Sae Am Song, Si Hyun Kim, Chang-Ki Kim, Heungsup Sung, Sunjoo Kim, Chulhun L Chang, Jeong Hwan Shin
Ann Clin Microbiol 2015 September, 18(3): 69-75. Published on 20 September 2015.
Background: There have been steady changes and improvements in diagnostic tests for Mycobacterium tuberculosis, so it is necessary to carry out periodic surveys to understand the current situation. The aims of this study were to investigate the changes in principal practices and quality control for M. tuberculosis using a nationwide survey in the Republic of Korea.
Methods: We constructed a questionnaire composed of four subseries with 42 items. We e-mailed this survey to members of the Korean Society of Clinical Microbiology from April to September 2014 and analyzed the replies.
Results: Employees at a total of 65 hospital laboratories and 5 commercial laboratories participated in the survey. AFB staining was reportedly performed in all 70 institutions, and fluorescent staining was used as the primary detection method in 59 (84.3%) laboratories. Solid and liquid culture methods for Mycobacterium were performed at 62 (88.6%) and 59 (84.3%) laboratories, respectively. There were 57 laboratories (90.5%) that identified strains growing on primary culture media using a rapid antigen kit or molecular method. The mean values of positive and contamination rates for solid culture media were 8.2% (range 3.7-19.9%) and 4.0% (0.4-8.4%), respectively. In liquid culture, the mean values of positive and contamination rates were 11.5% (4.8-22.3%) and 6.8% (0.3-18.7%), respectively.
Conclusion: There have been significant changes and improvements in overall mycobacterial testing, especially in the numbers of laboratories using fluorescent staining, liquid culture, and identification of M. tuberculosis cultured media compared with previous surveys in Korea.
[in Korean]
Joon Kim, Kyung Ho Choi, Young Sun Kim, Wee Gyo Lee
Ann Clin Microbiol 2015 September, 18(3): 76-81. Published on 20 September 2015.
Background: Vancomycin-resistant Enterococci (VRE) infections are caused by Enterococcus faecium in about 90% of the cases but can also be caused by Enterococcus faecalis. Thus, this study investigates factors that cause a low isolation rate of vancomycin-resistant E. faecalis (VREfs). To this end, the authors study the clinical traits, resistant gene structure, genomic classification, and molecular characteristics of the virulent factor.
Methods: From January 2001 through September 2011, 17 vanA-containing E. faecalis isolates were collected from hospitalized patients at Ajou University Hospital in Korea. Identification, antimicrobial susceptibility testing, and PCR of van and esp genes were performed. Pulsed-field gel electrophoresis (PFGE) was used for strain typing. PCR and sequencing of the internal regions of Tn1546 were performed for structural analysis of the van gene.
Results: Of 4,235 VRE infections, 3,918 (92.5%) were caused by E. faecium, and 95 (2.2%) were caused by E. faecalis. In 67% of VREfs infections, there was a preceding occurrence of E. faecium infection. All isolates were of genotype vanA. Our isolates were divided into three types according to the distribution of IS elements integrated into Tn1546 (types I to IIb). The PFGE results showed no clonal relatedness among isolates.
Conclusion: Our study found that VREfs infections affect patients who have experienced vancomycin-resistant E. faecium. (VREfm) infection or undergo invasive procedures. The VREfs seems to involve the horizontal transfer of Tn1546 transposon from VREfm.
[in Korean]
Irene Jo, Chang Eun Song, Kang Gyun Park, Yeon-Joon Park
Ann Clin Microbiol 2015 September, 18(3): 82-87. Published on 20 September 2015.
Background: Three chromogenic media using direct inoculation were compared with enriched enterococcosel broth for vancomycin-resistant Enterococcus faecium and/or Enterococcus faecalis (VRE) surveillance.
Methods: A total of 174 rectal swabs were included for VRE surveillance. The specimens were transferred in enterococcosel broth (EB). An aliquot of the broth was inoculated onto Brilliance VRE, chromID VRE, and VRESelect media and incubated for up to 48 h. We examined each media and EB after 24 h and 48 h of incubation. When appropriately colored colonies were observed, identification was confirmed using the VITEK-2 system and/or VITEK MS. Vancomycin susceptibility was confirmed by disk diffusion test. The presence of resistance genes was confirmed using Anyplex VanR Real-time Detection (Seegene, Korea).
