Annals of Clinical Microbiology, The official Journal of the Korean Society of Clinical Microbiology


Weeks in Review


Weeks to Publication
Indexed in KCI, KoreaMed, Synapse, DOAJ
Open Access, Peer Reviewed
pISSN 2288-0585 eISSN 2288-6850

September, 2002. Vol. 5 No. 2.

Review article

Current Status of Antifungal Suscepitibility Testing: Technical Advances and Clinical Applications

Jong Hee Shin

Ann Clin Microbiol 2002 September, 5(2): 69-76. Published on 20 September 2002.

최근 진균에 의한 중증감염의 빈도가 증가함에 따라 항진균제 감수성 검사의 필요성이 제기되었다[1-3]. 전신적 진균감염의 치료에는 오랫동안 amphotericin B와 flucytosine만이 사용되어 왔으나 근래에는 itraconazole, ketoconazole 및 fluconazole 등 이외에도 새로운 triazoles (voriconazole, ravuconazole 및 posaconazole)과 echinocandin제제(caspofungin, anidulafungin 및 micafungin) 등 다양한 항진균제가 개발되어 생체외 감수성검사를 통해 선택이 가능해졌다[3]. 또 후천성면역결핍증 환자에서 발생한 재발성 구인두 칸디다증(oropharyngeal candidiasis)의 치료를 위해 fluconazole을 장기 투여한 경우 fluconazole 내성 Candida albicans가 출현했다고 보고[4, 5]됨에 따라 항진균제 내성의 검출도 필요해졌다. 따라서 항진균제 감수성 검사는 최근 큰 진전을 보이고 있다[6-11].

[in Korean]

Original article

Trends of Viral Respiratory Pathogens Detected in Pediatric Patients, 1996 Through 2001

Kyutaeg Yi, Jung Oak Kang, Jae Won Oh, Si Young Ham, Tae Yeal Choi

Ann Clin Microbiol 2002 September, 5(2): 77-83. Published on 20 September 2002.

Background:Acute lower respiratory tract infections are common causes of hospitalization in children and viruses are major causative agents. The causative viruses are known to be variable by age, region, or year. We investigated the recent 5-year epidemics of respiratory viruses for pediatric patients in two university hospitals in Korea.

Material and Methods:From July 1996 through June 2001, viral agents were detected for the 2,317 pediatric patients who were hospitalized with acute respiratory tract infection in Hanyang University Hospital and Hanyang University Guri Hospital. We obtained nasopharyngeal aspirates on the day of admission and detected the viruses by indirect immunofluorescent staining method (Respiratory panel I viral Screening & Identification Kit, Light Diagnostics, Chemicon, Temecula, CA, USA).

Results:The causative viral agents were detected in 737(31.76%) patients. They were respiratory syncytial virus of 53.6%, influenza A virus 38.6%, adenovirus 5.5%, influenza B virus 1.9%, and parainfluenzavirus 0.4%. The epidemics of RSV were found during winter, but the epidemics of influenza A were found more frequently in spring, which had tendency of following the epidemic of RSV. Adenovirus was detected sporadically throughout year. RSV was found more frequently in patient with bronchiolitis and pneumonia and also found more frequently in patient less than 6 month of age. Influenza A and adenovirus were in patients of pneumonia and in more frequently in patient one to two year of age.

Conclusion:Viruses were the leading causative agents of acute lower respiratory tract infections in pediatric patients. RSV was the most important causative agent. Influenza A virus was the second frequent viral agent and detection rate was higher than other reports. The detection rate of parainfluenza virus was lower than other reports from Korea or from abroad.

[in Korean]

Original article

Phenotypes and Interpretive Reading of Antimicrobial Susceptibility Tests for Clinical Isolates of Several Species

Dae-Gu Son, Eun-Hee Kwon, Hye-Gyung Bae, Woon-Bo Heo, Nan-Young Lee,Dong-Il Won, Kyung-Eun Song, Jang-Soo Suh, Won-Kil Lee

Ann Clin Microbiol 2002 September, 5(2): 84-96. Published on 20 September 2002.

