Sook-Jin Jang
Ann Clin Microbiol 2005 April, 8(1): 1-9. Published on 20 April 2005.
The liberal use of antibiotics in human medicine and animal husbandry has promoted the spread of multiple antibiotic resistance. Molecular mechanisms for the acquisition of resistance genes by integron-mediated recombination was discovered recently during an intensive study of antibiotic resistance. Integrons are best known as the genetic agents responsible for the capture and spread of antibiotic resistance determinants among diverse Gram-negative clinical isolates. These DNA elements, mobilized by broad-host-range conjugative plasmids, have the ability of horizontal transfer of antibiotic resistance genes between interspecies of bacteria. The association of integrons with mobile elements promotes their vertical transmission from plasmids to the bacterial chromosome and among different replicons, contributing to the dissemination of resistance genes. Integrons have been found widely distributed among resistant bacteria circulating in hospitals and in the community and have been reported from all continents. The evolution of multi-drug resistance seems to proceed continuously through the acquisition and clustering of dispersed resistance genes by integrons. For public health, proper strategies should be instituted to reduce the potential for dissemination of these genes.
[in Korean]
Sang Jin Eun, Woon Bo Heo, You Kyung Kim, Nan Young Lee, Won Kil Lee, and Sung Chul Chae
Ann Clin Microbiol 2005 April, 8(1): 10-16. Published on 20 April 2005.
Background: Although there are growing evidences linking Chlamydophila pneumoniae infection to myocardial infarction, it remains controversial. The authors intended to assess whether C. pneumoniae infection is associated with myocardial infarction.
Methods: Sera and peripheral mononuclear cells (PMNCs) were collected from 54 cases of acute myocardial infarction (MI), 33 cases of old MI, and 60 normal controls. Anti-C. pneumoniae IgG and IgM antibodies were measured using a microimmunofluorescence (mIF) method, and C. pneumoniae DNA was detected using polymerase chain reaction (PCR).
Results: Seropositivity of anti-C. pneumoniae IgM antibody by mIF was shown 5.0% in control group, 29.6% (OR=8.00) in the acute MI and 6.1% (OR=1.23) in old MI group. Seropositivity of antiC. pneumoniae IgG antibody were 60.0 % in control group, 92.6% (OR=8.33) in the acute MI and 87.9% (OR= 4.83) in old MI group. The antibody titers in the acute MI and old MI group tended to be higher compared to those in control group. No C. pneumoniae DNA was detected in any case by PCR.
Conclusion: The seropositivity and antibody titers were significantly higher in the acute MI and old MI group than in control group, suggesting that C. pneumoniae infection may be a risk factor for myocardial infarction.
[in Korean]
Ji Hae Kang, Il Kwon Bae, Su Bong Kwon, Seok Hoon Jeong, Jongwook Lee, Wee Gyo Lee, Jung Oak Kang, Ji Young Ahn, Seong Geun Hong, Jong Hee Shin, Young Uh, Yeon Jun Park, Eui-Chong Kim, Kyungwon Lee, Dongeun Yong, and Gun Jo Woo
Ann Clin Microbiol 2005 April, 8(1): 17-25. Published on 20 April 2005.
Background: The aim of this study is to determine the nationwide prevalence of Ambler class A extended-spectrum β-lactamase (ESBL)-producing Escherichia coliand Klebsiella pneumoniae and to characterize genotypes of ESBLs.
Methods: During the period of February through July, 2003, E. coli and K. pneumoniae isolates were collected from 12 hospitals in Korea. Antimicrobial susceptibilities were tested by disk diffusion method, and ESBL-production was determined by the double-disk synergy test. MICs of β-lactam antibiotics were tested by agar dilution method. Searches for blaTEM , blaSHV , blaCTX-M , blaPER-1 , blaVEB , blaIBC , blaGES and blaTLA genes were performed by PCR amplification, and the genotypes of ESBLs were determined by direct nucleotide sequence analysis of amplified products.
