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

October, 2006. Vol. 9 No. 2.

Original article

Antimicrobial Resistance and Occurrence of Virulence Factors in Enterococci Isolated from Patients with Bacteremia and Urinary Tract Infection

Wee Gyo Lee, Il Joong Park, Ji Young Huh, Eui-Chong Kim, Kyungwon Lee, Mi-Na Kim, Chulhun L. Chang, Sunjoo Kim, Young Uh, Insoo Rheem, Gyoung Yim Ha, and Hye Soo Lee

Ann Clin Microbiol 2006 October, 9(2): 77-83. Published on 20 October 2006.

Background: Enterococci have become increasingly predominant as causative agents of nosocomial infections. Infections due to multi-drug resistant enterococci have drawn increasing attention during the past two decades. The purpose of the present study was to evaluate the occurrence of virulence factors and antimicrobial resistance in enterococci isolated from patients with bacteremia or urinary tract infection. 

Methods: A total of 209 strains of enterococi (102 Enterococcus faecalis and 107 E. facium) isolated during 8 months of 2005 were collected from 10 university hospitals in Korea. Disk diffusion susceptibility tests were performed using Mueller-Hinton agar. The antimicrobial resistance genes and virulence factors were determined using PCR. 

Results: In E. faecalis, the rate of resistance to ciprofloxacin, tetracycline, and quinupristindalfopristin was 27.4%, 83.3%, and 85.2%, respectively; no isolates were resistant to ampicillin, vancomycin, teicoplanin, or linezolid. In E. faecium, the rate of resistance to ampicillin, ciprofloxacin, tetracycline, vancomycin, and teicoplanin was 86.9%, 87.9%, 8.4%, 19.6%, and 6.5%, respectively; no strains were resistant to quinupristin-dalfopristin or linezolid. All the E. faecalis strains tested were found to harbor multiple virulence factors, but E. faecium strains were generally without virulence factors except esp. The prevalence of the esp gene was significantly higher in enterococci isolated from urinary tract infection than in those from bacteremia. 

Conclusion: A similar pattern of resistance to antimicrobial agents and prevalence of virulence factors was observed in both the enterococci isolated from bacteremia and urinary tract infection. Our study indicates that host factors are more likely than bacterial properties to influence the development of bacteremia. 

[in Korean]

Original article

Multilocus Sequence Typing of Clonal Changes of Methicillin-resistant Staphylococcus aureus Isolated from Intensive Care Unit Patients: 1996 versus 2004

Ji Young Huh, Jongyoun Yi, Ki Ho Hong, and Eui-Chong Kim

Ann Clin Microbiol 2006 October, 9(2): 84-89. Published on 20 October 2006.

Background: Methicillin-resistant Staphylococcus aureus (MRSA) accounts for more than 70% of S. aureus isolates from tertiary-care hospitals in Korea. Recently, a multilocus sequence typing (MLST) scheme has been used to study the local and global epidemiologies of MRSA. The aim of this study is to compare the genetic background of MRSA strains isolated in the same ward during two different periods. 

Methods: To investigate clonal changes of endemic MRSA isolates between 1996 and 2004, we studied a total of 33 MRSA strains (16 from 1996 and 17 from 2004) isolated in the intensive care units of a tertiary-care hospital in Korea. The isolates were analyzed for their sequence types by MLST and for their antimicrobial susceptibilities by the disk diffusion method. 

Results: ST5 was the most frequent type (n=11, 68.7%) in 1996, followed by ST254 (n=3, 18.8%) and ST1 (n=2, 12.5%). In 2004, ST239 was the most frequent type (n=10, 58.8%), followed by ST5 (n=6, 35.3%). 

Conclusion: The major clone type of MRSA isolates from intensive care unit patients changed from ST5 in 1996 to ST239 in 2004.

Original article

Influence of a Change in the Hospital Environment on Hospital-Acquired Urinary Tract Infection

Bo-Rae G. Park, Hye-Ryoun Kim, and Mi-Kyung Lee

Ann Clin Microbiol 2006 October, 9(2): 90-95. Published on 20 October 2006.

Background: To estimate the influence of a change in the hospital environment on a hospitalacquired urinary tract infection (HAUTI), we analyzed and compared the rates of HAUTI and the associated risk factors between an old hospital (Phil-dong) and a new hospital (Heucksuck-dong) of Chung-Ang University.

Methods: Retrospective studies of patients with urinary tract infection were conducted at the old and new hospital during the period from July 2003 to June 2004 and from January to December 2005, respectively. HAUTI was defined as the isolation of one or two microorganisms at greater than CFUs/mL from urine at 48 hours or more after admission. The risk factors of HAUTI included sex, age, duration of hospitalization, as well as malignancy, chronic disease, diabetes mellitus, intensive care unit care, immune deficiency, renal function, Foley catheterization, and immobility.

