Hae-Sun Chung, Dongen Yong
Ann Clin Microbiol 2020 June, 23(2): 55-56. Published on 20 June 2020.
The official journal of the Korean Society of Clinical Microbiology, the Annals of Clinical Microbiology, set a goal to be indexed in Scopus in 2023. To achieve this, an improved manuscript management system has been established, starting with Volume 23, Issue 1 in 2020. The managing compant has been changed to DocuHut Co., LTD. (http://www.docuhut.com/), and both the journal’s website (www.acm.or.kr) and the submission system have been reorganized.
[in Korean]
Eun-Jung Cho, Eun Jin Lee, Younggil Cha, Nuri Lee, Ki Ho Hong, Hee Jin Huh, Young Joo Cha, Hyun Soo Kim
Ann Clin Microbiol 2020 June, 23(2): 57-66. Published on 20 June 2020.
Molecular diagnostic techniques are used for the diagnosis and monitoring of viral infections. The performance of the in vitro diagnostic assays is important for an accurate and prompt diagnosis. Positive clinical samples or reference materials (RMs) are essential for the development, validation, and verification of the assays for molecular diagnostics-based virus detection. Since it is difficult to obtain positive clinical samples, the need for RMs with required properties is increasing. In this review, the types, manufacturing methods, and verification of RMs for genetic testing of virus are discussed along with the producers involved in their production, sale, and distribution.
[in Korean]
Kibum Jeon, Seung Soon Lee, Hyun Soo Kim, Jae-Seok Kim, Young Kyung Lee, Wonkeun Song, Han-Sung Kim
Ann Clin Microbiol 2020 June, 23(2): 67-72. Published on 20 June 2020.
Background: Carbapenem-resistant Acinetobacter baumannii (CRAB) has emerged as an important nosocomial pathogen.The purpose of this study was to determine the effective methods for performing surveillance cultures of CRAB.
Methods: Nasal and rectal swabs were obtained concurrently from hospitalized intensive care unit patients colonized with CRAB. All the samples were inoculated in CHROMagar Acinetobacter medium with CR102 (CHROMagar), MacConkey agar medium supplemented with 5 µg/mL imipenem (MCA-IPM), and triptic soy broth medium supplemented with 5 µg/ mL imipenem (TSB-IPM). CRAB detection rates for each sample were compared.
Results: The CRAB detection rate in either one of the nasal or rectal swabs from the 37 patients tested were 89.2% (33/37) with the use of CHROMagar, 78.4% (29/37) with the use of MCA-IMP, and 86.5% (32/37) with the use of TSB-IMP.
Conclusion: We determined that concurrent use of both nasal and rectal swabs and CHROMagar could be an effective method for CRAB surveillance cultures.
Viga Rolly, Eun Jung Lee, Eun-Jeong Yoon, Seok Hoon Jeong
Ann Clin Microbiol 2020 June, 23(2): 73-80. Published on 20 June 2020.
Background: Ideal dose of the antimicrobials should be decided by considering their killing dynamics since sufficient elimination of the causative microorganisms is critical for proper antimicrobial treatment. In this study, the bactericidal activities of carbapenems by resistance mechanisms were assessed for carbapenem-resistant Pseudomonas aeruginosa.
Methods: Minimal inhibition concentrations (MICs) of carbapenems were determined by broth dilution method and the resistance mechanisms were identified by PCR and DNA sequencing. The expression levels of efflux pumps were determined by reverse transcriptase real-time PCR. Time-kill curves were plotted by time-course numeration of the viable cells grown under imipenem and meropenem at 1× and 4×MICs, respectively.
Results: One P. aeruginosa strain was susceptible, whereas three were resistant to carbapenems by defective OprD, efflux pump overproduction, and/or IMP-6 production. The susceptible strain had imipenem and meropenem MICs of 2 and 1 mg/L, respectively. The MICs were elevated by eight-fold by defective OprD, 16- and 32-fold by the pump overproduction, and four- and >64-fold by the combination of two determinants and the IMP-6 carbapenemase. While both the carbapenems showed time-dependent bactericidal activity to the susceptible isolate, either of the carbapenem-resistant determinants, such as decreased membrane permeability, carbapenemase production, or the defective OprD, presented concentration-dependent bacteriostatic activity.
