When is Bacteria in Urine NOT a Urinary Tract Infection?

Asymptomatic bacteriuria (ASB)

What is it?

Most of the time, urine is sterile. This means there are no bacteria growing in it. However, when someone has symptoms of a urinary tract infection, bacteria will be present and grow in the urine.

There are cases, though, where a large amount of bacteria is present in the urine but there are no symptoms of infection. This is called asymptomatic bacteriuria (ASB).

How does it happen?

Well, unfortunately, the reasons for ASB are not clear. Medical science has only discovered that it is more likely to occur if someone:

• Has a urinary catheter

• Is female, especially if sexually active and/or has diabetes

• Is pregnant

• Is an older adult (15% occurrence rate in ages 65-79, ≥ 40% in ages 80 and older)

• Has recently had urinary tract surgery

It is also unclear why the bacteria don't cause symptoms. It may be that ASB is caused by weaker (less "virulent") bacteria, though experts cannot say for sure.

Is antibiotic treatment required?

No, with very few exceptions. Most people who have ASB do not need treatment because the bacteria are not causing any harm. Conversely, treating ASB can make it harder to tackle infections in the future due to creating antibiotic resistance or reaction through unnecessary treatment. Therefore, in most cases, ASB should not be treated.

In fact, a 2019 study found that antibiotic treatment of ASB was associated with a 37% longer stay in the hospital, without improved clinical outcomes.

Without symptoms being present, even people who are older adults, have diabetes, or have a urinary catheter do not need treatment. Those treated are namely pregnant women or people who have had recent urinary tract surgery.

Can ASB lead to UTI?

ASB places vulnerable persons or those who have a weakened immune system at higher risk of developing a UTI, though having ASB does not mean they will get a UTI. A provider will consider treating select people with prophylactic antibiotics (antibiotics for prevention of UTI), namely those who are pregnant, have recently had urinary tract surgery, or have conditions that cause urinary tract damage (kidney stones or backward flow of urine from the bladder to the kidneys, called urinary reflux).

UTI symptoms

Regardless of the presence of ASB, older adults are also more prone to UTI. So, if your loved one experiences any of the following symptoms common to UTI, contact their provider right away.

• Changes in urinary habits that include increased frequency or urgency 

• Pain or burning during urination

• Foul odorous urine, and/or urine that is discolored, cloudy, or appears to have solid flakes  

• Pain or tenderness in the pelvis, lower back, or abdomen 

• Fever (though keep in mind many older adults don't mount a fever)

• Nausea, with or without vomiting

• Unusual or excessive fatigue (tiredness, easily exhausted)