Bakground: In recent years, knowledge of bacterial resistance to antimicobials has expanded in important ways. Availability of an increasing number of antibiotics allows more precise individualization of resistance phenotypes and recording susceptibility results as patterns or phenotypes is valuable for both surveillance and patient care. If the patterns of resistance to panels of related antimicrobials are considered the underlying mechanisms can often be inferred. And the inferred mechanisms make the clinician to be advised to use alternative treatment. Interpretation of resistance phenotypes is based on the comparison of clinical isolates with prototype susceptible bacteria belonging to the same species. But interpretative reading of antimicrobial susceptibility tests requires an immense knowledge of antibiotics. Such interpretative reading is best achieved by computerized expert systems.

Methods: The authors attempt to determine phenotypes for the clinically isolated strains for each class of drugs tested by the Vitek 2 systemTM(bioMerieux, Marcy I’Etoile, France) using the Advanced Expert SystemTM(AES, bioMerieux, Marcy I’Etoile, France). A total of 91, 107, 89, 65, 251, 113, 47, 33, 23, 122 and 110 isolates of Staphylococcus aureus, coagulase negative staphylococci, Enterococcus faecalis, Enterococcus facium, Escherichia coli, Klebsiella pneumoniae, Serratia marcescens, Enterobacter cloacae, Enterobacter aerogenes, Pseudomonas aeruginosae and Acinetobacter baumannii, were examined respectively.

Results: Biological correction based on the phenotype was recommended from 2.2% of E. faecalis to 46.8% of S. marcescens and therapeutic correction, from 7.3% of A. baumannii to 60.9% of E. aerogenes. A total of 25, 26, 18, 19, 22, 22, 15, 15, 17, 19, 19 phenotypes of S. aureus, coagulase negative staphylococci, E. faecalisE. facium, E. coli, K. pneumoniae, S. marcescens, E. cloacae, E. aerogenes, P. aeruginosa and A. baumannii, were detected respectively. Association of resistance mechanism from S. aureus, coagulase negative staphylococci, E. coli, K. pneumoniae, S. marcescens, show 10, 11, 6, 4 and 3 pairs from resistant phenotypes, respectively.

Conclusion: Vitek AES potentially provides a tool to assist the development of antimicrobial susceptibility interpretation in the clinical microbiology laboratory. The inferred mechanisms make the clinician to be advised to use alternative treatment.

[in Korean]

Original article

Characterization of Extended-Spectrum-β-Lactamase Genes from Clinical Isolates of Enterobacter species

Jeong Man Kim, Seok Hoon Jeong, Bit Na Kim, Ji Hyun Sung, Jong Chul Kim, Hyunjung Jang

Ann Clin Microbiol 2002 September, 5(2): 97-104. Published on 20 September 2002.

Background: Among Enterobacter spp. isolates from clinical specimens in Korea, the incidence of resistance to expanded-spectrum cephalosporins is becoming an ever-increasing problem. This study was designed to determine the prevalence of expanded-spectrum cephalosporins-resistant Enterobacter spp. isolates from patients in a tertiary care hospital in Busan, Korea, and to characterize the mechanism of resistance.

Materials and Methods: Nonduplicated clinical isolates of Enterobacter spp. were collected during the period of 1999-2000 in Kosin Medical Center, Busan, Korea. Antimicrobial susceptibilities were tested by disk diffusion method. Cefotaxime-resistant or intermediate isolates were examined for extended-spectrum β-lactamase (ESBL)-production by double disk synergy (DDS) test. Minimal inhibitory concentrations were determined by agar dilution method. For detection of blaTEM and blaSHV genes, polymerase chain reactions (PCRs) were performed, and the DNA sequences of blaTEM and blaSHV genes were determined by using dideoxy-chain termination method.

