Verification of the Performance of the Panbio COVID-19 Ag Rapid Test Device for Implementation in the Clinical Laboratory / 이화의대지

Objectives@#The Panbio COVID-19 Ag Rapid Test Device (Panbio COVID-19 Ag, Abbott Rapid Diagnostics) is a lateral flow immunochromatographic assay targeting the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) nucleoprotein in nasopharyngeal specimens for the diagnosis of coronavirus disease 2019 (COVID-19). This study aimed to verify the performance of the Panbio COVID-19 Ag for implementation in clinical laboratories. @*Methods@#Sixty nasopharyngeal swab specimens (30 positive and 30 negative) dipped in transport medium, and COVID-19 was confirmed using real-time RT-PCR using Allplex SARS-CoV-2 assay (Seegene), were tested using the Panbio COVID-19 Ag. Reproducibility was evaluated using positive and negative control materials. Sensitivity and specificity were calculated based on the results of realtime RT-PCR as the standard test method. @*Results@#Reproducibility was confirmed by the consistent results of repeated tests of the quality control materials. The overall sensitivity and specificity of Panbio COVID-19 Ag were 50.0% and 100.0%, respectively. Panbio COVID-19 Ag demonstrated high sensitivity (88.2%) in analyzing the detection limit cycle threshold (Ct) value of 26.67 provided by the manufacturer as a positive criterion, and the sensitivity was 100.0% for the positive criterion of Ct values <25, although it was less sensitive for Ct ≥ 25. @*Conclusion@#Considering the high sensitivity for positive samples with Ct values <25 and the rapid turnaround of results, Panbio COVID-19 Ag can be used in clinical laboratories to diagnose COVID-19 in limited settings.

A rare, likely pathogenic GCK variant related to maturity-onset diabetes of the young type 2: A case report

Maturity-onset diabetes of the young (MODY) is caused by autosomal dominant pathogenic variants in one of 14 currently known monogenic genes. Characteristics of patients with MODY include early-onset clinical disease with a family history of diabetes and negative autoantibodies and may present with heterogeneous phenotypes according to the different subtypes. Here, we report a patient with early-onset diabetes who presented asymptomatic mild fasting hyperglycemia with the absence of autoantibodies. She was diagnosed with glucokinase (GCK)-MODY caused by a GCK variant, c.1289T>C (p.L430P), identified by targeted gene-panel testing, and the affected father had the same variant. We interpreted this rare missense variant as a likely pathogenic variant and then she stopped taking oral medication. This case highlights the usefulness of genepanel testing for accurate diagnosis and appropriate management of MODY. We also note the importance of familial genetic testing and genetic counseling for the proper interpretation of MODY variants.

Evaluation of the AdvanSure TB/NTM Plus Real-Time PCR Assay for the Simultaneous Detection of Mycobacterium tuberculosis and Nontuberculous Mycobacteria from Clinical Specimens / 대한임상미생물학회지

Background@#The AdvanSure TB/NTM plus real-time PCR (AdvanSure plus PCR; LG Chem., Korea) assay has been developed to increase the diagnostic sensitivity of nontuberculous mycobacteria (NTM) compared with the currently used the AdvanSure TB/NTM real-time PCR (AdvanSure PCR;LG Chem., Korea) assay. In this study, we aimed to evaluate the performance of the AdvanSure plus PCR comparing the results with mycobacterial culture and the AdvanSure PCR. @*Methods@#Patients (n=199) with suspected NTM or Mycobacterium tuberculosis complex (MTC) were tested using AdvanSure plus PCR, AdvanSure PCR, acid-fast bacilli staining, and mycobacteria culture. Additionally, 200 DNA samples (n=100, MTC and n=100, NTM) were obtained from positive MTC or NTM cultures for evaluation using the AdvanSure plus PCR assay. @*Results@#The two real-time PCR systems showed a 94.0% (n=187/199) concordance rate (Kappa=0.94). Based on culture results, the sensitivity and specificity for the detection of MTC were 100% (45/45) and 83.8% (129/154) using AdvanSure plus PCR, and 100.0% (45/45) and 99.3% (153/154) using AdvanSure PCR, respectively. The sensitivity and specificity for NTM detection were 68.0% (n=17/25) and 90.2% (n=157/174), respectively, with AdvanSure plus PCR, and 64.0% (n=16/25) and 95.4% (n=166/174), respectively, using AdvanSure PCR. With culturepositive samples, AdvanSure plus PCR tested positive for 100% of both the MTC and NTM specimens. Seven (out of 200) culture-positive samples tested positive for both MTC and NTM using the AdvanSure plus PCR. @*Conclusion@#AdvanSure plus PCR had increased sensitivity but decreased specificity compared with AdvanSure PCR for the detection of NTM. The AdvanSure plus PCR assay can be used for the simultaneous detection of MTC and NTM in direct specimen and culture.

