What is the most common bacterial pathogen responsible for cystitis (UTIs)?

Escherichia coli is the most common bacterial pathogen responsible for cystitis, commonly known as urinary tract infections (UTIs). This organism is typically part of the normal flora of the gastrointestinal tract but can ascend and colonize the urinary tract, leading to infection.

The structure of E. coli, particularly its pili (fimbriae), allows it to adhere to the uroepithelium, which is crucial for evading the host's flushing mechanism during urination. Additionally, certain virulence factors produced by E. coli, such as toxins and capsular materials, contribute to its pathogenicity and the severity of infection.

Other bacteria like Pseudomonas, Proteus, and Klebsiella can also cause UTIs, but they are less common than E. coli. Pseudomonas is often associated with complicated cases or healthcare-associated infections. Proteus species can contribute to UTIs, particularly in patients with urinary tract abnormalities, but they are also not as prevalent as E. coli. Klebsiella, while capable of causing UTIs, tends to be less frequent compared to E. coli in otherwise healthy populations. Thus, E. coli's predominance in causing uncomplicated cystitis makes it the primary pathogen in most