Results: Of the 174 rectal swab specimens, 73 VRE were isolated. For enterococcosel broth, Brilliance VRE, chromID VRE, and VRESelect, the sensitivity at 24 h was 79.2%, 83.3%, 79.2%, and 79.2%, respectively. The sensitivity at 48 h was 91.7%, 93.1%, 91.4%, and 90.3%, respectively. The specificity at 24 h was 85.3%, 97.1%, 98.0%, and 98.0%, while that at 48 h was 79.4%, 85.3%, 95.2%, and 95.1%, respectively. The specificity of chromogenic media at 24 h and 48 h was significantly higher than that of EB. Furthermore, the specificity at 48 h was significantly higher for chromID VRE and VRESelect than Brilliance VRE, although color distinction was easier with VRESelect.
Conclusion: Based on our results, use of chromID VRE or VRESelect is more reliable and convenient for screening of VRE. In addition, five vanA-positive Enterococcus gallinarum, Enterococcus avium and Enterococcus durans were isolated, and two of them (one E. avium and one E. durans) were detected only on VRESelect.
Hae In Bang, Hyun Mi Lim, Eui Young Jang, Eun Su Park, Eun Jung Lee, Tae Hyong Kim, Rojin Park, Jeong Won Shin, Tae Youn Choi
Ann Clin Microbiol 2015 September, 18(3): 88-93. Published on 20 September 2015.
Background: Blood culture is a critical test for diagnosing bloodstream infections. Frequent microbial contamination during sampling and testing leads to abuse of antimicrobial agents. We evaluated methods for reducing contamination and obtaining more reliable results.
Methods: We analyzed blood cultures obtained between 2009 and 2015. We established 6 quality indicators: true positive rate, contamination rate, blood sampling volume, number of sets of blood cultures, delayed transportation rate, and percentage of samples collected from the femoral region, with reference to the CLSI guideline M47-A, 2007. Education was provided for interns and nurses responsible for blood sampling and transportation of specimens, and data were analyzed monthly.
Results: At baseline, the true positive rate was 12.8%, and the contamination rate was 4.0%. During the intervention period, these were decreased to 10.9% and 1.9%, respectively. The percentage of samples smaller than 5 mL decreased from 29.7% to 2.7- 11.3%. The rate of one set of blood cultures being ordered was always ＜5%. The delayed transportation rate decreased from 35.6% to 5.5-7.7%. Finally, the percentage of samples collected from the femoral region decreased from 41.5% to 22.0-31.0%, because of which we did not attain our goal, 20.8%.
Conclusion: The results showed improvements in contamination rate, specimen volume, specimen transportation time, and the percentage of samples collected from the femoral region. The quality management of blood cultures in 2011 was comparatively poor, which led to increased contamination rate, large number of samples containing ＜5 mL of blood, and increased percentage of samples collected from the femoral region. Thus, quality improvement methods can produce more reliable results of blood cultures.
[in Korean]
Jeong In Lee, Shinae Yu, Jong Sin Park, Eun-Jeong Joo, Jong Hee Shin, Min-Jung Kwon
Ann Clin Microbiol 2015 September, 18(3): 94-97. Published on 20 September 2015.
Cyberlindnera fabianii (previously known as Hansenula fabianii, Pichia fabianii, and Lindnera fabianii) is a yeast species that forms a biofilm, allowing it to resist azole drugs. In this study, we report a case of fungemia with C. fabianii that was successfully treated with anidulafungin. In this case, the organism was initially misidentified as Candida utilis (with a high probability of 93%, suggesting good identification) using the VITEK 2 yeast identification card (YST ID; bioMérieux, USA). The species responsible for the patient’s fungemia was correctly identified after sequencing the internally transcribed spacer region and the D1/D2 domain of the large subunit (26S) rDNA gene. The CLSI M27-A3 broth microdilution method was used to determine the in vitro antifungal activity of anidulafungin and fluconazole against C. fabianii. The MICs of anidulafungin and fluconazole were found to be 0.03 μg/mL and 2 μg/mL, respectively. The patient recovered after 14 days of anidulafungin treatment.
Yong Kwan Lim, Se Min Oh, Oh Joo Kweon, Mi-Kyung Lee
Ann Clin Microbiol 2015 September, 18(3): 98-101. Published on 20 September 2015.
Clostridium ramosum is Gram-positive anaerobic bacillus and is known as a non-pathogenic enteric bacterium. It is a member of the RIC group, which is a subgroup of Clostridium having atypical characteristics. Rarely, it has been reported as a pathogen of otitis media in young children or the cause of infection in immunosuppressed adults. Here, we report the first two Korean cases of C. ramosum bacteremia in colon cancer and pressure sore cases, respectively.
[in Korean]
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