Jung Oak Kang, M.D.
Ann Clin Microbiol 2001 March, 4(1): 1-4. Published on 20 March 2001.
최근 바이러스 배양검사가 의료보험에 인정되는 검사법으로 자리잡았으므로, 향후 바이러스배양검사를 실시하는 임상병리과가 늘어나리라 짐작된다. 그러나 바이러스배양검사는 많은 비용과 인력, 그리고 공간이 필요하므로 도입하기가 쉽지는 않을 것이다. 이에 비하여 분자생물학기법을 이용한 병원균의 검출은 그 비용 효과적인 문제점에도 불구하고 폭발적으로 늘어나고 있다. 특히 배양이 까다로운 균이나 바이러스의 검출에 가장 널리 이용되고 있으며 향후 점차 증가될 전망이다[1-3]. 각종 바이러스의 분자생물학적 검사를 도입하기 위하여, 배양이 가능한 바이러스의 경우, 새 검사법의 민감도, 특이도 측정, 양성대조군의 준비 및 정량검사 등을 위하여 바이러스의 정량검사가 가장 기본적으로 필요하다. 저자 역시 바이러스의 핵산증폭검사를 도입하기 위하여 그리고 새로이 도입되는 핵산증폭법 및 기기의 평가를 위하여 바이러스 정량검사를 시도하였으며, 이 경험을 나누고자 배양이 가능한 바이러스를 중심으로 바이러스정량법을 정리하여 본 논문을 쓰게 되었다.
[in Korean]
Hee Joo Lee, M.D.
Ann Clin Microbiol 2001 March, 4(1): 5-10. Published on 20 March 2001.
Salmonella는 사람을 비롯하여 여러 동물을 감염시키며, 혈액, 변 및 농 등 다양한 검체에서 분리되며, 장외 조직을 침투하여, 장염에서 장티푸스에 이르기까지 다양한 감염을 일으킬 수 있다[1]. 과거 우리 나라에서 분리된 Salmonella 중 대부분은 Salmonella Typhi 였으나 1970년대 후반부터는 Salmonella Typhi 의 분리가 줄어들고 다른 혈청군의 Salmonella, 특히 B군의 증가가 현저하였다[2-4]. 또한 항균제 내성 양상도 달라지고 있어, 이들의 변화 양상과 아울러 생화학적 성상 및 역학적 성상을 관찰하고자 하였다.
[in Korean]
In Ki Paik, M.D., Yong Soon Kim, M.D., Won Chang Shin, M.D., and Jin Ho Lee, M.D.
Ann Clin Microbiol 2001 March, 4(1): 11-15. Published on 20 March 2001.
Backgrounds : Culture of Helicobacter pylori (H. pylori) from gastric biopsy specimens is a standard method with high specificity among H. pylori diagnostic tools and is also essential for antibiotic susceptibility test. The authors compared 5 selective media for H. pylori culture and tested fresh human serum instead of fresh animal blood as a media composite.
Methods : Gastric biopsy specimens from endoscopic examination were obtained from 50 patients (gastric ulcer:33, duodenal ulcer:12, stomach cancer:5) and they were finely minced with a tissue grinder. Specimens were inoculated onto 5 media (1. Columbia agar with 5% sheep blood, 2. Columbia agar with 10% human serum, 3. Thayer-Martin agar with 5% sheep blood, 4. T-M agar with 10% human serum, 5. T-M agar with 10% hemoglobin) and cultured for 3∼7 days under microaerophilic condition. Gram stain, oxidase, catalase, and urease tests, were undertaken on typical colonies for diagnosis of H. pylori.Contamination by other organisms, number and size of H. pylori colonies were compared for each media.
Results: Positive culture rate of H. pylori was not significantly different among 4 media except TM agar with 10% hemoglobin. However T-M agar with 10% fresh human serum was considered as the best composition for culture of H. pylori because it had the least contaminating organisms and produced the largest colony sizes.
Conclusions: These findings suggest that T-M agar with 10% fresh human serum can replace columbia agar with 5% sheep blood which has been commonly used for culture of H. pylori from gastric biopsy specimens. Fresh human serum, which is easily obtained in the clinical laboratory, can replace animal bloods in making media for H. pylori.
[in Korean]
Kap Jun Yoon, M.D., Young Uh, M.D., Gyu Yel Hwang, M.S., In Ho Jang, M.S., Mi Kyung Lee, M.T.
