Most common cause of acute UTI:

→ 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.