Tae Yeal Choi, M.D.
Ann Clin Microbiol 2000 March, 3(1): 1-4. Published on 20 March 2000.
클라미디아는 비운동성의 그람 음성 세균으로 살아있는 세포 내에서만 살수 있다. 독특한 생활사를 가지고 있으며 세포질 내 봉입체를 형성하며 증식한다. 바이러스와 다른 점은 DNA, RNA를 함께 가지고 있고 그람음성세균의 세포막 구조를 가지고 있어 세균으로 분류되었다. 뿐만 아니라 광범위 항생제에 감수성이 있으며, 군체에 필요한 에너지는 숙주 세포로부터 획득하여 살아가는 세균이다.
[in Korean]
Chang Kyu Lee, M.D.
Ann Clin Microbiol 2000 March, 3(1): 5-15. Published on 20 March 2000.
인터넷의 발달은 사회 생활 전반에 걸쳐 가히 혁명적인 변화를 가져오고 있다. 이제는 강연도 실험에서 자연과 더불어 살피게 각국과 무역을 하는 것이 가능하게 되었다. 분자생물학 분야에서도 지난 10여년간에 걸쳐 엄청난 양의 정보들이 쏟아져 나오므로 이제는 더 이상 문헌을 찾고 교과서를 뒤적이는 방식으로는 새로운 첨단의 지식들과 발전들을 추적해 가는 것이 불가능하게 되었다. 다행히도 수많은 정보들이 전자 책(electronic media)에 저장됨으로 전철된 software 와 인터넷 통신망만 있으면 이들을 효과적으로 이용할 수 있게 되었다. 특히 우리나라와 같이 아직 전반적인 연구와 infra가 잘 구축되어 있지 않은 국가에서 이러한 인터넷의 장점을 잘 활용하여 구미에 대한 최신 연구기법들이 보유하고 있는 정보를 자신들의 적절히 이용할 수만 있다면 우리가 겪게 되는 많은 어려움들을 줄여나갈 수 있다고 생각된다. 본문에서는 PC를 통한 DNA와 관련된 여러 정보들을 어떻게 얻고 활용할 수 있는가를 개략적으로 기술해 보고자 한다.
[in Korean]
Won-Kil Lee, M.D.
Ann Clin Microbiol 2000 March, 3(1): 16-22. Published on 20 March 2000.
한 때는 그 원인이 감염병이라고 생각하지 않았던 만성병 중에도 그 원인이 새로운 미생물로 밝혀진 것들이 늘 보고되고 있다. 동맥경화증과 Chlamydia pneumoniae, 소화성 궤양 및 위암과 Helicobacter pylori의 관련성 등이 대표적인 예이다. 1991년 zur Hausen(2)은 전세계적으로 인간의 모든 암종 중에 상당한 비율이 바이러스의 감염과 관련되어 있다고 주장하였다. 사람 유두종바이러스(HPV), 자궁경부암 및 피부암), 사람 T세포림프구백혈병바이러스(HTLV), 발생지역에서 성인 T세포 백혈병과 림프종), 사람 간염바이러스(HBV), 간암 및 Epstein-Barr바이러스(EBV), Burkitt 림프종 등이 포함되었다. 새로운 바이러스의 관련이 밝혀지고 있으며, 향후 더 많은 바이러스가 암의 원인이 될 것으로 보여 앞으로 이 비율은 더욱 증가할 것으로 추측된다. 현재는 H. pylori (위암, mucosa-associated lymphoid tissue(MALT) 림프종), C형 간염바이러스(HCV), 간암, non-Hodgkin 림프종), 사람 헤르페스바이러스 6(HHV, non-Hodgkin 림프종), 사람 헤르페스바이러스 8(Kaposi sarcoma herpesvirus, KSHV, Kaposi sarcoma(KS), Castleman disease 및 체내 림프종) 등의 관련이 밝혀져 있다.
[in Korean]
Hyun Ju Jung, M.D., Seon Ju Kim, M.D., Kook Young Maeng, M.D., and Chulhun Ludgerus Chang, M.D.
Ann Clin Microbiol 2000 March, 3(1): 23-29. Published on 20 March 2000.
Background: It is difficult to control an outbreak of Shigella infection, because of the ease of transmission and the resistance to multiple antibiotics. Recently, there were outbreaks of Shigella infection in Chinju area. The objective of this study was to investigate the molecular epidemiology of the outbreaks using pulsed-field gel electrophoresis (PFGE).