Results: From 1999 to 2000, a total of 306 Enterobacter spp. strains were isolated from patients in Kosin Medical Center. Forty one percents of Enterobacter spp. isolates were susceptible to cefotaxime. Among 90 isolates resistant or intermediate to cefotaxime, 26 isolates (29%) showed positive results in double disk synergy test. Among DDS-positive- isolates, 22 isolates contained both of blaTEM and blaSHV genes, while one isolate only contained blaTEM gene and two isolates only contained blaSHV gene. Among 64 DDS-negative isolates, 47 isolates contained blaTEM genes, and 12 isolates also contained blaSHV genes. Nucleotide sequence analysis of PCR products from 10 DDS-positive and 6 DDS-negative isolates, which contained both of blaTEM and blaSHV genes, revealed that blaTEM-1b and blaSHV-12 genes were the dominant types of β-lactamase gene.

Conclusion: Expanded-spectrum cephalosporins-resistant Enterobacter spp. were wide spread in Kosin Medical Center, Busan, Korea. Some of the resistant isolates acquired resistance by production of ESBLs, and blaSHV-12 gene was the most frequent ESBL gene in cefotaxime-resistant Enterobacter spp. 

[in Korean]

Original article

Evaluation of Various Methods for Detection of Methicillin Resistance Staphylococcus aureus (MRSA)

Hye Soo Lee, Hyun Lim

Ann Clin Microbiol 2002 September, 5(2): 105-110. Published on 20 September 2002.

Background: Traditional antimicrobial susceptibility test methods for detection of methicillin resistant Staphylococcus aureus(MRSA) require 24 hours to perform. In addition, accuracies of these methods can be influenced by prevalence of strains that express heterogeneous resistance. The mechanism of methicillin resistance in S. aureus is based on the production of an additional lowaffinity penicillin binding protein (PBP 2a), which is encoded by mecA gene. Therefore, PCR for mecA gene and immunological methods for PBP 2a could be used to determine resistance, but most clinical laboratories do not have resources to efficiently perform these technique on routine basis. Recently, slide latex agglutination test using latex particles sensitized with a monoclonal antibody against PBP 2a for the direct detection of PBP 2a was developed. In this study, we evaluated this new latex agglutination test, and compared to oxacillin disk diffusion test and PCR detection of mecA gene for detection of MRSA.

Methods: A total 151 clinical isolates of coagulase positive S. aureus were selected. All isolates were subjected to “blinded”testing with oxacillin disk diffusion, PBP 2a latex agglutination, and mecA PCR for detection of MRSA.

Results: Of 151 S. aureus, 116 (76.8%) strains were MRSA. The sensitivities and specificities of disk diffusion, latex agglutination and PCR were 94.0 and 91.4%, 97.4 and 100%, 98.3 and 100%, respectively.

Conclusions: PCR for detection of mecA gene and latex agglutination test for PBP 2a are more sensitive and specific methods for detection of MRSA than oxacillin disk diffusion test. Latex agglutination test is rapid, simple, and easier to perform than PCR. In conclusion, PBP 2a detection with latex agglutination test has the potential to be used for routine applications in the microbiology laboratory where mecA gene detection with PCR is not readily available.

[in Korean]

Original article

Detection of Methicillin-Resistance of Coagulase-negative Staphylococci

Young-Uk Cho, Jeong-Don, Hye-Young Park, Mi-Na Kim

Ann Clin Microbiol 2002 September, 5(2): 111-118. Published on 20 September 2002.

Background:Coagulase-negative staphylococci (CNS) has been considered as a major causative agent of nosocomial infections. A prompt and accurate detection of methicillin resistance (MR) in staphylococci is a current issue of clinical microbiology laboratories. This study was purposed to evaluate various methods for detecting MR from CNS.

