BACKGROUND: Vancomycin-dependent enterococci (VDE) are clinically equivalent to vancomycin-resistant enterococci (VRE), but more difficult to detect. This study was purposed to characterize VDE microbiologically and epidemiologically. METHODS: The patients from whom VDE were detected from April 2007 to March 2008 were investigated. For available isolates, minimal inhibitory concentrations (MICs) of and the levels of dependence on vancomycin and teicoplanin were measured by E test (AB Biodisk, Sweden), and a test for reversion of VDE to non-dependent VRE (NDVRE) and pulsed field gel electrophoresis (PFGE) were performed. Patients' demographic and clinical findings were reviewed via electronic medical records. RESULTS: VDE were recovered from 6 (2.2%) of 272 patients carrying VRE during this study period. All patients were already colonized or infected by VRE and treated with vancomycin for 13 to 107 days. VDE were isolated from pleural fluid (one), urine (four), and stool (one). All isolates carried vanA with vancomycin MICs of >256 microgram/mL, but two of them had intermediate susceptibilities to teicoplanin. Because 4 VDE isolates were reverted to NDVRE with single passage, vancomycin dependence was measurable for only two isolates as equal and above 0.064 and 0.5 microgram/mL respectively, and was reverted after 5 and 7 passages, respectively. Six VDE isolates showed no related clones in PFGE analysis, and 3 of 4 available pairs of initial VRE isolates and subsequent VDE isolates were identical clones. CONCLUSIONS: VDE were not rare and seemed to emerge independently from VRE with a prolonged use of vancomycin. Vancomycin-dependence was reverted within several passages.
Adult ; Aged ; Electrophoresis, Gel, Pulsed-Field ; Enterococcus/classification/drug effects/*isolation & purification ; Female ; Humans ; Infant ; Male ; Microbial Sensitivity Tests ; Middle Aged ; Urinary Tract Infections/diagnosis/microbiology ; Vancomycin/*pharmacology ; Vancomycin Resistance

BACKGROUND: The combined use of liquid media and solid media is recommended for mycobacterial culture. We evaluated diagnostic performance of combination of BACTEC Mycobacteria Growth Indicator Tube (MGIT; Becton Dickinson, USA) and 2% Ogawa media (Korean Institute of Tuberculosis, Korea) for recovery of mycobacteria. METHODS: In September 2007, 1,764 specimens from 1,059 patients were cultured with MGIT and Ogawa. Acid fast bacilli (AFB) smear was fluorochrome-stained. The isolates were identified into Mycobacterium tuberculosis (MTB) and nontuberculous mycobacteria (NTM) with PCR using Seeplex TB Detection Kit (Seegene, Korea). Recovery rate, time to detection (TTD), contamination rate, mixed growth rate and species distribution were analyzed. RESULTS: Two hundred thirty-five specimens (13.3%) from 165 patients (15.6%) were positive for mycobacterial culture. Recovery rates of mycobacteria from the group using both media, MGIT only, and Ogawa only were 13.3%, 12.1%, and 7.8%, respectively. While MGIT recovered 98.9% of MTB and 79.7% of NTM, Ogawa recovered 65.9% of MTB and 54.1% of NTM. TTDs of total mycobacteria/MTB/NTM in MGIT and Ogawa were 10.6/11.4/9.7 days and 31/29/33 days, respectively. MGIT TTDs of total mycobacteria/MTB/NTM from AFB-positive specimens were significantly shorter than those of AFB-negative specimens; 8.2/9.5/4.4 days vs 11.6/12.7/10.7 days. Contamination and mixed growth rate of MGIT were 9.6% and 3.7%. Primary culture of Ogawa recovered 1 MTB and 1 NTM among the 170 MGIT-contaminated specimens and 38 mycobacteria among 66 specimens that showed mixed cultures of MGIT. CONCLUSIONS: MGIT warrants sensitive and rapid isolation of mycobacteria. However, the combination of MGIT and Ogawa is more desirable to recover mycobacteria in the case of contaminations or mixed cultures.
*Culture Media ; False Positive Reactions ; Humans ; Mycobacterium/*growth & development/isolation & purification ; Mycobacterium Infections/*diagnosis/microbiology ; Mycobacterium tuberculosis/*growth & development/isolation & purification ; Reagent Kits, Diagnostic ; Sensitivity and Specificity ; Sputum/microbiology ; Time Factors

