Lorian V, Atkinson B
Antimicrob Agents Chemother. 1977 Mar;11(3):541-52. doi: 10.1128/AAC.11.3.541.
Single strains of Proteus mirabilis, Escherichia coli, and Staphylococcus aureus were grown on filter membranes placed on agar containing concentration series of mecillinam (FL 1060), 6-aminopenicillanic acid (6-APA), or ampicillin. P. mirabilis and E. coli were also exposed to combinations of mecillinam or 6-APA with ampicillin. Colony-forming units were counted, and cells were examined by interference phase-contrast and transmission electron microscopy. Mecillinam and 6-APA were very effective in reducing the viability of the two gram-negative species, but they were less effective against S. aureus. Combinations of mecillinam and 6-APA with ampicillin acted synergistically against the gram-negative bacilli. When the antibiotics were presented consecutively, their effects on viability were usually no greater than the effects of the individual antibiotics acting alone. When P. mirabilis and E. coli were exposed to mecillinam alone or in combination with ampicillin, the cells became rounded. 6-APA alone or in combination with ampicillin produced elongated polymorphic cells in these species. The most unusual morphological effects were ultrastructural. Mecillinam and, to a lesser extent, 6-APA produced inward growth of numerous pairs of trilamellar membranous structures within the cells. It is possible that these membranes represent the growth initiation of aberrant cross walls. Both mecillinam and 6-APA produced multiple, thick cross walls in S. aureus.
奇异变形杆菌、大肠杆菌和金黄色葡萄球菌的单一菌株在置于含有美西林（FL 1060）、6-氨基青霉烷酸（6-APA）或氨苄青霉素浓度系列的琼脂上的滤膜上生长。奇异变形杆菌和大肠杆菌也暴露于美西林或6-APA与氨苄青霉素的组合中。计算菌落形成单位，并通过干涉相差显微镜和透射电子显微镜检查细胞。美西林和6-APA在降低这两种革兰氏阴性菌的活力方面非常有效，但它们对金黄色葡萄球菌的效果较差。美西林和6-APA与氨苄青霉素的组合对革兰氏阴性杆菌具有协同作用。当抗生素连续使用时，它们对活力的影响通常不大于单独使用单个抗生素的效果。当奇异变形杆菌和大肠杆菌单独或与氨苄青霉素联合暴露于美西林时，细胞会变圆。单独使用6-APA或与氨苄青霉素联合使用会在这些菌种中产生伸长的多形细胞。最不寻常的形态学效应是超微结构方面的。美西林以及在较小程度上6-APA会在细胞内产生大量成对的三层膜状结构向内生长。这些膜有可能代表异常横壁的生长起始。美西林和6-APA都会在金黄色葡萄球菌中产生多个厚横壁。