Results: The rates of HAUTI at the old and new hospital were 2.9% (206 cases per 7,088 patients) and 2.0% (289 per 14,704), respectively (P<0.05), but there were no statistical differences in the associated risk factors between the two hospitals (P>0.05).

Conclusion: Although both the old and new hospitals were served by the same health-care staff and inspectors using the same methods, the rate of HAUTI was significantly lower at the new hospital. This suggests that a change of the hospital environment, including new instruments and equipment, has an influence on the rate of HAUTI.

[in Korean]

Original article

Detection of Cytomegalovirus by Dual-PCR

Won Ho Choe , Jung Oak Kang, Tae Yeal Choi, and Youhern Ahn

Ann Clin Microbiol 2006 October, 9(2): 96-101. Published on 20 October 2006.

Background: Cytomegalovirus (CMV) infection is a major cause of morbidity and mortality in transplant recipients and immunocompromised patients. We compared the results of a dual polymerase chain reaction (dual-PCR) and an antigenemia (Ag) test for detection of CMV from blood samples.

Methods: Between February 2002 and May 2005, we analyzed 175 blood samples submitted for CMV tests at Hanyang University Hospital. The late antigen (LA) and major immediate early (MIE) genes of CMV were concurrently amplified in the dual-PCR. The lower matrix protein pp65 of CMVwas detected for the Ag test (Chemicon, Temecula, CA, USA).

Results: The positive rate of the dual-PCR was 14.3% (25/175) and that of the Ag test was 13.1% (23/175). The concordance rate of the dual-PCR and Ag test was 85.1% (149/175), while the discordance rate was 14.9% (26/175).

Conclusion: The dual-PCR is a useful method for the early detection of CMV, but we recommendusing both the dual-PCR and Ag test for detection of CMV due to a high discordance rate of the two methods.

[in Korean]

Original article

Emergence of CTX-M-12, PER-1 and OXA-30 β-Lactamase-Producing Klebsiella pneumoniae

Il Kwon Bae, Yu Nae Lee, Seok Hoon Jeong, Kyungwon Lee, Dongeun Yong, Jongwook Lee, Seong Geun Hong, Eui-Chong Kim, Yeon Jun Park, Tae Yeal Choi, Young Uh, Jong Hee Shin, Wee Gyo Lee, Ji young Ahn, Sung-Hee Lee, Gun-Jo Woo, and Hyo-Sun Kwak

Ann Clin Microbiol 2006 October, 9(2): 102-109. Published on 20 October 2006.

Background: The aim of this study was to determine a nation-wide prevalence of Ambler class A and D extended-spectrum β-lactamase (ESBL) in Klebsiella pneumoniae isolates in Korea.

Methods: During the period of April to May 2005, 189 isolates of K. pneumoniae were collected from 11 Korean hospitals. Antimicrobial susceptibilities to ceftazidime and cefotaxime were tested by the disk diffusion method, and ESBL production was determined by double-disk synergy test. Determinants of ceftazidime or cefotaxime-resistance were transferred to Escherichia coli J53 (azide-resistant) by transconjugation. Genotypes of class A and D ESBL genes were determined by PCR amplification and sequencing.

Results: One hundred-sixty isolates of K. pneumoniae showed positive results in double-disk synergy test. The most prevalent ESBL was SHV-12 (n=148). Also detected were genes encoding ESBLs including TEM-52 (n=1), SHV-2a (n=2), CTX-M-3 (n=15), CTX-M-9 (n=6), CTX-M-12 (n=2), CTX-M-14 (n=9), CTX-M-15 (n=1), PER-1 (n=1), GES-5 (n=3), and OXA-30 (n=2) β-lactamases.

Conclusion: With the emergence of CTX-M-12, PER-1, and OXA-30 β-lactamases, the ESBLs in K. pneumoniae isolates are becoming more diverse in Korea. 

[in Korean]

Original article

In Vitro Antimicrobial Activities of Silver Nanoparticles (NANOVER) against Clinical Isolates

Woon Bo Heo , Sang Heun Lee, and Won Kil Lee

Ann Clin Microbiol 2006 October, 9(2): 110-114. Published on 20 October 2006.

Background: Silver has extensive and powerful antimicrobial activities and silver-containing materials have been widely used in many medical fields. Recently nanoparticulate silver was developed and it is superior to other types of silver in the antimicrobial activity and cytotoxicity. There have been no data from Korea on its antimicrobial activity, and we evaluated the antimicrobial activity of NANOVER against common clinical isolates.

