Ponmalar Ilanila Ilangumaran, Swain Jitendriya, Basu Jaydeep K
Center for Biosystems Science and Engineering, Indian Institute of Science, C.V. Raman Avenue, Bengaluru, 560012, Karnataka, India.
Department of Physics, Indian Institute of Science, C.V. Raman Avenue, Bengaluru, 560012, Karnataka, India.
Biochim Biophys Acta Biomembr. 2022 Aug 1;1864(8):183935. doi: 10.1016/j.bbamem.2022.183935. Epub 2022 Apr 21.
Ciprofloxacin (CPX), a second generation fluoroquinolone antibiotic, is used as a primary antibiotic for treatment against gastroenteritis, drug-resistant tuberculosis, and malignant otitis externa. CPX is a broad spectrum antibiotic that targets the DNA gyrase of both Gram-positive and Gram-negative bacteria. Irrational and improper usage of CPX results in emergence of CPX resistant organisms emphasizing the importance of using lethal doses of CPX. Here, we have systematically analysed the effect of CPX at sub lethal concentrations on live E. coli membrane and growth dynamics. As a result of CPX interaction at sub-lethal concentrations, we detected filamentation of the bacterial cells during cell division. Although CPX is a DNA targeting antibiotic and did not result in considerable increase of live E. coli cell surface roughness, we observed significant enhancement in the lipid diffusion coefficients possibly due to disrupted lipid packing or altered lipid composition. Interestingly, we seem to observe slightly higher extent of lipid diffusion alteration when bacterial inner membrane specific label FM4-64 was used in comparison to the non-specific membrane dye. Both these results are contrary to that observed in bacterial cells for colistin, a membrane targeting antibiotics. Our work highlights the need for using multiple, complementary surface and depth sensitive techniques to obtain information on the realistic nature of bacterial cell membrane remodelling due to non-membrane targeting antibiotics. Our work could have implications for identification of potential biomembrane markers at sub-lethal concentrations even for antibiotics which are non-membrane targeting that could help in unravelling pathways for emergence of antimicrobial resistance.
环丙沙星（CPX）是第二代氟喹诺酮类抗生素，用作治疗肠胃炎、耐药结核病和恶性外耳道炎的一线抗生素。CPX是一种广谱抗生素，可靶向革兰氏阳性菌和革兰氏阴性菌的DNA旋转酶。CPX的不合理和不当使用导致了对CPX耐药的生物体出现，这凸显了使用致死剂量CPX的重要性。在此，我们系统地分析了亚致死浓度的CPX对活大肠杆菌膜和生长动力学的影响。由于亚致死浓度下CPX的相互作用，我们在细胞分裂过程中检测到细菌细胞的丝状化。尽管CPX是一种靶向DNA的抗生素，且未导致活大肠杆菌细胞表面粗糙度显著增加，但我们观察到脂质扩散系数显著提高，这可能是由于脂质堆积破坏或脂质组成改变所致。有趣的是，与非特异性膜染料相比，当使用细菌内膜特异性标记FM4-64时，我们似乎观察到脂质扩散改变的程度略高。这两个结果都与在细菌细胞中观察到的针对膜的抗生素多粘菌素的结果相反。我们的工作强调需要使用多种互补的表面和深度敏感技术，以获取关于非膜靶向抗生素导致细菌细胞膜重塑的实际性质的信息。我们的工作可能对鉴定亚致死浓度下的潜在生物膜标记物具有启示意义，即使对于非膜靶向抗生素也是如此，这可能有助于揭示抗菌耐药性出现的途径。
