임상미생물검사 신빙도 조사 결과보고(1997)

Abstract

Two trials of external quality assessment for Clinical Microbiology were performed in 1997. 4 total of ten specimens were distributed. All except two specimens contained pure cultures of single bacterial pathogens : one contained two enteric pathogens and two commensals of enteric origin ; the other contained two enteric flora, but no pathogens. Five specimens containing six pathogens were distributed to 179 laboratories with 175 returns (85.6%) In Trial I and five specimens containing 4 pathogens to 235 laboratories with 191 returns (81.3% ) in Trial Ⅱ. The percentage of fully correct identification of 9 pathogens(one was removed from assessment because of possible contamination) was 76.7% on the average compared with 62.9%(P<0.001) in 1996 and 82.4%(P<0.001) in 1995. As was expected, the laboratories In tertiary care hospitals(83.5%) performed significantly better than other laboratories(75.0% ) (P<0.001). The relatively poor performance by the other laboratories was attributable, as was in previous years, in part to their failure to Isolate and identify two pathogens seperately from a stool specimen containing normal flora and poor performance on identification of Aspergilluss fumigatus and chryseobacterium indologenes. The performance on antibacterial susceptibility testing of 4 pathogens, Proteus mirabilis, Salmonella, Shigella sonnei, and Micrococcus luteus, was excellent with very few major and minor errors. For other pathogens, some problems were encountered. The majority of the laboratories who perform the disk diffusion method for susceptibility testing of Staphylococcus aureus failed to recognize minute colonies growing inside of the zone of inhibition around the oxacillin disk and, therefore, reported the organism as methicillin susceptible instead of being resistant. The susceptibility testing of C. indologenes by the disk diffusion method was less reliable than by the microdilution method. A few disagreements were still noted this year, but much less than in previous years, between reported zone sizes and their interpretation according to the NCCLS standards. The external quality assessment program of KSQACP should be continued with an increasing participation of clinical laboratories to improve the quality of diagnostic micro biology in Korea.