Ciprofloxacin

Escherichia coli ATCC 25922, Enterobacter cloacae ATCC 13047, Klebsiella pneumoniae ATCC 13883, Pseudomonas aeruginosa ATCC 27853, and Acinetobacter baumannii 17978 were obtained from the American Type Culture Collection (Manassas, VA). Strains were stored at −80°C in tryptic soy broth (BD Diagnostics, Franklin Lakes, NJ) containing 50% glycerol (Sigma-Aldrich, St. Louis, MO).
Meropenem was from Ark Pharm (Arlington Heights, IL), cefepime was from Chem Impex (Wood Dale, IL), gentamicin was from Alfa Aesar (Haverhill, MA), and ciprofloxacin was from US Biological (Salem, MA). Antibiotic stock solutions were prepared in water for manual dilution-based testing or in water containing 0.3% polysorbate-20 as required for liquid handling by the HP D300 digital dispenser (HP Inc., Palo Alto, CA).⁹ We previously determined through extensive analysis that polysorbate-20 at the concentrations used in assay wells has no effect on MIC determinations for all antibiotics examined.^{5 (link), 10 (link)}

Human PSMA-expressing PC-3 prostate cancer cells (PC3-PIP) and isogenic PSMA-negative control cells (PC3-Flu) were obtained from Dr. Warren Heston (Cleveland Clinic, Cleveland, OH) (19 (link)). Human PSMA-expressing LMD-MDA-MB-231 breast cancer cells (LMD-PSMA) and isogenic PSMA-negative control cells (LMD) were previously developed (20 (link)). Cells were cultured in RPMI 1640 (Corning Cellgro, Manassas, VA) plus 10% FBS (Sigma-Aldrich, St. Louis, MO), 50 μg/ml Gentamicin (Quality Biological, Gaithersburg, MD) and 5 μg/ml Ciprofloxacin (US Biological, Salem, MA). Cells were maintained at 37°C, 5% CO₂ in a humidified incubator. Cells were authenticated by STR profiling (Johns Hopkins GRCF DNA services; November 2015) and confirmed > 90% homology with parental ATCC cell lines. Further mycoplasma monitoring occurs semiannually.

PSMA-expressing LNCaP cells were obtained from ATCC (Manassas, VA. Cat# CRL1740). Both the PSMA-expressing PC3-PIP and PSMA-negative PC3-FLU cell lines were obtained from Dr. Warren Heston. LMD and LMD-PSMA cells were generated by lentiviral transduction of cells derived from lung metastasis of mice bearing orthotopic MDA-MB231 tumors that were provided by Dr. Sridhar Nimmagadda (Supplmentary Methods). All cells were cultured in RPMI 1640 medium (Corning Cellgro, Manassas, VA. Cat# 10-040) with 10% FBS (Sigma-Aldrich, St. Louis, MO. Cat# F4135-500ML), 50 ug/ml of Gentamicin (Quality Biological, Gaithersburg, MD. Cat# 120-099-661) and 5 ug/ml of Ciprofloxacin (US Biological, Salem, MA. Cat# C5074). Cells were passaged at confluency of 90% at a dilution of 1:10. Cell cultures were maintained in 5% CO₂, at 37°C in a humidified incubator.