Eun-Ha Koh, Sunjoo Kim
Ann Clin Microbiol 2008 April, 11(1): 1-4. Published on 20 April 2008.
Background: Group A streptococci (GAS) are the most common cause of pharyngitis in children. The streptococci in throat cultures from healthy elementary school children in Jinju were compared with previous results.
Methods: Throat cultures were taken from 1,402 healthy school children in 2006. β-hemolytic streptococci (BHS) were identified with a bacitracin disk (0.04 U) and latex agglutination test (Seroiden Strepto Kit, Eiken, Tokyo, Japan).
Results: Two-hundred sixteen (15.4%) and 149 (10.6%) cultures grew BHS and GAS, respectively. The isolation rate of GAS was significantly lower than in 2004 (16.0%) or 2002 (16.9%) (P＜0.05). Among BHS, the prevalence of group A strains (69.0%) decreased significantly compared with 2004 (84.9%) and 2002 (83.8%) (P＜0.05). None of the 1st-grade children yielded BHS or GAS.
Conclusion: The isolation rates of BHS and GAS from healthy school children were lower in 2006 than in previous years. Natural immunization against the common serotypes or improvement in individual hygiene might have played roles in the reduction of isolations of GAS.
Ja Young Lee, Jeong Hwan Shin, Hyun-Kyung Lee, Seong-Mi Yu, Eun Hee Park, Hee Ryune Lee, Jae Hyen Kim, Hye Ran Kim, Chi Sook Moon, Young Jae Kim, Jeong Nyeo Lee
Ann Clin Microbiol 2008 April, 11(1): 5-10. Published on 20 April 2008.
Background: We noticed a sudden increase in the isolation of Klebsiella oxytoca from bronchial washing specimens during May to June 2006. An epidemiological investigation was conducted to identify the cause of the outbreak and to implement appropriate infection control measures.
Methods: A total of 18 isolates of K. oxytoca were found. The 14 bronchial washing specimens that yielded K. oxytoca were taken in the outpatient bronchoscopy suite, and the other 4 specimens were obtained by a portable bronchoscopy. The medical records and microbiologic findings of these patients were reviewed. Environmental samples from two bronchoscopes and the bronchoscopy suite were cultured. The relations between the available 10 isolates from bronchial washing fluid were investigated by pulsed-field gel electrophoresis (PFGE).
Results: No patients were judged to have had true infections attributable to K. oxytoca either before or after bronchoscopy. Cultures of samples from two bronchoscopes and related environment did not grow K. oxytoca. The PFGE analysis showed that 8 of 10 isolates had a similar pattern of DNA fragments. An infection control strategy was implemented, including adequately cleaning and disinfecting the bronchoscopes, and a sharp reduction in the incidence of K. oxytoca from bronchial washing samples followed.
Conclusion: The sudden increase of K. oxytoca from bronchial washing specimens was a pseudo-outbreak. We presumed that the bronchoscopes became contaminated during a procedure in a patient colonized with K. oxytoca in the upper-respiratory tract.
[in Korean]
Sung Ha Kang, Young Ree Kim
Ann Clin Microbiol 2008 April, 11(1): 11-17. Published on 20 April 2008.
Background: The referral hospital is somewhat isolated from the mainland due to its island status; thus, microorganisms isolated from blood cultures might have a distinct pattern in their frequency and antibiogram. We attempted to uncover these characteristics.
Methods: The isolates from blood cultures at the Cheju University Hospital during 2003∼2007 were analysed. After inoculation in aerobic and anaerobic bottles, blood specimens were cultured using BacT/ Alert system, and the isolates were identifieded and antimicrobial susceptibilities were tested using Vitek II system.
Results: The overall positive rate of blood cultures was 9.6% and contamination rate was 3.6%. The most commonly isolated pathogens were Escherichia coli, Staphylococcus aureus, and Klebsiella pneumoniae. Gram positive rod, gram negative cocci, and anaerobes were not isolated, but fungi were isolated in 0.6% of blood cultures. The prevalence of methicillin-resistant S. aureus (MRSA) was 68.0% in 2003, 41.4% in 2004, 48.1% in 2005, 54.5% in 2006, and 65.2% in 2007. The prevalence of vancomycin-resistant enterococcus (VRE) was 0% in 2003 and 2004, 16.7% in 2005, 10.0% in 2006, and 9.5% in 2007.
Conclusion: The most commonly isolated pathogens were similar to those from other hospitals, but the isolation rates of MRSA and VRE by year showed different patterns. Also, gram positive rods, gram negative cocci and anaerobes were not isolated. To help the choice of empirical antibiotic treatments, we need complementary measures to upgrade microorganism isolation systems and further studies including the monitoring of antibiotic use.
