My training has mainly been as a clinical microbiologist, and my research has focused on the effect of physiological conditions on antimicrobial activity, mutational mechanisms and bacterial evolution during infection. Particularly, I am interested in determining the critical steps in antibiotic resistance development during urinary tract infection. My scientific achievements include elucidating the presence of Escherichia coli strains with slightly higher antibiotic resistance than is common for the susceptible population, but still below the clinical breakpoint. These strains are named low-level resistant, and are considered and intermediary stage in the development of high-resistant strains. Low-level resistant appears to facilitate the selections of fully resistant strains, allowing bacterial growth at clinical relevant concentrations. Therefore, low-level resistant mutants are arguably the first step on the evolutionary pathway to producing high-level resistance, and consequently their dissemination and evolution might influence the outcome of antibiotic treatment. Currently, a special emphasis in my research is to develope and implement new diagnostic strategies to ensure prompt diagnosis and treatment of patients with severe infections.