효과적인 자동 미생물 동정기기용 Card Panel 선택을 위한 Acinetobacter baumannii와 유사 그람 음성 세균에 대한 선별검사법 개발

Development of an Assay for Differentiation of Acinetobacter baumannii from Other Gram-negative Bacteria for Effective Automatic Microorganism Identification Card Panel Selection

Gram-negative bacteria that have a similar colonial appearance to Acinetobacter baumannii are often difficult to select for antibiotic susceptibility test card for fermentative and non-fermentative bacteria used in Vitek2 automatic microorganism identification devices. As a result of card-mismatching, the economic and time loss occurs continuously. In the current study, it has been found that oxidase positive reaction was negatively changed when A. baumannii suspension was reacted with 1% oxidase reagent and human serum. For that reason, it has been examined whether this reaction could be used as a differentiating test for A. baumannii from other gram-negative strains with similar characteristics of colonies. Pre-treated suspensions with heat, protease inhibitor, and dithiothreitol were showed that the induction of reductive reaction was due to the action of A. baumannii exoenzyme. In order to investigate the clinical applicability of this method, a total of 340 isolates were assayed for the validation of our reagent. The analysis result of kappa coefficient of the automatic microorganism identification devices and our reagent was 0.96, indicating a high agreement between the two methods. The results of this study showed that the screening test using our reagent was able to accurately select A. baumannii compared to the current work type, which relies on the subjective screening of gram-negative bacteria with similar appearance of colonies. The reagent that we invent could be contributed to improving the quality of identification of microorganisms especially for A. baumannii.