Wonmok Lee

Comparison of matrix-assisted laser desorption ionization-time-of-flight mass spectrometry assay with conventional methods for detection of IMP-6, VIM-2, NDM-1, SIM-1, KPC-1, OXA-23, and OXA-51 carbapenemase-producing Acinetobacter spp., Pseudomonas aeruginosa, and Klebsiella pneumoniae.

Matrix-assisted laser desorption ionization-time-of-flight mass spectrometry assay was able to detect carbapenemase producers, including SIM-1 or OXA-51, within 4 hours using 20 μL of 0.5 g/L ertapenem solution as a substrate. This assay is more rapid and accurate than the modified Hodge test and 3-dimensional extract bioassay. Hence, it can be used an alternative test to identify carbapenemase-mediated carbapenem resistance in Gram-negative bacteria.

CTX-M-55-type extended-spectrum β-lactamase-producing Shigella sonnei isolated from a Korean patient who had travelled to China

We report a case of CTX-M-55-type extended-spectrum β-lactamase (ESBL)-producing Shigella sonnei infection in a 27-year-old Korean woman who had traveled to China. The patient was admitted to the hospital due to abdominal pain, watery diarrhea, and fever (39.3℃). S. sonnei was isolated from her stool specimens, and the pathogen was found to be resistant to cefotaxime due to CTX-M-55-type ESBL. Insertion sequence (IS)Ecp1 was found upstream of the blaCTX-M-55 gene. The blaCTX-M-55 gene was transferred from the S. sonnei isolate to an Escherichia coli J53 recipient by conjugation. Pulsed-field gel electrophoresis and Southern blotting revealed that the blaCTX-M-55 gene was located on a plasmid of approximately 130 kb.

Evaluation of VITEK mass spectrometry (MS), a matrix-assisted laser desorption ionization time-of-flight MS system for identification of anaerobic bacteria.

Background By conventional methods, the identification of anaerobic bacteria is more time consuming and requires more expertise than the identification of aerobic bacteria. Although the matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) systems are relatively less studied, they have been reported to be a promising method for the identification of anaerobes. We evaluated the performance of the VITEK MS in vitro diagnostic (IVD; 1.1 database; bioMérieux, France) in the identification of anaerobes. Methods We used 274 anaerobic bacteria isolated from various clinical specimens. The results for the identification of the bacteria by VITEK MS were compared to those obtained by phenotypic methods and 16S rRNA gene sequencing. Results Among the 249 isolates included in the IVD database, the VITEK MS correctly identified 209 (83.9%) isolates to the species level and an additional 18 (7.2%) at the genus level. In particular, the VITEK MS correctly identified clinically relevant and frequently isolated anaerobic bacteria to the species level. The remaining 22 isolates (8.8%) were either not identified or misidentified. The VITEK MS could not identify the 25 isolates absent from the IVD database to the species level. Conclusions The VITEK MS showed reliable identifications for clinically relevant anaerobic bacteria.

Polymorphisms in the Type IV Collagen Alpha3 Gene and the Risk of COPD

A number of genome-wide linkage analyses have identified the 2q33.3–2q37.2 region as the most likely to contain the genes that contribute to the susceptibility to chronic obstructive pulmonary disease (COPD). It was hypothesised that the type IV collagen α3 (COL4A3) gene, which is one of the genes located in the 2q33.3–2q37.2 region, may act as a low-penetrance susceptibility gene for COPD. To test this hypothesis, the association of COL4A3 -1162T>C, IVS2+12C>A, P141L, G162E, H451R, P574L and *315C>A polymorphisms with the risk of COPD was investigated in a case–control study of 311 COPD patients and 386 controls. The presence of at least one 451R allele was associated with a significantly higher risk of COPD compared with the 451 H/H genotype (adjusted odds ratio 1.48, 95% confidence interval (1.03–2.14)). When the subjects were stratified according to age and COPD severity, the 451R allele was associated with a significantly higher risk of COPD only in younger individuals with severe COPD (3.02 (1.37–6.67)). In conclusion, these findings suggest that the type IV collagen α3 gene contributes to the genetic susceptibility to chronic obstructive pulmonary disease.

Weissella confusa Bacteremia in an Immune-Competent Patient with Underlying Intramural Hematomas of the Aorta

Weissella confusa is a catalase-negative and gram-positive coccobacillus that is intrinsically resistant to vancomycin [1]. This species can cause infections, such as bacteremia, endocarditis, and abscess in immunocompromised patients [2-7]. Until now, reports on infections caused by W. confusa have been limited as this species has been frequently misidentified as Lactobacillus or Leuconostoc when identified using commercial kits [8]. Herein, we report the second case of W. confusa bacteremia in an immunocompetent patient from Korea, who had intramural hematomas of the aorta.