Results: Resistance rates of E. coli (n=246) and K. pneumoniae (n=239) isolates to ceftazidime were 8.5% and 20.1%, respectively. Most prevalent Ambler class A ESBL genotypes in E. coli isolates were blaCTX-M-15 (n=4) and blaCTX-M-3 (n=3), and each of blaCTX-M-14 , blaSHV-12 , and blaTEM-52 gene was also found in one isolate. Most prevalent ESBL genotypes in K. pneumoniae were blaSHV-12 (n=30) and blaCTX-M-3 (n=13), and blaCTX-M-14 (n=5). blaSHV-2a (n=3), blaSHV-5 (n=2), blaTEM-52 (n=1), blaGES-3 (n=2) genes were also found.
Conclusion: CTX-M-type ESBL-producing E. coli and K. pneumoniae isolates are spreading, and a GES-type ESBL has emerged in Korea.
[in Korean]
Woe Sook Yoon, Bo Young Lee, Il Kwon Bae, Su Bong Kwon, Seok Hoon Jeong, Tae Jeon Jeong, and Yeon Wook Jung
Ann Clin Microbiol 2005 April, 8(1): 26-33. Published on 20 April 2005.
Background: Spread of imipenem-resistant Pseudomonas aeruginosa isolates is an important clinical threat. The aim of this study is to survey the prevalence of carbapenem-resistant P. aeruginosa isolates in a university hospital, Busan, Korea, and to determine the mechanisms of the resistance.
Methods: P. aeruginosa isolates from the patients in Kosin University Gospel Hospital were collected during the period of June through September, 2004. Antimicrobial susceptibilities were tested by the disk diffusion method, and production of carbapenemase and metallo-β-lactamase was determined by the modified Hodge and EDTA-disk synergy tests, respectively. MICs were determined by the agar dilution method, and pIs of β-lactamases were determined by the isoelectric focusing. Genotypes of carbapenemases were determined by direct sequencing of amplified products.
Results: A total of 77 clinical isolates of P. aeruginosa were collected. Twenty-two (55.0%) and 15 (37.5%) isolates showed positive results in the modified Hodge and EDTA-disk synergy tests, respectively. Searches for blaOXA-23 and blaIMP-1 genes showed positive results in 15 and 12 isolates, respectively. MIC ranges of imipenem and meropenem to OXA-23-producing isolates were 8-16 ㎍/mL and 2-32 ㎍/mL, respectively, and those to IMP-1-producing isolates were 2-≥256 ㎍/mL and 2128 ㎍/mL, respectively.
Conclusion: Production of OXA-23 or IMP-1 is the most prevalent mechanism of imipenemresistance in P. aeruginosa isolates in a university hospital, Busan, Korea. Periodical surveys are necessary to monitor the spreading of imipenem-resistant isolates and emerging new mechanisms of imipenem-resistance.
[in Korean]
Eun Ha Koh, Sunjoo Kim, and In-Gyu Bae
Ann Clin Microbiol 2005 April, 8(1): 34-40. Published on 20 April 2005.
Background: Serratia marcescensis a well-known cause of nosocomial infections. We investigated an outbreak of S. marcescens infections in a surgical intensive care unit (SICU) and identified the source of the outbreak using pulsed-field gel electrophoresis (PFGE).
Methods: A total of 39 isolates of S. marcescens were included in this study: 28 isolates from the patients in the SICU and epidemiologically-unrelated 11 isolates from the patients in the general wards from May through August, 2003 at Gyeongsang National University Hospital. Twenty-six of the 28 isolates in the SICU were from the urine collected from indwelling urinary catheters. Fifty-six environmental samples, such as the hands of healthcare workers and urinals were cultured to identify the source of infection. Antimicrobial susceptibility tests by Vitek GNS card (bioMerieux) and PFGE were performed to identify the clonality of the isolates.
