Annals of Clinical Microbiology, The official Journal of the Korean Society of Clinical Microbiology


Weeks in Review


Weeks to Publication
Indexed in KCI, KoreaMed, Synapse, DOAJ
Open Access, Peer Reviewed
pISSN 2288-0585 eISSN 2288-6850

March, 2019. Vol. 22 No. 1.

Original article

Differences in Antimicrobial Resistance Phenotypes by the Group of CTX-M Extended-Spectrum β-Lactamase

Bareum Gwon, Eun-Jeong Yoon, Dokyun Kim, Hyukmin Lee, Jong Hee Shin, Jeong Hwan Shin, Kyeong Seob Shin, Young Ah Kim, Young Uh, Hyun Soo Kim, Young Ree Kim, Seok Hoon Jeong

Ann Clin Microbiol 2019 March, 22(1): 1-8. Published on 20 March 2019.

Background: Escherichia coli and Klebsiella pneumoniae clinical isolates producing CTX-M extended- spectrum β-lactamases (ESBLs) were assessed for antimicrobial resistance phenotypes varied by group of enzymes.

Methods: A total of 1,338 blood isolates, including 959 E. coli and 379 K. pneumoniae, were studied. All the strains were collected between January and July 2017 from eight general hospitals in South Korea. The species were identified by matrix-assisted laser desorption ionization-time of flight mass spectrometry. Antimicrobial susceptibilities were determined by disk diffusion methods and ESBL phenotypes by double-disk synergy tests using disks containing cefotaxime, ceftazidime, cefepime, aztreonam, and clavulanic acid (CA). The genes for β-lactamases were identified by PCR and sequencing.

Results: Of total microbes, 31.6% (303/959) E. coli and 24.0% (91/379) K. pneumoniae were resistant to cefotaxime and 28.1% (269/959) E. coli and 20.1% (76/379) K. pneumoniae were CTX-M-type ESBL producers. Among the detected CTX-M ESBLs, 58.0% (156/269) in E. coli and 86.8% (66/76) in K. pneumoniae belonged to group 1, 46.8% (126/269) in E. coli and 14.5% (11/76) in K. pneumoniae were group 9. Ten E. coli and one K. pneumoniae isolates co-produced both groups of CTX-M ESBL. The group 1 CTX-M producers had a higher level of resistance to cefotaxime, ceftazidime, cefepime, and aztreonam and exhibited stronger synergistic activities when combined with CA compared to group 9. 

Conclusion: ESBL phenotypes differ by CTX-M ESBL group and phenotype testing with drugs including 4th generation cephalosporins and monobactams is critical for screening CTX-M-producers with better sensitivity.

Original article

Development and Evaluation of Multiplex PCR for the Detection of Carbapenemase-Producing Enterobacteriaceae

Si Hyun Kim, Il Kwon Bae, Na Young Kim, Sae Am Song, Sunjoo Kim, Joseph Jeong, Jeong Hwan Shin

Ann Clin Microbiol 2019 March, 22(1): 9-13. Published on 20 March 2019.

Background: The isolation of carbapenemase-producing Enterobacteriaceae (CPE) has become increasingly common. Continuous surveillance for these organisms is essential because their infections are closely related to outbreaks of illness and are associated with high mortality rates. The aim of this study was to develop and evaluate multiplex PCR as a means of detecting several important CPE genes simultaneously.

Methods: We aimed to develop a multiplex PCR that could detect seven CPE genes simultaneously. The multiplex PCR was composed of seven primer sets for the detection of KPC, IMP, VIM, NDM-1, GES, OXA-23, and OXA-48. We designed different PCR product sizes of at least 100 bp. We evaluated the performance of this new test using 69 CPE-positive clinical isolates. Also, we confirmed the specificity to rule out false-positive reactions by using 71 carbapenem-susceptible clinical strains.

Results: A total of 69 CPE clinical isolates showed positive results and were correctly identified as KPC (N=14), IMP (N=13), OXA-23 (N=12), OXA-48 (N=11), VIM (N=9), GES (N=5), and NDM (N=5) by the multiplex PCR. All 71 carbapenem-susceptible clinical isolates, including Enterococcus faecalis, Escherichia coli, Klebsiella pneumoniae, Acinetobacter baumannii, and Pseudomonas aeruginosa, showed negative results.

Conclusion: This multiplex PCR can detect seven CPE genes at a time and will be useful in clinical laboratories.

[in Korean]

Original article

Genetic Variants and Haplotypes in the IL10 Gene and Their Association with Opportunistic Infections among HIV-Infected Patients in Korea in the Era of Highly Active Antiretroviral Therapy

In-Suk Kim, Hyung-Hoi Kim, Chulhun L. Chang

Ann Clin Microbiol 2019 March, 22(1): 14-22. Published on 20 March 2019.

Background: Genetic variants and haplotypes of the interleukin-10 (IL10) gene have been shown to affect clinical outcomes, including the incidence of opportunistic infections (OIs), in HIV-infected patients. This study investigated the effect of IL10 gene variants on susceptibility to OIs in HIV-infected Korean patients in the era of highly active antiretroviral therapy (HAART).

Methods: Eighty-five HIV-infected patients receiving HAART were enrolled in the study. OIs were diagnosed based on the published criteria of the Korean Society for AIDS. Three promoter SNPs and four haplotype-tagging SNPs (htSNPs) of IL10 were selected and genotyped. The haplotypes were reconstructed according to the genotyping data and linkage disequilibrium (LD) status of these SNPs.

Results: During the study, 38 OIs developed in 23 of the 85 patients (27.1%), at a rate of 1.7 episodes/ patient. Carrying the minor alleles at the rs1518111, rs3024490, and rs1800871 SNPs had a protective effect against OIs (adjusted P=0.035). Among the seven assessed variants, only three possible haplotypes were observed. The second most common haplotype, which was composed of the rs1518111 minor allele and the rs3021094 major allele showed a protective effect against OIs (P=0.0153).

Conclusion: This study demonstrated that some IL10 genetic variants and haplotypes are associated with protective effects against OIs in the era of HAART. These data suggest the potential of two htSNPs, rs1518111 and rs3021094, as markers revealing the genetic association of IL10 in Koreans. This is the first report on the association of IL10 with OIs in HIV-infected Korean patients in the era of HAART.

Case report

Bacterial Endocarditis Caused by Abiotrophia defectiva in a Healthy Adult: A Case Report with Literature Review

Hyunggon Je, Duyeal Song, Chulhun L. Chang

Ann Clin Microbiol 2019 March, 22(1): 23-27. Published on 20 March 2019.

Infective endocarditis caused by Abiotrophia defectiva is rarely encountered. A 67-year-old male transferred from a local hospital presented with severe dyspnea and pulmonary edema. Preoperative transthoracic echocardiography revealed severe mitral regurgitation with large vegetation. Blood cultures grew A. defectiva, a gram positive, nutritionally deficient streptococcus variant. Emergent mitral valve replacement through right thoracotomy was performed, and after completing six weeks of antibiotic combination therapy (vancomycin, ampicillin, and gentamicin), the patient recovered fully. Because of the need for prompt surgical treatment and long-term antibiotic therapy and lack of laboratory experience with the organism, physicians and laboratory workers should pay close attention to the possibility of A. defectiva infective endocarditis when gram positive cocci are detected in blood cultures.