobacteriaceae. Although mcr-1/mcr-2 were not detected in our study isolates, it is highly important to understand the mechanism of resistance dissemination and determine the resistant isolates by considering that colistin is a last-line antibiotic against infections of multidrug or carbapenem resistant gram-negative bacteria. Thus, it is suggested that these mechanisms should be followed-up in both clinical and non-clinical (e.g. isolates from food animals, raw meats and environment) isolates of special populations.

Investigation of an algorithm for anti HCV EIA reactivity in blood donor screening in Turkey in the absence of nucleic acid amplification screening.

PURPOSE: In this study we aimed to propose an algorithm for initial anti HCV EIA reactive blood donations in Turkey where nucleic acid amplification tests are not yet obligatory for donor screening. METHODS: A total of 416 anti HCV screening test reactive donor samples collected from 13 blood centers from three cities in Turkey were tested in duplicate by Ortho HCV Ab Version 3.0 and Radim HCV Ab. All the repeat reactive samples were tested by INNO-LIA HCV Ab 3.0 or Chiron RIBA HCV 3.0 and Abbott Real Time HCV. Intra-assay correlations were calculated with Pearson r test. ROC analysis was used to study the relationship between EIA tests and the confirmatory tests. RESULTS: The number of repeat reactive results with Ortho EIA were 221 (53.1%) whereas that of microEIA, 62 (14.9%). Confirmed positivity rate was 14.6% (33/226) by RIBA and 10.6% (24/226) by NAT. Reactive PCR results were predicted with 100% sensitivity and 95% specificity with S/CO levels of 8.1 with Ortho EIA and 3.4 with microEIA. CONCLUSIONS: Repeat reactivity rates declined with a second HCV antibody assay. Samples repeat reactive with one HCV antibody test and negative with the other were all NAT negative. All the NAT reactive samples were RIBA positive. None of the RIBA indeterminate or negative samples were NAT reactive. Considering the threshold values for EIA kits determined by ROC analysis NAT was decided to be performed for the samples above the threshold value and a validated supplemental HCV antibody test for the samples below.

Ureaplasma urealyticum: Presence among Sexually Transmitted Diseases.

The aim of this study was to detect the presence of Chlamydia trachomatis, Neisseria gonorrhoeae, Mycoplasma genitalium, Mycoplasma hominis, Trichomonas vaginalis, and Ureaplasma urealyticum in genital specimens of symptomatic patients. This study also examined the role of U. urealyticum in infections of the lower genital tract. Cervical and urethral samples from 96 patients (46 males, 50 females) were tested using the Seeplex(®) STD6 ACE kit. Consent forms were received and a questionnaire was applied. All statistical analyses were performed using the SPSS statistical software program (version 17.0). Among the samples tested, at least 1 pathogen was detected in 49% of the samples; specifically, the rate of detection of U. urealyticum, M. hominis, C. trachomatis, N. gonorrhoeae, M. genitalium, and T. vaginalis was 29.1%, 10.4%, 8.3%, 7.3%, 6.3%, and 4.2%, respectively. U. urealyticum was detected as the sole pathogen in samples from 10% of female patients and 28.3% of male patients (p = 0.035). U. urealyticum was present in 54.5% (18/33) of samples in which a single pathogen was detected and 71.4% (10/14) of samples in which multiple pathogens were detected. Among men, significant differences in discharge, dysuria, and pruritus were not noted among those with negative results (84.6%, 69.2%, and 38.5%, respectively), among those positive for only U. urealyticum (100%, 66.7%, and 26.7%, respectively), and those positive for N. gonorrhoeae, C. trachomatis, M. genitalium, and T. vaginalis (100%, 93.3%, and 26.7%, respectively). Detection of U. urealyticum, either alone or together with other pathogens, in a symptomatic group of patients is an important finding, particularly in men.

