Stock solutions were prepared for ofloxacin (Sigma–Aldrich), levofloxacin (Sigma–Aldrich), moxifloxacin (Bayer or Molekula) and gatifloxacin (Lupin, India or Sigma–Aldrich) at 10 000 mg/L in 0.1 N sterile NaOH and stored in aliquots at below −18°C for 1 year maximum. Leftover thawed aliquots were not refrozen.
Middlebrook 7H9 broth medium was prepared by adding distilled water, 10% Middlebrook OADC [Becton Dickinson (BD)], 0.5% glycerol (Sigma–Aldrich) and 0.1% casitone (BD) to Middlebrook 7H9 powder (BD) and stored at 2–8°C for 3 months maximum.
Middlebrook 7H9 broth medium was prepared by adding distilled water, 10% Middlebrook OADC [Becton Dickinson (BD)], 0.5% glycerol (Sigma–Aldrich) and 0.1% casitone (BD) to Middlebrook 7H9 powder (BD) and stored at 2–8°C for 3 months maximum.