Antibiotic Susceptibility of P. aeruginosa

Ten antibiotics (purchased from Oxoid Ltd., Basingstoke, UK), namely imipenem (10 µg), meropenem (10 µg), levofloxacin (5 µg), ceftazidime (30 µg), gentamycin (10 µg), amikacin (30 µg), aztreonam (30 µg), piperacillin (100 µg), cefepime (30 µg), and norfloxacin (10 µg), were selected for the antibiotic susceptibility test with P. aeruginosa using the disk diffusion susceptibility method [48 (link)]. Overnight bacterial culture in Tryptic Soy Broth (TSB) (Difco, San Diego, CA, USA) was adjusted to 0.5 McFarland turbidity standards. Subsequently, 0.1 mL of bacterial suspension was spread, using sterile swabs, on Mueller–Hinton agar plates (HI Media Lab. Pvt. Ltd. Ref. M173). Duplicate plates were prepared for each isolate. The antibiotic discs were placed on the agar plates (within 15 min of the inoculation) using sterile forceps, to apply the discs at a distance of 2 cm apart from each other, and incubated for 16–18 h at 37 °C. After incubation, inhibition zones were visible and measured with a ruler, with the measurements recorded in mm [49 (link)].