[in Korean]
Han-Sung Kim, Jae-Seok Kim, Chae-Ok Ha, Wonkeun Song, Kyu Man Lee
Ann Clin Microbiol 2008 April, 11(1): 18-22. Published on 20 April 2008.
Background: The MicroScan MICroSTREP plus panel for susceptibility testing of various streptococci, including Streptococcus pneumoniae, has recently been introduced in Korea. The current study evaluated the usefulness of MicroScan MICroSTREP plus panel for antimicrobial susceptibility test of S. pneumoniae.
Methods: A total of 75 clinical isolates of S. pneumoniae were tested for antimicrobial susceptibility to penicillin, cefotaxime, ceftriaxone, meropenem, vancomycin, clindamycin, erythromycin, and levofloxacin with the MicroScan MICroSTREP plus panel and clinical and laboratory standard institute (CLSI) reference broth microdilution method. For 46 of 75 isolates, additional susceptibility tests to penicillin and cefotaxime were performed with Etest.
Results: The overall essential agreement of MICs (within one dilution of MICs) defined by the MicroScan MICroSTREP plus panel and reference method was 93.0%. Overall there were 11.7% minor, 0.7% major, and 0.7% very major interpretative category errors observed. The results of antibiotic susceptibility testing by Etest were similar to those obtained by the MicroScan MICroSTREP plus panel.
Conclusion: The MicroScan MICroSTREP plus panel, a commercial broth microdilution method, has a comparable accuracy to CLSI broth microdilution method for the resistance testing of S. pneumonia. This panel can be used for determining susceptibilities of S. pneumoniae to a wide variety of antimicrobial agents in clinical microbiology laboratories.
[in Korean]
So Youn Shin, Sun Hoe Koo, Kye Chul Kwon, Jong Woo Park, Chi Seon Ko, Jung Hoon Song, Ji Youn Sung
Ann Clin Microbiol 2008 April, 11(1): 23-28. Published on 20 April 2008.
Background: The recently issued Korean version of antimicrobial susceptibility cards for Vitek 2 system uses an adjusted antimicrobial combination that reflects Korean clinical practice and CLSI guidelines. We evaluated the two Korean antimicrobial susceptibility testing cards for gram negative rods, AST N056 and AST N055.
Methods: The results of susceptibility tests were compared between the original and Korean cards. A number of the same antimicrobials included in the both cards were 15 in AST N041-AST N056 and 17 in AST N022-AST N055. Susceptibilities to the newly added antimicrobials, aztreonam, tobramycin, and meropenem for AST N056; and cefotaxime, levofloxacin, and minocycline for AST N055 were compared with those obtained by disc diffusion test and, in case of discrepancy, by confirmative Etest or broth dilution method.
Results: In comparison between AST N041 and AST N056 cards, the average discrepancy rate per strain was 0.34, minor error was 88.2%, and major error and very major error were both 5.9%. In comparison between AST N022 and AST055 cards, the average discrepancy rate per strain and very major error were 1.23 and 4.4%, respectively. The three antimicrobial agents added into AST N055 card showed highly discrepant results as a total of 49 items (44.1%) in 111 isolates were discrepant with very major error of 5.9% and major error of 2.0%.
Conclusion: AST N056 showed acceptable results in most items including the newly added antimicrobial agents. However, in the case of AST N055 card that showed a relatively high discrepancy, other indicator antibiotics should be referred to for newly added three antimicrobials. For the antibiotics that showed a high discrepancy between the original and Korean cards, a comparison study should be performed using the standard method and clinical isolates collected in Korea.
[in Korean]
Chae Lim Jung, Mi Kyung Kim, Dong Chun Seo, Mi Ae Lee
Ann Clin Microbiol 2008 April, 11(1): 29-33. Published on 20 April 2008.
Background: PCR assay has provided a mean of more rapid and sensitive detection of Mycobacterium tuberculosis (MTB) complex than conventional acid- fast bacilli (AFB) smears and MTB cultures. Using the recently developed AdvanSure TB/NTM kit (LG Life Science Diagnostic Division, Korea), which could differentiate nontuberculous mycobacteria (NTM) from MTB, this study compared clinical usefulness of real-time PCR assay and Amplicor MTB PCR assay (Roche Molecular Systems, USA) for diagnosis of tuberculosis.
Methods: A total of 213 specimens (148 respiratory and 65 nonrespiratory specimens) were tested by using real-time PCR, Amplicor MTB PCR, AFB smear, and MTB culture. The sensitivity and specificity of four methods were evaluated according to clinical diagnosis.
Results: Of six NTM grown in culture, four (67%) were detected by real-time PCR. The overall agreement of real-time and Amplicor MTB PCR was 92% (191/207). The overall sensitivity and specificity were 91% and 87%, respectively, for real-time PCR, and 86% and 93% for Amplicor MTB PCR. In nonrespiratory specimens, the sensitivities of real-time PCR, Amplicor MTB PCR, AFB smear, and MTB culture were 67%, 60%, 13%, and 40%, respectively, and the specificity of the four methods were all 100%.