Methods:We selected 78 CNS strains obtained from blood cultures from April 1999 through July 2001 including 20 strains of Staphylococcus epidermidis, 20 S. hominis (SHO), 19 S. capitis, 9 S. haemolyticus, 3 S. saccharolyticus, 1 S. saprophyticus (SAP), 2 S. warneri (SWA), 2 S. xylosus, 1 S. lugdunensis, and 1 S. auricularis. In addition, one SAP strain received from World Health Organization for proficiency tests was also studied. The following methods were compared to the mecA gene PCR: MicroScan PosCombo 12, oxacillin salt agar containing 6 ㎍/mL (OSA-6) or 0.6 ㎍/mL (OSA0.6) of oxacillin, oxacillin disk diffusion (ODD), and MRSA-Screen latex agglutination (LA) for detecting penicillin binding protein 2a.

Results:One SWA was failed in mecA-PCR and fifty-nine of 78 (75.6%) CNS were positive for mecA gene. The agreement rates, sensitivities, and specificities for each test were as follows: for MicroScan, 97.3%, 98.2%, 88.9%; for OSA-6 and OSA-0.6 at 24-h incubation, 79.5%, 74.6%, 94.7% and 79.5%, 72.9%, 100%, respectively, and at 48-h incubation, 91.0%, 91.5%, 89.5% and 91.0%, 96.6%, 73.7%, respectively; ODD, 84.6%, 84.7%, 84.2%; LA, 80.8%, 76.3%, 94.7%. One SHO and one SAP that were mecA-negative showed resistance in the MicroScan, ODD, and OSA.

Conclusions:MicroScan appears a reliable method to detect MR in all species of CNS except SHO and SAP. ODD and LA were not appropriate in detecting MRCNS due to a low sensitivity. Although OSA-0.6 at 48-h incubation showed a high sensitivity, the low specificity may limit a routine use in clinical laboratory.

[in Korean]

Original article

Genotyping of Vibrio parahaemolyticus by Infrequent Restriction Site Polymerase Chain Reaction

Dong G. Keum, Jung O Kang, Tae Y. Choi

Ann Clin Microbiol 2002 September, 5(2): 119-123. Published on 20 September 2002.

Background: Infrequent restriction site PCR (IRS-PCR) is a recently described DNA fingerprinting technique based on selective amplification of restriction endonuclease-cleaved fragments. We applied of IRS-PCR to clinical isolates of Vibrio parahaemolyticus associated with diarrhea.

Methods: IRS-PCR assay was performed with adaptors for XbaI and HhaI restriction sites. A total of 35 strains of V. parahaemolyticus which were isolated from clinical specimens of patients with diarrhea were analyzed. The isolates were collected from different geographic areas of Seoul (n=12), Incheon (n=21) and Gwangju (n=2) during 1998-2000 in Korea.

Results: In IRS-PCR, amplifed DNA fragments between 50 and 400 bp were found to be the most reproducible in this study. When V. parahaemolyticus isolates were amplified with AH1 and PX-G as primers, 35 isolates could be grouped into five IRS-PCR patterns: A (n=16), B (n=4), C (n=6), D (n=5) and E (n=4). The patterns were subdivided into 15 subtypes: A1, A2, B1, B2, B3, B4, C1, C2, C3, D1, D2, D3, E1, E2 and E3. The IRS-PCR patterns of V. parahaemolyticus did not show any relationship with serotype or geographic origin, but the isolates from same outbreak produced a same pattern(A1).

Conclusion:The results provide evidence of the discriminatory power of the IRS-PCR method as it applies to V. parahaemolyticus.

[in Korean]

Original article

Evaluation of Quantitative culture of Clostridium difficile From Fecal Specimens for the Diagnosis of C. difficile-associated Disease

Dongeun Yong, M.D., Hyuk Min Lee, M.D., Jong Ha Ryu, M.D., Kyung Ho Roh, M.D., Won Ho Kim, M.D., Kyungwon Lee, M.D., and Yunsop Chong, M.D.

