The activity of Aspergillus terreus ICMP 477 against antibiotic-sensitive and resistant strains of E. coli, K. pneumoniae, and S. aureus by zone of inhibition assay
To perform zone of inhibition (ZOI) testing, potato dextrose agar (PDA) plates were inoculated with a lawn of either antibiotic-sensitive E. coli (ATCC 25922) or resistant clinical isolates (CTX-M-9, CTX-M-14, CTX-M-15, NDM-1) or antibiotic-resistant K. pneumoniae (ATCC 700603, produces SHV-18). Similarly, Mueller-Hinton agar plates were inoculated with a lawn of either antibiotic-sensitive S. aureus (ATCC 29213) or antibiotic-resistant S. aureus (ATCC 33593). ICMP 477 was obtained from Manaaki Whenua - Landcare Research and grown on PDA plates for 36 days and fungal plugs removed using a 6 mm punch biopsy tool (Amtech Medical, New Zealand). Fungal plugs were placed onto the bacterial lawns, alongside PDA plugs containing no fungus as a control. Plates were incubated inverted at 37°C for 24 h before measuring any zones of inhibition (in mm) produced. A zone of 6 mm = no inhibition. Experiments were performed using three biological replicates with three technical replicates each.