Asymptomatic bacteriuria: bacteria in the urine without symptoms

Bacteriuria means bacteria in the urine. NICE defines asymptomatic bacteriuria as the presence of significant levels of bacteria in the urine in a person without signs or symptoms of a urinary tract infection. Its guideline on lower urinary tract infection (NG109) puts the threshold at greater than 10 to the power of 5 colony forming units per millilitre.

In other words, a urine test finds bacteria, but the person feels well and has no urinary symptoms. This is common, particularly in older people and people in care homes, and it is not the same as a UTI.

Because the bacteria are not causing harm, the question is whether to treat them. For most people, NICE says no.

The NHS lists symptoms of a UTI as pain or a burning sensation when peeing, needing to pee more often or urgently, cloudy pee, blood in the pee, lower tummy or back pain, a high or very low temperature and feeling tired or weak. In older, frail people or those with a urinary catheter, symptoms may include changes in behaviour such as acting agitated or confused, worse leaking of pee and new shivering or shaking.

NICE's quality standard notes that in older people symptoms can include non-specific signs of infection such as delirium. That is why symptom assessment matters: a person with bacteria in the urine and no symptoms has asymptomatic bacteriuria, while a person with symptoms may have a UTI and need assessment.

NICE's quality statement says men and non-pregnant women should not be prescribed antibiotics to treat asymptomatic bacteriuria. The rationale is that it is not a risk factor for harm in these groups. Unnecessary antibiotic treatment is associated with increased risk of adverse events and is of no clinical benefit, and it can increase the resistance of bacteria that cause UTIs, making antibiotics less effective in future.

NICE adds that antibiotics should not be routinely prescribed when a urine culture identifies bacteriuria in a person without symptoms, and that healthcare professionals should assess symptoms to decide if a urine sample should be sent for culture.

NG109 says asymptomatic bacteriuria is treated with antibiotics in pregnant women because it is a risk factor for pyelonephritis, a kidney infection, and premature delivery, and recommends offering an immediate antibiotic prescription to pregnant women with asymptomatic bacteriuria, taking account of recent urine culture and susceptibility results and previous antibiotic use.

The NHS also lists being pregnant among reasons to get urgent advice if a UTI is suspected. If you are pregnant and a urine test shows bacteria, your midwife or GP will explain the plan.

Testing urine in people with no urinary symptoms is likely to find bacteriuria in some, particularly older people, leading to unnecessary treatment. NICE therefore says that symptoms should be assessed and identified before a sample is sent for culture.

The NHS notes that a GP may diagnose a UTI without a urine test, may do a urine test if they think you may have one, and that antibiotics are not always needed. If you or a relative is unwell, mention any change in behaviour or confusion as well as urinary symptoms.

The NHS says to ask for an urgent GP appointment or call NHS 111 if you think you have a UTI and you are 65 or older, have a very high or low temperature, are shivering, are a man, have diabetes, your symptoms get worse quickly or do not improve within 48 hours, you keep getting UTIs, you use a catheter, you are pregnant, you have lower tummy or back pain, blood in your pee or a weakened immune system.

Call 999 or go to A&E if you or your child are confused, drowsy or have difficulty speaking. These signs can mean a more serious infection.

On the NHS, a GP, pharmacist or nurse assesses symptoms before deciding on a urine test or treatment, in line with NICE guidance.

A urine test result that shows bacteria without symptoms should be discussed with your GP, who can explain whether it needs any action in line with NICE advice.