What are the most common bacteria found in UTIs?
As mentioned previously, most UTIs are caused by facultative anaerobes from the bowel flora. Escherichia coli is the most common cause of UTIs, accounting for 85% of community-acquired and 50% of hospital-acquired infections. Other gram-negative Enterobacteriaceae, including Proteus and Klebsiella, and gram-positive Enterococcus faecalis and Staphylococcus saprophyticus, are responsibile for the remainder of most community-acquired infections. Nosocomial infections, or hospital-acquired UTIs, are frequently caused by Enterococcus faecalis as well as Klebsiella, Enterobacter, Citrobacter, Serratia, Pseudomonas Aeruginosa, Providencia, and Staph Epidermidis.