Conclusion: For diagnosis of tuberculosis, the sensitivity and specificity of the real-time PCR assay using AdvanSure TB/NTM kit and Amplicor MTB PCR were similar, and the former could differentiate NTM from MTB. The PCR assay can be considered as a more sensitive technique for the detection of MTB than the conventional AFB smear and culture.
[in Korean]
Joseph Jeong, Sung-Ryul Kim, Chulhun L. Chang, Seon Ho Lee
Ann Clin Microbiol 2008 April, 11(1): 34-42. Published on 20 April 2008.
Background: Infections caused by nontuberculous mycobacteria (NTM) are significantly increasing over the last decade. Due to the uncertainty in the clinical significance of these organisms, their effective diagnosis and treatment has been challenging. The purpose of this study was to investigate the distribution and clinical significance of NTM in clinical specimens.
Methods: Acid-fast culture positive 3,107 clinical specimens were identified by mycolic acid analysis using high performance liquid chromatography (HPLC.) The HPLC patterns of 384 NTM strains were compared with those of standard mycobacterium species. Clinical significance of NTM was investigated by a retrospective study including acid-fast stain and culture, medical history, symptoms and signs, radiological and other laboratory findings, pathologic findings, response to treatment, and follow-up study, and was confirmed according to the guideline of American Thoracic Society.
Results: Among the 3,107 Mycobacterium-positive specimens, 384 (12.4%) were found to be positive for NTM. Of these, 367 (95.6%) were successfully identified by HPLC as 19 different species, each of which comprising 0.3% to 15.9% of the total NTM, Studies on the pathogenic role of NTM showed that 0∼79.6% of each species or 0∼100% of isolates from each specimen could be considered clinically significant.
Conclusion: HPLC method is highly discriminative for the identification of NTM in clinical specimens. When NTM is isolated from clinical specimens in the Ulsan area, the findings from this study could serve as a database on which to determine its clinical significance depending on species type and also specimen type.
[in Korean]
Seung Hwan Oh, Young Jin Kim, Seung Kyu Park, Sang Hyun Hwang, Hyung Hoi Kim, Eun Yup Lee, Chulhun L. Chang
Ann Clin Microbiol 2008 April, 11(1): 43-48. Published on 20 April 2008.
Background: The purposes of the current study were to evaluate the concordant rates of anti-mycobacterial drug susceptibility test (DST) results in different solid media performed in different institutes, and to determine reliable susceptible testing methods.
Methods: One hundred and twenty two Mycobacterium tuberculosis strains were isolated from patients in A Hospital in 2005. DSTs were performed by the absolute concentration method using Löwenstein Jensen medium in both A Hospital (method A-1) and B Institute (method B-1) and by the proportion method using Middlebrook 7H10 agar in B Institute (method B-2). Nine drugs were used including isoniazid and rifampin. Sensitivity and specificity of each method were estimated by using the acceptable standard of 90% for isoniazid and rifampin and 80% for other drugs. The therapeutic outcomes of quinolone-administered patients were evaluated according to ofloxacin susceptibility results.
Results: Method B-1 showed sensitivity and specificity levels over the acceptable standard levels for all drugs. Method B-2 showed specificity lower than the acceptable levels for rifampin and cycloserine. Method A-1 showed specificity lower than the acceptable levels for isoniazid, streptomycin, p-aminosalicylic acid, and ofloxacin and sensitivity lower than the acceptable levels for prothionamide and cycloserine. The concordance rates of therapeutic outcomes with method B-1, method B-2, and method A-1 were 77%, 74%, and 65%, respectively.
Conclusion: The drug susceptibility results for some drugs were discordant between the testing laboratories and media, requiring an urgent application of quality control programs to raise the reliability of anti-mycobacterial DST.
[in Korean]
Hee-Young Yang, Hee-Joo Lee, Jin-Tae Suh
Ann Clin Microbiol 2008 April, 11(1): 49-55. Published on 20 April 2008.
Background: Fungemia has increased over the past decade and is an important cause of significant morbidity and mortality. Since 1980, there has been an increase in the worldwide studies of nosocomial bloodstream fungal infections. We analyzed the distribution and the clinical characteristics of fungemia at a tertiary care hospital, Kyung Hee University hospital.
Methods: We retrospectively reviewed medical records and laboratory findings of 139 patients who had fungemia from January 2000 to December 2006. We investigated the incidence of each fungal species, yearly occurrence, underlying diseases, hospitalized units, predisposing factors, use of the antifungal agents, mortality, and the characteristics of the expired group.
