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从患病锦鲤体内分离得到1株细菌ML1,经人工感染后发现ML1具有较高的致病性,临床症状与自然发病症状一致,96 h的LD50为5.0×107cfu/m L。ML1菌株革兰染色呈阴性,杆状。16S rRNA基因序列分析结果显示,序列片段长度为1 419 bp,ML1菌株在系统发育树上与嗜水气单胞菌聚类,相似性达到100%。综合VITEK 2 Compact全自动微生物鉴定仪的生理生化特征分析、形态学观察、人工感染以及16S rRNA基因序列分析,将ML1菌株鉴定为嗜水气单胞菌。ML1菌株的最适生长p H为7~9,最适生长温度为28℃。在28℃200 r/min条件下的生长周期是:0~4 h为生长延迟期,4~10 h为对数生长期,10~24 h为稳定期,24~48 h为衰亡期。药敏试验表明,ML1菌株对多黏霉素B、环丙沙星、诺氟沙星等高度敏感,对磺胺异恶唑中度敏感,对麦迪霉素、氨苄西林、林可霉素等不敏感。研究结果为指导临床合理用药提供了科学依据。
One strain of ML1 was isolated from diseased Koi. ML1 was found to be highly pathogenic after artificial infection. The clinical symptoms were consistent with the natural symptoms. The LD50 at 96 h was 5.0 × 107 cfu / m L. ML1 strain Gram-stained negative, rod-shaped. The 16S rRNA gene sequence analysis showed that the length of the fragment was 1 419 bp. The ML1 strain clustered with Aeromonas hydrophila in the phylogenetic tree and the similarity was 100%. According to the physiological and biochemical characteristics analysis, morphological observation, artificial infection and 16S rRNA gene sequence analysis of VITEK 2 Compact automatic microbial identification device, ML1 strain was identified as Aeromonas hydrophila. The optimum growth pH of strain ML1 was 7-9, and the optimum growth temperature was 28 ℃. The growth cycle at 200 r / min at 28 ℃ was: 0-4 h growth delay, 4-10 h growth logarithmic growth phase, 10-24 h stability phase, and 24-48 h decline phase. Susceptibility tests showed that the ML1 strain highly sensitive to methicillin B, ciprofloxacin, norfloxacin, moderate susceptibility to sulfamethoxazole, midecamycin, ampicillin, lincomycin, etc. are not sensitive. The results provide a scientific basis for guiding clinical rational drug use.