[Gut bacteria and antimicrobial resistance--what to worry about].

Gram negative and anaerobic bacteria from gut microbiota are important pathogens both in community-acquired and hospital infections. Escherichia coli is the the most common cause of adult bacteraemias in Finland. Antimicrobial resistance in these bacteria is a threatening phenomenon. Enterobacteriacae producing extended spectrum beta-lactamase (ESBL) have spead worldwide. The use of antimicrobial agents shifts the balance in gut microbiota and induces and selects bacterial resistance. When resistant bacteria cause infections, empiric antimicrobial therapy may not cover them, which may increase lenght of hospital stay, costs and mortality due to infections.