BACKGROUND: Accurate and rapid detection of extended-spectrum beta-lactamases (ESBLs) is important in guiding proper antimicrobial therapy for infected patients. We evaluated the performance of MicroScan NegCombo Type 44 panel (Dade Behring, USA), which was developed to confirm ESBL-producing Enterobacteriaceae using ceftazidime/clavulanate and cefotaxime/clavulanate. METHODS: From August 30 to September 20, 2007, 206 non-duplicate clinical isolates, including 106 Escherichia coli, 81 Klebsiella pneumoniae, 11 Klebsiella oxytoca, and 8 Proteus mirabilis were subcultured and tested with Type 32 and Type 44 panels. The results were compared with those of the CLSI phenotypic confirmatory test (CLSI-PCT) and disk approximation test (DAT). Isolates not susceptible to cefotetan or flagged as "Possible ESBL, unable to interpret confirm test (Possible ESBL)" on Type 44 panel were tested with boronic acid disks to confirm AmpC beta-lactamases (AmpC) production. RESULTS: Of the 206 isolates tested, 44 (21.4%) produced ESBL by CLSI-PCT or DAT, including 27 E. coli, 14 K. pneumoniae, 2 K. oxytoca, and 1 P. mirabilis. Thirty-eight isolates flagged as "Confirmed ESBL" on Type 44 panel were all confirmed as ESBL-producers. Of 14 K. pneumoniae flagged as "Possible ESBL", 6 were confirmed as ESBL and AmpC co-producers and 8 as AmpC-producers. CONCLUSIONS: Type 44 panel showed an excellent performance in detecting ESBL-producing E. coli, Klebsiella spp., and P. mirabilis. When flagged as "Confirmed ESBL", no other confirmatory test was necessary to report as ESBL; however, "Possible ESBL" required a differential test for AmpC production.
Bacterial Proteins/*biosynthesis ; Cefotetan/pharmacology ; Disk Diffusion Antimicrobial Tests ; Drug Resistance, Bacterial ; Escherichia coli/*enzymology/isolation & purification ; Humans ; Klebsiella/*enzymology/isolation & purification ; Proteus mirabilis/*enzymology/isolation & purification ; Reagent Kits, Diagnostic ; Sensitivity and Specificity ; beta-Lactamases/*biosynthesis

BACKGROUND: In 2010, the Clinical and Laboratory Standards Institute (CLSI) revised the minimum inhibitory concentration (MIC) breakpoints of cephalosporins and aztreonam to exempt extended-spectrum beta-lactamase (ESBL) confirmatory tests for Enterobacteriaceae. However, the CLSI did not change the MIC breakpoint of cefepime. Here, a proficiency survey of a strain of ESBL-producing Klebsiella pneumoniae was analyzed for MIC distribution and interpretation of cephalosporins and aztreonam. METHODS: The survey strain, K. pneumoniae, which produced SHV-18, was distributed to 170 clinical laboratories as 1 of 5 presumptive clinical specimens through the proficiency survey of the clinical microbiology division of the Korean Association of Quality Assurance for Clinical Laboratories (KAQACL). MIC, zone diameter of inhibition (ZDI), and interpretation of tested antimicrobials, methods of antimicrobial susceptibility testing (AST), and ESBL confirmatory results were collected. RESULTS: According to the revised breakpoints of the 2010 CLSI guidelines, MIC results indicated resistance to aztreonam in 100%, cefepime in 5.5%, cefotaxime in 20%, ceftazidime in 100%, and ceftriaxone in 100% of samples by broth microdilution methods. ZDI results also indicated resistance to aztreonam in 75%, cefepime in 0%, cefotaxime in 66.7%, ceftazidime in 100%, and ceftriaxone in 80% of samples by disk diffusion method. Ninety (75.6%) participants performed an ESBL confirmatory test, and 89 (98.9%) reported ESBL-positive tests. Of the 55 laboratories that tested the susceptibility of cefepime, 50 (90.9%) self-reported to be "resistant" because of ESBL-positive results. CONCLUSIONS: In conclusion, susceptibility testing of ESBL producers against certain cephalosporins is not reliable enough to apply the revised breakpoints presented in the 2010 CLSI guidelines. It is therefore necessary to reach a consensus for interpretation of ASTs of ESBL producers in Korea. Ideally, clinicians should be provided two interpretations based on both the revised breakpoints and ESBL confirmatory testing.
Aztreonam ; beta-Lactamases ; Cefotaxime ; Ceftazidime ; Ceftriaxone ; Cephalosporins ; Consensus ; Diffusion ; Enterobacteriaceae ; Klebsiella ; Klebsiella pneumoniae ; Korea ; Microbial Sensitivity Tests ; Pneumonia ; Sprains and Strains