Method: Thirteen S. flexneri strains, 25 S. sonnei strains from Chinju and 15 S. sonnei strains from Pusan were studied. All strains were isolated from stool cultures of diarrheal patients. Identification and antimicrobial susceptibility test of those were tested by Vitek GNI and GNS-LH. Chromosomal DNA restricted with XbaI was resolved by PFGE.
Result: All the S. flexneri strains and 23 (92%) S. sonnei strains from Chinju were resistant to one or more antimicrobial agents. All the clinical isolates of S. flexneri showed the same PFGE pattern which was different from type strain (KTCC 2517). PFGE patterns of 25 (100%) S. sonnei strains from Chinju and 12 (80%) S. sonnei strains from Pusan were identical to those of type strain (KTCC 2009). Three S. sonnei strains from Pusan showed distinct PFGE patterns, respectively.
Conclusion: PFGE demonstrated identical restriction pattern among most of Shigella isolates from Chinju and Pusan, indicating that an outbreak with genetically related strains had occurred. PFGE was useful for molecular epidemiology of Shigella outbreaks.
[in Korean]
Young Uh, M.D., In Ho Jang, M.D., Gyu Yel Hwang, M.D., Mi Kyung Lee, M.D. and Kap Jun Yoon, M.D.
Ann Clin Microbiol 2000 March, 3(1): 30-35. Published on 20 March 2000.
Background: Pigment production and acidification of ribose are most frequently used biochemical tests for the differentiation of three enterococcal species carrying vanC genes such as Enterococcus gallinarum, Enterococcus casseliflavus, and Enterococcus flavescens. However, pigment production may occasionally be negative in E. casseliflavus, and some of E. casseliflavus may be negative or delayed reaction with ribose fermentation test. So, we performed this study to find out biochemical tests capable of distinguishing the strains possessing vanC genotypes.
Methods: A total of 17 enterococci composed of 14 clinical isolates with motility or pigment positive strains and three ATCC strains (E. gallinarum ATCC 49573, E. casseliflavus ATCC 25788, and E. flavescens ATCC 49997) were tested by multiplex PCR of the vanC genes (vanC-1, vanC-2, and vanC-3) and various biochemical tests.
Results: Among the 17 isolates including three ATCC control strains, four were genotyped as VanC-1, 11 were VanC-2, one were vanC-2/3, and any of vanC genes were not detected in one clinical isolate, respectively. Among the enterococci with vanC genotype, acid production from α-D-cyclodextrin and hippurate hydrolysis were positive only in VanC-1 genotype (E. gallinarum), acid production from glycerol and methyl- α-D-mannopyranoside were positive only in VanC-2 genotype (E. casseliflavus), and acid production from rhamnose and pigment production were negative only in VanC-2 genotype. Acid production from α-D-cyclodextrin was negative only in VanC-2 genotype. The positive rate of ribose fermentation of VanC-1, VanC-2, and VanC-2/3 (E. flavescens) genotype were 100%, 82%, and 0%, respectively.
Conclusion: Acid production from rhamnose, α-D-cyclodextrin, β-D-cyclodextrin, glycerol and methyl- α-D-mannopyranoside, pigment production, and hippurate hydrolysis test were useful biochemical tests for differentiating E. gallinarum from E. casseliflavus. The production of acid from α-D-cyclodextrin, glycerol, methyl-α-D-mannopyranoside and ribose were suitable biochemical tests for differentiating E. casseliflavus from E. flavescens.
[in Korean]
Eun-Jee Oh, M.D., Jung-Do Jang, M.D., Yeon-Joon Park, M.D., Sun Moo Kim, M.D., Byung Kee Kim, M.D.
Ann Clin Microbiol 2000 March, 3(1): 36-42. Published on 20 March 2000.
Background: An accurate and rapid method for species identification of coagulase negative staphylococci (CNS) has been increasingly necessary for the clinical significance and planning the management of patients with staphylococcal infections. Recently, it has been reported that there is a highly conserved area on their 60KDa heat shock protein (HSP60) gene sequences between the interspecies of CNS and it can be amplified by a set of universal degenerate primer. This led us our attention to focus on whether the PCR-based RFLP method using Mse I restriction enzyme could be a useful tool for the species identification of CNS.
Methods: In the present study, we performed PCR-based RFLP analysis using a set of degenerate primers covering HSP60 and Mse I restriction enzyme on the seven reference strains and 25 clinical isolates (10 of S. epidermidis, 10 of S. haemolyticus, 4 of S. lugdunensis and 1 of S. warneri) which were previously identified by the API-STAPH, Vitek GPI card and/or with conventional biochemical test.
