Nam Hee Ryoo

Outbreak by meropenem-resistant Pseudomonas aeruginosa producing IMP-6 metallo-β-lactamase in a Korean hospital

Pseudomonas aeruginosa isolates containing the bla(IMP-6) gene were recovered from 5 patients hospitalized at a tertiary-care hospital in Korea. The bla(IMP-6) gene was in a class 1 integron containing 5 different insert gene cassettes. All of the isolates showed identical pattern in SpeI macrorestriction analysis.

Comprehensive analysis of blood culture performed at nine university hospitals in Korea.

Background Optimal blood culture performance is critical for successful diagnosis and treatment of sepsis. To understand the status of blood culture, we investigated several aspects of the procedure at 9 university hospitals. Methods The process of ordering blood culture sets and sampling volume for adults and children was investigated from January 2010 to April 2010, while the positive rate of detection and growth of skin contaminants were compared in 2009. Microbial growth in aerobic and anaerobic bottles was investigated prospectively. Results A majority of the hospitals used 2 sets of bottles for adults and 1 bottle for children. The average blood volume in each set was 7.7 mL for adults and 2.1 mL for children. The positive rate of microorganisms was 8.0%, and the isolation rate of the normal flora of the skin was 2.1%. Bacterial growth rates in aerobic and anaerobic bottles only were 31.8% and 24.5% respectively. Conclusions Ordering blood culture sets and sampling volumes did not comply with CLSI guidelines. However, the rate of positive cultures and skin contamination rates were acceptable. Anaerobic bottles are useful in enhancing the yield of microorganisms.

IS6110-Restriction Fragment Length Polymorphism and Spoligotyping Analysis of Mycobacterium tuberculosis Clinical Isolates for Investigating Epidemiologic Distribution in Korea

The Beijing family of Mycobacterium tuberculosis has been emerging in the world. However, there are few nationwide data of genotypic distribution in Korea. This study aimed to identify the genotypic diversity of clinical isolates of M. tuberculosis and to demonstrate the population of Beijing family in Korea. We collected 96 clinical M. tuberculosis isolates from 11 university hospitals nationwide in Korea from 2008 to 2009. We observed 24 clusters in IS6110-RFLP analysis and 19 patterns in spoligotyping. Seventy-five isolates were confirmed to be Beijing family. Two isolates of the K strain and 12 isolates of the K family strain were also found. We found that drug resistance phenotypes were more strongly associated with Beijing family than non-Beijing family (P=0.003). This study gives an overview of the distribution of genotypes of M. tuberculosis in Korea. These findings indicate that we have to pay more attention to control of M. tuberculosis strains associated with the Beijing family.

Characteristics of Microorganisms Isolated from Blood Cultures at Nine University Hospitals in Korea during 2009

Department of Laboratory Medicine & Genetics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Department of Laboratory Medicine, Institute of Health Sciences, Gyeongsang National University School of Medicine, Jinju, Department of Laboratory Medicine, Paik Institute for Clinical Research, Inje University College of Medicine, Busan, Department of Laboratory Medicine, Asan Medical Center and University of Ulsan College of Medicine, Seoul National University Hospital, Seoul, College of Medicine, Chungnam National University, Daejeon, School of Medicine, Keimyung University, Daegu, Hallym University College of Medicine, Seoul, College of Medicine, Wonkwang University, Iksan, Korea

Prevalence of Metallo-β-lactamases in Imipenem-non-susceptible Pseudomonas aeruginosa and Acinetobacter baumannii

Background: Metallo-β-lactamases (MBLs) have been reported in gram negative bacilli and are becoming increasingly important clinically because the enzymes hydrolyse almost all β-lactams, including carbapenems. Thus, the present study was conducted to determine the prevalence of MBL types in imipenem-nonsusceptible Pseudomonas aeruginosa and Acinetobacter baumannii isolated from a tertiary teaching hospital. Methods: Imipenem-nonsusceptible strains, 128 P. aeruginosa and 93 A. baumannii, were collected from clinical specimens. Identification and susceptibility tests were determined by Vitek GNI and GNS cards. MBL production was determined by modified Hodge test and imipenem-EDTA synergy test. Multiplex PCR amplification of MBL genes including blaIMP-1, blaVIM-1 and blaVIM-2 were performed. Results: Thirty-one P. aeruginosa (24.2%) isolates and 3 A. baumannii (3.2%) were found to be MBL producers. In P. aeruginosa, 20 (15.6%) and 11 (8.6%) isolates were positive for blaIMP-1 and blaVIM-2, respectively whereas 1 (1.0%) and 2 (2.2%) isolates in A. baumannii, respectively. Conclusion: IMP-1 is more prevalent MBL type than VIM-2 among imipenem-nonsusceptible P. aeruginosa unlike in other studies. Larger numbers of isolates and sequential studies are strongly recommended for the useful evaluation and monitoring of MBL production in the hospital setting to infection-control. (Korean J Clin Microbiol 2010;13:169-172)

Fecal Colonization of Enterobacteriaceae Carrying Plasmid-Mediated Quinolone Resistance Determinants in Korea