Ann Clin Microbiol 2002 September, 5(2): 124-128. Published on 20 September 2002.

Background: C. difficile-associated diarrhea (CDAD), the most frequently identified cause of nosocomial diarrhea, results from the overgrowth of cytotoxin (toxin B)-producing strains. The aim of this study was to evaluate the quantitative culture of Clostridium difficile to improve the laboratory diagnosis of CDAD.

Methods: The quantitative culture and cytotoxin gene results were evaluated based on the findings of colonoscopy and/or histology of the biopsy specimens.

Results: Among the 402 specimens with cytotoxin-positive isolates, 301 (74.9%) contained ≥106 CFU/mL of C. difficile. Nine (60%) of the 15 pseudomembranous colitis patients yielded ≥106 CFU/mL of toxigenic isolate. The proportion of cytotoxin gene-positive isolates was higher in the specimens with ≥106 CFU/mL of C. difficile than in those with 102-<103 CFU/mL (86.5% vs. 66.7%).

Conclusions: Quantitative culture may aid in the interpretation of toxigenic C. difficile culture results, and reduce false positivity, thus avoiding unnecessary treatment.

[in Korean]

Original article

Evaluation of a Modified Scheme for the Species Identification of Enterococci

Myungsook Kim, Sunhee Kim, Giyeon Kang, Dongeun Yong, Kyungwon Lee, Yunsop Chong, and Shin Moo Kim

Ann Clin Microbiol 2002 September, 5(2): 129-136. Published on 20 September 2002.

Background: Rapid species identification of enterococci is necessary for optimal treatment of infected patients as they are frequently resistant to various antimicrobial agents. Minimal identification scheme is necessary to cut the laboratory cost. In this study, a minimal identification system was modified to expand the identifiable species.

Methods:Performance of MGP test was compared to that of MIO motility test. Colonies on blood agar were used to inoculate primary identification media: SFA, BEAA, mannitol agar, tellurite agar, sorbose agar and MGP agar, which were prepared in biplates. Pigment production was tested when necessary using colonies on a blood agar. Isolates, which were not identifiable by the primary test, were inoculated to secondary test media: ADH, and arabinose-, raffinose- and sucrose-containing CTA. Vitek GPI cards were used to test isolates with a doubtful identification or no identification.

Results:MGP test was selected for the modified scheme, as it was more rapid and accurate than motility test. Among the 879 clinical isolates of enterococci, 462 (52.6%) and 3 (0.3%) were identified as E. faecalis and E. casseliflavus, respectively, by the primary test only. With the additional secondary tests, 379 (43.1%) isolates were identified as E. faecium. Vitek test showed the identification of 4 isolates with atypical test results and 5 isolates of rare species by modified scheme were correct. Nine isolates (1.0 %) were not identifiable by the modified scheme.

Conclusions: The modified minimal identification scheme which included MGP test identified most E. faecalis isolates rapidly and accurately. Most of E. faecium isolates were identified with the additional secondary tests. In conclusion, the system is useful for the identification of commonly isolated species of enterococci.

[in Korean]

Case report

Asymptomatic Urinary Tract Infection Caused by Shigella sonnei

Nam Yong Lee

Ann Clin Microbiol 2002 September, 5(2): 137-138. Published on 20 September 2002.

Shigella species usually produce self-limited gastrointestinal infections that rarely result in extraintestinal complications. Urirary tract infections (UTI) due to Shigella species are rare and Shigella sonnei UTI are particularly unusual. I report a case of asymptomatic UTI due to S. sonnei which was isolated from urine of a 56-year-old female complaining of fever, diarrhea and abdominal pain. S. sonnei was also isolated from stool of the patient. Shigella UTIs are reviewed.

