Microbiology General 2e9a2951 Most common cause of UTI in young female is ? A Staph saprophyticus B E.coli Klebsiella C Klebsiella D Proteus High-Yield Explanation Ans. is 'b' i.e., E.coli . E.coli causes 80-90% of acute uncomplicated bacterial lower tract infections (cystitis) in young women.