what bacteria causes uti

The main bacteria that causes a UTI is Escherichia coli (E. coli) , a type of gut bacteria that commonly travels from the bowel to the urethra and bladder.

Quick Scoop

Most common culprit

• E. coli causes the vast majority of urinary tract infections (often more than 70–80%).

• It usually comes from the intestine, then accidentally gets into the urinary tract (for example, after bowel movements, sex, or poor wiping technique).

Other bacteria that can cause UTIs

While E. coli is the star “villain,” other bacteria are also involved:

• Klebsiella species

• Proteus species (can be associated with kidney stones)

• Enterobacter species

• Pseudomonas species (more common in people with catheters or in hospitals)

• Serratia species (often hospital-related)

• Staphylococcus saprophyticus – a notable cause of UTIs in young, sexually active women

• Enterococcus faecalis and other enterococci

• Less commonly, other Staphylococcus species such as Staphylococcus aureus in certain settings

In short, when people ask “what bacteria causes UTI,” the single best answer is E. coli , but multiple other gram-negative and gram-positive bacteria can also be responsible depending on age, sex, health conditions, and whether the infection is community-acquired or hospital-acquired.

Information gathered from public forums or data available on the internet and portrayed here.