urinary tract infection
Meaning of urinary tract infection: One of the commonest reasons for an antibiotic prescription, and a diagnosis that rests on symptoms rather than on a urine test alone.
Definition of urinary tract infection
A urinary tract infection is an infection anywhere in the system that makes, stores and carries urine, from the kidneys down to the tube leading out of the body. Bacteria from the bowel are the usual cause, reaching the opening of that tube and multiplying in urine. Most infections stay in the bladder, where they cause burning, urgency and frequent passing of small amounts.
Where in the tract does the infection sit?
| Level | Name | What it typically causes |
|---|---|---|
| Urethra | Urethritis | Stinging on passing urine, discharge |
| Bladder | Cystitis | Burning, urgency, frequency, ache low in the abdomen |
| Kidney | Pyelonephritis | Fever, shivering, flank pain, feeling generally unwell |
| Urine only | Asymptomatic bacteriuria | Nothing at all |
The last row is not an infection in the ordinary sense. Bacteria live harmlessly in the urine of many older adults and of nearly everyone with a long-term catheter, and treating a laboratory result rather than an ill person is how that finding is most often mishandled.
Why is it so much commoner in women?
Distance, mainly. The tube carrying urine out is short in women and its opening sits close to the bowel, so bacteria have a brief journey to the bladder. In men the same journey is several times longer, which is why an infection in a man prompts a search for a reason, such as an enlarged prostate holding urine back. Anything that stops the bladder emptying completely, or leaves urine standing still, raises the risk in either sex: stones, narrowing, nerve damage, pregnancy and a catheter all do it. Sugar in the urine from poorly controlled diabetes feeds bacteria as well.
How is it confirmed?
A dipstick gives an answer in a minute by detecting the products of bacterial activity, but it reads positive in people with no illness and negative in some with a genuine infection, so symptoms carry more weight than the stick. A culture grows the organism, names it, and shows which antibiotics it still responds to, which matters because resistance among ordinary bowel bacteria is widespread. In frail older adults confusion or a fall is sometimes the only change noticed, and because bacteria are so often present without disease, treating every such change as an infection risks leaving the real cause unexamined.
Also known as
Used in a sentence
The urine culture grew a coliform organism consistent with a urinary tract infection.
Good to know
Bacteria in the urine without symptoms is a common finding in older adults and in people with long-term catheters, and it is a separate matter from an infection that is making somebody ill.
Word origin
Where “urinary tract infection” comes from
Urinary comes from the Latin urina; tract from tractus, a stretch or course, naming the passage that urine follows.