Ambulatory: E. coli (50–80%), Klebsiella (8–10%).
Staphylococcus saprophyticus (10–30%) is the second most common cause of UTI in young ambulatory women.
Hospital: E. coli, Proteus, Klebsiella, Serratia,Pseudomonas.
Epidemiology: women to men = 30 to 1 (short urethracolonized by fecal flora).
UTIs mostly caused by ascending infections:
In males: Babies with congenital defects; elderly with enlarged prostates.
UTI: dysuria, frequency, urgency, suprapubic pain.
Pyelonephritis: fever, chills and flank pain.
First Aid for the USMLE STEP1 -2007