Ann Clin Microbiol 2001 March, 4(1): 16-21. Published on 20 March 2001.
Background: Macrolide resistance in β-hemolytic streptococci has increased during the 1990s, and the proportion of MLS (Macrolide-lincosamide-streptogramin) resistance phenotypes and genotypes of β-hemolytic streptococci are quite different by geographical variation and study period. The aim of the present study was to determine the distribution of MLS resistance phenotypes and genotypes in β-hemolytic streptococci isolated from Wonju Christian Hospital.
Methods : The minimal inhibitory concentrations of erythromycin and clindamycin of 426 β-hemolytic streptococci isolated from clinical specimens between 1990 to 1999 were determined by agar dilution method. MLS resistance phenotypes were determined by double disk diffusion method using erythromycin and clindamycin disk, and genotypes were determined by polymerase chain reaction (PCR). The PCR primers for erm(A), erm(B), erm(C), erm(TR), and mef(A) were used in these study.
Results: The proportion of MLS resistance phenotypes of 80 erythromycin-resistant β-hemolytic streptococci were 60.0% for constitutive phenotype, 23.8% for M phenotype, and 16.2% for inducible phenotype. The proportion of three MLS resistance phenotypes of group A streptococci were nearly equal. About three-fourths of group B streptococci had the constitutive phenotypes, whereas three-fourths (75%) of group G streptococci had the M phenotypes. All MLS resistant strains carried the erm(B) genes in constitutive phenotypes, erm(TR)genes in inducible phenotypes, and mef(A) genes in M phenotypes, respectively.
Conclusions : Mechanisms and phenotype proportions of MLS resistance are different by species in β-hemolytic streptococci. It is possible that MLS resistance genes have transferred among β-hemolytic streptococci because the erythromycin resistance genes are the same in β-hemolytic streptococci.
[in Korean]
Young Uh, Gyu Yel Hwang, In Ho Jang, Hyeun Gyeo Lee, An Suk Jeoung, Soon Deok Park, Jeong Seog Son, and Kap Jun Yoon
Ann Clin Microbiol 2001 March, 4(1): 22-27. Published on 20 March 2001.
Background: Although most of aerobic gram-positive bacilli have been considered to be contaminants, gram-positive bacilli should be identified to the species level if they are isolated from sterile body sites such as blood, and from adequately collected clinical specimens if they are the predominant organisms. However, identification of gram-positive bacilli are difficult due to the enormous diversity of these organisms and the small number of readily available commercial identification systems in clinical laboratories. Gram-positive bacilli and coccorods isolated from blood cultures were tested with BBL Crystal Gram-Positive (GP) Identification (ID) system in order to evaluate the system’s usefulness of identifying these bacteria.
Methods : Thirty-seven stock strains of aerobic gram-positive bacteria isolated from blood cultures between October 1998 and November 1999 at Wonju Christian Hospital were simultaneously tested by BBL Crystal GP ID system and API system. Three kinds of API system (API Coryne, API 50 CHB, and API 20 Strep) were tested according to gram stain results. Gram-positive bacilli or gram-positive coccorods consecutively isolated from blood cultures from May to November in 2000 were identified by BBL Crystal GP ID system.
Results : Among the 37 stock strains of aerobic gram-positive bacteria, agreement rate of identification between Crystal GP ID system and API system were 88% to the genus level and 63% to the species level in Bacillus species, and 90% to the genus level in Corynebacterium species. The isolation rate of gram-positive bacteria from blood cultures from May to November in 2000 to the genus level were: Bacillus; 41.9%(18/43), Corynebacterium; 37.2%(16/43), and the other grampositive coccorods; 20.9%(9/43).
Conclusions: Crystal GP ID system is a useful identification system which, when combined with basic microbiological tests, should lead to satisfactory identification results for gram-positive bacteria isolated from blood cultures.
[in Korean]
Young Uh, M.D., In Ho Jang, M.S., Kap Jun Yoon, M.D., Hyun Soo Kim, M.D., and Hyo Youl Kim, M.D.
Ann Clin Microbiol 2001 March, 4(1): 28-32. Published on 20 March 2001.
Background : Vibrio species may be classified as halophilic or nonhalophilic on the basis of their requirement of NaCl for optimal growth. Recently, attention has been focused on the halophilic vibrios and Vibrio cholerae non-O1/O139 causing extraintestinal infections such as septicemia. The aim of this study is to elucidate the isolation rate and clinical manifestations of Vibrio species isolated from clinical specimens between 1996 and 2000 at Wonju Christian Hospital.
