de Almeida Keyla C, Lima Thais B, Motta Dielle O, Silva Osmar N, Magalhães Beatriz S, Dias Simoni C, Franco Octávio L
1] Centro de Análises Proteômicas e Bioquímicas, Pós-Graduação em Ciências Genômicas e Biotecnologia, Universidade Católica de Brasília, Brasília, Brazil [2] Pós-Graduação em Patologia Molecular, Universidade de Brasília, Brasília, Brazil.
Centro de Análises Proteômicas e Bioquímicas, Pós-Graduação em Ciências Genômicas e Biotecnologia, Universidade Católica de Brasília, Brasília, Brazil.
J Antibiot (Tokyo). 2014 Oct;67(10):681-7. doi: 10.1038/ja.2014.48. Epub 2014 May 7.
Antimicrobial peptides (AMPs) are multifunctional compounds that may show antimicrobial and immunomodulatory activities. With the rapid increase in the incidence of multidrug-resistant bacteria, there is an enormous interest in AMPs as templates for the production of new antibiotics. However, there are concerns that the therapeutic administration of AMPs can select resistant strains. In order to distinguish between resistant and non-resistant strains and verify resistance specificity to AMPs, in this study a magainin I-resistant Escherichia coli model was used. First, the identity of all strains was confirmed by matrix-assisted laser desorption ionization-time of flight (MALDI-TOF)-MS, VITEK 2 and MicroScan, and the susceptible and magainin-resistant strains were successfully differentiated by MALDI-TOF-MS analysis. Furthermore, cross-resistances to a broad spectrum of antibiotics were evaluated, showing that all E. coli strains are susceptible to the drugs tested, suggesting that the resistance seems to be specific to AMPs. Finally, the specific resistance to magainin I compared with other AMPs was checked by microdilution. This experiment showed that the magainin MICs were 62 and 104 μM for susceptible and resistant strains, respectively. The other AMPs MICs were 3.4 μM to proline-arginine-rich 39-amino-acid peptide, 43 μM to porcine myeloid antimicrobial 23-amino-acid peptide-23 and 1.2 μM to cecropin P1 for all strains, demonstrating any additional resistance to peptides here evaluated, confirming that the resistance seems to be essentially specific to magainin I. In summary, the data reported here reinforce the proposal that magainin I seems not to be merely a membrane disruptor, probably showing additional molecular targets in pathogenic bacteria.
抗菌肽（AMPs）是具有多种功能的化合物，可能具有抗菌和免疫调节活性。随着耐多药细菌发病率的迅速上升，人们对将抗菌肽作为生产新型抗生素的模板产生了浓厚兴趣。然而，有人担心抗菌肽的治疗性给药可能会筛选出耐药菌株。为了区分耐药菌株和非耐药菌株，并验证对抗菌肽的耐药特异性，本研究使用了一种对蛙皮素I耐药的大肠杆菌模型。首先，通过基质辅助激光解吸电离飞行时间质谱（MALDI-TOF-MS）、VITEK 2和MicroScan确认了所有菌株的身份，并通过MALDI-TOF-MS分析成功区分了敏感菌株和对蛙皮素耐药的菌株。此外，评估了对多种抗生素的交叉耐药性，结果表明所有大肠杆菌菌株对所测试的药物均敏感，这表明耐药性似乎是抗菌肽特有的。最后，通过微量稀释法检测了与其他抗菌肽相比对蛙皮素I的特异性耐药性。该实验表明，敏感菌株和耐药菌株的蛙皮素最低抑菌浓度（MIC）分别为62和104μM。所有菌株对富含脯氨酸-精氨酸的39氨基酸肽的MIC为3.4μM，对猪髓样抗菌23氨基酸肽-23的MIC为43μM，对天蚕素P1的MIC为1.2μM，表明对这里评估的肽没有额外的耐药性，证实耐药性似乎基本上是蛙皮素I特有的。总之，此处报道的数据进一步支持了蛙皮素I似乎不仅仅是一种膜破坏剂的观点，它可能在病原菌中显示出额外的分子靶点。