Methods: Minimum inhibitory concentrations (MICs) of NANOVER for clinical isolates were determined using the agar dilution method of Clinical and Laboratory Standard Institute. A total of 45 isolates were tested including 4 reference strains (Staphylococcus aureus ATCC 25923, Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853, Enterococcus faecalis ATCC 29212), 5 strains of methicillin-resistant S. aureus (MRSA), 7 strains of methicillin-sensitive S. aureus (MSSA), 14 strains of E. coli, and 15 strains of P. aeruginosa.

Results: The MICs of S. aureus to NANOVER were under 12.5 μg/mL regardless of the methicillin sensitivity or resistance. The other isolates showed the MICs under 12.5 to 6.25 μg/mL.

Conclusion: NANOVER has strong and extensive antimicrobial activities to common clinical isolates including those resistant to other antimicrobials.

[in Korean]

Original article

Evaluation of Automatic Acid-Fast Bacilli Stainer AT-2000F

Shin Young Kim, Eun Kyoung Yang, Young Jin Kim, Sun Min Lee, Eun Yup Lee, Young Kil Park, Gill Han Bai, and Chulhun L. Chang

Ann Clin Microbiol 2006 October, 9(2): 115-118. Published on 20 October 2006.

Background: Sputum smear microscopy is rapid, economic, and useful to detect patients with transmittable tuberculosis, albeit laborious. We aimed to evaluate the usefulness of an automated acid-fast bacilli stainer, which had been developed for lowering the labor and maintaining or increasing the staining quality.

Methods: One hundred sputum samples including some known positive smear specimens which were selected from clinical specimens requested for smear and culture for mycobacteria at Pusan National University Hospital, were used for evaluation. Auramine/rhodamine fluorescent acid-fast stainings were performed manually or by using the automated stainer, AT-2000F (Dagatron, Ilsan, Korea). Ziehl-Neelsen stain was also performed simultaneously.

Results: Concordance rate between automated and manual fluorescent stains was 98.0% and that between automated fluorescent and manual Ziehl-Neelsen stains was 88.0%. In all discordant cases, the automated stains showed one-grade higher results compared to the respective manual fluorescent or Ziehl-Neelsen stains. With the automatic stainer, all staining procedures were processed automatically except for slide loading and unloading. The process time was reduced by a half, and the slide-to-slide or day-to-day variations of staining quality were reduced compared with the manual fluorescent stain.

Conclusion: Acid-fast bacilli stain using automated stainer AF-2000F can reduce the processing time, labor, and variations of staining quality, and enhance or maintain the detection of positive smears.

[in Korean]

Original article

Identification of Candida Species by Multiplex Polymerase Chain Reaction

Mi-Kyung Lee, Hye-Ryoun Kim, and Young-Jo Lee

Ann Clin Microbiol 2006 October, 9(2): 119-124. Published on 20 October 2006.

Background: Polymerase chain reacation (PCR)-based methods have been described for rapid detection and identification of Candida spp. Multiplex PCR assay was developed using internal transcribed spacers and topoisomerase II gene for the accurate identification of Candida species.

Methods: We designed Dual Specificity Oligo (DSO) primers for multiplex PCR. Multiplex PCR was followed by agarose gel electrophoresis to test 8 type strains (C. albicans, C. parapsilosis, C. glabrata, C. tropicalis, C. krusei, C. guilliermondii, C. lusitaniae, C. dubliniensis) and 96 clinical isolates (C. albicans 51 isolates, C. parapsilosis 10 isolates, C. glabrata 10 isolates, C. tropicalis 9 isolates, C. krusei 6 isolates, C. guilliermondii 5 isolates, C. lusitaniae 5 isolates) of Candida spp.

Results: With multiplex PCR using DSO primers, the eight Candida type strains each could be easily differentiated and all 96 clinical isolates were identified as the same species as were identified by the conventional method.

Conclusion: Multiplex PCR followed by electrophoresis can be useful for the simple and rapid identification of Candida species in routine laboratories.

[in Korean]

Original article

Interpretation of Susceptibility Tests in Consideration of Tissue Concentrations of Antimicrobials

Chae Hoon Lee, Hee Soon Cho, and Nam Hee Ryoo

Ann Clin Microbiol 2006 October, 9(2): 125-130. Published on 20 October 2006.

Background: For an optimum treatment of infections, appropriate antimicrobials should be selected according to the results of antibiotic susceptibility test (AST). However, the present AST does not take into account of antimicrobial concentrations in tissues, although different tissues have different distribution of antimicrobials. Thereby we intended to evaluate the usefulness of interpreting antimicrobial susceptibility depending on tissue concentrations of antimicrobials. 

