Villar H E, Longo L, Arena M F, Laurino G, Hoffman M
Laboratorio de Bacteriología, Hospital General de Agudos Dr. Enrique Tornú, Buenos Aires, Argentina.
Enferm Infecc Microbiol Clin. 1998 Jun-Jul;16(6):261-4.
To compare the bactericidal activity and frequency of mutation for meropenem and imipenem against Proteus mirabilis, Morganella morganii and Providencia rettgeri.
Minimum inhibitory concentrations (MIC) were determined by agar dilution method. Bactericidal activities were evaluated by killing curves method employing 4 and 16x MIC. One-step resistant mutant selection was performed by spreading more than 5 x 10(8) UFC/ml on cystine-lactose-electrolyte deficient agar containing 4 times the MIC of meropenem or imipenem.
MIC were 8 to 16 times lower for meropenem. After 24 h, bactericidal activity was observed for meropenem at 4 and 16 x MIC against 76.7 and 100% of the strains in comparison to 26.7 and 83.3% with imipenem. After 24 h incubation with imipenem, re-growth occurred in 80 and 90% of P. mirabilis and M. morganii strains, respectively. Imipenem resistant mutants were selected from 3 strains of P. mirabilis. One of them was stable and MIC of meropenem and imipenem were 8 to 16-fold higher.
From the laboratory point of view we consider that meropenem is more active against Proteeae because it was more potent in terms of inhibitory and bactericidal activity. In addition the risk to select for resistant mutants was significant with imipenem and P. mirabilis.
比较美罗培南和亚胺培南对奇异变形杆菌、摩根摩根菌和雷氏普罗威登斯菌的杀菌活性及突变频率。
采用琼脂稀释法测定最低抑菌浓度（MIC）。通过采用4倍和16倍MIC的杀菌曲线法评估杀菌活性。通过将超过5×10⁸CFU/ml菌液涂布于含4倍美罗培南或亚胺培南MIC的胱氨酸-乳糖-电解质缺乏琼脂上进行一步耐药突变体筛选。
美罗培南的MIC低8至16倍。24小时后，美罗培南在4倍和16倍MIC时对76.7%和100%的菌株有杀菌活性，相比之下亚胺培南分别为26.7%和83.3%。用亚胺培南孵育24小时后，奇异变形杆菌和摩根摩根菌菌株分别有80%和90%出现再生长。从3株奇异变形杆菌中筛选出亚胺培南耐药突变体。其中1株稳定，美罗培南和亚胺培南的MIC高8至16倍。
从实验室角度来看，我们认为美罗培南对变形杆菌属更具活性，因为它在抑制和杀菌活性方面更强。此外，亚胺培南对奇异变形杆菌有显著的选择耐药突变体的风险。
