Chang-Ki Kim, Chulhun L. Chang
Ann Clin Microbiol 2009 December, 12(4): 147-153. Published on 20 December 2009.
Clinical microbiology laboratories play a critical role in diagnosing tuberculosis (TB) and monitoring its treatment. Poor quality laboratory services remain a major barrier to diagnosis by microscopy and culture, and may complicate the interpretation of drug susceptibility testing (DST) results. External quality assessment (EQA) for microscopy is an important component of quality assurance, and includes panel testing, slide rechecking, and on-site supervision. Periodic panel testing is the simplest way to assess the performance of laboratories. Rechecking of a sample of routine smears by a higher-level laboratory is the method of choice for evaluation and continuous motivation of peripheral laboratories. On-site supervision allows the observation of workers’ performance under actual conditions, including equipment handling, laboratory safety, adequacy of supplies, and the processes used for smearing, staining, reading, recording, and reporting. Culture performance is not easily measured, and existing EQA programs are not sensitive enough to estimate the sensitivity of the process. Therefore, laboratory regulations and accreditation programs are critical to assure the quality of cultures. The Supranational Reference Laboratory Network (SRLN) was organized in 1994 to ensure optimal performance of laboratories conducting DST. A panel of 30 pretested and coded isolates is exchanged annually within the network for proficiency testing. It has been demonstrated that education and an EQA program can improve the proficiency of TB laboratories. However, quality programs in Korea are still weak. Expanded and strengthened laboratory quality improvement systems are necessary to achieve TB control in this country.
[in Korean]
Jong Hee Shin
Ann Clin Microbiol 2009 December, 12(4): 154-158. Published on 20 December 2009.
Clinical microbiology laboratories play a critical role in diagnosing tuberculosis (TB) and monitoring its treatment. Poor quality laboratory services remain a major barrier to diagnosis by microscopy and culture, and may complicate the interpretation of drug susceptibility testing (DST) results. External quality assessment (EQA) for microscopy is an important component of quality assurance, and includes panel testing, slide rechecking, and on-site supervision. Periodic panel testing is the simplest way to assess the performance of laboratories. Rechecking of a sample of routine smears by a higher-level laboratory is the method of choice for evaluation and continuous motivation of peripheral laboratories. On-site supervision allows the observation of workers’ performance under actual conditions, including equipment handling, laboratory safety, adequacy of supplies, and the processes used for smearing, staining, reading, recording, and reporting. Culture performance is not easily measured, and existing EQA programs are not sensitive enough to estimate the sensitivity of the process. Therefore, laboratory regulations and accreditation programs are critical to assure the quality of cultures. The Supranational Reference Laboratory Network (SRLN) was organized in 1994 to ensure optimal performance of laboratories conducting DST. A panel of 30 pretested and coded isolates is exchanged annually within the network for proficiency testing. It has been demonstrated that education and an EQA program can improve the proficiency of TB laboratories. However, quality programs in Korea are still weak. Expanded and strengthened laboratory quality improvement systems are necessary to achieve TB control in this country.
[in Korean]
Eunha Koh, Sunjoo Kim, In-Suk Kim, Kook-Young Maeng, Soon-Ae Lee
Ann Clin Microbiol 2009 December, 12(4): 159-162. Published on 20 December 2009.
Background: Ureaplasma urealyticum and Mycoplasma hominis are associated with an increased risk of pregnancy complications, such as preterm birth and premature membrane rupture. The purpose of this study was to determine the isolation rates and antimicrobial susceptibilities of genital mycoplasma in a sample of pregnant women from Jinju, Korea.
Methods: Vaginal swabs were obtained from 258 pregnant women between 2004 and 2008 and tested for the presence of U. urealyticum and M. hominis at Gyeongsang National University Hospital. The identification and antimicrobial susceptibilities of U. urealyticum and M. hominis were determined with a commercially available kit, the Mycoplasma IST2 Kit (bioMe- rieux, Marcy-l’Etoile, France), and evaluated according to standards set by the Clinical and Laboratory Standards Institute (CLSI).
Results: U. urealyticum only was detected in 105 specimens (38.6%), while M. hominis only was detected only in 2 specimens (1.8%). Seven specimens (6.7%) were positive both for U. urealyticum and M. hominis. Susceptibilities of U. urealyticum to azithromycin, erythromycin, clarithromycin, and doxycycline were 75.2%, 82.9%, 88.6%, and 88.6%, respectively, while almost all of the isolates were susceptible to josamycin (99.0%) and pristinamycin (100%). The susceptibility of U. urealyticum to ofloxacin and ciprofloxacin was 56.2% and 15.2%, respectively.
Conclusion: The rate of isolation of genital mycoplasma in pregnant women was 44.2% in Jinju; most of the mycoplasma were U. urealyticum. U. urealyticum and M. hominis were highly resistant to quinolones, but susceptible to josamycin. Therefore, empirical treatment without prior identification and determination of the antimicrobial susceptibility of genital mycoplasma will fail in many cases.