BACKGROUND: The aim of this study was to investigate the current status of fungal cultures and the identification tests used by diagnostic laboratories in Korea. METHODS: From 22 October to 30 November 2013, we surveyed 76 laboratories, participating in the regular proficiency survey program of The Korean Association of Quality Assurance for Clinical Laboratory, with a questionnaire on fungal cultures and their identification tests. In March 2014, five mold were distributed to ninety-one participating laboratories, as an educational challenge. RESULTS: Fifty-six (73.7%) out of seventy-six laboratories replied to the survey questionnaire. Yeast was identified using commercial kits in all laboratories and to species level in 82.1% of the laboratories, whereas moulds were mainly identified by morphological examinations, to species level in 41.1% of the laboratories. The response rate to the five proficiency specimens was 67.0%–71.1%. The percentage of correctly identified dermatophytes was lower than that of Aspergillus species. CONCLUSIONS: An improvement is required in the mould culturing and identification techniques used in diagnostic laboratories in Korea.
Arthrodermataceae ; Aspergillus ; Fungi ; Korea* ; Surveys and Questionnaires ; Yeasts

BACKGROUND: Fecal occult blood tests (FOBTs) have been widely used as a means of colorectal cancer screening. Automated FOBTs using immunologic principles have the advantages such as quantitation, high specificity, and high throughput. We evaluated a newly-introduced automated FOBT analyzer, OC-SENSOR neo (OC neo) (Eiken Chemical Co., Japan). METHODS: The precision, linearity, and carry-over rate of OC neo were assessed with specimens prepared in accordance with the guidelines of CLSI. We performed a parallel test between OC neo and OC-SENSOR I (OC I) (Eiken Chemical Co.) using 300 consecutive stool specimens and 60 OC I-positive specimens. The results were analyzed with SPSS version 13.0 (SPSS Inc., USA). RESULTS: The coefficients of variation (CV) of within-run, between-run, and between-day using OCControl L (Eiken Chemical Co.) of ca. 150 ng/mL were 3.5-7.8%, 4.5-8.8% and 4.9-5.0%, respectively. The linear regression coefficient and carry-over rate with the range of 67.8-939.4 ng/mL were 0.9998 (P<0.001), and 0.1%, respectively. Correlation coefficient between OC neo and OC I was R(2)=0.954 (P<0.001) for 60 OC I-positive specimens. The positive and negative interpretations of 300 consecutive specimens by OC neo were completely consistent with those of OC I. CONCLUSIONS: Because OC neo showed an excellent performance and a good correlation with OC I, OC neo warrants to be a reliable quantitative FOBT system for high volume laboratories.
Colorectal Neoplasms/*diagnosis ; Hemoglobins/*analysis ; Humans ; Mass Screening/*instrumentation/methods ; *Occult Blood ; Reproducibility of Results ; Sensitivity and Specificity