Results: Twenty of the 28 S. marcescens isolated from the patients in the SICU showed the identical PFGE fingerprint pattern and two isoates had a closely-related pattern with the outbreak strain. The isolates from urine in the SICU were resistant to almost all the antibiotics tested except imipenem and cotrimoxazole. Nine of the 11 isolates from the general wards had PFGE patterns and antimicrobial susceptibility results different from those of the outbreak clone. Five samples from used-urinals and one from disinfected-urinal of 56 environmental samples grew S. marcescens that were resistant to the all antibiotics tested except imipenem and cotrimoxazole.
Conclusion: The outbreak of urinary tract infections in SICU was due to a clonal spread of a single strain of S. marcescens that was multiple resistant to antibiotics except imipenem and cotrimoxazole. The source of outbreak appeared to be inadequately disinfected urinals.
[in Korean]
Woon-Bo Heo, Young-Kyung Kim, Sang-Jin Eun, Jae-Ki Ryu, and Won-Kil Lee
Ann Clin Microbiol 2005 April, 8(1): 41-46. Published on 20 April 2005.
Background: There is some evidence linking the infections with common organisms such as Chlamydophila pneumoniae, cytomegalovirus (CMV), Helicobacter pylori and HIV to myocardial infarction (MI). We had performed a serologic study to assess whether C. pneumoniae, CMV, H. pylori and HIV infections are associated with MI.
Methods: Serum samples were obtained from 54 cases of acute MI, 33 cases of old MI, and 60 normal controls. C-reactive protein (CRP) as an inflammation marker was measured and antibodies to C. pneumoniae, CMV, H. pylori and HIV were assayed by ELISA. Odds ratios (OR) were calculated against control group.
Results: CRP was significantly higher in the acute MI and old MI group. ORs of C. pneumoniae infection increased considerably in the acute MI (IgM 1.57, IgG 4.80) and old MI group (IgM 2.42, IgG 5.18). ORs of CMV infection were 3.30 in the acute MI and 5.12 in old MI group. ORs of H. pylori infection showed below 1 in the acute MI and old MI. Anti-HIV antibody showed all negative result in three groups, so OR could not be calculated.
Conclusion: C. pneumoniae and CMV infections appear to be risk factors for MI.
[in Korean]
Jongwook Lee, Sun Moon Kim, Euyi Hyeog Im, Young Woo Choi, Yoon Mee Kim, Pum Soo Kim, and Jae Hag Lee
Ann Clin Microbiol 2005 April, 8(1): 47-50. Published on 20 April 2005.
Background: The most commonly used regimen for the eradication of Helicobacter pylori is combination of a proton pump inhibitor, clarithromycin, and two other antibiotics, metronidazole and amoxicillin. The increase in resistance to antibiotics seems to result in a decrease in eradication efficacy for H. pylori. We investigated the prevalence of antibiotic resistance in H. pylori isolated in Daejeon area.
Methods: A total of 31 clinical isolates of H. pylori were collected from the patients who underwent upper gastrointestinal endoscopy in Keonyang University Hospital during the period from March to July 2004. Antibiotic susceptibility tests for metronidazole, amoxicillin, and clarithromycin were performed by the E test (AB Biodisk, Sweden) on an egg yolk medium containing triphenyltetrazolium. The resistance break points for amoxicillin, metronidazole, and clarithromycin were defined as 0.5 ㎍/mL, 8㎍/mL, 1 ㎍/mL, respectively.
Results: Resistance to amoxicillin, metronidazole, and clarithromycin was detected in 7.4% (2/ 27), 25.8% (8/31), 3.6% (1/28), respectively.
Conclusion: The resistance to amoxicillin and clarithromycin was uncommon in Daejeon area.
[in Korean]
Eun-Ha Koh, and Sunjoo Kim
Ann Clin Microbiol 2005 April, 8(1): 51-56. Published on 20 April 2005.