So Young Kim, Gayoung Lim, Min Jin Kim, Jin Tae Suh, Hee Joo Lee
Ann Clin Microbiol 2009 December, 12(4): 163-168. Published on 20 December 2009.
Background: Blood culture is the definitive method for the diagnosis and treatment of bacteremia and fungemia. Analysis of blood cultures positive for pathogenic species and trends in antimicrobial susceptibility can help delineate appropriate and experimental treatment strategies. In this study, we investigated the incidence of pathogenic species and trends in antimicrobial susceptibility in blood cultures collected from 2003 to 2007 to help clinicians to determine the best methods of diagnosis and treatment. Changes between previously published analyses and this study were also investigated.
Methods: Five-year blood culture results obtained at Kyung Hee University Hospital between 2003 and 2007 were analyzed to determine the bacterial and fungal species present and the antimicrobial susceptibility of the isolates. Antimicrobial susceptibility was tested by the broth microdilution method and the CLSI disk diffusion method.
Results: Among the 66,437 blood cultures, 5,645 were positive. Of the positive blood cultures, 59.8% were positive for aerobic and facultative anaerobic gram-positive cocci. Coagulase-negative staphylococci (CoNS) were frequently isolated. The numbers of anaerobic species and fungi decreased over the years.
Conclusion: CoNS were the microorganisms most commonly isolated from blood cultures at Kyung Hee University Hospital. The number of cultures positive for fungi was higher than that reported in previous studies, but the absolute isolation rate over five years decreased. Anaerobic species were much less frequently isolated than reported for other hospitals.
[in Korean]
Min Jung Kim, Dae Hyuk Kang, Jae Im Park, Tae Yeal Choi
Ann Clin Microbiol 2009 December, 12(4): 169-173. Published on 20 December 2009.
Background: Methicillin-resistant Staphylococcus aureus (MRSA) is a significant pathogen in both nosocomial and community settings, and screening for a carrier is an important infection control practice in many hospitals. We evaluated the sensitivity and specificity of the ChromID MRSA assay (bioMérieux, Marcy I’Etoile, France).
Methods: A total of 190 clinical samples were collected from the anterior nares of premature infants in a newborn intensive care unit (N-ICU). Equal volumes (100μL) of the samples were inoculated on mannitol salt agar with oxacillin 6 mg/L (MSAO) and ChromID MRSA after emulsifying the screening swab in brain-heart Infusion broth with oxacillin 6 mg/L (BE). The specimens in BE were subcultured on ChromID MRSA after an overnight incubation.
Results: Twenty-one of 190 samples (11%) was positive for MRSA by BE. After a 24 h incubation, the sensitivity/specificity of MSAO was 52%/98% and that of ChromID MRSA was 62%/100%, and at 48 h, the sensitivity/specificity of MSAO was 62%/92% and that of ChromID MRSA was 81%/99%.
Conclusion: ChromID MRSA is a useful selective medium for the rapid isolation and identification of MRSA.
[in Korean]
Young Uh, Seong Jin Choi, In Ho Jang, Kwan Soo Lee, Hyun Mi Cho, Ohgun Kwon, Kap Jun Yoon
Ann Clin Microbiol 2009 December, 12(4): 174-179. Published on 20 December 2009.
Background: The prevalence of neonatal group B streptococcal infection depends mainly on the colonization rate of pregnant women by group B streptococci (GBS). Although the colonization rate of Korean women by GBS is considered lower than in other countries, recent data on the maternal colonization rate of GBS are sparse.
Methods: From August 2008 to June 2009, swab specimens from the anorectus, vagina, and urethral orifice of a sample of 234 pregnant Korean women were placed in new Granada medium (NGM-H), tube medium (NGM-T), commercial NGM (NGM-B), and selective Todd-Hewitt broth (S-THB) for 18∼24 hours in 5% CO2 at 35oC. Agar dilutional antimicrobial susceptibility tests, serotyping, and PCR were performed for GBS isolates.
Results: The colonization rate of GBS in pregnant women was 11.5% (27/234). Of the specimen cultures, 9.8% of anorectal cultures were positive, 8.1% of urethral orifice cultures were positive, and 7.3% of vagina cultures were positive. The detection rate of GBS in the different culture media was S-THB (96.3%), NGM-B (92.6%), NGM-H (88.9%), and NGM-T (85.2%). The distribution of GBS serotypes was as follows: III (29.6%), V and VI (22.2%), Ib and II (11.1%), and Ia (3.7%). 33.3% of GBS isolates were resistant to erythromycin and 44.4% to clindamycin. Among the nine erythromycin-resistant isolates, eight were serotype V and VI, which are erm(B) positive serotypes.
Conclusion: The colonization of pregnant women by GBS, and the incidence of resistance of the GBS isolates to erythromycin and clindamycin were higher than those previously reported. Serotypes V and VI, GBS serotypes that carry the erm(B), are novel serotypes that have not previously been identified in pregnant Korean women.
