Annual Report on External Quality Assessment Scheme for Clinical Microbiology in Korea (2014)

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.

Pitfalls of the Clinical and Laboratory Standards Institute's Revised Breakpoints on Interpretation of the Cephalosporin Susceptibility of an Extended-Spectrum beta-lactamase Producing Klebsiella pneumoniae: Analysis of a 2010 Nationwide Proficiency Surve / 임상검사와정도관리

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.

Human Leukocyte Antigen Typing Proficiency Surveys in Korea, 2005-2006 / 대한진단검사의학회지

BACKGROUND: To monitor the performance of histocompatibility testing laboratories, HLA proficiency survey in Korea has been conducted biannually since 1996. In this report, we summarized the results of the surveys performed in recent two years (2005-2006). METHODS: A total of four proficiency surveys were performed, in which 59-61 laboratories participated. Each survey included three tests for HLA class I (serology and DNA) and class II (DNA) typing and six tests for HLA crossmatch. RESULTS: The overall concordance of serologic typing was 98.9% (355/359) for HLA-A, 97.5% (350/ 359) for HLA-B, and 94.7% (337/356) for HLA-C. The antigens assigned correctly by less than 95% of the participating laboratories were A26 (93.8%), B38 (94.2%), Cw3/Cw10 (90.9%), Cw6 (94.4%), and Cw8 (74.3%). The overall concordance rates of DNA typing were 99.6% (533/535) for HLA-A, 99.8% (539/540) for HLA-B, and 100% (392/392) for HLA-C. Correct assignment of HLA-DRB1 and -DQB1 was reported by 99.2% (98.1-100%) and 96.7% (88.9-100%) for the generic level and 100% and 95.8% (75-100%) for the allelic level, respectively. On the average 3.8% (0-7.7%) of the total laboratories showed unacceptable results in the crossmatch tests. CONCLUSIONS: The rates of correct antigen identification and of unacceptable crossmatch were similar to those of previous surveys, which were considered satisfactory. The Korean proficiency survey program may have contributed to a high quality of HLA tests today and should be continued for further improvements of the tests tomorrow.

HLA Typing Proficiency Survey in Korea, 2003-2004 / 대한진단검사의학회지

BACKGROUND: HLA proficiency survey in Korea started in 1996 and the results of the survey were last reported in 1999. In this report, we summarized the results of the survey performed in recent 2 years. METHODS: A total of four proficiency surveys were performed, in which 54-59 laboratories participated. Each survey included 3 tests for HLA class I (serology and DNA) and class II (DNA) typing and 6 for HLA crossmatch test (3 cells x 2 sera). RESULTS: Overall concordance of serologic typing was 99.5% (436/438) for HLA-A, 95.7% (419/438) for HLA-B, and 94.8% (199/210) for HLA-C. The antigens assigned incorrectly by more than 5% of the participating laboratories were B54 (10.3%), B55 (10.3%), B27 (5.4%), Cw6 (22.9%), and C-blank (5.7%). Overall concordance rates of DNA typing were 99.7% (393/394) for HLA-A, 99.8% (415/416) for HLA-B, 100% (156/156) for HLA-C. Correct assignment of HLA-DRB1 and -DQB1 was reportred by 99.7% (98.1-100%) and 99.2% (88.9-100%) for generic and 99.2% and 98.1% (80-100%) for allelic level, respectively. Most laboratories (93.5-97.9%) were using sensitive methods of crossmatch such as T-long, T-AHG, and flowcytometry. The proportion of laboratories evaluated as unacceptable was on the average 3.1% of total laboratories. CONCLUSIONS: The rate of correct identification of HLA antigens was higher this time than in the previous survey in 1999. The rate of unacceptable crossmatch was also low enough to be satisfactory. It is thought that the proficiency survey has contributed to the high quality of HLA tests in the participating laboratories and should be continued to maintain the proficiency in Korea.

Results of the HLA Typing Proficiency Survey in Korea, 2000-2002 / 대한진단검사의학회지

BACKGROUND: HLA proficiency survey was started in 1996 in Korea, and the results of the 1996-1998 surveys were reported previously. Here, we report the results of the surveys performed in recent three years (2000-2002). METHODS: Six surveys were carried out with the participation of 52-54 laboratories. For each survey, 3 peripheral blood samples and 2 sera were distributed for 3 HLA class I serology, 3 HLA class I DNA, 3 HLA class II DNA, 6 HLA crossmatch, and 3 PRA tests. RESULTS: Overall consensus of serologic typing was similar to the results of the previous survey: HLA-A 93.5%, HLA-B 88.3%, and HLA-A, B 82.7%. There were an increasing number of the laboratories that were using DNA typing for HLA-DR (51 laboratories, 94%) and HLA-A and B (26 laboratories, 48%). Overall consensus of DNA typing was very high: HLA-A 100%, HLA-B 99.1%, HLAC 97.9%, HLA-DRB1 low/high resolution 99.2/99.0%, HLA-DQB1 low/high resolution 99.3/97.5%. HLA crossmatch (T cells) was reported by 44-49 laboratories, and the use of sensitive methods was increased: AHG 33 laboratories and flow cytometry 7 laboratories. For incompatible (positive) crossmatches, 4.9% (0-14.3%) of cytotoxicity tests and 7.1% (0-16.7%) of flow tests were reported as negative. PRA was reported by 5 laboratories only. CONCLUSIONS: The use of DNA tests for HLA typing and AHG or flow cytometry methods for HLA crossmatch tests has much increased compared to the previous report. A continuous survey program would play an important role in the standardization and maintenance of laboratory proficiency in histocompatibility testing in Korea.

Two-Year Study on the HLA Typing Proficiency Survey in Korea, 1996-1998 / 대한임상병리학회지

BACKGROUND: To standardize the histocompatibility testing among different laboratories, we have developed and performed a proficiency survey (external quality control) program in HLA typing with participation of nationwide HLA laboratories in Korea. METHODS: During a two-year period, four trials of proficiency survey were performed with 35-39 participating laboratories. Test number and items included in each survey were 3 HLA class Iantigen typings, 2 class II DNA typings, and 6 HLA crossmatch tests (3 cells x 2 sera). RESULTS: HLA class I serological typing was performed on a total of 12 whole blood specimens representing 7 HLA-A and 17 HLA-B antigens. More than 90% of the laboratories correctly identified 7 HLA-A (A2, A3, A11, A24, A26, A30, A33) and 13 HLA-B antigens (B7, B8, B13, B14, B27, B35, B48, B51, B52, B54, B58, B60, B61). Lower consensus (<90%) was obtained for B62, B67, B75, and B15 (B*1511). Considerable difference in antigen detection rate was observed between different commercial trays used. HLA class II DNA typing was performed on a total of 8 DNA specimens representing 13 HLA-DRB1 and 11 DQB1 alleles. For HLA-DRB1 typing (16-26 laboratories), correct assignment rate was very high (98%) for generic level, but lower (80%) for allele level. For DQB1 typing (5-8 laboratories), 100% consensus was obtained for allelic level. With respect to HLA crossmatching, detection rate of incompatibility was very low in the 1st trial. HLA crossmatch workshop on the standardization of typing methods was performed after the 1st trial, and thereafter the number of laboratories using sensitive methods were increased and the detection rate of incompatible crossmatch was much improved (1st 29-46%, 2nd 78-97%). CONCLUSIONS: Through these HLA typing proficiency surveys, standardization of test methods and improvement of typing results were obtained. A continuous survey program would play an important role for improving success rate of organ transplantations in Korea.