Methods : Stool specimens were inoculated onto the thiosulfate-citrate-bile salt-sucrose media, blood cultures were performed by automated blood culture systems with commercial bottles, and the others were cultured according to the routine procedures.
Results : The isolation rate of Vibrio in decreasing order were: V. parahaemolyticus; 87%(62/71), V. alginolyticus; 6%(4/71), V. cholerae non-O1; 4%(3/71), and V. vulnificus; 3%(2/71). The proportions of gastroenteritis and septicemia by Vibrio species were 89% and 7%, respectively. Patients with gastroenteritis recovered without special problem, but the mortality of septicemia was 80%.
Conclusions : Ninety-seven percentage of clinical isolates of Vibrio species were halophilic vibrios, and the mortality of Vibrio septicemia was as high as 80%.
[in Korean]
Jong Hee Shin, M.D., Chang Jae Lee, M.D., Jee Yeon Lee, M.D., Jeong Won Song, M.D., Seong Jung Kee, M.D., Soon Pal Suh, M.D., and Dong Wook Ryang, M.D.
Ann Clin Microbiol 2001 March, 4(1): 33-39. Published on 20 March 2001.
Background : Aspergillus species are second only to Candida species as the most commonly isolated fungi from clinical specimens. As well as the identification of the Aspergillus species, it has been necessary for epidemiological studies to differentiate between strains of the same species. We performed genotypic identification and characterization of species and strains within the genus Aspergillus by using RAPD.
Methods : A total of 63 clinical strains of Aspergillus species (including 21 A. fumigatus, 12 A. flavus, 12 A. niger, 12 A. terreus, 3 A. nidulans, and 3 A. sydowii) from 63 patients was analyzed. For RAPD alanysis, M13 primer (5’GAGGGTGGCGGTTCT3’) and five random 10-mer primers (OPC-6, 7, 10, 18 and 20; Operon Technologies, USA) were used.
Results : The RAPD patterns by M13 primer appeared to be identical when the isolates of the same Aspergillus species were compared. Distinctive and reproducible sets of amplification products by primer M13 were observed for different Aspergillus species: 60 of 63 (95%) isolates were correctly identified by the RAPD analysis using primer M13. RAPD patterns obtained from different strains of the same Aspergillus species by five OPC primers were far more similar than those derived from different Aspergillus species, but the RAPD profiles with some OPC primers showed polymorphism among isolates of the same Aspergillus species. The application of some OPC primers made it possible to cluster the isolates of the same Aspergillus species into several groups.
Conclusion : These results indicate that RAPD can be useful for the rapid identification of Aspergillus species and for strain typing in the epidemiological investigations.
[in Korean]
Chulhun L. Chang, M.D., Dae Young Seo, M.D., Tae Hee Park, M.D., Jeong Seon Park, M.D., and Weon Joo Hwang, M.T.
Ann Clin Microbiol 2001 March, 4(1): 40-44. Published on 20 March 2001.
Background: Mycobacterial false-positive cultures have rarely been recognized in Korea, even though the rate of false-positive cultures of Mycobaterium tuberculosis has ranged from 0.4% to 4.0%. We estimated the false-positive rates by the review of medical records from whom mycobacterial cultures were requested, retrospeaively, after a bout of false-positive cultures was discovered in specimens treated in a single day.
Methods : Of the total 2,245 specimens, including 337 positive cultures of mycobacteria, during the period of January and June 1999, seventy-two specimens that showed colonies less than or equal to 5 colonies were reviewed, and classified as tuberculosis-likely group, tuberculosis-unlikely group and unclassifiable group by the clinical and radiological evidences, anti-tuberculosis therapy, and microbiological results.
Results : Tuberculosis-unlikely group was 21 specimens from 20 patients, and unclassifiable group was five specimens from four patients. So, the false-positive rates were estimated as 0.91.1% of total cultures and 6.2-7.7% of positive cultures, according to excluding or including the unclassifiable group.
Conclusion: Care should be taken for lowering false-positive mycobacterial cultures. Especially when a culture turned out to be positive with low colony isolates, more careful interpretations should be preceded before reporting the results by the review of medical records and communication with physician in charge.