[in Korean]

Case report

A Case of Vibrio cholerae non-O1/non-O139 Gastroenteritis

Key Earn Lee, and Ji-Hyun Cho

Ann Clin Microbiol 2002 September, 5(2): 139-142. Published on 20 September 2002.

Vibrio cholerae is an autochthonous inhabitant of estuarine and seawater environment and is a facultative pathogen for humans. V. cholerae non-O1/non-O139 strains are associated with gastroenteritis, septicemia and/or extraintestinal infections. But the reported cases of gastroenteritis by non-O1/non-O139 serotype, are rare in Korea. The authors isolated V. cholerae non-O1/nonO139 strain from a stool of a 67 year-old-woman who had suffered from diabetes, hypertension and Alzheimer disease and analyzed presence of toxin genes by multiplex PCR method.

[in Korean]

Case report

A Case of Cryptococcal Peritonitis and Causative Organisms of Peritonitis in a Continuous Ambulatory Peritoneal Dialysis Patient

Hae Il Park, Kyu Taeg Yi, Jung Oak Kang, and Tae Y. Choi

Ann Clin Microbiol 2002 September, 5(2): 143-146. Published on 20 September 2002.

Peritonitis in patients on continuous ambulatory peritoneal dialysis (CAPD) remains a major problem. Peritonitis due to Cryptococcus neoformans is an unusual complication. A 68-year-old woman on prednisolone for Behcets disease and adrenal insufficiency was admitted with chronic renal failure and CAPD was initiated. During her stay in hospital, she was treated with multiple antibiotics for urinary tract infection and CAPD peritonitis with methicillin resistant Staphylococcus aureus (MRSA). She was deteriorated insidiously and C. neoformans was cultured in the dialysate but not in the blood, urine and stool. After three days, she died. We reviewed 385 organisms isolated from 1,325 peritoneal dialysate specimens between 1990 and 2002. Staphylococcus aureus was most frequently isolated (22.6%). Fungus comprises 10.1% of the isolated organisms.

[in Korean]

Case report

A Case of Malassezia furfur Fungemia Associated with Central Venous Catheter Receiving Lipid Supplementation

Namhee Ryoo, Jung Sook Ha, Dong Seok Jeon, Jae Ryong Kim

Ann Clin Microbiol 2002 September, 5(2): 147-150. Published on 20 September 2002.

Although Malassezia furfur is normal skin flora causing superficial skin diseases, cases of fungemia have been reported recently in premature newborns or immunocompromised patients related to prolonged central venous catheterization for lipid supplementation. We report a case of M. furfur fungemia in a premature infant receiving intravenous lipid supplementation through central venous circulation. She was treated only with antifungal agents without removal of the catheter or discontinuation of lipid supplementation. Soon after, symptoms and signs of the patient seemed to be improved. However, central venous catheter was removed because of recurrent septicemia of Staphylococcus aureus and the culture of central venous catheter tip showed colonization of M. furfur.

[in Korean]

Case report

A Case Report of Invasive Infection due to Trichosporon beigelii in a Patient with Acute Leukemia

Hyun Lim, Dal Sik Kim, Hye Soo Lee, and Sam Im Choi

Ann Clin Microbiol 2002 September, 5(2): 151-154. Published on 20 September 2002.

Systemic infection due to Trichosporon beigelii is uncommon but increasingly reported in immunocompromised patients. Trichosporonosis is often refractory to conventional antifungal therapy and frequently fatal. We report a case of systemic T. beigelii infection in a patient with acute leukemia. The 35-year-old male patient had been diagnosed as acute myelogenous leukemia with severe neutropenia and received cytotoxic drug therapy. As a fever developed on the day 21 of chemotherapy, broad spectrum antibiotics were administered empirically. Even though an antifungal drug, amphotericin B was replaced because the blood cultures resulted in T. beigelii, the patient died of the septic shock. We think that T. beigelii should be included as a potential life-threatening pathogen capable of causing widespread systemic disease in the immunocompromised host.

[in Korean]