Urinary infections

Cystitis and pyelonephritis

The difference lies in how far the infection climbed: whether it stayed in the bladder or reached the kidney. And that difference decides everything from the treatment to whether you need admitting.

Warning signs: when not to wait

Seek help immediately, without waiting for an appointment, if any of these appear:

• Fever with rigors, above all if you are shivering uncontrollably.
• Severe pain in the flank or back, on one side only.
• Vomiting that prevents you keeping down fluids or medication.
• Confusion or disorientation, especially in older people: it may be the only sign.
• Stopping passing urine or passing only minimal amounts.
• Fever together with a known stone in the kidney or ureter. An obstructed, infected kidney is a genuine emergency: antibiotics will not resolve it, it has to be decompressed.
• Any urinary fever if you are diabetic, immunosuppressed, have a solitary kidney or are pregnant.

Complicated and uncomplicated

This is the classification that decides how deeply to investigate, and it is frequently misread. "Complicated" does not mean severe: it means there is a factor enabling it or making it harder to treat.

Only cystitis in a woman who is not pregnant, with no abnormality of the urinary tract and no condition compromising her defences, counts as uncomplicated. Everything else is complicated:

• Any urinary infection in a man. The male urethra is long and the urinary tract better protected; an infection appearing forces the question of what allowed it.
• Pregnancy.
• Structural or functional abnormalities: stones, obstruction, prostatic enlargement, a bladder that empties poorly, reflux.
• Catheters, whether long-term or recent.
• Poorly controlled diabetes, immunosuppression, kidney failure.
• A transplanted or solitary kidney.
• Infection acquired in hospital or caused by resistant bacteria.

Recurrent infection

There is a specific definition, and it is worth knowing because it marks the point at which giving further courses of antibiotics without investigating stops being reasonable:

• Two episodes in six months, or three in twelve months, confirmed by urine culture.
• Relapse is when the same bacterium returns within a few weeks: it suggests the infection was never eradicated, or that there is a reservoir —a stone, a prostate, a catheter.
• Reinfection is when a different bacterium returns later: it points to exposure and host defence factors rather than a persistent focus.

The distinction matters because relapse obliges you to look for the cause, while reinfection is addressed with preventive measures.

What is investigated, and when

• Urine culture with sensitivities before starting antibiotics, whenever the picture is not simple cystitis in a young woman.
• Ultrasound of the kidneys and bladder, including measurement of what remains in the bladder after passing urine. It is simple, non-invasive and settles many questions.
• CT in pyelonephritis that does not improve within 48 to 72 hours, or where obstruction or an abscess is suspected.
• Cystoscopy in selected cases: recurrent infections with no clear cause, or if there was blood in the urine outside the infective episode.

What helps to prevent them

• Drinking more fluid. It is one of the few measures a clinical trial has shown reduces recurrences, and it costs nothing.
• Passing urine after intercourse and not holding on.
• Correcting the underlying factor: treating prostatic obstruction, removing an unnecessary catheter, dealing with a stone, controlling diabetes. In men this is what genuinely changes the outlook.
• Vaginal oestrogen in postmenopausal women with recurrent infections: it is among the best-supported measures.
• Low-dose antibiotic prophylaxis, in selected cases and for a limited period.

When it is not an infection

Some patients have spent years receiving antibiotics for "infections" that were never confirmed. If your cultures come back negative repeatedly, other causes of the same symptom deserve considering:

• Interstitial cystitis, or bladder pain syndrome.
• Urethritis from sexually transmitted infections, which need different testing and different treatment.
• Chronic prostatitis in men, which causes burning and urgency with no demonstrable infection.
• Overactive bladder, which produces urgency and frequency without pain on passing urine.