Annual proficiency surveys were performed in March, June and September 2014 by clinical microbiology division of The Korean Association of Quality Assurance for Clinical Laboratory. Parasitology part has been newly incorporated in this survey. For each trial, three sets which were composed of different combinations of five bacteria and yeast were distributed for gram stain, culture, identification, and antimicrobial susceptibility tests of general bacteriology and five fixed sputum smear on slides were distributed for acid fast bacilli stain. Two advanced bacteriology survey materials for culture and identification of anaerobic bacteria and mold were distributed to the voluntary participants in every trial and five mycobacterial culture and identification specimens, five anti-tuberculosis susceptibility testing specimens, and two Mycobacterium tuberculosis strains for rapid detection of rifampin and isoniazid resistance were distributed to the voluntary participants in March and June trials. Five virtual microscopic slides for stool parasite examination were open for the registered participants in June trial. A total of 340 laboratories were enrolled and 330 (97.0%), 331 (97.4%), and 331 (97.4%) returned the results on trial I, II, and III, respectively. For bacterial identification, the percent acceptable identification of Burkholderia cepacia, Klebsiella pneumoniae, Streptococcus pyogenes, Staphylococcus aureus, Pseudomonas aeruginosa, Streptococcus pneumoniae, Streptococcus agalactiae, Plesiomonas shigelloides, and Enterococcus faecalis were greater than 95%. Group C and group D Salmonella species challenged as the different sets of M1422 resulted in the acceptable rate lower than 95% because nine participants reported the identification of different sets. Surveillance cultures for methicillin-resistant S. aureus and vancomycin-resistant enterococci were correctly determined by 89.6% and 69.0% of the respondents, respectively. Correct identification to species level of Candida albicans, Candida auris, Candida glabrata, and Candida parapsilosis were 86.1%, 1.6%, 48.1%, and 83.8%. Vancomycin disk diffusion test in S. aureus, missing oxacillin screen or penicillin susceptibility test in S. pneumoniae and lack of reliable methods of quinolone resistance detection in Salmonella species caused unacceptable results in antimicrobial susceptibility testing. Advanced bacteriology trials revealed low performance in species identification of mold. Mycobacterial culture, identification and susceptibility test performance was kept in excellence. The performance of identification of stool parasites was acceptable >90% for detection of helminth eggs and amebic cysts but 28.6% false positive responses resulted from negative specimens. In conclusion, species-level identification of fungi of both candida species and mold were challenging to clinical microbiology laboratories. Vancomycin disk diffusion method for S. aureus and lack of proper penicillin susceptibility test for S. pneumoniae were still common cause of inaccurate results. Virtual microscopic survey has been successfully introduced in parasitology.
Bacteria ; Bacteria, Anaerobic ; Bacteriology ; Burkholderia cepacia ; Candida ; Candida albicans ; Candida glabrata ; Surveys and Questionnaires ; Diffusion ; Eggs ; Enterococcus faecalis ; Fungi ; Helminths ; Isoniazid ; Klebsiella pneumoniae ; Korea* ; Methicillin Resistance ; Mycobacterium tuberculosis ; Ovum ; Oxacillin ; Parasites ; Parasitology ; Penicillins ; Plesiomonas ; Pneumonia ; Pseudomonas aeruginosa ; Rifampin ; Salmonella ; Sputum ; Staphylococcus aureus ; Streptococcus agalactiae ; Streptococcus pneumoniae ; Streptococcus pyogenes ; Vancomycin ; Yeasts

Two trials of external quality assessment for clinical microbiology laboratories were performed in 2007. A total of 14 specimens were distributed. Six specimens were distributed to 317 laboratories with 305 (96.2%) returns in Trial I, and 8 specimens to 320 laboratories with 309 returns (96.5%) in Trial II. For the first time, two slide specimens for mycobacterium stain (AFB) were distributed in Trial II. The acceptable percentages of Gram stain were relatively good for both stainability and morphology. The acceptable percentages of bacterial identification (correct answers to species level) on Streptococcus pyogenes, Branhamella catarrhalis, Escherichia coli, Enterococcus faecalis, Aeromonas hydrophilia and Yersinia enterocolitica (Trial I) were 83.5%, 70.8%, 98.1%, 87.0%, 89.2%, and 97.0%, respectively. The acceptable percentages of bacterial identification on Staphylococcus aureus, Pseudomonas aeruginosa, Candida tropicalis, Listeria monocytogenes, Enterococcus casseliflavus and Klebsiella pneumoniae (Trial II) were 98.1%, 97.7%, 71.6%, 77.4%, 72.4% and 96.2%, respectively. The acceptable percentages for antimicrobial susceptibility tests on E. coli and E. faecalis (Trial I), and S. aureus and P. aeruginosa (Trial II) were relatively good compared to data of recent three years. The acceptable percentages for AFB stain in Trial II were relatively high. In summary, the acceptable percentages of bacterial stain and identification were relatively good. However, it is still necessary that the quality assurance of the individual laboratories should be improved for antimicrobial susceptibility tests, and the selection of the most appropriate antimicrobial agents to test should be also considered.
Aeromonas ; Candida tropicalis ; Enterococcus ; Enterococcus faecalis ; Escherichia coli ; Klebsiella pneumoniae ; Korea ; Listeria monocytogenes ; Moraxella (Branhamella) catarrhalis ; Mycobacterium ; Pseudomonas aeruginosa ; Staphylococcus aureus ; Streptococcus pyogenes ; Yersinia enterocolitica

