Kidney Infection

When the urinary tract (urethra) gets infected by bacteria (Bladder infection) usually from:

• The rectum
• Vagina

Our immune system can usually stop  the bacteria but at times the bacteria travels upwards along the ureters towards kidneys, here it can multiply into a full-blown infection and one has more severe symptoms.

Those with weak immune systems

• Patients who are have increased complications of kidney infection are:
  • Immunocompromised patients
  • Uncontrolled diabetes
  • Problems and or physical anatomy of their abdominal and bladder
  • Kidney failure
  • Hospital- acquired infections

Females have a much higher risk of kidney infections compared to males because:

• Female have a shorter urethra, which allows bacteria to reach and infect the bladder far more easily.
• Opening to the urethra in females is significantly closer to the rectum, where Urinary tract infection – causing bacteria are known to settle and grow.
• Males have prostate fluids and semen which is believe to help against infections.

Recurrent urinary tract infections (rUTI):

• Recurrent urinary tract infections (rUTI) as ≥ 2 culture-proven symptomatic UTIs in 6 months or ≥ 3 in 12 months, and recommends confirming prior episodes with documented positive urine cultures before giving antibiotics or prevention treatments.

Regular urine infections can lead to the following risk factors:

• Outflow obstruction to benign prostate hyperplasia (prostate gland is enlarged and not cancerous)
• Urethral strictures (scarring that narrows the tube that carries urine out of the body, called the urethra leading to les urine output)
• Lack of nerve control on the bladder (leading to poor urine outflow and urinary retention)
• Oestrogen depletion
• Urine and/or faecal incontinence (going to the toilet more often than usual)
• Urine catheterization (need of a catheter)

Urinary tract infection – children. National Institute for Health and Care Excellence . 2024. https://cks.nice.org.uk/topics/urinary-tract-infection-children

Recurrent UTIs in children

Recurrent UTIs in children can occur even after proper treatment and may indicate an underlying anatomical or functional abnormality, with a diagnosis made if any of the following scenarios occur:

• Two or more episodes of UTI with acute pyelonephritis or upper UTI;
• One episode of acute pyelonephritis or upper UTI, plus one or more episodes of cystitis or lower UTI;
• Three or more episodes of cystitis or lower UTI.

• Identifying recurrent UTIs is crucial, as they are associated with an increased risk of renal scarring, high blood pressure (hypertension) and chronic kidney failure, particularly in younger children.

Recurrent urinary tract infections (UTIs). Nemours KidsHealth. 2021. https://kidshealth.org/en/parents/recurrent-uti-infections.html

Kaufman J, Temple-Smith M, Sanci L. Urinary tract infections in children: an overview of diagnosis and management. bmjpo. 2019;3(1):e000487. doi:10.1136/bmjpo-2019-000487

• These cases often warrant specialist advice.
• Prophylactic antibiotics may be considered after optimising behavioural and hygiene measures.

Urinary tract infection – children: Management of recurrent UTI in children. National Institute for Health and Care Excellence . https://cks.nice.org.uk/topics/urinary-tract-infection-children/management/recurrent-uti-in-children/

Diagnosis Test

Children

• All children with a suspected UTI should be assessed for risk of serious infection.
• Those identified as high-risk, such as children who are systemically unwell, showing signs of sepsis or with concerning clinical features, should be referred urgently to an appropriate specialist.
• In the community or primary care setting, this usually means referral to the on-call paediatric team at the nearest hospital or to emergency services if the situation dictates.
• This team can consist of nurses and paediatric doctors, to infectious diseases consultants.
• Antibiotic treatment should be started without delay, even if a urine sample has not yet been obtained.

A urine sample should be sent for microscopy and culture in the following circumstances:

• Children with fever ≥38°C without a clear source;
• Suspected pyelonephritis;
• If they remain unwell after 24 hours despite having another identified or suspected source of infection (e.g. respiratory tract infection, otitis media, skin infection).

• In children aged under three months, urgent referral to a specialist is needed for the initiation of parenteral antibiotics and a urine sample should always be sent.
• In children aged over three months, a dipstick test should be performed and management should be based on the results.

The Pharmaceutical Journal, PJ, September 2025, Vol 315, No 8001;315(8001)::DOI:10.1211/PJ.2025.1.375188

Others:

• Urine tests
  • White blood cells (pyuria)
  • Leukocyte esterase
  • Nitrites (often indicate certain bacteria)
  • Blood in urine (haematuria)
  • Bacteria
• Urine culture
• Blood tests
  • Complete blood count
  • CRP and/or ESR
  • Blood culture- to detect bacteria
• Kidney function tests
  • Creatinine and eGFR
• Imaging tests i.e. Kidney stones
• Kidney ultrasound
• CT scan of pelvis
• Tests for structure of kidney
• Tests for urinary reflux