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Mycobacterium은 느리게 성장한다. 따라서 고체배지는 8주 , 액체배지는 6주 동안 사용하여야 한다. 이 연구의 목적은 Mycobacterium을 빠르게 성장시킬 수 있는 성장 인자를 찾고, 신속한 동정을 위한 고체배지를 개발하는 데 도움을 주는 것이다. DifcoTM Mycobacteria 7H11 agar (Becton, Dickinson and Company)에 activated charcoal, defibrinated sheep blood, L-ascorbic acid를 첨가하여 10종의 Mycobacteria 가지고 Mycobacterium 성장 인자 3가지를 평가하였다. 집락의 검출 시간 및 판독 용이성을 현재의 방법과 비교하였다. 빠르게 성장하는 Mycobacterium 있어 새로운 배지와 기존의 배지에서 검출 시간의 차이는 새로운 배지가 더 빠르다는 것을 확인시켜 주었다. M. kansasii 와 M. intracelluare는 7H11 배지보다 7H11 C 배지에서 더 빠르게 자라는 것으로 확인되었다. MTB는 7H11 C 배지에서 다른 배지보다 빠르게 성장하였다. 이 연구는 2 두 가지 성장 인자가 빠르게 성장하는 Mycobacteria과 느리게 성장하는 Mycobacteria 에 영향을 주는 것으로 확인되었다. 7H11 C 배지는 색상 대비로 인하여 10종의 모든 Mycobacterium에서 기존배지보다 더 뛰어난 판독 용이성을 보여 주었다. 특히, MTB가 성장했을 경우 집락의 크기가 다른 배지에서 보다 커서 시각화가 용이하였다.

The ASTA MicroIDSys system (ASTA, Suwon, Korea) is a newly developed Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) system for identification of microorganisms. We compared the performance of the ASTA MicroIDSys system with that of the VITEK MS system (bioMerieux, Marcy l'Etoile, France) for identifying clinical microorganisms. A total 2055 isolates including 1910 bacteria and 145 yeasts were tested. Among them, the VITEK MS correctly identified 1999 (97.3%) isolates to species level and 26 (1.3%) to the genus level. The ASTA MicroIDSys correctly identified 1988 (96.7%) isolates to species level and 28 (1.4%) to the genus level. The VITEK MS and ASTA MicroIDSys misidentified one isolate and four (0.2%) isolates, respectively, and provided no identification for 29 (1.4%) and 35 (1.7%) isolates, respectively. The performance of the ASTA MicroIDSys was comparable to that of the VITEK MS for identification of clinically relevant bacterial and yeast isolates.

Background We evaluated the two in-house sample preparation methods (saponin method (SAP) and [saponin + Sputazyme] method (SSPZ)) for direct identification of microorganisms using MALDI-TOF MS from positive blood culture bottles. Also, we evaluated the [saponin + Sputazyme] method for direct antimicrobial susceptibility testing (AST) using Vitek 2 system. Methods For direct identification, 163 prospective, monomicrobial positive blood culture bottles and 25 contrived blood culture bottles spiked with 25 infrequently isolated bacterial strains were included. For direct AST, pellets obtained by SSPZ method from 102 prospective blood culture bottles were tested. The results from the direct identification and AST were compared with those from the routine diagnostic method performed with colonies sub cultured on solid media. Results In 163 prospective specimens, SAP method correctly identified 132/163 (81.0%) isolates and SSPZ method correctly identified 148/163 (90.8%) isolates (P = .018). Among the 92 Gram-positive isolates, the correct identification rate was significantly higher with the SSPZ method than the SAP method (92.4% vs. 81.5%), respectively (P = .041). However, the SSPZ method failed to identify Streptococcus pneumoniae . Among the 64 Gram-negative isolates, the correct identification rate was 82.8% (53/64) and 87.5% (56/64) for the former and the latter method, respectively (P = .491). Compared with standard methods direct AST showed 98.5% (1523/1547) agreement. Conclusion The addition of Sputazyme improved the identification of commonly isolated bacteria, especially for Gram-positive isolates and yeasts and can be applied for direct antimicrobial susceptibility testing of bacteria. Although SAP method showed better results for Campylobacter spp. and anaerobic bacteria , considering their very low incidence, routine use of SSPZ will be more practical.