Which bacteria is primarily responsible for causing pyelonephritis?

The primary bacterium responsible for causing pyelonephritis is Escherichia coli. This organism is a common cause of urinary tract infections (UTIs) and is particularly known for its virulence in ascending infections, leading to renal involvement. When E. coli enters the urinary tract, it can ascend from the bladder to the kidneys, causing inflammation and infection in the renal parenchyma, which characterizes pyelonephritis.

It's worth noting that other bacteria can also be implicated in urinary tract infections, but E. coli accounts for the majority of cases of pyelonephritis. Its structure and adhesion factors enable it to effectively colonize the urinary tract, while its ability to evade the immune response contributes to its pathogenicity in renal infections.

Understanding the role of E. coli in pyelonephritis is crucial for diagnosis and treatment, as it influences the choice of antibiotics and management strategies for affected patients.