Hae Seon Nam

Evaluation of New Rapid Antigen Test for Detection of Pandemic Influenza A/H1N1 2009 Virus

ABSTRACT We evaluated the SD Bioline Influenza Ag A/B/A(H1N1) Pandemic test kit and compared it with real-time reverse transcriptase PCR (RT-PCR) for its ability to detect H1N1 2009. The sensitivity and specificity of the test kit for H1N1 2009 were 77% and 100%, respectively.

Evaluation of Peptide Nucleic Acid Probe-based Real-time PCR for Detection of Mycobacterium tuberculosis Complex and Nontuberculous Mycobacteria in Respiratory Specimens

Background A peptide nucleic acid (PNA) probe-based real-time PCR (PNAqPCR™ TB/NTM detection kit; PANAGENE, Korea) assay has been recently developed for the simultaneous detection of Mycobacterium tuberculosis complex (MTBC) and nontuberculous mycobacteria (NTM) in clinical specimens. The study was aimed at evaluation of the performance of PNA probe-based real-time PCR in respiratory specimens. Methods To evaluate potential cross-reactivity, the extracted DNA specimens from Mycobacterium species and non-mycobacterial species were tested using PNA probe-based real-time PCR assay. A total of 531 respiratory specimens (482 sputum specimens and 49 bronchoalveolar washing fluid specimens) were collected from 230 patients in July and August, 2011. All specimens were analyzed for the detection of mycobacteria by direct smear examination, mycobacterial culture, and PNA probe-based real-time PCR assay. Results In cross-reactivity tests, no false-positive or false-negative results were evident. When the culture method was used as the gold standard test for comparison, PNA probe-based real-time PCR assay for detection of MTBC had a sensitivity and specificity of 96.7% (58/60) and 99.6% (469/471), respectively. Assuming the combination of culture and clinical diagnosis as the standard, the sensitivity and specificity of the new real-time PCR assay for detection of MTBC were 90.6% (58/64) and 99.6% (465/467), respectively. The new real-time PCR for the detection of NTM had a sensitivity and specificity of 69.0% (29/42) and 100% (489/489), respectively. Conclusions The new real-time PCR assay may be useful for the detection of MTBC in respiratory specimens and for discrimination of NTM from MTBC.

Evaluation of a new immunochromatographic assay kit for the rapid detection of norovirus in fecal specimens.

Rapid and accurate detection of norovirus is essential for the prevention and control of norovirus outbreaks. This study compared the effectiveness of a new immunochromatographic assay kit (SD BIOLINE Norovirus; Standard Diagnostics, Korea) and real-time reverse transcription-PCR (RT-PCR) for detecting norovirus in fecal specimens. Compared with real-time RT-PCR, the new assay had sensitivity, specificity, positive predictive value, and negative predictive value of 76.5% (52/68), 99.7% (342/343), 98.1% (52/53), and 95.5% (342/358), respectively. The sensitivity of the assay was 81.8% (18/22) for GII.3 and 75.7% (28/37) for GII.4. None of the 38 enteric virus-positive specimens (3 for astrovirus, 5 for enteric adenovirus, and 30 for rotavirus) tested positive in the cross-reactivity test performed by using this assay. The new immunochromatographic assay may be a useful screening tool for the rapid detection of norovirus in sporadic and outbreak cases; however, negative results may require confirmatory assays of greater sensitivity.

Evaluation of peptide nucleic acid array for the detection of hepatitis B virus mutations associated with antiviral resistance

A major problem of long-term antiviral therapy in chronic hepatitis B patients is the emergence of hepatitis B virus (HBV) mutations associated with drug resistance. Recently, a new array using peptide nucleic acids (PNAs), which are synthetic nucleic acid analogues, was developed for the detection of HBV mutations at six different codon positions associated with lamivudine (LAM) and adefovir (ADV) resistance. We compared the PNA array with direct sequencing and reverse hybridization (INNO-LiPA) in 73 samples obtained from chronic hepatitis B patients. The PNA array detected mutations associated with LAM and/or ADV resistance in 60 (82.2%) of the 73 samples. The overall concordance rate of PNA array and INNO-LiPA compared with direct sequencing was 99.5% and 98.2%, respectively. The rate of complete concordance between PNA array and INNO-LiPA was 92.7%. The PNA array assay results were comparable with INNO-LiPA for detection of HBV mutations associated with antiviral resistance.

Comparison of PNA probe-based real-time PCR and Cobas TaqMan MTB for detection of MTBC

We compared the sensitivities and specificities of peptide nucleic acid (PNA) probe-based real-time PCR (PNAqPCR™ TB/NTM) and Cobas TaqMan MTB assays for detection of Mycobacterium tuberculosis complex (MTBC) in clinical specimens. A total of 425 clinical specimens including 360 respiratory specimens and 65 non-respiratory specimens were evaluated for comparative analysis. In respiratory specimens, the sensitivity of TaqMan MTB and PNAqPCR assay for detection of MTBC was 82.9% and 91.5%, respectively. In non-respiratory specimens, the sensitivity of the TaqMan MTB and PNAqPCR assay was 23.1% and 76.9%, respectively. Overall, the sensitivity and specificity of the TaqMan MTB assay for detection of MTBC was 76.9% and 100%, respectively. The PNAqPCR assay had a sensitivity and specificity of 90% and 99.7%, respectively.

Efficacy of Intravenous Immunoglobulin Therapy in Childhood Atopic Dermatitis

Objective: Atopic dermatitis (AD) is a chronic inflammatory skin disease with significant morbidity, and for which there is a need for safe and effective alternative therapies. Although a few observations on the efficacy of intravenous immunoglobulin (IVIG) in AD have been reported, clinical evidence of effectiveness from controlled trials is lacking. Therefore, the purpose of this study was to clarify whether IVIG therapy (1.0 g/kg body weight at each monthly visit for 6 months) is effective in childhood atopic dermatitis and to analyze the clinical characteristics of IVIG responses in this disease. Methods: Forty three atopic dermatitis patients who had characteristic clinical features of atopic dermatitis were included in this study. The patients received an injection of IVIG at 1.0 g/kg body weight at each monthly visit for 6 months. Laboratory tests were performed for blood chemistry, total immunoglobulin E, immunoglobulin G/immunoglobulin A/immunoglobulin M, blood eosinophil count, and C-reactive protein. Results: In total forty three atopic dermatitis patients, only 14 patients completely underwent 6 cycles, but other 29 patients incompletely (1–5 cycles). In the 14 patients, there were just 13 records of scoring atopic dermatitis (SCORAD) index. The mean SCORAD score in the 13 patients was 39.6± 24.4. SCORAD score decreased significantly (initial SCORAD, 39.6± 24.4; final SCORAD, 21.3± 15.6; P= 0.016). Conclusion: IVIG therapy may be recommended in the treatment of recalcitrant atopic dermatitis. In addition, further investigation on predictive markers for responses of IVIG therapy in atopic dermatitis may be needed.