Mechanisms of resistanceBacterial resistance to Ceftazidime may be due to one or more of the following mechanisms:- hydrolysis by beta lactamases. Ceftazidime may be efficiently hydrolysed by certain of the extended spectrum beta lactamases (ESBLs) and by the chromosomally encoded (AmpC) enzymes that may be induced or stably derepressed in certain aerobic gram negative bacterial species- reduced affinity of penicillin binding proteins for Ceftazidime- outer membrane impermeability, which restricts access of Ceftazidime to penicillin binding proteins in gram negative organisms- drug efflux pumpsBreakpointsClinical MIC breakpoints to separate susceptible (S) pathogens from resistant (R) pathogens according to EUCAST are:- Enterobacteriaceae: S≤1.0 mg/l; R>8 mg/l.- Pseudomonas spp.: S≤8 mg/l; R>8 mg/l.- Non-species related breakpoints: S≤4 mg/l; R>8 mg/l.
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