This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Microbiology
Most common cause of UTI in young female is ? 
Select and explain. 
A. Staph saprophyticus, B. E.coli Klebsiella, C. Klebsiella, D. Proteus
B: E.coli Klebsiella
Answer: B: E.coli Klebsiella 
Explanation: Ans. is 'b' i.e., E.coli . E.coli causes 80-90% of acute uncomplicated bacterial lower tract infections (cystitis) in young women.