Proteus mirabilis is the most likely cause of the urinary tract infection in the 2-year-old boy. Hence the correct option is e.
The most likely cause of the urinary tract infection in the 2-year-old boy with an indwelling urinary catheter is Proteus mirabilis. The identification of a lactose-negative, oxidase-positive, gram-negative rod points toward this organism. Proteus mirabilis is known for its association with urinary tract infections, particularly in the context of instrumentation or catheterization.
The use of urinary catheters can facilitate the ascent of bacteria into the urinary tract, leading to infection. Proteus mirabilis is recognized for its urease activity, which can alkalinize urine and contribute to the formation of urinary tract stones. In post-operative settings, where catheters are frequently used, vigilance for nosocomial infections caused by Proteus mirabilis is essential, and appropriate antibiotic therapy targeting this organism may be warranted. Hence the correct option is e.