Conclusion: Different killing dynamics of the carbapenems were observed depending on the resistance determinants, and the results would guide a proper treatment strategy for the patients using these drugs.
Jun Sung Hong, Byeol Yi Park, Dokyun Kim, Kunhan Kim, Kyoung Hwa Lee, Nan Hyoung Cho, Seok Hoon Jeong
Ann Clin Microbiol 2020 June, 23(2): 81-92. Published on 20 June 2020.
Background: The prevalence of carbapenemase-producing Enterobacteriaceae (CPE), especially the KPC-2-producing Klebisella pneumoniae, is rapidly increasing and becoming a menace to global public health. This study aims to present the molecular epidemiology of the KPC-2-producing K. pneumoniae isolates emerged in a tertiary hospital in South Korea and describe its clinical significance.
Methods: This study included carbapenem-resistant K. pneumoniae isolates collected from a tertiary hospital from April to December in 2018. Antimicrobial susceptibility of K. pneumoniae isolates was tested using disk diffusion method. PCR and DNA sequence analyses were performed to identify the resistance genotype. In addition, the molecular epidemiology was investigated using pulsed-field gel electrophoresis (PFGE) and multilocus sequencing typing (MLST).
Results: Total 100 KPC-2-producing K. pneumoniae isolates were collected, which were mainly classified into two pulsotypes according to the XbaI restriction digestion pattern by PFGE analysis (pulsotype A, n = 31; pulsotype B, n = 63). The isolates exhibiting pulsotype A belonged to ST395 and the remaining isolates exhibiting pulsotype B were attributed to ST307 by MLST analysis.
Conclusion: This study investigated clinical information and molecular bacterial profiles for KPC-2-producing K. pneumoniae isolates. These findings indicate that the proper infection control activities are needed to prevent the spread of multidrug-resistant organisms such as CPE, which could cause high mortality in clinical field.
[in Korean]
Sang-wook Kim, Young-Hee Park, Young Jin Ko, Yoon Ho Kim, Chang Hyun Kim, Chae Seung Lim
Ann Clin Microbiol 2020 June, 23(2): 93-104. Published on 20 June 2020.
Background: The disease burden caused by Mycobacterium tuberculosis (MTB) complex continues to decrease in most countries. However, the diseases caused by the nontuberculous mycobacteria (NTM) become a public health problem. This study aimed to compare the diagnostic accuracy of three real-time PCR assays: AdvanSure TB/NTM real-time PCR kit (AdvanSure; LG Chem., Korea), Genedia MTB/NTM detection kit (Genedia; Green Cross MS, Korea), and PowerChek MTB/NTM Real-time PCR kit (PowerChek; Kogenebiotech, Korea) for the detection of MTB complex and NTM.
Methods: Total 102 acid-fast bacilli (AFB) smear-positive and 177 smear-negative specimens from Korea University Medical Center, Guro Hospital, were enrolled. The AFB smear-positive and negative specimens were collected from November 2016 to October 2017 and November to December 2018, respectively. DNA extraction was performed using Genedia Mycobacteria DNA prep Kit (Green Cross MS, Korea). The statistical analysis was performed using MedCalc 18.11.6 (MedCalc Software, Belgium).
Results: Among 261 specimens, 64 showed MTB complex growth and 28 exhibited NTM growth. The sensitivity, specificity, positive predictive value, and negative predictive value of AdvanSure/Genedia/PowerChek kits for MTB were 96.9%/95.3%/96.9%, 98.5%/99.5%/98.5%, 58.9%/80.9%/58.9%, and 99.9%/99.9%/99.9%. Whereas those for NTM detection were 81.5%/44.4%/88.9%, 99.6%/100.0%/98.7%, 57.3%/100.0%/32.8% and 99.9%/99.6%/99.9%, respectively. The area under the receiver operating characteristic curve of AdvanSure and PowerChek for NTM detection was statistically different from that of Genedia (P<0.0001).
Conclusion: Three real-time PCR assays were reliable for MTB complex in AFB-positive and -negative specimens. There was a difference between these three reagents for the accuracy of NTM detection.
[in Korean]
Chorong Hahm, Min-Kyung So, Hae-Sun Chung, Miae Lee
Ann Clin Microbiol 2020 June, 23(2): 105-116. Published on 20 June 2020.
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 culture-positive 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.
[in Korean]
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