[in Korean]
Wonkeun Song, M.D., Tae Jae Lee, M.T., Seung Joo Kim, R.N., Min-Jeong Park, M.D., and Kyu Man Lee, M.D.
Ann Clin Microbiol 2001 March, 4(1): 45-51. Published on 20 March 2001.
Background: Methicillin-resistant Staphylococcus aureus (MRSA) is the most common nosocomial pathogen, which is particularly prevalent in intensive care units (ICUs). We performed this study to investigate the modes of transmission of MRSA and the role of nasal carriage of MRSA to subsequent MRSA infection in ICU.
Methods: From September to November 1997, all patients admitted for more than two days to the ICU were studied prospectively. Nasal swabs were obtained at admission and weekly during the ICU stay. Surveillance cultures of nares of the ICU personnels were done. Molecular typing was performed with repetitive sequence-based PCR (rep-PCR).
Results: At ICU admission 34 patients (21.0%: 19 MSSA, 15 MRSA) were MRSA nasal carrier, while 126 patients were free of nasal colonization. During the ICU stay 12 (9.5%: 3 MSSA, 9 MRSA) of the 126 noncolonized patients became nasal carriers (P <0.05). S. aureus infections (all MRSA) were documented in 14 (15 isolates, 8.6%) of the total 162 patients. S. aureus infections were significantly higher for those patients who were nasal carriers at ICU admission than for those found to be initially negative (P <0.05). Two different type (A, 7 isolate; B, 8 isolates) of rep-PCR patterns were identified. All four nasal and seven clinical isolates from the patients, and four nasal isolates from the ICU personnels were mixed with A and B patterns, respectively.
Conclusion : Nasal colonization was related to the increased incidence of MRSA infections. Patients or ICU personnels who were nasal colonized with MRSA seemed to be a major source for transmission of MRSA in the ICU.
[in Korean]
Do-Hang Kim, Tae-Jun Yoon, Chulhun L. Chang, and Sang-Jun Lee
Ann Clin Microbiol 2001 March, 4(1): 52-57. Published on 20 March 2001.
Background: Increase of immunocompromised patients and frequent use of indwelling catheters cause staphylococcal bacteremia, especially due to coagulase-negative staphylococci (CNS), in contrast with Staphylococcus aureus in the past. And, infections of methicillin-resistant staphylococci have been increasing in number from 1970s. In this study, species of staphylococcal isolates from blood were demonstrated, and their methicillin susceptibilities were evaluated for the empirical choice of antibiotics.
Methods : One hundred and seventy-five staphylococcal strains isolated from blood culture at Pusan National University Hospital during the year 1999 were included. Species identification, susceptibility tests by agar dilution and disk diffusion methods, and mecA gene detection by polymerase chain reaction were performed.
Results : S. aureus (41%), S. epidermidis (30%), S. auricuralis, S. intermedius, S. haemolyticus, S. capitis, S. simulans, S. sciuri, S. homis, and S. warneri were identified. Thirty-one stains (43.4%) of S. aureus, 43 stains (83%) of S. epidermidis, and 24 stains (46%) of other CNS are resistant to oxacllin. The results of disk diffusion test were consistant with agar dilution tests in all S. aureus strains and 95.5% of CNS strains. The results of mecA gene detection were consistant with agar dilution methods in 96.8% of S. aureus and 89.6% of CNS.
Conclusions : Not only S. aureus and S. epidermidis but also other various species of staphylococci were recovered from blood, and methicillin-resistant strains reached 43.2% of S. aureus, and 64.4% of CNS. These results would help for physicians to choose primary empirical therapeutic agents of patients who are suggestive of staphylococcal bacteremia.
[in Korean]
Yeong Sic Kim, Yong Hyun Jo, Hee Joo Lee, Jin Tae Suh, and Young Ja Lee
Ann Clin Microbiol 2001 March, 4(1): 58-61. Published on 20 March 2001.
Background: It takes long time to cultivate Mycobacterium tuberculosis on solid media from clinical specimens. Although there is progress in the detection of tuberculosis using liquid media, Ogawa media is broadly used in Korea. In the 1990s, the BACTEC 460 system (Becton Dickinson, Sparks, MD, USA) was used in some laboratories in Korea, but at present, it is not used because of the accumulation of radioactive waste and the risk of cross-contamination. The BACTEC MGIT 960 system (Becton Dickinson, Sparks, MD, USA) is one of the new systems using liquid media. MGIT system uses oxygen-quenching fluorescence sensor technology instead of radioactive material. We evaluated MGIT for the sensitivity and specificity for the diagnosis of Mycobacterium tuberculosis by comparison with Ogawa media.
