新型氟喹诺酮衍生物对水产致病菌及其生物被膜的抑制作用研究北大核心

【目的】细菌的耐药性给动物抗感染和疾病治疗带来了极大的困难和挑战,生物被膜是导致细菌耐药性的主要原因之一,本研究检测分析了氯丙酰基克林沙星对7株菌株的抗菌活性及其生物被膜形成能力,以期发现氯丙酰基克林沙星是否具有抗菌活性。【方法】本研究通过打孔法和微量肉汤二倍稀释法进行常规药敏试验以测定最小抑菌浓度(minimum inhibitory concentration,MIC)和最小杀菌浓度(minimum bactericidal concentration,MBC),通过结晶紫染色法检测这7株受试菌在药物亚抑菌浓度下的生物被膜形成能力以及生长速率来测定氯丙酰基克林沙星的抑菌能力。【结果】实验结果显示,氟喹诺酮类衍生物氯丙酰基克林沙星药物对4株受试革兰氏阴性菌的MIC≤10 mg/L、MBC≤48 mg/L,对3株受试革兰氏阳性菌也呈现敏感状态(MIC≤10 mg/L,MBC≤10 mg/L)。结晶紫染色法检测发现,这7株受试菌在药物亚抑菌浓度下的生物被膜形成能力以及生长速率显著下降,说明氯丙酰基克林沙星在亚抑菌浓度即具有良好的抑菌活性。【结论】本研究证明氯丙酰基克林沙星可用作抗菌剂,并为新型生物被膜抗菌剂或细菌感染治疗药物的开发提供了新的依据。     

Dose and effect of methyl-2-benzimidazolylcarbamate in the "mammalian spot test", an in vivo method for the detection of genetic alterations in somatic cells of mice.

In the spot test, mouse embryos which are heterozygous for four different recessive coat-colour genes are treated in utero by injection of a mutagen into the peritoneal cavity of the mother or by other appropriate routes of administration. If this treatment leads in a pigment precursor cell to an alteration of the wild type allele of one of the genes under study or to its loss, a colour spot in the adult coat may be seen. Peroral application of 100-300 mg methyl-2-benzimidazolylcarbamate (MBC)/kg to the mother during the tenth day postconception led to an increase in the frequency of colour spots in the coats of offspring. The data are consistent with the hypothesis that MBC is a point mutagen.     

Antibiotic MIC/MBC analysis of Bacillus-based commercial insecticides: use of bioreduction and DNA-based assays

Bacillus thuringiensis subsp israelensis (Bti) and subsp kurstaki (Btk); (2) vegetative cells derived from these BT products; and (3) Gram-positive and Gram-negative bacteria used as controls. The XTT-kinetic assay improved sensitivity and early reading of MIC breakpoints. The conventional colony count method for determining minimal bactericidal concentration (MBC) was used to validate a multi-sample dot-blot assay in which organisms in individual MIC assays are trapped free of residual antibiotic and their viability is estimated by in situ conversion of MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide] to insoluble formazan. Tolerance (MBC/MIC) for most antibiotics was low (≤4). Resistance to β-lactams was attributed to β-lactamase activity in both BT products and cultures derived from them. MIC and MBC breakpoints in spore-based assays were also approximated by changes in genome copy, using δ-endotoxin and β-lactamase genes as probes. The DNA assays are effective for monitoring and authenticating organisms in microbe-containing biotechnology products. Received 29 September 1998/ Accepted in revised form 12 February 1999