Kidney infections, also known as pyelonephritis, are a common type of urinary tract infection (UTI). They occur when bacteria travel up the ureters to infect one or both kidneys. Kidney infections often develop as a complication of an untreated lower UTI, such as a bladder infection (cystitis).
Do kidney infections show up in urine tests?
Yes, kidney infections will usually show up in a urine test. When bacteria infect the kidneys, they can spill over into the urine and be detected through urinalysis and urine culture tests. Some of the signs that point to a kidney infection on a urine test include:
- Positive leukocyte esterase – This indicates white blood cells in the urine, signaling inflammation
- Nitrites – Bacteria can convert nitrates in urine to nitrites, so their presence indicates bacteria
- Protein – Kidney infections can cause protein to leak into the urine
- Bacteria – A urine culture can identify the actual bacteria causing an infection and help select an antibiotic for treatment
- Blood – Kidney infections may cause blood in the urine from inflammation
However, it’s important to note that a perfectly normal urinalysis does not definitively rule out a kidney infection. Some cases may not show abnormalities, especially in the very early stages. Doctors will also consider symptoms and usually order imaging tests to check for kidney infection if it is suspected clinically.
What are the symptoms of a kidney infection?
Common signs and symptoms of kidney infection include:
- Fever and chills
- Pain in the back, side, or groin
- Abdominal pain
- Frequent and painful urination
- Urgency to urinate despite an inability to pass much urine
- Pus or blood in the urine
- Nausea and vomiting
- Fatigue and illness feeling
Symptoms may come on rapidly and severely if the kidney infection arises suddenly. They tend to come on more gradually if the infection moves up from an untreated lower urinary tract infection like cystitis. Some people with a kidney infection have few or minimal symptoms.
What tests are used to diagnose a kidney infection?
Doctors use a few different tests to diagnose a kidney infection. These include:
- Urinalysis – Checks for signs of infection in a urine sample like leukocytes, bacteria, nitrites, blood, and protein.
- Urine culture – Involves growing any bacteria from a urine sample in a lab to identify the type of bacteria causing infection.
- Blood tests – May reveal increased white blood cell count from infection. They also assess kidney function.
- Medical imaging – CT scan or ultrasound of the kidneys can check for abscesses, swelling, and structural abnormalities indicating infection.
A combination of urinalysis, urine culture, and medical imaging provides the most definitive diagnosis. The blood tests also give additional information about the severity of infection and any impact on the kidneys.
Can untreated kidney infections cause permanent damage?
Yes, untreated kidney infections can permanently damage the kidneys and lead to serious complications. Bacteria from an infection can destroy delicate kidney tissues. Some potential consequences include:
- Sepsis – Bacteria from kidney infection entering the bloodstream can lead to dangerous sepsis.
- Kidney scarring – Permanent scarring impairs kidney function and raises long-term risks.
- Chronic kidney disease – Kidney function may progressively deteriorate after damage from an untreated infection.
- High blood pressure – Kidney scarring can disrupt the organ’s role in regulating blood pressure.
- Pregnancy complications – Kidney infections during pregnancy increase risks to mother and baby.
That’s why prompt antibiotic treatment for kidney infections is crucial to avoid permanent damage. Even a single kidney infection can start a progressive decline in normal kidney function over months or years.
What antibiotics are used to treat kidney infections?
Doctors typically prescribe oral antibiotics to treat simple kidney infections. A urine culture identifies the bacteria causing the infection so doctors can select an antibiotic that targets that specific germ. Common antibiotic choices may include:
- Ciprofloxacin
- Levofloxacin
- Nitrofurantoin
- Cephalexin
- Amoxicillin-clavulanate
For severe kidney infections, doctors often administer intravenous antibiotics, such as gentamicin, ceftriaxone, cefepime, or ampicillin, in the hospital. IV antibiotics work faster than oral therapy. Patients stay in the hospital 2-3 days on average to monitor the response to IV antibiotics before transitioning to oral antibiotic therapy.
How long does it take for a kidney infection to clear with antibiotics?
With prompt appropriate antibiotic treatment, most kidney infections will clear within 1-2 weeks. People generally start to improve within a few days of starting an antibiotic. However, it can then take 7-14 days for all symptoms to fully resolve after completing the antibiotic course.
It is essential to finish the entire antibiotic prescription, even if feeling better. This helps ensure the bacteria are fully eradicated and the kidney infection does not recur or spread. Within 1-2 weeks after finishing treatment, doctors will recheck a urine test to confirm the infection has resolved.
Can kidney infections recur after antibiotic treatment?
Yes, it is possible for kidney infections to recur in some cases after antibiotic treatment. Recurrence may happen if:
- The initial antibiotic dose or duration was insufficient to fully treat the infection.
- Bacteria remain within kidney tissues or stones after treatment.
- An anatomical abnormality exists in the urinary tract that predisposes to repeat infections, like an obstruction or urine reflux.
- The infection stems from a source outside the urinary tract, like the bloodstream.
To reduce the risk of recurrent kidney infections, doctors consider extended antibiotic courses, urinary tract imaging, and potential surgical interventions. For frequent recurrences, doctors may prescribe suppressive low-dose antibiotics.
How can you prevent a kidney infection from recurring?
Some methods to help prevent repeat kidney infections include:
- Drinking plenty of fluids to maintain hydration and frequent urination.
- Urinating shortly after intercourse to flush out bacteria.
- Taking showers rather than baths, which can expose the urethra to more bacteria.
- Wiping front-to-back after using the toilet.
- Taking daily preventive antibiotics if recommended by your doctor.
- Promptly treating any UTIs or other suspected infections.
- Having any urinary tract obstructions or reflux issues corrected through procedures.
Making lifestyle changes to promote urinary tract health provides the best protection against repeat infections. Seeking care quickly at the first suspicion of another infection is also key.
Can kidney infections be fatal?
Kidney infections can potentially become life-threatening, but fatal outcomes are relatively rare with prompt modern medical care. However, kidney infections can turn fatal if:
- Sepsis develops and goes untreated – Bacteria entering the blood from the kidneys can lead to catastrophic sepsis, especially in vulnerable groups like the elderly or immunocompromised.
- The infection spreads to other organs outside the urinary tract.
- Vital kidney functions are lost – Both kidneys may shut down after extensive damage, causing sudden kidney failure.
- Toxins build up and become imbalanced after kidney damage.
- Disease complications like pneumonia, meningitis, or endocarditis arise.
So although death is not common today, untreated or progressive kidney infections still have the potential to become life-endangering. Seeking care quickly at the first signs of kidney infection remains vital.
Conclusion
In summary, kidney infections will typically show up on standard urine tests like urinalysis and urine cultures. However, normal urine findings cannot definitively exclude a kidney infection, so doctors also rely on medical imaging and clinical evaluation. Prompt and proper antibiotic treatment can usually clear up a kidney infection and prevent the potentially serious complications of permanent kidney damage, recurrent infections, and rarely, fatal outcomes. Paying attention to any suggestive symptoms and seeking prompt medical care remains key to treating kidney infections before they can do long-term harm.