Yeon-Joon Park, Wonkeun Song
Ann Clin Microbiol 2013 September, 16(3): 111-119. Published on 20 September 2013.
The Clinical and Laboratory Standards Institute (CLSI) and the European Committee on Antimicrobial Susceptibility Testing (EUCAST) have recently revised the susceptibility interpretive criteria of oxyimino-β-lactams and carbapenems for Enterobacteriaceae. According to the new criteria, susceptibility testing results are sufficient to detect extended-spectrum β-lactamases (ESBLs) and carbapenemases; it is not necessary to perform ESBL or carbapenemase detection tests for therapeutic purposes. Thus, it has been recommended that these related tests be performed only for infection control. These changes in the susceptibility guidelines are supported by some clinical cases and the results of pharmacodynamic and animal studies. However, differences still exist between the breakpoints established by the CLSI and EUCAST with regard to some oxyimino-β-lactam and carbapenem antibiotics, in particular, the breakpoints for ceftazidime and cefepime established by the CLSI are higher than those established by the EUCAST. Also, similar numbers of successful and unsuccessful cases have been reported regarding the use of cephalosporins or carbapenems in treating infections caused by low-minimal inhibitory concentration (MIC) ESBL-producers or low-MIC carbapenemase-producers. Finally, routine susceptibility test methods are not as accurate as research-purpose test methods, showing differences in MICs ranging approximately from 1 to 8 μg/mL. In conclusion, it is strategically prudent to continue to perform ESBL and carbapenemase detection tests and to avoid the use of the corresponding antimicrobial agents for the treatment of ESBL- or carbapenemase-producing bacterial infections.
[in Korean]
Youngsik Lim, Yangsoon Lee, Younghee Seo, Jong Hwa Yum, Dongeun Yong, Kyungwon Lee, Yunsop Chong
Ann Clin Microbiol 2013 September, 16(3): 120-125. Published on 20 September 2013.
Background: Gram-negative bacilli can be stored in cystine tryptic agar (CTA) at room temperature for over 1 year, but we experienced a loss of imipenem resistance among VIM-2-producing isolates. The aims of this study were to determine the frequency of loss of IMP-1 and VIM-2 genes during storage in CTA at room temperature and to document any change in the MIC of antimicrobial agents and the location of the gene.
Methods: Bacteria were isolated from clinical specimens at Severance Hospital collected from 1995-2000. Modified Hodge and double disk synergy tests were performed for screening of MBL-production isolates, and blaIMP-1 and blaVIM-2 were detected by PCR. Loss of resistance was tested in CTA at room temperature. PFGE and hybridization using a blaVIM-2 probe were carried out to determine the location of the VIM-2 gene.
Results: When VIM-2- and IMP-1-producing strains of eight P. aeruginosa and two Acinetobacter spp. were stored in CTA at room temperature, some isolates lost imipenem resistance after 3 days and 90% lost resistance after 15 weeks. Loss of resistance genes resulted in a decrease of the MIC of imipenem from 32-128 μg/mL to 0.5-8 μg/mL for P. aeruginosa, and from 32 μg/mL to 0.25-4 μg/mL for Acinetobacter spp. Hybridization of I-CeuI and S1-digested and PFGE suggested that VIM-2 genes are located on approximately 50-100 kb or 400 kb plasmids.
Conclusion: Isolates may lose resistance genes when stored in CTA at room temperature. Therefore, it is necessary for MBL-production tests including the Modified Hodge test and double disk synergy test and detection of MBL genes.
[in Korean]
In-Ho Jang, Soon Deok Park, Young Uh, Gyu-sang Lee, Jong-Bae Kim, Il Choi
Ann Clin Microbiol 2013 September, 16(3): 126-133. Published on 20 September 2013.
Background: Multi-drug resistant (MDR) Acinetobacter baumannii has emerged as a significant infectious agent in hospitals worldwide. The purpose of this study was to determine the molecular characterization of MDR A. baumannii clinical isolates.
Methods: Two hundred eighty-five strains of non-duplicated A. baumannii collected from March to November 2011 from a university hospital laboratory located in the Wonju area of the Gangwon province of Korea were analyzed for MDR genes.
Results: All of the 285 imipenem-resistant A. baumannii isolates were encoded by a blaOXA-23-like gene, and all isolates with the blaOXA-23-like gene had the upstream element ISAba1. The 16S rRNA methylase gene armA was detected in 153 (50.2%) clinical isolates, but rmtA, rmtB, rmtC, rmtD and npmA were not detected in any isolates in the present study. The gene encoding aac(6′)-Ib was the most prevalent aminoglycoside-modifying enzyme. The sequencing data for the quinolone resistance-determining region of gyrA and parC revealed the presence of Ser (TCA) 83 to Leu (TTA) and Ser (TCG) 80 to Leu (TTG) substitutions. All but one of the 285 A. baumannii isolates showed similar band patterns on repetitive extragenic palindromic-PCR profiles.
Conclusion: The molecular characteristics of the resistance genes of MDR A. baumannii isolates obtained from the Wonju area of Gangwon province were similar to those of other areas in Korea.
