Staphylococcus aureus rosenbach

Staphylococcus aureus Rosenbach (S. aureus, gram-positive, ATCC 14458) and Pseudomonas aeruginosa (Schroeter) Migula (P. aeruginosa, gram-negative, ATCC 10145) and were purchased from American Type Culture Collection (ATCC, Manassas, VA) and used by following the supplier’s protocol. Briefly, bacteria were kept at −80°C. Prior to use, bacteria were grown in 100 mL of Bacto Agar medium (Becton Dickinson) overnight. Then 1 mL of bacteria containing medium was applied to 100 mL of fresh agar medium for 2 hrs. Bacteria were then spun down at 4,500 rpm for 10 min at 4°C. Finally, bacteria were resuspended in sterile PBS to OD600=0.1. This protocol results in an inoculum of 5×10⁶ CFU in 50 μL (as confirmed by direct count).

All microbes used in this work were purchased from American Type Culture Collection (ATCC, Manassas, VA): E. coli (ATCC-15597), Staphylococcus epidermidis (ATCC-14990), Staphylococcus aureus Rosenbach (ATCC-12600), Staphylococcus aureus MRSA (ATCC-BAA1754), Pseudomonas aeruginosa PAO1 (ATCC-10145), and Candida albicans (ATCC-18804). All strains were incubated at 37 °C at 150 rpm until a midexponential phase was acquired to harvest the cells by centrifugation at 3800 × g for 8 min. E. coli was grown on a Luria-Bertani (LB) broth; S. epidermidis, P. aeruginosa, and S. aureus Rosenbach were grown on nutrient broth; S. aureus (MRSA) was grown on a TSB; and C. albicans was grown on a yeast mold broth. These initial cultures were then adjusted to an optical density of 1 at 600 nm and had an initial total cell number ranging from 1 × 10⁷ cells per mL to 1 × 10⁸ cells per mL, as confirmed by plate counting.