Background: The carrier study of group A streptococci (GAS), the most common cause of bacterial pharyngitis, is important to understand the epidemiology of GAS in the region. The authors performed throat cultures from the children of four elementary schools in Jinju area to investigate current microbiological characteristics in this area.
Methods: Throat cultures were taken from 2,351 healthy elementary school children (male 1,311 and female 1,040) from October through December, 2004. Two schools are located in rural areas, while the other two schools are in Jinju city. Beta-hemolytic streptococci (BHS) were identified with bacitracin disk (0.04 U) and latex agglutination test (Seroiden Strepto Kit, Eiken).
Results: Four-hundred forty-three (18.8%) yielded BHS from 2,351 school children. Serogrouping revealed 84.9% of group A, 5.9% of group C, 4.7% of group B, 3.6% of group G, and 0.9% of nongroup A, B, C, G in a decreasing order. Isolation rate of GAS was similar between girls and boys. Children of elementary schools in rural areas showed significantly higher isolation rates (18.621.7%) compared to those (12.5-12.7%) in urban areas.
Conclusion: The isolation rate of BHS was 18.8% in Jinju area, 2004. Group A was 84.9% and group C was next common. Although the isolation rate of GAS was similar by age or sex, it showed a significant difference by the location of the schools.
[in Korean]
Eun-Ha Koh, and Sunjoo Kim
Ann Clin Microbiol 2005 April, 8(1): 57-65. Published on 20 April 2005.
Background: The aim of this study is to assess the prevalence and to investigate the molecular epidemiology of Ambler class A extended-spectrum β-lactamase (ESBL)-producing Enterobacter cloacae isolates in a university hospital in Busan, Korea.
Methods: Non-duplicated clinical isolates of E. cloacae from patients admitted in Kosin University Gospel Hospital were collected during the period from January through September, 2003. ESBL-production was examined by the double-disk synergy test (DDST) and the transferability of cefotaxime-resistance by conjugation. MICs of β-lactam antibiotics were determined by the agar dilution method and Ambler class A ESBL genes were searched by PCR amplification. Enterobacterial repetitive intergenic consensus (ERIC) PCR was performed to investigate epidemiological relationships among blaCTX-M-9 gene-carrying E. cloacae isolates.
Results: Antimicrobial resistance rates of E. cloacae isolates (n=148) to ceftazidime, cefotaxime, and aztreonam were 50.0%, 29.6%, and 48.0%, respectively. Among 50 E. cloacae isolates intermediate or resistant to more than one expanded-spectrum β-lactam agent, 41 (27.7%) showed positive results in DDST; of these 41 isolates, 1 was found to carry blaTEM-52 gene, 16 carried blaSHV-12 gene, 4 blaCTX-M-9 gene, and 19 both blaSHV-12 and blaCTX-M-9 genes. The 23 E. cloacae isolates carrying blaCTX-M-9 gene showed 9 different profiles by ERIC PCR.
Conclusion: ESBL-producing E. cloacae was not uncommon in a university hospital in Busan, Korea. The commonest types of ESBLs produced by E. cloacae isolates were SHV-12 and CTX-M9. CTX-M-9 ESBL-producing E. cloacae isolates showed diverse ERIC-PCR profiles, indicating that they were not originated from a common source.
[in Korean]
Hyukmin Lee, Dongeun Yong, Kyungwon Lee, Seong Geun Hong, Eui-Chong Kim, Seok Hoon Jeong, Yeon Jun Park, Tae Yeal Choi, Young Uh, Jong Hee Shin, Wee Kyo Lee, Jongwook Lee, Ji Young Ahn, Sung-Hee Lee, and Gun-Jo Woo
Ann Clin Microbiol 2005 April, 8(1): 66-73. Published on 20 April 2005.
Background: With the emergence and prevalence of new resistant bacteria, it is crucial to investigate the nationwide resistance rates. This study analyzed the antimicrobial resistance rates of major bacteria isolated from patients visiting 12 university and general hospitals nationwide during the first half of 2004.