Methods: Gram-negative bacilli isolated from clinical specimens at Yeungnam University Hospital during the period from January to July, 2006 were evaluated retrospectively. The data on blood concentration, half life and tissue distribution of antimicrobials with variable administration route and dosage were collected and arranged in the forms of previous reports. The diameters of the zone of inhibition from the disc diffusion method were converted to minimum inhibitory concentration (MIC) and the organism was regarded as resistant if the converted concentration was higher than the expected concentration in the tissue. 

Results: Among the data reported as susceptible, antimicrobial concentrations in peritoneal fluid and bile showed a relatively good relationship with AST. But, aminoglycosides and carbenicllin concentrations in wounds and respiratory tissues were shown to be inadequate, thus resulting in a low bacteriologic cure. In cerebrospinal fluid, ciprofloxacin was less effective regardless of dosage. 

Conclusion: Antimicrobial concentration is variable in different tissues and more information on antimicrobial tissue distribution is needed for the appropriate treatment of infections. Reporting of MIC rather than AST with breakpoints should be considered for selection of antimicrobials. Therefore, an interpretation of AST in consideration of the tissue concentration would be more helpful for prevention of major errors and control of infections.

[in Korean]

Case report

A Case of Fungal Keratitis Caused by Colletotrichum Species

Sang Hoon Song, Joon Jeong Park, Kyo Sun Shin, Sae Ik Joo, Gwang Ja Lee, Kyoo Won Lee, Hyun Lee, and Eui Chong Kim

Ann Clin Microbiol 2006 October, 9(2): 131-136. Published on 20 October 2006.

Colletotrichum is mainly a fungal pathogen of plants, but sporadic cases of human infection have been reported recently. Most of them are fungal keratitis and only a few cases have been reported worldwide. A 63-year-old female farmer developed foreign body sensation and watering in her left eye following trauma by rice leaves. At presentation, her visual acuity decreased and corneal ulcer and inflammation in anterior chamber were observed on a slit lamp examination. Numerous hyphae were found on Gram stain and a rapidly growing mold with cup-shaped acervuli and falcate and nonseptate conidia was observed on fungal culture. As morphological findings did not lead to definite differentiation of the organism, sequencing of the D1-D2 domain of 28S rDNA was performed. It proved to be Colletotrichum species and the patient was treated with amphotericin and natamycin eye drop, but complicated by acute glaucoma. This is the first report of Colletotrichum keratitis in Korea and suggests that its infection should be considered in patients with fungal keratitis.

[in Korean]

Case report

A Case of Bacteremia Caused by Leuconostoc lactis Identified by 16S rRNA Sequencing

Gee-Young Kim, Myung-Hee Kim, Su-Yon Park, Myung-Jae Park, Jin-Tae Suh, and Hee-Joo Lee

Ann Clin Microbiol 2006 October, 9(2): 137-141. Published on 20 October 2006.

Leuconostoc spp. used to be considered nonpathogens to human, but human infections have been reported including bacteremia in compromized patients. Leuconostoc spp. may be misidentified as lactobacilli, streptococci, pediococci and enterococci due to atypical biochemical tests. Leuconostoc spp. are intrinsically resistant to vancomycin. We report a case of bacteremia caused by Leuconostoc lactis identified by 16S rRNA sequencing; the isolate was not identified by commercial kits.

[in Korean]

Case report

A case of Corynebacterium xerosis Infection in Cerebrospinal Fluid and Ventriculoperitoneal Shunt

Won Mok Lee, Jung Sook Ha, Nam Hee Ryoo, Dong Seok Jeon, and Jae Ryong Kim

Ann Clin Microbiol 2006 October, 9(2): 142-145. Published on 20 October 2006.

Corynebacterium xerosis is a normal flora of the skin, mucous membrane and gastrointestinal tract. Although not usually considered to be a pathogen, it occasionally causes serious infections in immunocompromised hosts. We report a case of a shunt infection by C. xerosis developed in a 58year-old woman following the insertion of a ventriculoperitoneal shunt. The organism was also isolated from the cerebrospinal fluid and blood. The isolate was resistant to most of the antibiotics tested except for vancomycin. However, in spite of treatment with vancomycin, the patient was expired after 5 months.

[in Korean]

Case report

Salmonella Osteomyelitis of the Sternoclavicular Joint Mimicking Tuberculosis in an Otherwise Healthy Person

Young Dae Kim, Sun Min Lee, Bong Soo Son, Eun Yup Lee, and Chulhun L. Chang

Ann Clin Microbiol 2006 October, 9(2): 146-148. Published on 20 October 2006.

Osteomyelitis caused by Salmonella Typhi is rare in an otherwise healthy person. Here, we describe a case of Salmonella osteomyelitis in a sternoclavicular joint mimicking malignancy or tuberculosis, in an immunocompetent patient. Salmonella infection should be included in the differential diagnosis of osteomyelitis, especially in patients with a previous history of diarrhea.