<prompt> Most common cause of acute UTI:E.coliKlebsiellaStrep. faecalisStaph. saprophyticus  <response>: Acute uncomplicated UTI:- Escherichia coli cause about 80 of UTI. 20 UTI caused by:- Gram negative enteric bacilli Klebsiella proteus. Gram positive cocci Streptococcus faecalis. Staphylococcus saprophyticus - restricted to infection in young sexually active women. 