Anaplastic Large Cell Lymphoma with Massive Eosinophilia and Complex Karyotype Initially Misdiagnosed as Chronic Eosinophilic Leukemia

We report a patient with massive eosinophilia and a complex karyotype that was initially misdiagnosed as chronic eosinophilic leukemia (CEL), but later diagnosed as anaplastic large cell lymphoma (ALCL) masked by massive eosinophilia. The complex karyotype observed at initial diagnosis remained unchanged later, after the evidence of bone marrow involvement of ALCL was obtained. At diagnosis, genetic aberrations corresponding to metaphase cytogenetics were not identified by interphase fluorescence in situ hybridization, although abnormal results were noted at follow-up. Together, these observations indicate that the complex karyotype at initial work-up has been derived from a low proportion of lymphoma cells with high mitotic ability that were not identified by microscopy, rather than from massive eosinophils. These findings suggest that our patient had ALCL with secondary eosinophilia rather than CEL since initial diagnosis.

Neutrophilic Leukemoid Reaction Associated with Malignancy Initially Suspected as Chronic Neutrophilic Leukemia

Although neutrophilia can manifest from various causes, it is important to be able to distinguish chronic neutrophilic leukemia (CNL) from neutrophilic leukemoid reactions (NLR). In this paper, we describe four cases of leukocytosis with neutrophilia, including one case of CNL with a T618I mutation in colony stimulating factor 3 receptor (CSF3R) and three cases of NLR associated with malignancy or sepsis, which were initially suspected as CNL. Of the three NLR cases, one was associated with ovarian cancer, one with monoclonal gammopathy of undetermined significance and one with multiple myeloma with sepsis. This study demonstrated that confirming the clonality of myeloid cells with CSF3R T618I could contribute to making an accurate differential diagnosis between CNL and NLR in patients with solid cancers or plasma cell neoplasms caused by paraneoplastic syndromes and/or infection.

Effects of Blood Volume Monitoring on the Rate of Positive Blood Cultures from the Emergency Room / 대한임상미생물학회지

BACKGROUND: Blood cultures are essential in diagnosing and treating sepsis. There are several factors that affect the diagnostic yield of blood cultures such as the number of blood sampling episodes, the incubation period, the type and volume of culture media, and the amount of blood drawn. This study aimed to elucidate whether monitoring the volume of blood drawn with an educational intervention could affect the diagnostic quality of blood cultures. METHODS: We implemented quality monitoring for the blood volume drawn during blood culture testing for adults in an emergency room. We instructed the nurses in the emergency room to draw the optimal amount of blood and to reduce the number of blood culture sets from three to two. We analyzed and compared the amount of blood drawn, the rate of positive blood cultures, the contamination rate, and time to positivity (TTP) between 908 patients pre-intervention and 921 patients post-intervention. RESULTS: The amount of blood drawn increased from 0.7±0.3 mL per bottle (pre-intervention) to 6.5±1.7 mL per bottle (post-intervention) (P<0.0001). The rate of positive blood culture post-intervention (12.14%) was higher than that pre-intervention (6.65%) (P<0.0001). The contamination rate post-intervention (1.82%) was also significantly greater than that pre-intervention (0.60%) (P<0.0001). Except for anaerobes, there was no significant difference in the distribution of microorganisms between the pre- and post-intervention periods. The TTP for anaerobe bottles post-intervention was significantly shorter than that of pre-intervention (16.1±16.3 versus 18.6±18.3 h). CONCLUSION: This study suggests that continuing education about adequate blood volume and aseptic techniques is needed to increase the rate of positive blood cultures and reduce the contamination rate of blood cultures.