Results: All the seven reference strains revealed that each strain has a distinct electrophoresed band patterns with combination of different number (up to 8) and size of fragments. And these distinct band patterns showed remarkable concordance with the seven reference strains and 25 clinical isolates.
Conclusion: These results strongly suggest that the PCR-RFLP method using degenerate primers covering the HSP60 gene and Mse I digestion enzyme offer a convenient and accurate tool for species-specific identification of CNS.
[in Korean]
Jung Oak Kang, M.D., Jeong Don Chae, M.D., Jeong In Eom, M.D., Dongsoo Han, M.D., Pil Whan Park*, M.D., Ile Kyu Park, M.D. and Tae Yeal Choi, M.D.
Ann Clin Microbiol 2000 March, 3(1): 43-47. Published on 20 March 2000.
Background: The most reliable and accurate diagnostic method of Clostridium difficile-associated disease (CAD) is considered the detection of toxin B in stool using the cell culture cytotoxicity assay. But cytotoxicity assay needs cell culture facilities and labor intensive. We evaluated an automated enzyme-linked fluorescent immunoassay for the detection of Clostridium difficile (C. difficile) toxin A in stool specimens.
Methods: Two hundred sixty-seven stool specimens were cultured anaerobically on cycloserine-cefoxitin-fructose-egg yolk (CCFA) media and tested for toxin A with the VIDAS C. difficile toxin A II (CDA 2, bioMerieux sa, France) according to the manufacturer’s instruction. Cytotoxicity assay for toxin B (C. difficile Tox-B test, TechLab, Blacksburg, USA) was performed with 42 toxin A positive and 40 toxin A negative specimens using HEp-2 cell monolayers grown in the 96-well microplates.
Results: Toxin A positive rate (26.2%) was significantly higher (P=0.013) than the culture positive (17.6%) and the agreement was 82.4%. The agreement between the toxin A test and the cytotoxicity assay was 92.7%. The sensitivity and specificity of toxin A test were 89.4% and 100%, respectively. All the 42 toxin A positives showed cytotoxicity, but among the 40 toxin A negatives, 5 showed cytotoxicity in cell monolayers.
Conclusion: There was no significant difference between the automated, rapid toxin A test and cytotoxicity assay (P=0.07>0.05), so rapid toxin A test could be used as a routine method. However, toxin A negative and toxin B positive C. difficile would not be detected by the toxin A test only.
[in Korean]
Jin Hee Park, M.D., Jung Won Huh, M.D. and Mi Ae Lee, M.D.
Ann Clin Microbiol 2000 March, 3(1): 48-52. Published on 20 March 2000.
Background: The diagnosis of tuberculosis has been based on the detection of tubercle bacilli by acid-fast stain of smear or cultures, and recently the serologic diagnosis of tuberculosis has been provided a means of sensitive and specific detection of Mycobacterium tuberculosis. We evaluated the utility of enzyme immunoassay using determiner Tuberculosis Glicolipids (TBGL) antibody kit (Kyowa Medex Co. Ltd, Japan) to detect anti-TBGL antibody for diagnosis of pulmonary tuberculosis.
Methods: Anti-TBGL antibody assay was performed to the sera from 44 patients with active pulmonary tuberculosis (17 patients with smear positive, 7 patients with only culture positive, 20 patients with clinically active tuberculosis) and 80 controls (30 healthy controls, 24 patients with non-tuberculous respiratory diseases, 26 patients with inactive tuberculosis). We compared the sensitivity and specificity of anti-TBGL antibody with culture and AFB stain.
Results: Anti-TBGL antibodies were detected in 16 of 17 (94%) smear positive patients, 4 of 7 patients with only culture positive and 16 of 20 (80%) smear negative patients who had been clinically diagnosed as active pulmonary tuberculosis. Nine (35%) out of 26 patients with inactive tuberculosis, one (4%) out of 24 patients with non-tuberculous respiratory diseases and no one of healthy control had a positive antibody response. Overall sensitivity, specificity of the anti-TBGL antibody assay were 82%, 88%, respectively and sensitivities and specificities of culture and AFB smear were 64%, 97% and 49%, 100%, respectively. Anti-TBGL antibody titers in patients with active tuberculosis were significantly higher than control group (P<0.05).