Evaluation of Invasive and Noninvasive Methods for the Diagnosis of Helicobacter Pylori Infection

Objective: The present study was conducted to evaluate invasive and noninvasive diagnostic methods for detection of Helicobacter pylori (H. pylori) in patients admitted with dyspeptic complaints and to compare sensitivities and specificities. Method: Sets of four gastric biopsy specimens were obtained from a total of 126 patients included in the study. The presence of H. pylori was determined by invasive tests including culture, rapid urease test, polymerase chain reaction (PCR) and histopathology. Among noninvasive tests, urea breath test, serological tests and enzyme-linked immunosorbent assay (ELISA) were performed. Results: H. pylori was isolated in 79 (62.7%) gastric biopsy cultures, whereas positivity was concluded for 105 (83.3%) patients by rapid urease test, for 106 (84.1%) by PCR, for 110 (87.3%) by histopathology, for 119 (94.4%) by urea breath test, and for 107 (84.9%) by ELISA. In the present study, the culture findings and histopathological examination findings were accepted as gold standard. According to the gold standard, urea breath test had the highest sensitivity (96.5%) and the lowest specificity (30%), whereas culture and histopathology had the highest specificities (100%). Conclusion: The use of PCR invasively with gastric biopsy samples yielded parallel results with the gold standard. PCR can be recommended for routine use in the diagnosis of H. pylori.

Are interleukin-6, body mass index and atopy crucial in infantile intussusception?

OBJECTIVE: To determine the role of inflammation related to body mass index (BMI) and atopy in the etiology of idiopathic intussusception (IS) which is seen more frequently in obese children and which is considered to increase in the allergy season. METHODS: The study comprised a study group consisting of 22 infants with IS and a control group consisting of 20 healthy infants with age and BMI matched. In both groups, gender, weight, height, month of birth, month of admittance (allergy season) of each infant were recorded. Information regarding whether or not the child had any skin rash, atopy, oral allergy syndrome, and whether or not the patient had been fed cow's milk and breast milk was recorded. Hemoglobin (Hb) levels, white blood cell (WBC) and eosinophil counts, interleukin-6 (IL-6) levels and allergy panel were studied in all patients. Additionally, cross reactive protein (CRP) and blood urea nitrogen (BUN) levels were determined in the study group. During statistical comparison p < 0.05 was considered statistically significant. RESULTS: Mean IL-6 levels in the control and study groups were 1.59 ± 0.15 pg/ml and 4.12 ± 5.04 pg/ml, respectively. IL-6 levels were statistically different between each groups and between cases with barium reduction and cases reduced manually by laparotomy within the study group. Both groups were similar statistically with regard to the others parameters. No atopy was detected by allergy panel. When binary logistic regression analysis with the cut-off value of IL-6 set as 1.6 pg/ml was applied to all data, statistically significant values were obtained only when the case was in the study group and when CRP levels were increased (p = 0.05 and p = 0.001, respectively). CONCLUSIONS: We demonstrated that IL-6 levels are increased in the study group, especially in the operated patients, however, that high BMI and atopy have no effects on this fact and that atopy is not associated with IS in the clinical study.

Detection of hepatitis B virus deoxyribonucleic acid using real-time polymerase chain reaction method in pooled-plasma samples of Turkish blood donors.

BACKGROUND: The extent and the number of routine tests performed for blood donor screening to avoid infections transmitted through blood transfusion have been gradually increasing worldwide and is determined nationally. Following the publication of the new "blood and blood components regulation", the blood banking and transfusion system is through a reorganization stage in Turkey. The national guideline including the donor screening algorithms is to be published which requires national data to be created. The aim of this study is to investigate HBV DNA in pooled plasma samples of blood donors in Turkey, which is a middle endemicity country for HBV infection. STUDY DESIGN AND METHODS: Presence of HBV DNA was investigated using real-time polymerase chain reaction (RT-PCR) method in 187 pooled plasma samples prepared from 4484 blood donors, whose screening tests were found to be negative. The seropositivity for HBsAg of the blood donors in the study blood center is 2.2%. RESULTS: The rate of false-positivity of the RT-PCR method was found to be 1.6% for the mini pools and 0.04% for the individual blood donors. HBV DNA was not detected in any of the donor bloods. CONCLUSION: The hospital blood centers in Turkey still have a high proportion of first time donors and replacement donors; also seropositivity of HBsAg in Turkish blood donors is high compared to Europe and US. Our data pointed to the high false positivity rate of RT PCR method which needs to be evaluated in creating national donor screening algorithms.