Kidney Infection (Acute Pyelonephritis): When Antibiotics Are Not Enough

နောက်ဆုံး ပြင်ဆင်သည် ဩဂုတ် 27, 2026

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A kidney infection is a bladder infection that has climbed. It is far more serious than the cystitis it usually starts as, and it is one of the conditions in urology where the difference between a good outcome and a disaster is measured in hours.

If you have fever with flank pain

Get seen today. Not with a leftover antibiotic from a previous episode, and not by waiting to see whether it settles overnight. In an emergency in Thailand, call 1669. Go to hospital immediately rather than to a clinic if any of the following are present:

• Confusion, drowsiness, or feeling profoundly unwell in a way that is different from ordinary illness.
• Shaking chills, rapid breathing, a racing pulse, or feeling faint on standing.
• Passing very little or no urine.
• Vomiting so much you cannot keep fluids or tablets down.
• Known kidney stones, a ureteric stent, one kidney, or a kidney transplant.
• ကိုယ်ဝန်, at any severity.

• ထိုင်းနိုင်ငံ ဆီးလမ်းကြောင်းဌာန ဘန်ကောက်ဆေးရုံ အွန်လိုင်းဘွတ်ကင်လုပ်ခြင်း။ 02-310-3009 bhquro@bdms.co.th
• Samitivej Sriracha ဆေးရုံ Chonburi 088-022-1445

The distinction that matters most: is the kidney also blocked?

This was absent from the earlier version of this article entirely, and it is the most important thing a urologist has to say about kidney infection.

Most kidney infections settle with antibiotics. An infected kidney that is also obstructed — by a stone, a narrowing or a tumour — does not. Antibiotics travel in the bloodstream and cannot sterilise infected urine trapped behind a blockage; the pressure keeps rising, bacteria enter the bloodstream, and a patient can deteriorate from unwell to critically ill within hours.

That situation is a surgical emergency, and the treatment is drainage — a stent passed up to the kidney, or a tube through the skin — done urgently, with the stone or the underlying cause dealt with later once the infection has settled. It is not something antibiotics can be given time to work on.

Which is why the practical rule is: fever with flank pain in someone known to have stones, or who is not improving on antibiotics, needs a scan rather than a stronger prescription. See also narrowing of the ureter, which produces the same problem without a stone.

How it happens

အက်စ်ခေရီရှားကိုလိုင်, a normal inhabitant of the bowel, is responsible for most cases. It reaches the kidney in one of two ways:

1. Climbing up from the bladder — by far the commoner route. The bacteria carry fine hair-like projections that let them grip the lining and work upwards from the urethra through the bladder and ureter.
2. Through the bloodstream — uncommon, and mainly in people whose immunity is impaired.

It is several times commoner in women, whose urethra is short, with young sexually active women, infants, older people and pregnant women most affected.

Two groups where it is never just a kidney infection

• Men. Pyelonephritis is uncommon in men, and when it happens it is a reason to look for why — a stone, obstruction from the prostate, an abnormality of the urinary tract. Treating the infection and stopping there misses the point.
• Pregnancy. Kidney infection in pregnancy is a serious event that usually needs admission, threatens the pregnancy, and is exactly what screening for bacteria in the urine without symptoms at the first antenatal visit is designed to prevent.

ရောဂါလက္ခဏာများ

• ဖျားခြင်း။ ကိုယ်ပူခြင်း, often high and coming on suddenly, frequently with shaking chills.
• ခါးနာခြင်း။, usually on one side, over the kidney rather than low in the abdomen.
• Nausea and vomiting.
• Often, though not always, burning and frequency alongside — and sometimes blood in the urine.

It develops fast, typically over hours. In older people the picture can be quieter and more confusing — confusion, unsteadiness or simply being unwell, sometimes without much fever — which is one reason kidney infection is missed in that group. Tapping over the kidney reproduces the pain, which is a useful bedside sign.

Tests and treatment

Urine testing shows inflammatory cells and bacteria, and a urine culture is taken before antibiotics are started — this is not a formality. It takes around two days and it is what allows a broad antibiotic to be narrowed to the right one, and what identifies a resistant organism if the first choice fails. Blood tests and blood cultures are added where the illness is more severe.

The earlier version described imaging as optional and reserved for severe cases. That is broadly right and worth stating more precisely, because it is how obstruction gets found. A scan is indicated where there are known stones, where the patient is a man, where there is diabetes or a single kidney, where the illness is severe — and, most importantly, where fever has not settled after about two to three days of appropriate antibiotics. A patient who is not improving is assumed to have something that needs draining until a scan says otherwise.

Antibiotics are started immediately after the culture is taken, by mouth for milder illness at home, intravenously in hospital for anyone vomiting, unstable, pregnant, or not improving. Finish the full course even once you feel well within a couple of days, and do not treat this with antibiotics bought over the counter — a partial course quietens the symptoms while leaving infection in the kidney and selecting for resistance.

What can go wrong

With prompt treatment the outlook is good. Delay, or an unrecognised blockage, allows an abscess in or around the kidney, bacteria in the bloodstream with septic shock, permanent scarring of the kidney, and — in people with diabetes especially — a rare gas-forming infection that destroys the kidney and is life-threatening. Diabetes is the single risk factor that turns a manageable infection into a dangerous one, which is why it lowers the threshold for admission and for scanning.

Preventing it happening again

• Drink enough that urine stays pale, in the region of two litres a day for most people. This is a measure for between episodes; it does not treat an infection that is already established.
• Do not hold urine when you feel the urge.
• Wipe front to back, and pass urine after sex.
• Get recurrent infections properly investigated rather than treated repeatedly. Repeated kidney infections, and any in a man, warrant looking for a cause — see why bladder infections keep coming back နှင့် how to prevent them without antibiotics.

Frequently Asked Questions About Kidney Infection

What are the symptoms?

Fever, often high and sudden with shaking chills; one-sided flank pain over the kidney; and nausea or vomiting. Burning and frequency are often present too. It develops over hours. In older people it can present as confusion or simply being unwell without much fever.

Why would antibiotics not be enough?

Because antibiotics cannot sterilise infected urine trapped behind a blockage. An infected kidney that is also obstructed by a stone or a narrowing is a surgical emergency needing urgent drainage, and a patient can deteriorate within hours. This is why failure to improve within two to three days prompts a scan rather than a stronger prescription.

Can I treat it at home?

Milder cases are treated at home with tablets after assessment and a urine culture. What is not safe is self-treating with leftover or over-the-counter antibiotics, which quietens symptoms while leaving infection in the kidney. Vomiting, instability, pregnancy, diabetes, a single kidney, known stones or failure to improve all point to hospital.

I am a man and I have had a kidney infection. Does that matter?

Yes. It is uncommon in men, so it is treated as a reason to look for an underlying cause — a stone, obstruction from the prostate, or an abnormality of the urinary tract. Treating the infection alone leaves the reason it happened unaddressed.

How do I stop it coming back?

Keep fluid intake up so urine stays pale, do not hold urine, wipe front to back, pass urine after sex — and have recurrent episodes investigated rather than repeatedly treated, since repetition usually means something is being missed.

Arranging a consultation

An acute episode goes to hospital, not to an appointment. Afterwards, or for recurrent infections, Dr. Soarawee Weerasopone sees patients at ဘန်ကောက်ဆေးရုံ