[in Korean]
Sun-Hwa Lee, Kyoung Un Park, Hae-Kyung Lee, Mi Young Kim, Jin Yong Kim, Won Kyoung Kwon, Lee Sun Park
Ann Clin Microbiol 2009 December, 12(4): 180-185. Published on 20 December 2009.
Background: Group B Streptococcus (Streptococcus agalactiae, GBS) is a major cause of severe infections in neonates, including bacteremia, pneumonia, and meningitis, and is generally vertically transmitted from a colonized, pregnant woman to her infant. Penicillin is the drug of choice to treat GBS infections, because GBS strains are uniformly susceptible to penicillin. Recently, however, penicillin resistant GBS strains have been reported and the rates of erythromycin and clindamycin resistance have increased. We evaluated the perineal colonization rates and antimicrobial susceptibility of GBS strains isolated from pregnant and non-pregnant women.
Methods: The antibiotic susceptibilities of a total of 180 GBS strains isolated from two university hospitals and one reference laboratory between May 2008 and January 2009 were determined using disk diffusion and broth microdilution methods. The presence of erythromycin resistance genes was confirmed by PCR.
Results: The average colonization rate of pregnant women was 5.5%. The overall colonization rates of pregnant and non-pregnant women ranged between 5.5% and 7.5%. All 180 GBS strains were susceptible to penicillin. Fifty strains (27.8%) were resistant to erythromycin, whereas 78 (41.1%) were resistant to clindamycin. The ermB gene was identified in 40 isolates and 44 isolates had constitutive macrolide- lincosamide-streptogramin B resistance phenotypes.
Conclusion: Our findings indicate an increased GBS colonization rate and an increase in macrolide resistance in GBS strains in recent years, emphasizing the need for further surveillance and continual monitoring of antimicrobial susceptibility.
[in Korean]
Semi Jeon, Junyoung Kim, Harim Lee, Minyoung Son, Misun Park, Bokkwon Lee, Seonghan Kim
Ann Clin Microbiol 2009 December, 12(4): 186-192. Published on 20 December 2009.
Background: The incidence of infectious diarrheal disease in Korea has decreased over the past decade, but traveler’s diarrhea (TD) is increasing in frequency. We therefore investigated the distribution of the causative agents of TD.
Methods: A total of 132 rectal swab specimens were acquired from TD patients who entered the country via Gimhae International Airport. The specimens were screened for 12 bacterial pathogens by real-time PCR, and target pathogens were isolated from the PCR positive specimens using conventional microbiological isolation methods.
Results: A total of 93 specimens (70.5%) showed positive PCR screening results, and of these specimens, nine species and 50 isolates (37.9%), including Vibrio parahaemolyticus (18 isolates) and ETEC (17 isolates), were isolated. No specimens were PCR positive for Listeria monocytogenes or Campylobacter jejuni, and no pathogenic Bacillus cereus were isolated.
Conclusion: Even though viruses and EAEC were not included as target pathogens, the high isolation rate of these pathogens in this study provides indirect evidence that most cases of pathogen-negative TD are caused by undetected bacterial agents. Furthermore, our study results confirm the effectiveness of real-time PCR-based screening methods. This study is the first report in Korea to demonstrate that ETEC and V. parahaemolyticus are the major causative pathogens of TD, and this knowledge can be used to help treat and prevent TD.
[in Korean]
Young Uh, In Ho Jang, Kwan Soo Lee, Ohgun Kwon, Kap Jun Yoon
Ann Clin Microbiol 2009 December, 12(4): 193-200. Published on 20 December 2009.
Background: To access the clinical usefulness of MicroScanⓇ Synergies plus Combo Panels (Siemens, USA) for the identification and antimicrobial susceptibility test (AST) of Gram-negative bacteria (GNB) and Gram-positive cocci (GPC), we compared MicroScanⓇ Synergies plus Combo Panels with MicroScanⓇ conventional Combo Panels.
Methods: One-hundred four isolates of GNB were simultaneously tested with MicroScanⓇ Synergies plus Neg Combo Type 2 Panel (SINC2) and MicroScanⓇ Neg Combo Panel Type 44 (NC44). One-hundred isolates of GPC were simultaneously tested with MicroScanⓇ Synergies plus Pos Combo 3 Panel (SIPC3) and MicroScanⓇ Pos Combo 1A (PC1A).
Results: Of the GNB isolates, agreement rate of identification between SINC2 and NC44 were 92.3% to the species level and 93.3% to the genus level. Of the GPC isolates, agreement rate of identification between SIPC3 and PC1A were 85.0% to the species level and 100% to the genus level. Of the GNB isolates, agreement rate of AST according to antimicrobial agents between SINC2 and NC44 ranged from 86.5% to 100%. Among GPC isolates, agreement rate of AST according to antimicrobial agents between SIPC3 and PC1A were higher than 96.0% with the exception of gentamicin and quinupristin-dalfopristin.
Conclusion: Compared with MicroScanⓇ conventional Combo Panels (NC44, PC1A), MicroScanⓇ Synergies plus Combo Panels (SINC2, SIPC3) showed high agreement rate of identification and AST, and had the advantage of more rapid reporting.
[in Korean]
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