Characteristics and dynamics of bacterial populations during postantibiotic effect determined by flow cytometry
Characteristics and dynamics of bacterial populations during postantibiotic effect determined by flow cytometry
复制标题
DOI：
10.1128/aac.42.5.1005
复制
发表时间：
1998-05-01
影响因子：
4.9
通讯作者：
Gudmundsson, S
中科院分区：
文献类型：
--
作者：
Gottfredsson, M;Erlendsdóttir, H;Gudmundsson, S
在抗生素暴露后和抗生素后效应（PAE）期间，细菌超微结构的变化已被电子显微镜（EM）证实。EM是定性的，并受到个人的解释。相比之下，流式细胞术提供定性和定量信息。通过碘化丙啶染色、流式细胞仪和荧光显微镜分析，研究了抗菌剂暴露期间和PAE期间大肠杆菌和铜绿假单胞菌的大小和核酸含量。大肠埃希菌暴露后，亚胺培南和环丙沙星对铜绿假单胞菌的敏感性降低。用荧光显微镜观察了大肠杆菌对氨苄青霉素、头孢曲松和环丙沙星的抗菌作用，并观察到丝状菌的形态学变化。这些变化通过前向光散射（FSC）和流式细胞仪测定的核酸含量的增加来反映。这些变化在20至35分钟达到高峰，并且细菌在药物去除后90分钟后恢复正常。与此相反，环丙沙星诱导的亚群在经典定义的PAE结束后>180 min才恢复正常，利福平导致形成FSC低的小生物体，而庆大霉素暴露后未观察到明显特征。对于铜绿假单胞菌，暴露于亚胺培南后检测到可识别的大球状细胞亚群和核酸含量增加，这些变化持续超过PAE，如活力计数所定义。在环丙沙星暴露后检测到具有增加的FSC的Swedish微生物，甚至在细菌生长期间持续存在。总之，对于β-内酰胺类抗生素和环丙沙星，PAE的特征在于动态形成核酸含量增加的扩大细胞群，而利福平诱导生物体中的大小和核酸含量减少。流式细胞术是PAE期间细菌表型特征的未来研究的理想方法。
Changes in bacterial ultrastructure after antibiotic exposure and during the postantibiotic effect (PAE) have been demonstrated by electron microscopy (EM), However. EM is qualitative and subject to individual interpretation. In contrast, flow cytometry gives qualitative and quantitative information. The sizes and nucleic acid contents of Escherichia coli and Pseudomonas aeruginosa were studied during antimicrobial exposure as well as during the PAE period by staining the organisms with propidium iodide and analyzing them with flow cytometry and fluorescence microscopy, The effects of ampicillin, ceftriaxone, ciprofloxacin, gentamicin, and rifampin were studied for E. coli, whereas for P. aeruginosa imipenem and ciprofloxacin were investigated, After exposure of E. coli to ampicillin, ceftriaxone, and ciprofloxacin, filamentous organisms were observed by fluorescence microscopy, These changes in morphology were reflected by increased forward light scatter (FSC) and nucleic acid content as measured by flow cytometry, For the beta-lactams the extent of filamentation increased in a dose-dependent manner after drug removal, resulting in formation of distinct subpopulations of bacteria. These changes peaked at 20 to 35 min, and bacteria returned to normal after 90 min after drug removal. In contrast, the subpopulations induced by ciprofloxacin did not return to normal until >180 min after the end of the classically defined PAE, Rifampin resulted in formation of small organisms with low FSC, whereas no distinctive characteristics were noted after gentamicin exposure. For P. aeruginosa an identifiable subpopulation of large globoid cells and increased nucleic acid content was detected after exposure to imipenem, These changes persisted past the PAE, as defined by viability counting. Swollen organisms with increased FSC were detected after ciprofloxacin exposure, even persisting during bacterial growth. In summary, for beta-lactam antibiotics and ciprofloxacin, the PAE is characterized by dynamic formation of enlarged cell populations of increased nucleic acid content, whereas rifampin induces a decrease in size and nucleic acid content in the organisms, Flow cytometry is an ideal method for future studies of bacterial phenotypic characteristics during the PAE.