[in Korean]
Young-Eun Kim, Hee Jae Huh, Yu-Yean Hwang, Nam Yong Lee
Ann Clin Microbiol 2013 September, 16(3): 134-139. Published on 20 September 2013.
Background: Due to a reduction in the number of parasite infections, attention paid to the importance of intestinal parasites has decreased. However, intestinal parasite infections remain ubiquitous and have reappeared as a growing problem in recent decades due to changing lifestyles such as increased overseas travel. In this study, we evaluated trends in intestinal parasite infection using stool examination in a single institute.
Methods: From January 2003 to December 2012, we reviewed all stool examination results performed at Samsung Medical Center. Fecal examinations were performed by formalin-ether sedimentation.
Results: A total 429,866 stool examinations were performed resulting in 14,672 cases with positive findings of helminth eggs or protozoan cysts, of which the positive rate was 3.41% on average. The annual positive rate decreased from 5.68% in 2003 to 2.43% in 2012. The positive rate of intestinal parasites, excepting Endolimax nana and Entamoeba coli, was 1.52% on average. Positive rates decreased from 2.13% to 1.10% for helminth egg detections and from 2.55% to 1.30% for protozoan cyst detections during the same time period. Among nematodes, Trichuris tricuria was the most common and had an increasing positive rate after 2010. Clonorchis sinensis was the most prevalent trematode parasite, with an annual average of 528 cases.
Conclusion: Infection rates of intestinal parasites have decreased over the last 10 years. However, Trichuris tricuria has reappeared and has become a major contributor to parasite infections. Further education and control efforts are needed for greater prevention and eventual eradication of parasitic infections.
[in Korean]
Ji Yeon Sohn, Kyung Sun Park, Ji-Youn Kim, Chang-Seok Ki, Nam Yong Lee
Ann Clin Microbiol 2013 September, 16(3): 140-144. Published on 20 September 2013.
Background: Xpert Flu (Cepheid, USA) allows for fully automated real-time RT-PCR using a single-use disposable cartridge. The aim of this study was to evaluate Xpert Flu for the detection of influenza A virus and subtype A/H1N1/2009 pandemic virus.
Methods: We conducted a prospective comparison study for Xpert Flu with the RealTime ready Influenza A/H1N1 Detection Set (Roche Diagnostics, Germany). Analytical specificities of the assays were determined by testing commonly encountered respiratory viral pathogens, including parainfluenza virus type 1/2/3, rhinovirus A, rhinovirus B, metapneumovirus, adenovirus, and coronavirus. The analytical sensitivities and workflow of both methods were also assessed.
Results: A total of 102 consecutive clinical specimens were tested by both methods. Total agreement between the two methods was estimated to be 99.0% (101/102): 11 A/H1N1/2009 and 3 seasonal influenza A by the RealTime ready Influenza A/H1N1 Detection Set; 10 and 3 by Xpert Flu. No cross-reactivity was observed between influenza A/H1N1/2009 and other respiratory viral pathogens in either method. The limits of detection of the RealTime ready Influenza A/ H1N1 Detection Set and Xpert Flu were 500 TCID50/ mL and 20 TCID50/mL, respectively. Xpert Flu required 85 minutes (10 minutes of hands-on time) for processing, while RealTime ready Influenza A/ H1N1 Detection Set took 128 minutes (30 minutes of hands- on time).
Conclusion: The results of Xpert Flu were comparable to those of the RealTime ready Influenza A/H1N1 Detection Set. It is of note that the fully automated and closed system of Xpert Flu could be advantageous for reducing hands-on time and for preventing cross-contamination during the testing process.
[in Korean]
Jeongsook Yoon
Ann Clin Microbiol 2013 September, 16(3): 145-148. Published on 20 September 2013.
Urinary isolates and antimicrobial resistance of a primary hospital representing community were analyzed. The β-lactam and aminoglycoside resistances of E. coli and P. aeruginosa were lower than that seen in a tertiary hospital. Imipenem-resistant P.aeruginosa or VRE was not isolated; however the prevalence of ESBL was thought to be similar to that observed in a tertiary hospital.
[in Korean]
Sunjoo Kim
Ann Clin Microbiol 2013 September, 16(3): 149-151. Published on 20 September 2013.
Several members of the Korean Society of Clinical Microbiology (KSCM) have attended general meetings of the Japanese Society for Clinical Microbiology (JSCM) for more than 6 years. Although the composition of the JSCM is quite different from that of the KSCM and the formal language of the meeting is Japanese, it is worth reviewing the program to gain an overview of the direction and progress of the JSCM. The author is convinced that there is a lot to learn from the JSCM, especially in terms of how to maintain a very low antibiotic resistance rate, and how to prevent hospital-acquired infections. I hope that both academic societies will develop further and create a continuous exchange of helpful information, which could act as a good model for exchange between other specialty groups in separate countries.
[in Korean]
Kon-Hee Lee, Wonkeun Song, Min-Jeong Park, Jeongwon Hyun, Hyun Soo Kim, Kyu Man Lee
Ann Clin Microbiol 2013 September, 16(3): 152. Published on 20 September 2013.
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