Results: The most common species isolated was C. albicans (40.3%), followed by C. tropicalis (24.5%). Overall, fungemia occurrence showed an increasing trend during the study period, except for the year 2004. Common predisposing factors were previous antimicrobial therapy (89.2%), central venous catheter (78.4%), and ICU admission state at diagnosis (59.7%). among the 139 patients, 98 (70.5%) were treated. Primary choice of antifungal agents included fluconazole (70.4%) and amphotericin B (29.0%). Overall mortality was 38.9% with the highest rate (47.1%) in patients with C. tropicalis and the lowest one (22.2%) in patients with C. parapsilosis. Predisposing factors for mortality due to fungemia in the univariate analysis included only mechanical ventilation (P=0.008).
Conclusion: Fungemia in the tertiary care hospital was caused predominantly by C. albicans and followed by C. tropicalis. The mortality rate was high and interspecies differences existed.
[in Korean]
Hye Ryoun Kim, Mi Kyung Lee, Sung Tae Hong, Jong Yil Chai
Ann Clin Microbiol 2008 April, 11(1): 56-62. Published on 20 April 2008.
Background: Serologic tests for specific antibody nowadays are widely employed for the diagnosis of parasitic diseases. Recently, an increasing numbers of kits have adopted enzyme-linked immunosorbent assay (ELISA) for the detection of parasitic antibodies. In this study, we evaluated two ELISA reagents for the diagnosis of parasitic diseases.
Methods: A total of 553 serum and 156 CSF samples were assayed using an in-house micro-ELISA and GenediaⓇ Ab ELISA (Green cross PBM, Korea) for Cysticercus, Paragonimus westermani, Clonorchis sinensis, and Sparganum. We reviewed the medical records of all patients. The results from GenediaⓇ Ab ELISA kit were compared with those from the in- house micro-ELISA method.
Results: The overall concordance rate between the two ELISA tests was 95.5%. When compared with the clinical information, the sensitivity, specificity, positive predictive value, and negative predictive value of the in-house micro-ELISA were 100%, 99.0∼99.6%, 82.4∼96.4%, and 100%, and the respective figures for GenediaⓇ Ab ELISA kit were 92.9~100%, 88.0∼ 97.3%, 41.7∼50%, and 99.9~100% with kappa agreement of 0.53-0.63. Comparison of two ELISA methods showed a significant difference (P＜0.05). Retesting of 85 discordant samples showed that the concordance rate of the in-house ELISA was 97.7% and that of GenediaⓇ Ab ELISA was 28.2%.
Conclusion: GenediaⓇ Ab ELISA kit showed an intermediate level of kappa agreement compared with the in-house ELISA. Further studies are necessary to improve the concordance rate of the two methods, and a careful interpretation of these results is required for a precise diagnosis.
[in Korean]
Kyeong Seob Shin, Bo Ra Son, Hye Won Jeong
Ann Clin Microbiol 2008 April, 11(1): 63-65. Published on 20 April 2008.
Granulicatella adiacens is one of the fastidious gram positive cocci previously described as nutritionally variant streptococci due to their requirement of L-cysteine, pyridoxal, or thiol compounds for growth. These bacteria have been identified as significant causative agents of endocarditis, opthalmic infections, and meningitis. We report a case of septicemia caused by G. adiacens in an 80-year-old patient with cholangiocarcinoma. The organism was identified by phenotypic and 16S rRNA sequencing analyses.
[in Korean]
Seok Ho Yoon, Il Joong Park, Wee Gyo Lee
Ann Clin Microbiol 2008 April, 11(1): 66-68. Published on 20 April 2008.
Escherichia coli O157 is an important serotype of enterohemorrhagic E. coli that causes hemorrhagic colitis worldwide. Outbreaks of E. coli O157 have been assocoated with contaminated food like meat, raw milk, and water, but recently vegetables and fruits have accounted for a growing number of recognized outbreaks. We isolated verotoxin producing E. coli O157 from the stool of a 3 year-old female with bloody diarrhea and abdominal pain. The child had been eating salad with vegetables and fruits frequently.
[in Korean]
Eun-Ha Koh, Sunjoo Kim
Ann Clin Microbiol 2008 April, 11(1): 69-70. Published on 20 April 2008.
α-hemolytic streptococci (AHS) are common normal oropharyngeal flora that can transfer antibiotic-resistance genes to Streptococcus pneumoniae. Reports on antibiotic resistance in AHS from throats are rare in Korea. A total of 333 healthy school children were subjected to recovery of AHS from the throat, and antibiotic susceptibility tests were screened with the disk diffusion method. The rate of resistance to erythromycin was 22.2%, to clindamycin 12.0%, and to cefotaxime 3.0%. Whereas the resistance rate of S. pneumoniae to erythromycin exceeds 70% in Korea, pharyngeal AHS showed low resistance rates.
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