The aims of the current study were to investigate the prevalence and molecular characteristics of plasmid-mediated quinolone resistance (PMQR) genes from colonizing fecal organisms and to compare the incidence and subtype of these genes according to bacterial species and hospital at five tertiary-care hospitals in Korea. A total of 500 nonduplicated clinical isolates of Enterobacteriaceae were obtained from fecal specimens at five tertiary-care hospitals between March and May 2008. The PMQR genes (qnrA, qnrB, qnrS, aac(6)-Ib-cr, and qepA) were amplified by PCR and confirmed by direct sequencing of the PCR products. A total of 83 (16.6%) qnr-positive isolates were detected. The prevalence rates of qnrA, qnrB, and qnrS were 1.4%, 13.6%, and 1.6%, respectively. The species distributions of qnrB-positive isolates were Klebsiella pneumoniae (37/109; 33.9%), Citrobacter freundii (10/34; 29.4%), Citrobacter braakii (8/13; 61.5%), and Escherichia coli (8/275; 2.9%). Sixteen subtypes of qnrB were detected, including seven novel variants. The prevalences of aac(6)-Ib-cr and qepA were 15.6% (n=78) and 0.6% (n=3), respectively. The aac(6)-Ib-cr gene was detected in 39 (47.0%) of 83 qnr-positive isolates and 39 (9.4%) of 417 qnr-negative isolates There was one qepA variant containing a novel mutation (Ala231Val). The prevalence of PMQR genes was high in Enterobacteriaceae from stool specimens in Korea, and there was a close relation between qnr and aac(6)-Ib-cr.

Evaluation of the Usefulness of Selective Chromogenic Agar Medium (ChromID VRE) and Multiplex PCR Method for the Detection of Vancomycin-resistant Enterococci

BACKGROUNDnAccurate and early detection of vancomycin-resistant enterococci (VRE) is critical for controlling nosocomial infection. In this study, we evaluated the usefulness of a selective chromogenic agar medium and of multiplex PCR for detection of VRE, and both these techniques were compared with the conventional culture method for VRE detection.nnnMETHODSnWe performed the following 3 methods for detecting VRE infection in stool specimens: the routine culture method, culturing in selective chromogenic agar medium (chromID VRE, bioMérieux, France), and multiplex PCR using the Seeplex® VRE ACE Detection kit (Seegene Inc., Korea) with additional PCR for vanC genes.nnnRESULTSnWe isolated 109 VRE strains from 100 stool specimens by the routine culture method. In chromID VRE, all the isolates showed purple colonies, including Enterococcus gallinarum and E. raffinosus, which were later identified using the Vitek card. All VRE isolates were identified by the multiplex PCR method; 100 were vanA-positive E. faecium, 8 were vanA- and vanC-1-positive E. gallinarum, and 1 was vanA-positive E. raffinosus.nnnCONCLUSIONSnFor VRE surveillance, culturing the isolates in chromID VRE after broth enrichment appears to be an accurate, rapid, and easy method for routine screening test. Multiplex PCR is relatively expensive and needs skilled techniques for detecting VRE, but it can be an auxiliary tool for rapid detection of genotype during a VRE outbreak.

mRNA Expression and RNA Editing (2451 C-to-U) of IL-12 Receptor β2 in Adult Atopic Patients

Interleukin (IL)-12 activates T helper (Th) 1 cells to produce interferon (IFN)-γ which inhibits atopic inflammation. IL-12 acts through interaction with its receptor, especially β2 subunit. In several studies, the low production of IFN-γ in peripheral mononuclear cells of atopic patients on response to IL-12 stimulation has been reported. Therefore we investigated the IL-12 receptor β2 (IL-12Rβ2) mRNA expression and RNA editing, nucleotide 2451 C-to-U conversion, to find the cause of low responsiveness to IL-12 in atopy. Quantitative real time PCR for mRNA expression and sequence analysis for RNA editing were performed in 80 atopic patients and 54 healthy controls. The expression of IL-12Rβ2 mRNA was significantly lower in atopic patients than healthy controls (p<0.05). In sequence analysis, RNA editing on nucleotide 2451 was not found from either atopic patients or healthy controls. In additional evaluation, there was no relationship between expression of IL-12Rβ2 mRNA and serum total IgE or blood eosinophil count. Reduced IL-12Rβ2 mRNA expression in atopic patients indicate the reduced capacity to respond to IL-12 which induce IFN-γ production and this may contribute to Th2-skewed immune response in atopy.

A Multicentre Study about Pattern and Organisms Isolated in Follow-up Blood Cultures

accounted for 2.3% of events, whereas immune clea- rance was confirmed in 8.5% of events. Previously undetected pathogens were isolated in 5.2% of the follow-up cultures, the majority of which grew after an interval of six days. Skin contaminants were de- tected in 7.6% of the repeated cultures, and 76.1% of the follow-ups displayed no growth of microorganisms. Conclusion: The most common numbers of repeat culture requests were two and three, and these were typically performed within three days of the initial culture. Among the follow-up cultures, new patho- gens were identified in 5.2%, and the majority of this group likely presented for follow-up during a new dis- ease episode. (Ann Clin Microbiol 2013;16:8-12)

Phialemonium obovatum Keratitis after Penetration Injury of the Cornea

Phialemonium keratitis is a very rare case and we encountered a case of keratitis caused by Phialemonium obovatum (P. obovatum) after penetrating injury to the cornea. This is the first case report in the existing literature. A 54-year-old male was referred to us after a penetration injury, and prompt primary closure was performed. Two weeks after surgery, an epithelial defect and stromal melting were observed near the laceration site. P. obovatum was identified, and then identified again on repeated cultures. Subsequently, Natacin was administered every two hours. Amniotic membrane transplantation was performed due to a persistent epithelial defect and impending corneal perforation. Three weeks after amniotic membrane transplantation, the epithelial defect had completely healed, but the cornea had turned opaque. Six months after amniotic membrane transplantation, visual acuity was light perception only, and corneal thinning and diffuse corneal opacification remained opaque. Six months after amniotic membrane transplantation, visual acuity was light perception only, and corneal thinning and diffuse corneal opacification remained.