What is the most common pathogen associated with pyelonephritis?

Escherichia coli is the most common pathogen associated with pyelonephritis, which is a type of urinary tract infection that affects the kidneys. This bacterium accounts for a significant majority of the cases due to its prevalence in the gastrointestinal tract, where it normally resides. E. coli can ascend from the lower urinary tract to the kidneys, especially in individuals with certain risk factors, such as urinary tract obstructions or catheter use.

Understanding the other organisms listed helps contextualize the specific role of E. coli in pyelonephritis. While Staphylococcus aureus and Enterococcus faecalis can be associated with urinary infections, they are typically less common as the primary pathogens in pyelonephritis compared to E. coli. Klebsiella pneumoniae is another potential pathogen that can cause urinary tract infections, but it does not have the same prevalence as E. coli in cases of pyelonephritis. Thus, the predominance of E. coli in this context highlights its specific virulence factors and ability to cause infection in the renal system.