Methods: The antimicrobial resistance rates of major bacteria isolated from 12 leading university and general hospitals nationwide were investigated. The antimicrobial susceptibility patterns of major bacteria isolated from clinical specimens between April and November 2004 were summarized for each institution and analyzed according to the patient’s hospitalization status.
Results: Methicillin-resistant Staphylococcus aureus (MRSA), a major nosocomial pathogen, was isolated at a rate of 67% overall and 86% in ICU patients. Vancomycin-resistant Enterococci (VRE) were found in 1% of Enterococcus faecalis and 20% of Enterococcus faecium. The proportion of penicillin-resistant Streptococcus pneumoniae was high at 70%. The ampicillin resistance rate of Haemophilus influenzae ranged from 40% to 63%, with an average of 54%, and the β-lactamase production rate was similar to the resistance rate. The resistance rates to third-generation cephalosporins were 7-10% in Escherichia coli and 26-31% in Klebsiella pneumoniae. The resistance rates for major nosocomial pathogens such as Citrobacter freundii, Enterobacter cloacae, and Serratia marcescens were 22-30%, 35-44%, and 15-22%, respectively. The resistance rates of Pseudomonas aeruginosa to imipenem and meropenem were 26% and 21%, respectively. The resistance rates of Acinetobacter baumannii to imipenem and meropenem were 17% and 32%, respectively, which were higher than those for other gram-negative bacilli. The resistance rates of Stenotrophomonas maltophilia to cotrimoxazole and levofloxacin were 46% and 44%, respectively.
Conclusion: In conclusion, the antimicrobial resistance rates of major pathogens isolated from clinical specimens of domestic patients remained high, with more resistant strains isolated from wards and ICU patients where there was a higher antimicrobial selection pressure than from outpatients. Regular nationwide surveys of antimicrobial resistance rates, along with the establishment of infection control measures to prevent the spread of resistant bacteria, are deemed necessary.
[in Korean]
Key-Earn Lee, Young-Jin Lee, and Ji-Hyun Cho
Ann Clin Microbiol 2005 April, 8(1): 74-81. Published on 20 April 2005.
Background: This study investigated the appropriate number of sputum specimens and the usage patterns of tuberculosis tests (acid-fast staining, mycobacterial culture, and direct PCR) in the diagnosis of pulmonary tuberculosis.
Methods: We retrospectively analyzed the results of tuberculosis tests (8,216 acid-fast staining, 4,728 mycobacterial cultures, and 345 direct PCR) on 8,216 sputum specimens from 1,520 tuberculosis patients diagnosed through patient history and positive mycobacterial culture from September 2000 to March 2004.
Results: The first sputum specimen was positive in 77.6% of cases by acid-fast staining, with additional detection rates of 14.3%, 4.1%, and 4.0% for the second, third, and subsequent specimens, respectively. For mycobacterial culture, the rates were 78.6%, 14.6%, 4.0%, and 2.9%, and for direct PCR, the rates were 83.6%, 12.3%, 2.7%, and 1.4%. When three sputum specimens were submitted, the detection rates were 14.0% for acid-fast staining and 13.4% for mycobacterial culture. For direct PCR, when four or more specimens were tested, the detection rate was 9.9%. Specimens of inadequate quality accounted for 72.2% of acid-fast staining, 73.1% of mycobacterial culture, and 80.8% of direct PCR tests. The quality of sputum specimens was related to the detection rates in acid-fast staining (P = 0.000) and mycobacterial culture (P = 0.038), but not in direct PCR (P = 0.607).
Conclusion: For the diagnosis of pulmonary tuberculosis, it is appropriate to perform staining and culture on three consecutive sputum specimens. Education on the correct use of tuberculosis tests and proper specimen collection is deemed necessary.
[in Korean]
Jung Oak Kang, Dongsoo Han, and Tae Yeal Choi
Ann Clin Microbiol 2005 April, 8(1): 82-89. Published on 20 April 2005.
