Jeonghyun Chang, Sang-Hyun Hwang, Mi-Na Kim, Heungsup Sung
Ann Clin Microbiol 2017 June, 20(2): 21-26. Published on 20 June 2017.
Human cytomegalovirus (CMV) is a clinically important pathogen that causes significant morbidity and mortality in immunocompromised patients and is typically monitored using real-time polymerase chain reaction (real-time PCR). International standards and certified reference materials were recently developed by the WHO, providing the opportunity to standardize viral load reporting. Clinical microbiologists who conduct quantitative CMV DNA testing should be aware of technical issues that can affect the analytical and clinical performance of the method used. These include specimen type, limits of detection and quantification, linear range, reproducibility, and wide variability in viral load values among different assays. Specimen types for testing include whole blood, plasma, serum, and peripheral blood leukocytes. The tests that use whole blood and peripheral blood leukocytes have higher sensitivities. Adsorption chromatography methods are widely used for nucleic acid extraction, and efficiencies can differ between manual and automatic processes. The most common method for quantitative CMV DNA testing is real-time PCR. All CMV testing methods require quality control at the pre-analytic, analytic, and post-analytic stages. In transplant patients, specific quantitative results and monitoring of any changes at follow-up are important. Five to seven days is an adequate follow-up interval in this regard, and drug-resistant CMV should be suspected if there is no response to therapy. One specimen type should be chosen for follow-up quantitative CMV DNA testing, optimized according to WHO standards. Further studies are needed to better standardize CMV testing approaches and to determine the appropriate clinical cut-off level.
[in Korean]
Ki Ho Hong
Ann Clin Microbiol 2017 June, 20(2): 27-34. Published on 20 June 2017.
As many emerging human infections are caused by viruses, laboratory-acquired viral infection will become more common. However, additional knowledges is needed, including actual incidence, disinfectant, and prevention. Although the general biosafety principles of viruses do not differ from those of other microorganisms, biosafety guidelines and programs are not immutable and could vary according to virus and laboratory environment. Most laboratory-acquired viral infections reported in the literature were caused by violation of biosafety principles.
[in Korean]
Yiel-Hea Seo, Ji-Hun Jeong, Hwan Tae Lee, Woo-Jae Kwoun, Pil-Whan Park, Jeong-Yeal Ahn, Kyung-Hee Kim, Ja Young Seo
Ann Clin Microbiol 2017 June, 20(2): 35-41. Published on 20 June 2017.
Background: Cumulative blood culture data provide clinicians with important information in the selection of empiric therapy for blood stream infections.
Methods: We retrospectively analyzed blood culture data from a university hospital during the period from 2006 to 2015. Only the initial isolates of a given species for each patient were included.
Results: The number of blood cultures per 1,000 inpatient-days increased from 64 in 2006 to 117 in 2015. The ratio of significant pathogens to total isolates was 0.56-0.63. The most common organisms were Escherichia coli in 2006-2010 but changed to coagulase-negative staphylococci (CoNS) in 2011. The proportion of Staphylococci aureus was decreased during the study period, but Klebsiella pneumoniae was increased. Enterococci were increased, especially E. faecium, which was more frequently isolated than E. faecalis in 2015. Pseudomonas aeruginosa was decreased during the study, but Acinetobacter baumannii was increased. The prevalence of methicillin-resistant S. aureus (MRSA) changed from 62.2% to 53.9%, while vancomycin-resistant E. faecium increased to 35.8%. Extended-spectrum beta-lactamase (ESBL)-producing E. coli and K. pneumoniae increased to 25% and 34%, respectively, in 2015. Starting in 2008, three E. coli and 11 K. pneumoniae isolates were carbapenem-resistant Enterobacteriaceae (CRE), and three were carbapenemase- producing Enterobacteriaceae (CPE). The prevalence of imipenem-resistant A. baumannii rapidly increased during the study period.
Conclusion: About 60% of all blood isolates were significant pathogens. The most common isolates changed from E. coli to CoNS in 2011. ESBL-producing E. coli and K. pneumoniae, vancomycin-resistant E. faecium, and imipenem-resistant A. baumannii were increased during the study, while the proportion of MRSA tended to decrease slightly. Of the total isolates, 14 were CRE, and 3 were CPE.
[in Korean]
Sun Young Park, So Young Kim, Won Jung Choi, Seok-Hyun Kim, Seong Geun Hong
Ann Clin Microbiol 2017 June, 20(2): 42-51. Published on 20 June 2017.
Background: Group B streptococcus (Streptococcus agalactiae, GBS) was reported as a major cause of neonatal infection and death. To prevent vertical transmission, CDC recommended that all women in week 35-37 of pregnancy should receive the GBS colonization test. We conducted a systematic review and meta-analysis to evaluate diagnostic accuracy and detection rate of real-time PCR for GBS in pregnant women.
Methods: The literature review for GBS using real-time PCR was done including KoreaMed, Ovid- MEDLINE, Ovid-EMBASE, and Cochrane Library on November 3, 2015. 443 articles were collected. Two authors select articles and evaluated the quality of studies using Scottish Intercollegiate Guidelines Network tool independently.
Results: Diagnostic accuracy of the real-time PCR was assessed by meta-analysis through 34 articles (13,516 for real-time PCR, 1,815 for culture and other comparison test). The GBS colonization was assessed through 34 articles, which reported varying values of 2.0-69.2% using real-time PCR. The real-time PCR for GBS was shown to have overall sensitivity of 0.93 (95% CI 0.92-0.94, I2=86.3%), overall specificity of 0.96 (95% CI 0.96-0.96, I2= 90.2%), SROC AUC of 0.99.
Conclusion: Real-time PCR is an effective test for detecting GBS colonization in pregnant women, resulted in preventing the infection in a new born baby.
[in Korean]
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