[A case of partial trisomy 15q25.3-qter].

A 15q25-qter partial trisomy characterized by pre or postnatal overgrowth, tall stature, macrocephaly and craniosynostosis has rarely been reported. The cause of overgrowth has been thought to be the triplication of the insulin-like growth factor 1 receptor (IGF1R) gene located on the 15q26.3. We report a patient with partial trisomy 15q25.3-qter showing mental retardation, developmental delay, macrocephaly, long narrow face, ptosis, high palate arch, scoliosis, clinodactyly and overgrowth. Additional material located on terminal 2q was found in karyotyping analysis. In bacterial artificial chromosome (BAC) clone-based-array comparative genomic hybridization (aCGH) analysis, a gain of 31 clones on 15q25.3-qter and a loss of 2 clones on 2q37.3 were observed. An extra copy of IGF1R gene was observed on derivative chromosome 2 in FISH analysis. In conclusion, the patient was diagnosed to have de novo 46,XX,der(2)t(2;15)(q37.3;q25.3) chromosome complement. Adequate genetic counseling and regular follow-ups would be needed for the patient.

Comparison of the Automated cobas u 701 Urine Microscopy and UF‐1000i Flow Cytometry Systems and Manual Microscopy in the Examination of Urine Sediments

The cobas u 701, a new automated image‐based urine sediment analyzer, was introduced recently. In this study, we compared its performance with that of UF‐1000i flow cytometry and manual microscopy in the examination of urine sediments.

Establishing Quality Control Ranges for Antimicrobial Susceptibility Testing of Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus: A Cornerstone to Develop Reference Strains for Korean Clinical Microbiology Laboratories

Quality control (QC) processes are being performed in the majority of clinical microbiology laboratories to ensure the performance of microbial identification and antimicrobial susceptibility testing by using ATCC strains. To obtain these ATCC strains, some inconveniences are encountered concerning the purchase cost of the strains and the shipping time required. This study was focused on constructing a database of reference strains for QC processes using domestic bacterial strains, concentrating primarily on antimicrobial susceptibility testing. Three strains (Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus) that showed legible results in preliminary testing were selected. The minimal inhibitory concentrations (MICs) and zone diameters (ZDs) of eight antimicrobials for each strain were determined according to the CLSI M23. All resulting MIC and ZD ranges included at least 95% of the data. The ZD QC ranges obtained by using the CLSI method were less than 12 mm, and the MIC QC ranges extended no more than five dilutions. This study is a preliminary attempt to construct a bank of Korean QC strains. With further studies, a positive outcome toward cost and time reduction can be anticipated.

The influence of vitamin C on the urine dipstick tests in the clinical specimens: a multicenter study.

Vitamin C may interfere with the results of urine dipstick tests. We investigated the incidence of urinary vitamin C and its interference with urine dipstick reagents using a vitamin C dipstick.

BRCA1/2 mutations, including large genomic rearrangements, among unselected ovarian cancer patients in Korea

Objective We performed small-scale mutation and large genomic rearrangement (LGR) analysis of BRCA1/2 in ovarian cancer patients to determine the prevalence and the characteristics of the mutations. Methods All ovarian cancer patients who visited a single institution between September 2015 and April 2017 were included. Sanger sequencing, multiplex ligation-dependent probe amplification (MLPA), and long-range polymerase chain reaction (PCR) were performed to comprehensively study BRCA1/2. The genetic risk models BRCAPRO, Myriad, and BOADICEA were used to evaluate the mutation analysis. Results In total, 131 patients were enrolled. Of the 131 patients, Sanger sequencing identified 16 different BRCA1/2 small-scale mutations in 20 patients (15.3%). Two novel nonsense mutations were detected in 2 patients with a serous borderline tumor and a large-cell neuroendocrine carcinoma. MLPA analysis of BRCA1/2 in Sanger-negative patients revealed 2 LGRs. The LGRs accounted for 14.3% of all identified BRCA1 mutations, and the prevalence of LGRs identified in this study was 1.8% in 111 Sanger-negative patients. The genetic risk models showed statistically significant differences between mutation carriers and non-carriers. The 2 patients with LGRs had at least one blood relative with breast or ovarian cancer. Conclusion Twenty-two (16.8%) of the unselected ovarian cancer patients had BRCA1/2 mutations that were detected through comprehensive BRCA1/2 genetic testing. Ovarian cancer patients with Sanger-negative results should be considered for LGR detection if they have one blood relative with breast or ovarian cancer. The detection of more BRCA1/2 mutations in patients is important for efforts to provide targeted therapy to ovarian cancer patients.