Positions of conserved regions and mutations are numbered according to the Ambler scheme [69]. Susceptibilities to clinically significant β-lactam antibiotics range from 1.5 to 3 µg/ml (wild-type) [33,34,36,64], ≥256 µg/ml (C69Y) [33,34,64] and 24 to 64 µg/ml (P167S) [36,64] for ceftazidime, and 3 to 8 µg/ml (wild-type) and 16 to 32 µg/ml (P72F) for amoxicillin–clavulanic acid [64,67]. By comparison, the meropenem MICs in all isolates are not significantly affected and range from 0.75 to 1.5 µg/ml [36,64]. Current susceptibility breakpoints are ≤8 µg/ml for ceftazidime, ≤8 µg/ml for amoxicillin and ≤4 µg/ml for clavulanic acid.