[Pitfalls in determining resistance].

Selection of the optimal antimicrobial therapy is often crucial for the morbidity and mortality associated with an infection. A reliable antibiogram provides the basis for antibiotic therapy optimization. In case of life-threatening infections, minimal inhibitory concentration values should be available so that, in conjunction with knowledge of the pharmacokinetic properties of the respective antibiotics, a rational selection addressing the individual case is feasible. If only categorized results (susceptible, intermediate, resistant: S-I-R) are available, they should be established according to European Committee on Antimicrobial Susceptibility Testing (EUCAST) guidelines in order to avoid therapeutic failures.