[Bacterial urinary tract infections--what is only an annoyance, when is risk involved?].

Bacterial UTI are common infections in outpatients as well as in the hospital. The discrimination in uncomplicated and complicated UTI has been proven clinically relevant. Diagnosis of UTI is based on patients history, physical examination and laboratory testing of urine and blood. Bacterial virulence factors on the one hand and the integrity of the defense mechanisms of the host on the other hand determine the course of the infection. If the defense is deteriorated by genetic or acquired complicating factors, complications and long term sequelae are at risk. Symptoms of uncomplicated UTI are usually unambiguously detectable, whereas in complicated UTI initial symptoms can be more discrete, because of sometimes lower pathogenetic properties of uropathogens. In uncomplicated UTI the most important pathogen is Escherichia coli. In complicated UTI the bacterial spectrum is wider, including Gram-positive bacteria and multiresistant pathogens. Therapy in uncomplicated UTI is essentially antibacterial, whereas in complicated UTI additional treatment of complicating factors is mandatory.