Men get urinary tract infections when bacteria, most often from the gut, enter the urethra and travel upward into the bladder. While UTIs are far less common in men than women, they become increasingly likely with age. Among men 18 to 24, the annual incidence is about 0.9%, but it climbs steadily and reaches 7.7% in men 85 and older. Half of all male UTIs treated at Kaiser Permanente Southern California over a recent decade occurred in men 65 and older.
How Bacteria Enter and Take Hold
The vast majority of male UTIs start the same way: bacteria that normally live in the intestines migrate to the skin around the urethral opening, colonize the tissue there, and then travel up the urethra into the bladder. The male urethra is significantly longer than the female urethra, which is why men get far fewer infections overall. But length alone isn’t a guarantee of protection.
Whether an infection actually develops depends on three things: how aggressive the bacteria are, how many of them are present, and how well your body’s defenses are working. The single most important defense is urinary flow itself. Each time you urinate, the stream physically flushes bacteria out before they can attach to the bladder wall. Anything that weakens that flushing mechanism, whether it’s incomplete emptying, infrequent urination, or a physical blockage, tips the odds in the bacteria’s favor.
The Bacteria Behind Most Infections
E. coli, a bacterium that lives harmlessly in the gut, causes roughly 25% of male UTIs. That’s a smaller share than in women, where E. coli dominates. In men, other gut bacteria like Proteus and Providencia account for a large portion of remaining cases, with Klebsiella, Pseudomonas, and enterococci showing up less frequently. The bacterial profile shifts depending on how the infection was acquired. In chronic bacterial prostatitis, for example, E. coli is responsible for about 80% of cases.
Why UTIs Become More Common With Age
In younger men, UTIs are uncommon enough that doctors often investigate whether something unusual is going on. After age 50, infections become much more routine, largely because of changes in the prostate and bladder function.
An enlarged prostate, known as benign prostatic hyperplasia, is one of the most frequently cited risk factors. As the prostate grows, it can squeeze the urethra and obstruct the flow of urine out of the bladder. The logic is straightforward: if the bladder doesn’t empty completely, the leftover urine gives bacteria a warm, stagnant environment to multiply in. That said, the research picture is more nuanced than it appears. Studies have not definitively proven that the volume of urine left after voiding directly predicts infection rates in older men without neurological conditions. The obstruction itself, rather than the residual urine alone, likely plays the more important role.
The Prostate as an Ongoing Source
The prostate gland sits just below the bladder and wraps around the urethra, which means bacteria passing through the urinary tract can seed the prostate tissue. Men with lower UTIs are more likely to develop bacterial prostatitis, and UTIs that keep coming back or resist treatment can evolve into chronic bacterial prostatitis. Once bacteria establish themselves in the prostate, they’re difficult to eliminate completely because the gland’s tissue doesn’t allow antibiotics to penetrate easily. This creates a cycle: the infected prostate acts as a reservoir, periodically releasing bacteria back into the urinary tract and causing recurrent infections.
Catheters and Medical Procedures
Any medical instrument that enters the urethra can carry bacteria directly into the bladder, bypassing the body’s natural defenses entirely. Urinary catheters are the biggest culprit. About 75% of UTIs acquired in hospitals are associated with a catheter, and 15 to 25% of hospitalized patients have one placed at some point during their stay. The single most important risk factor for developing a catheter-related UTI is how long the catheter stays in place. Every additional day increases the chance that bacteria will travel along the tube and colonize the bladder.
Other procedures that involve instruments entering the urethra, such as cystoscopy or urological surgery, carry similar risks, though typically for a shorter exposure window.
Diabetes and Immune-Related Risks
Poorly controlled diabetes creates several conditions that favor urinary infections at once. When blood sugar runs high, excess glucose spills into the urine. That sugar-rich urine is essentially a growth medium for bacteria. Diabetes can also damage the nerves controlling the bladder, a form of autonomic neuropathy, leading to incomplete emptying and urine retention.
Beyond these mechanical effects, high blood sugar directly impairs the immune system. White blood cells become less effective at reaching, engulfing, and killing bacteria. Bacterial strains also adhere more readily to the cells lining the urinary tract in people with diabetes, particularly when glucose control is poor. The combination of more bacterial fuel, weaker immune surveillance, and stronger bacterial attachment makes diabetic men considerably more vulnerable.
Recognizing Symptoms
A bladder infection in men typically causes a burning sensation during urination, an urgent or frequent need to urinate, and urine that looks cloudy or smells unusual. You might notice discomfort in the lower abdomen or pelvis. Some men see blood in their urine. These symptoms can overlap with prostatitis or an enlarged prostate, which is one reason doctors usually run a urine test rather than relying on symptoms alone.
When Infection Spreads to the Kidneys
A UTI that isn’t treated, or that doesn’t respond to initial treatment, can travel from the bladder up the ureters to the kidneys. A kidney infection is a more serious condition that typically announces itself with fever, chills, nausea or vomiting, and pain in the back, side, or groin, on top of the usual urinary symptoms. Urine may contain pus or blood.
A severe kidney infection can lead to bacteria entering the bloodstream, a condition that requires intravenous antibiotics in a hospital. In rare cases, this can progress to widespread tissue damage or become life-threatening. Men whose urinary flow is already compromised, whether from an enlarged prostate, a catheter, or neurological conditions affecting the bladder, face a higher risk of this kind of progression. Prompt treatment of a straightforward bladder infection is the most effective way to prevent it from climbing higher in the urinary tract.