Conclusions: The anti-TBGL antibody assay was sensitive, rapid and convenient. This assay will be useful as a tool for the diagnosis of tuberculosis in combination with other conventional tests.
[in Korean]
Chulhun L. Chang, M.D., Tae Hee Park, M.D., Joseph Jeong, M.D., Hyung Hoi Kim, M.D. and Weon Joo Hwang, M.T.
Ann Clin Microbiol 2000 March, 3(1): 53-56. Published on 20 March 2000.
Background: The purpose of this study was to discover ways to screen urine culture specimens through Gram stains, urine stick analyses and microscopic examinations for the laboratory cost saving.
Methods: One hundred and fifty-eight urine specimens for culture were included. Fifty uL of urine were inoculated onto one well each of 10-well slide, dried on the hot plate, and Gram-stained. The results combined with routine urinalyses including urine nitrite and leukocyte esterase, and pyuria, were compared with the routine culture results.
Results: The screening of bacteriuria by Gram stains, urinalyses and microscopic examinations revealed the high sensitivity (91.9%) and negative predictive value (95.5%) with cost saving of 41.8% of inoculating media. Not considering the Gram stains, the screening revealed 83.8% sensitivity and 92.5% negative predictive value, even if the cost saving of inoculating media were as high as 50.1%.
Conclusion: It was demonstrated that it was sensitive and economic and produced rapid preliminary results to screen bacteriuria by the Gram stains combined with urinalyses and microscopic examinations.
[in Korean]
Myung Hyun Nam, M.D., Hee Yeon Woo, M.D., Jang Ho Lee, M.T. and Nam Yong Lee, M.D.
Ann Clin Microbiol 2000 March, 3(1): 57-61. Published on 20 March 2000.
Background: Coagulase negative staphylococcus (CNS) spp. is a major pathogenic organism of nosocomial and community-acquired urinary tract infections, and causes infections in the immunocompromised host, and, in particular, bloodstream infections in patients with indwelling devices. High prevalence of methicillin resistance has been noticed in CNS which also have been recognized as an important multidrug resistant pathogen. The optimal phenotypic method for detecting methicillin resistance still remains controversial, and new guidelines for detecting methicillin resistance of CNS was proposed by NCCLS in January 1999. We evaluated the relationship between mecA gene by PCR method and antimicrobial susceptibility tests according to the new NCCLS guidelines.
Methods: A total of 82 CNS isolates were examined for oxacillin MICs and penicillin MICs by disk diffusion and agar dilution method according to NCCLS guidelines, and detection of mecA gene by PCR.
Results: In disk diffusion method, 66 strains (80.5%) and 63 strains (76.8%) showed resistance to penicillin and oxacillin, respectively, and in agar dilution method, 71 strains (86.6%) and 53 strains (64.6%), respectively. In PCR method, mecA genes were detected in 49 strains (59.8%). Comparing with mecA gene detection by PCR method, the sensitivity of disk diffusion and agar dilution method was 95.8% and 89.8%, respectively. However, the sensitivity of disk diffusion and agar dilution method was 65.3% and 75.5%, respectively using previous NCCLS criteria.
Conclusion: The new criteria of NCCLS detects the methicillin resistance induced by mecA gene more sensitively than the previous one.
[in Korean]
Jae-Sook Ryu, Kyong Yoon, Seo-Eun Ha, Duk-Young Min, and Myoung-Hee Ahn
Ann Clin Microbiol 2000 March, 3(1): 62-68. Published on 20 March 2000.
Background: Direct wet mount examination of vaginal secretion, widely applied for the diagnosis of Trichomonas vaginalis infection in woman patients, is rapid and economical. However, the sensitivity of this technique is not so high. In this study enzyme-linked immunosorbent assay (ELISA) was employed for the detection of serum anti-T. vaginalis IgG antibodies from vaginal trichomoniasis patients.
Methods: Eighty sera from trichomoniasis patients who visited a Dr. Yoon Kyong’s Obstetric & Gynecologic Clinic in Songnam and 30 non-infected healthy men were tested for detection of anti-T. vaginalis IgG antibody. Soluble lysate and excretory-secretory antigen prepared by mixing of six isolates of T. vaginalis, and lysate from one isolate (KT4) were used as antigen for ELISA.
Results: The sensitivity of ELISA using mixed lysate of six isolates was 95.0%, and the sensitivity of the lysate from KT4 and mixed excretory-secretory antigen from 6 isolates were 86.4% and 76.3%, respectively. Specificities of ELISA by the three antigens were 93.3%, 96.3% and 92.0%, respectively.
