Mueller hinton broth and agar

Reference strain Escherichia coli ATCC 25922 (Microbiologics^®, Saint Cloud, MN, USA) was used as recommended by the CLSI. Mueller-Hinton broth and agar, Trypticasein-Soy agar, Nutrient agar and Blood agar were acquired from Becton Dickinson (BD, Franklin Lakes, NJ, USA). Soft agar was prepared with 0.6 g agar base (BD, Franklin Lakes, NJ, USA) and 0.6 g NaCl (Promega, Madison, WI, USA).
Saline solution (0.85% NaCl) (J.T. Baker, Phillipsburg, NJ, USA) was used for washing and maintaining cultures. 2% DMSO (J.T. Baker, Phillipsburg, NJ, USA) was used as dissolvent for essential oils. Antibiotics cloramphenicol, cefotaxime, and amikacin were purchased from AMSA (Coyoacan, CDMX, Mexico).
LIVE/DEAD^® BacLight™ Bacterial Viability and Counting kit (Cat. L34856, Thermo Fisher, Waltham, MA, USA) was used for sample staining.
McFarland turbidity standard was prepared by mixing 0.05 mL of 1.175% barium chloride dihydrate (BaCl₂•2H₂O), with 9.95 mL of 1% sulfuric acid (H₂SO₄). All standard preparations were verified in a Coleman spectrophotometer at 600 nm (abs. 0.063) previous to be used.

Staphylococcus aureus GRP-0057, Klebsiella pneumoniae GRP-0107, and Pseudomonas aeruginosa strains GRP-0019, GRP-0049, GRP-0036, and ATCC 27853 were used to infect the mice in the different models. The microorganisms were grown to log phase in Mueller-Hinton broth and agar for susceptibility tests, and in trypticase soy broth and agar for animal infection models (all from Becton Dickinson, Sparks, MD, USA). Staphylococcus aureus ATCC 29213, K. pneumoniae ATCC 43816 and P. aeruginosa 27853 were the quality control strains in susceptibility tests; Kocuria rhizophila ATCC 9341 was the seeding organism for microbiological assays. We bought the antibiotics from well-reputed local drugstores and reconstituted them following manufacturer instructions. The products, both licensed for human use by INVIMA (the Colombian DRA), included a generic product of imipenem (Inem, Ivax Pharmaceuticals, Mexico) and the innovator (Tienam, Merck Sharp & Dohme, Elkton, VA). Both products came in vials with a lyophilized powder containing imipenem 500 mg and cilastatin 500 mg; lot numbers and additional information about the products employed in this study are described in S1 Table.