Background: We compared currently available four antimicrobial susceptibility test methods for H. pylori to find out a practical method suitable for testing a few strains of H. pylori at a time in the clinical microbiology laboratory.
Methods: With 37 clinical isolates of H. pylori, antimicrobial susceptibility tests were performed against amoxicillin (AMX), clarithromycin (CLR), and metronidazole (MTZ) using disk diffusion method with egg yolk emulsion (EYE) media, E test with EYE and Mueller Hinton blood agar plate (MH BAP), and modified broth microdilution methods (mBMD).
Results: The results of AMX and CLR showed a complete agreement between the four methods. For MTZ, however, a significant discrepancy was observed between the results obtained by the four methods. In four strains exhibiting high minimal inhibitory concentrations (MIC, ≥32 mg/L) to MTZ, category agreement was excellent, but correlation was not good in 13 strains with the MTZ MICs of 8 to 16 mg/L. In 20 strains with MTZ MICs between 0.25 mg/L and 4 mg/L, category agreement was excellent, but correlation between MICs or inhibitory zone diameters was not good. Etest EYE and Etest MH BAP methods showed a 100% agreement in the susceptibility category of MTZ.
Conclusion: In routine practice, the most practical method for testing susceptibility of H. pylori to AMX and CLR seems to be the disk diffusion method with EYE or MH BAP. But for MTZ, a duplicate test using both Etest and disk diffusion test is recommended until more standardized, economical, and technically easier test methods become available.
[in Korean]
Young Uh, Byoung Geun Han, Gue Yel Hwang, Hyeun Gyeo Lee, Kap Jun Yoon, and Hyo Youl Kim
Ann Clin Microbiol 2005 April, 8(1): 90-93. Published on 20 April 2005.
Listeria monocytogenes is the causative agent in a spectrum of human disease ranging from gastroenteritis to invasive infections such as meningitis, encephalitis, and septicemia. Elderly patients or persons who have lower cell-mediated immunity with predisposing conditions such as transplants, lymphomas, and AIDS, are especially susceptible. The tropism of L. monocytogenes for the central nervous system leads to severe disease, often with high mortality. We report a case of L. monocytogenes meningitis in a 58-year old woman with end stage renal disease. The patient was discharged without neurological sequelae after antibiotic treatment.
[in Korean]
Woon Bo Heo, You Kyung Kim, Nan Young Lee, and Won Kil Lee
Ann Clin Microbiol 2005 April, 8(1): 94-98. Published on 20 April 2005.
Nosocomial opportunistic infections including fungal infections continue to increase with a longer survival of immunocompromised patients. Disseminated candidiasis is the most common nosocomial fungal infection and the frequency of isolation of non-Candida albicans organisms besides C. albicans is increasing as causative organisms. We detected numerous yeast cells incidentally in a peripheral blood smear of an infant with congenital heart disease who was treated with total parenteral nutrition and catheterization, and had a history of antibiotics use during a long hospitalization period. Pichia anomala was isolated from the blood and pleural effusion.
[in Korean]
Gyoung Yim Ha, and Moon Yeun Kim
Ann Clin Microbiol 2005 April, 8(1): 99-104. Published on 20 April 2005.
The introduction of a new, fully automated system into the clinical microbiology laboratory contributes to a rapid identification of microorganisms with accurate and reliable results, but such a system requires a high cost and additional tests for identification of some species. For instance, additional tests on oxidase, indole, motility, hemolysis, and pigmentation are needed in the correct identification by using Vitek GNI+ system (bioMerieux Vitek Inc., MO, USA). In particular, Vibrio and Aeromonas species are occasionally identified incorrectly when an automated system is used, and thus conventional biochemical tests may be more reliable in the identification of such species. We experienced three cases of incorrect identification of Vibrio parahaemolyticus, Vibrio cholerae, and Aeromonas veronii biovar sobria as Vibrio alginolyticus by using Vitek GNI+ card.
[in Korean]
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