Positive blood culture specimens for direct bacteria identification and drug susceptibility test with domestic instrument

ZHAO Huihai; QIN Lixia; ZHANG Pan; ZHOU Jingyan; LI Shiying; ZHANG Haipu

Abstract：Objective To explore the efficacy of direct identification and susceptibility testing for positive blood cultures with a home-made micro-organism identification and susceptibility system. Methods Two hundred positive blood culture samples were collected from the bethune international peace hospital between March and December 2015. The identification and susceptibility testing was carried out using a manual method, routine method and direct method. The correct rate, miss rate, and error rate of the susceptibility testing with the routine method and direct method were analyzed and compared. Results A total of 95 strains of G-bacilli and 105 strains of G+ coccus were detected from 200 samples. G- bacillus and G+ coccus identified by the routine method were compared with those by the direct method. There was no significant difference in the correct rate (87.37％, 85.26％), miss rate (8.42％, 9.47％) and error rate (4.21％,5.26％) of G- bacillus detection between these two methods. There was also no significant difference in the correct rate (86.67％,84.76％), miss rate (10.48％, 11.43％), and error rate (2.86％,3.81％) of G+ coccus detection between the two groups. The results of susceptibility testing of G- bacilli were not significantly different between the routine method and the direct method, for the correct rate was 95.85％ and 94.42％,miss rate 3.28％ and 4.15％, and error rate was 0.87％ and 1.42％ respectively. There was, however, significant difference in the results of the susceptibility testing of G+ coccus between the routine method and the direct method, for the correct rate was 96.96％ and 89.94％ (χ2=67.72, P=0.00),miss rate 2.68％ and 7.62％ (χ2=41.98, P=0.00), and error rate was 0.36％ and 2.44％ (χ2=26.43, P=0.00) respectively. Conclusion The use of positive blood cultures for direct identification and susceptibility testing with a home-made micro-organism system can provide quick and accurate results at a low cost, which can be widely used clinically.