Conclusions: It is suggested that ELISA using mixed lysate of T. vaginalis six isolates could be useful tools for the diagnosis of trichomoniasis.
[in Korean]
Soo Jin Choi, M.D., Sang Hyun Hwang, M.D., Joon Seok Park, M.D., Mi-Na Kim, M.D. and Chik Hyun Pai, M.D.
Ann Clin Microbiol 2000 March, 3(1): 69-74. Published on 20 March 2000.
Background: Although enriched broth cultures have been recommended as an adjuvant to the direct plating of tissue and body fluid specimens, the cost-effectiveness of broth cultures has been questioned in regard with the clinical significance of “broth only isolates (BOI)”. The purpose of this study was to investigate the usefulness of thioglycollate broth (THIO) cultures.
Methods: We reviewed retrospectively results in the culture specimens of body fluids, tissue biopsies, and puses received during the month of July 1997. All specimens were inoculated into THIO in addition to agar plates. We reviewed the medical records of culture-positive patients to determine the clinical significance and relevance of their isolates. Clinically significant isolates were defined as those for which an appropriate antimicrobial therapy was done except one judged as contaminants by clinicians and clinically relevant isolates as the clinically significant one isolated first.
Results: Of 2,008 specimens, 512 (25.4%) from 365 patients grew 561 isolates including 464 plate isolates and 97 BOI. Two hundred eighty nine (62.3%) of the 464 isolates from plate cultures were clinically significant, compared to only 12 (12.4%) of 97 BOI (P<0.05). Only four (4.1%) BOI were clinically relevant, including one Pseudomonas aeruginosa from ascites, one Klebsiella pneumoniae and two Staphylococcus aureus from tissue specimens.
Conclusion: A routine use of enriched broth culture rarely recover clinically relevant isolates. Considering the laboratory and medical costs of the recovery of contaminants and clinically irrelevant isolates, the enrichment broth cultures should be used more selectively.
[in Korean]
Jun Wan Park, M.D., Hae Shim Choi, M.T., and Eui Chong Kim, M.D.
Ann Clin Microbiol 2000 March, 3(1): 75-78. Published on 20 March 2000.
Methicillin-resistant Staphylococcus aureus small colony variants (SCVs) are frequently auxotrophic for hemin, menadione, thiamine, and CO₂ involved in biosynthesis of the electron transport chain element. This phenotype grows slowly, and forms very small, nonhemolytic colonies in routine culture, so it may be led to the misidentification of this organism. We isolated an organism with catalase-positive, gram-positive cocci in cluster from the urine of a 55-years-old woman with persistent and relapsing bladder stone, who had undergone the antibiotic treatment with cefotaxime, ceftizoxime, amikacin, and/or micromoncin, intermittently for three years. The possibility of SCVs should have been ruled out because this organism didn’t grow on Mueller-Hinton agar (MHA) for the susceptibility test. It formed small colonies on blood agar plate overnight, and grew only on MHA with supplement of hemin, or with 5% CO₂. This organism was coagulase-positive, DNase-positive, manitol-salt positive, and identified as S. aureus with VITEK GPI card. The susceptibility test could be performed after adding hemin(1mg/mL) into bacterial suspension and showed susceptibility against vancomycin, teicoplanin, and rifampin. Because these phenotypes can be misidentified as other non-pathogenic organisms due to their atypical characteristics, we should consider SCVs in case of small, nonhemolytic colonies with catalase-positive, gram-positive cocci in cluster, showing no growth on MHA. In addition, Infections caused by SCVs are recently recognized in relation to persistent and relapsing infection, so they could be isolated from the patients with long-term antibiotic therapy.
[in Korean]
Hyun Yong Hwang, M.D., Seok Hoon Jeong, M.D., Tae Jeon Jeong, M.T., Byeong Gil Choi, M.T., Sang Uk Lee, M.D. and Mi Hyang Kim, M.D.
Ann Clin Microbiol 2000 March, 3(1): 79-81. Published on 20 March 2000.
V. parahaemolyticus was isolated from blood culture of a 34-year old female patient with HCV viral hepatitis and liver cirrhosis. V. parahaemolyticus is one of the frequent causative agents of gastrointestinal infection, but rarely causes septicemia. This case is thought to be the 3rd report of V. parahaemolyticus septicemia in Korea.
[in Korean]
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