Ciprofloxacin

A. baumannii strains BAA‐1709, 19606, BAA‐1789 (MDR strain), BAA‐1792 (MDR strain), S. aureus strain 6538, E. coli strain 25922, E. aerogenes 13048, K. pneumonia 700603, and Pseudomonas aeruginosa strain 9027 were purchased from American Type Culture Collection (ATCC). The antibiotics rifampicin, tetracycline, azithromycin, ciprofloxacin, ceftazidime, and colistin sulfate were bought from MedChem Express. Colistimethate sodium was purchased from Cayman Chemical. Penicillin G was obtained from Sigma‐Aldrich. Gentamicin was purchased from Gold Biotechnology. Polymyxin B was bought from Merck. Imipenem was obtained from MerckSharp & Dohme Corp. Peptide R₁₀ (RRRRRRRRRR‐CONH2) was bought from GL Biochem (Shanghai). MM 4–64 dye (N‐(3‐triethylammoniumpropyl)‐4‐(6‐(4‐(diethylamino)phenyl)hexatrienyl)pyridinium dibromide) was purchased from Santa Cruz. SYTOX Green was purchased from Life Technologies.

AF and antibiotics [fosfomycin (FOF); ciprofloxacin (CIP); tetracycline (TET); linezolid (LZD); chloramphenicol (CHL); levofloxacin (LVX); teicoplanin (TEC); clindamycin hydrochloride (CLI) hydro; gentamicin (GEN); vancomycin (VAN)] were purchased from the MedChemExpress company (Monmouth Junction, NJ, United States). E. faecalis ATCC 29212, S. aureus ATCC25923 and ATCC29213 were kindly provided by Juncai Luo (Tiandiren Biotech, Changsha, China). S. epidermidis RP62A and ATCC 12228 were given by Di Qu (Shanghai Medical College of Fudan University), S. aureus ATCC43300 (MRSA), Newman, and RJ-2 were given by Min Li (Renji Hospital, Shanghai Jiao Tong University School of Medicine). Other clinical strains were isolated from the wound secretion or sputum of inpatients at the Third Xiangya Hospital of Central South University. Staphylococcus spp. were grown in tryptic soy broth (TSB) broth medium (Solarbio, Shanghai, China), and E. faecalis was grown in brain heart infusion (BHI) broth medium (Solarbio, Shanghai, China) at 37°C.

Staphylococcus aureus Newman, ATCC 43300 and RJ-2 (MRSA) were provided by Min Li (Shanghai Jiao Tong University). Mingqiang Qiao (Nankai University) provided the Pseudomonas aeruginosa PAO1. Enterococcus faecalis ATCC 29212, Acinetobacter baumannii ATCC 1195, Klebsiella pneumoniae ATCC 700603, Escherichia coli ATCC 25922, and S. aureus ATCC 29213 were provided by Juncai Luo (Tiandiren Biotech). Staphylococcus epidermidis ATCC 12228 was provided by Di Qu (Fudan University). Clinical strains concluding SA 76 (MRSA) and PA47 were collected in the Third Xiangya Hospital, Central South University (She et al., 2020b (link)). All the Gram-positive strains were cultured in tryptic soy broth (TSB) or brain–heart infusion broth (BHI) (Solarbio, Beijing, China). Gram-negative strains were cultured in Luria–Bertani broth (LB) (Solarbio) medium. CC, tobramycin, ciprofloxacin, clindamycin, vancomycin, teicoplanin, and oxacillin were purchased from the MedChem Express, while gentamicin and amikacin were bought from Aladdin (Shanghai, China) and were dissolved in DMSO or deionized water.