Gram-Positive Bacteria in UTIs

Urinary tract infections can be caused by either Gram-positive bacteria or Gram-negative bacteria, but are caused more frequently by Gram-negative bacteria.

Identification

• Determining whether a person's urinary tract infection is Gram-positive or Gram-negative helps doctors choose which antibiotic is likely to be most effective in treating it. This is done using Gram's method.

Gram's Method

• Gram-positive bacteria retain the violet stain used in Gram's method, devised in 1882 by Hans Christian Gram, a Danish bacteriologist.

Types of Bacteria

• Staphylococcus saprophyticus causes 10 percent to 20 percent of urinary tract infections in sexually active young women, and the bacteria also can cause male urinary tract infections. Enterococci cause 1.3 percent of the urinary tract infections in the United States each year. Most of these are secondary infections acquired in the hospital. Ureaplasma parvum, which colonizes the human urinary tract, can cause male urethritis, a type of urinary tract infection when caused by bacteria.

Treatment

• Your doctor may prescribe a broad-spectrum antibiotic (effective against many Gram-positive and Gram-negative bacteria) or a narrow-spectrum antibiotic (effective mainly against Gram-positive bacteria).

Prevention

• To prevent urinary tract infections, drink plenty of water daily, urinate often, and if you are a woman, urinate after having sex.