Which of the following organisms is the most common cause of urinary tract infection (UTI) in children?
A. Klebsiella
B. Staphylococcus
C. Escherichia coli
D. Pseudomonas
Correct Answer: C. Escherichia coli
E. coli is the most common organism associated with the development of UTI. Escherichia coli is the most common organism in uncomplicated UTI by a large margin. Pathogenic bacteria ascend from the perineum, causing the UTI. Women have shorter urethras than men and therefore are far more susceptible to UTI. Very few uncomplicated UTIs are caused by blood-borne bacteria.
Option A: E.coli causes the vast majority of UTIs but other organisms of importance include proteus, klebsiella, and enterococcus. The diagnosis of UTI is made from the clinical history (symptoms) and urinalysis with confirmation by a urine culture, but the proper collection of the urine sample is important.
Option B: Staphylococcus aureus is a major bacterial human pathogen that causes a wide variety of clinical manifestations. Infections are common both in community-acquired as well as hospital-acquired settings and treatment remains challenging to manage due to the emergence of multi-drug resistant strains such as MRSA (Methicillin-Resistant Staphylococcus aureus).
Option D: Although Klebsiella, Staphylococcus, and Pseudomonas species may cause UTIs, the incidence of UTIs related to each is less than that for E. coli. Pseudomonas aeruginosa is commonly found in the environment, particularly in freshwater. It is commonly an opportunistic pathogen and is also an important cause of nosocomial infections like ventilator-associated pneumonia, catheter-associated urinary tract infections, and others.