Urinary tract infections in infants are rare, affecting between 1 and 5 percent of newborns. In this age group, symptoms of urinary tract infection are nonspecific, and include temperature instability, vomiting or feeding intolerance, irritability, jaundice and poor weight gain. Diagnosis is important, as these infants usually also present with bacteremia (spread of bacteria in the bloodstream) and the urinary tract infection can have long-term consequences.
Bacterial Causes
Most cases of urinary tract infection in infants are caused by a group of bacteria called gram-negative rods. This alludes to the description of the bacteria when looked under the microscope. The most common gram-negative rod that causes urinary tract infections in newborns is Escherichia coli (E.coli). E. coli is the most common cause of urinary tract infection in all age groups. Other bacteria that cause urinary tract infections in infants include Klebsiella, Enterobacter, Citrobacter and Proteus
Fungal Causes
Fungi can cause urinary tract infection in infants, but these are rare. Fungal infection usually occurs in premature infants, who are more susceptible to opportunistic infections because their immune systems is not fully developed and because of procedures done on them during their stay in the neonatal intensive care unit.
Anatomic Causes
There are anatomical abnormalities that predispose infants to have urinary tract infections. The most common is vesico-ureteral reflux (VUR). In VUR, the urine flows back from the bladder towards the kidney, instead of flowing down into the bladder and out of the body. This can predispose infants to pyelonephritis, an infection of the kidney's upper urinary tract. Vesico-ureteral reflux can also result in renal scarring and the possibility of permanent kidney damage.
Congenital Causes
Anatomical congenial abnormalities are also associated with urinary tract infections in infants. Posterior urethral valves are small pieces of tissue that interrupt the normal flow of urine in the urethra, resulting in urinary reflux. Other congenital abnormalities include duplication of any part of the urinary tract, like the ureters; congenital cyst formation in the kidneys; and other conditions in which the ureters don't attach in the right way to the kidneys, or if the kidneys are malformed.
About Circumcision
There are several studies that suggest an association between uncircumcised infants and an increase in the incidence of urinary tract infections in this group. Despite this evidence, the American Academy of Pediatrics does not recommend routine circumcision of male infants.