Methods: A total of 232 sputum specimens were collected from patients admitted to the hospital. All specimens were processed by 4% NaOH and 0.5% NALC. After inoculation of MGIT with 0.5 mL and Ogawa with 0.3 mL of the processed specimen, the media were observed every 3 days until 6 weeks and 8 weeks, respectively.
Results: A total of 99 isolates of mycobacteria were recovered from 232 specimens. Ninety nine isolates were detected with MGIT, as contrasted with 64 detected with Ogawa media. The mean times to detection of the Mycobacterium species were 12.6 days for MGIT, 23.7 days for Ogawa media. Contamination rates were 5.1% for MGIT, 5.6% for Ogawa media.
Conclusion: From our study, we conclude that MGIT is a superior method for recovery rate and time to detection of Mycobacteria to Ogawa media.
[in Korean]
Gyu Yel Hwang, Young Uh, Hyun-Joo Kim, In Ho Jang, and Kap Jun Yoon
Ann Clin Microbiol 2001 March, 4(1): 62-66. Published on 20 March 2001.
Background : Accurate detection of extended spectrum β-lactamase (ESBL) is important because ESBLs producing organisms may appear susceptible to oxyimino-β-lactams in standard susceptibility tests, but are considered to be clinically resistant to these drugs. Conventional antimicrobial susceptibility test methods do not reliably detect ESBL production. Molecular techniques and NCCLS broth dilution method, which detect ESBL production, may be time consuming, expensive and technically difficult to perform. The purpose of this study is to evaluate the clinical usefulness of NCCLS ESBL phenotypic confirmatory test by disk diffusion method.
Methods : For 96 Escherichia coli and 49 Klebsiella pneumoniae isolates collected between December 2000 to February 2001, double disk synergy test, NCCLS ESBL screening and phenotypic confirmatory test by disk diffusion test were performed. The ESBL producer was defined as organism showed an increase in the zone diameter of ≥5 mm for either antimicrobial agent such as cefotaxime and ceftazidime tested in combination with clavulanic acid versus its zone when tested alone.
Results : The sensitivity of NCCLS ESBL phenotypic confirmatory test were as follows: cefotaxime/clavulanic acid disk; 100% in K. pneumoniae and 83% in E. coli, and ceftazidime/clavulanic acid disk; 94% in K. pneumoniae and 67% in E. coli, respectively. Among the organisms with positive to NCCLS ESBL phenotypic confirmatory test, the detection rate of antimicrobial agents in double disk synergy test were as follows: K. pneumoniae; cefotaxime (84%), aztreonam (74%), and ceftazidime (52%), and E. coli; cefotaxime (44%), ceftazidime (44%), and aztreonam (39%).
Conclusions : The NCCLS ESBL phenotypic confirmatory test by disk diffusion method is easy, rapid, and sensitive method, suitable for routine use in the clinical laboratory.
[in Korean]
Kyong-Ah Yun, M.D., Mi-Na Kim, M.D., Chik Hyun Pai, M.D., and Han Joo Lee, M.D.
Ann Clin Microbiol 2001 March, 4(1): 68-71. Published on 20 March 2001.
Yersinia pseudotuberculosis is a relatively infrequent cause of human infections, mostly as intestinal yersinosis. A septicemic form of Y. pseudotuberculosis infection has been reported only rarely. It is usually seen in patients with underlying disorders such as diabetes, hepatic cirrhosis or iron overload. A 63-year-old man with diabetes mellitus and liver fibrosis was admitted to Asan Medical Center via emergency department because of epigastric pain, fever and watery diarrhea; he was septic. The stool culture did not grow Salmonella, Shigella, or Yersinia. But, in the blood culture Y. pseudotuberculosis grew from one anaerobic vial among two sets of aerobic and anaerobic blood cultures. Serotype of Y. pseudotuberculosis strain was could not be determined because it was a rough type. The isolate was positive in the autoagglutination test and polymerase chain reaction for the virF gene. The serum levels of iron, TIBC and ferritin were within normal range. The patient received ceftriaxone therapy for 3 days and was discharged with a clinical improvement.
[in Korean]
For Authors
Publisher
Sponsors