Two trials of external quality assessment for clinical microbiology laboratories were performed in 2007. A total of 14 specimens were distributed. Six specimens were distributed to 317 laboratories with 305 (96.2%) returns in Trial I, and 8 specimens to 320 laboratories with 309 returns (96.5%) in Trial II. For the first time, two slide specimens for mycobacterium stain (AFB) were distributed in Trial II. The acceptable percentages of Gram stain were relatively good for both stainability and morphology. The acceptable percentages of bacterial identification (correct answers to species level) on Streptococcus pyogenes, Branhamella catarrhalis, Escherichia coli, Enterococcus faecalis, Aeromonas hydrophilia and Yersinia enterocolitica (Trial I) were 83.5%, 70.8%, 98.1%, 87.0%, 89.2%, and 97.0%, respectively. The acceptable percentages of bacterial identification on Staphylococcus aureus, Pseudomonas aeruginosa, Candida tropicalis, Listeria monocytogenes, Enterococcus casseliflavus and Klebsiella pneumoniae (Trial II) were 98.1%, 97.7%, 71.6%, 77.4%, 72.4% and 96.2%, respectively. The acceptable percentages for antimicrobial susceptibility tests on E. coli and E. faecalis (Trial I), and S. aureus and P. aeruginosa (Trial II) were relatively good compared to data of recent three years. The acceptable percentages for AFB stain in Trial II were relatively high. In summary, the acceptable percentages of bacterial stain and identification were relatively good. However, it is still necessary that the quality assurance of the individual laboratories should be improved for antimicrobial susceptibility tests, and the selection of the most appropriate antimicrobial agents to test should be also considered.
Aeromonas ; Candida tropicalis ; Enterococcus ; Enterococcus faecalis ; Escherichia coli ; Klebsiella pneumoniae ; Korea ; Listeria monocytogenes ; Moraxella (Branhamella) catarrhalis ; Mycobacterium ; Pseudomonas aeruginosa ; Staphylococcus aureus ; Streptococcus pyogenes ; Yersinia enterocolitica

Annual external quality assessment was performed three times for clinical microbiology division of The Korean Association of Quality Assurance for Clinical Laboratory. For each trial, three sets composed of different combinations of four bacteria and one yeast were distributed for culture, identification, and antimicrobial susceptibility tests. A total of 340 laboratories were enrolled and 330 (97.0%), 331(97.4%), and 331(97.4%) returned the results on trial I, II, and III, respectively. For bacterial identification, the correct identification of gram-negative bacilli, Staphylococcus aureus, Staphylococcus epidermidis, Staphylococcus capitis, Streptococcus agalactiae, Listeria monocytogenes, and Candida species was greater than 95%. However, correct identification of Staphylococcus lugdunensis, Corynebacterium striatum, Vibrio vulnificus, Aeromonas hydrophila, Cryptococcus neoformans, and Malassezia pachydermatis was relatively less accurate, with values of 95.4%, 89.9%, 50.7%, 91.3%, 93.6%, and 93.9%, respectively. Surveillance cultures for vancomycin-resistant enterococci and methicillin-resistant S. aureus were correctly determined by 95.4% and 93.9% of the respondents, respectively. False carbapenem-resistance due to AmpC beta-lactamase, disk diffusion testing for vancomycin in Staphylococcus species, oxacillin and penicillin susceptibility testing in S. lugdunensis and false imipenem-resistance in Proteus species were common sources of inaccurate results. The accuracy of species identification for Corynebacterium species and Vibrio species requires improvement. Consistent problems occurred with antimicrobial susceptibility testing of vancomycin for Staphylococcus species using the disk diffusion method.
Aeromonas hydrophila ; Bacteria ; beta-Lactamases ; Candida ; Corynebacterium ; Cryptococcus neoformans ; Surveys and Questionnaires ; Diffusion ; Korea ; Listeria monocytogenes ; Malassezia ; Methicillin Resistance ; Oxacillin ; Penicillins ; Proteus ; Staphylococcus ; Staphylococcus aureus ; Staphylococcus epidermidis ; Staphylococcus lugdunensis ; Streptococcus agalactiae ; Vancomycin ; Vibrio ; Vibrio vulnificus ; Yeasts