Final answer:
Escherichia coli (E. coli) is the most common cause of community-acquired urinary tract infections, commonly introduced into the urinary tract through fecal matter and diagnosed through routine urinalysis.
Step-by-step explanation:
The most common pathogen responsible for community-acquired urinary tract infections (UTIs) is Escherichia coli (E. coli). This gram-negative bacterium, commonly found in the digestive tract, often causes UTIs through fecal contamination, particularly in women due to the close proximity of the anus to the urethra. By establishing itself in the urethra and possibly moving up to the bladder or kidneys, E. coli can cause infections such as cystitis or pyelonephritis. Staphylococcus aureus, Klebsiella pneumoniae, and Pseudomonas aeruginosa can also cause UTIs, but are less common compared to E. coli. Infections by E. coli can often be detected by routine urinalysis which checks for nitrites produced by E. coli and other bacteria that convert nitrate to nitrite in urine. Good hygiene practices are crucial for preventing UTIs caused by E. coli.