Kidney Infection Treatment and Medications

Urinary tract infections are an all-too-common experience and usually resolve after a few days of antibiotics. Sometimes, however, the bacteria infecting the bladder can work their way up to the kidneys and provoke a much more urgent and hazardous infection. Fortunately, kidney infections can be rapidly resolved with the right antibiotics, but early diagnosis and treatment are crucial.

What is a kidney infection?

Kidney infection, or pyelonephritis, is a bacterial infection of the kidneys that constitutes a medically urgent condition requiring immediate antibiotic treatment. Untreated kidney infection runs the risk of an abscess, kidney damage, loss of kidney function, blood poisoning (sepsis), and, in a worst-case scenario, kidney failure.

Kidney infections are a commonly experienced type of kidney disease, accounting for over 250,000 cases per year. They are typically caused by an active urinary tract infection (UTI) that begins in the bladder, called cystitis. Because women are at a higher risk for cystitis, they are also at a higher risk for kidney infection. Approximately 15-17 out of every 10,000 women are diagnosed with kidney infection annually, compared to 3-4 out of every 10,000 men. Other risk factors include urinary system blockage, a compromised immune system, urinary catheters, or vesicoureteral reflux, a condition in which urine flows up from the bladder back into the kidneys.

Most kidney infections are the result of urinary tract infections caused by a bacteria called Escherichia coli, or E. coli, which normally lives in the colon. Bacteria that find their way into the bladder and go untreated can travel up the ureters, the tubes that connect the kidneys to the bladder, and spread to the kidneys and their collecting systems.

In some cases, however, the infection can be caused by a stone blocking urine flow, or in very rare cases, a pathogen may infect the kidneys directly from the bloodstream.

Healthcare professionals distinguish between uncomplicated and complicated kidney infections. Uncomplicated kidney infection occurs in women with a healthy immune system and functioning kidneys and generally occurs in the childbearing age range of 15-45 years of age. Complicated kidney infection occurs in people with compromised immune systems, kidney damage, chronic kidney disease, transplanted kidneys, kidney stones, kidneys with structural abnormalities, or diabetes. A kidney infection that occurs in men automatically defaults to the complicated category. Infancy, advanced age, pregnancy, and kidney infections that do not improve with antibiotics also count as complications. Complicated kidney infection is a more hazardous condition and can sometimes require hospitalization.

Both uncomplicated and complicated kidney infections are urgent medical conditions. Early diagnosis and treatment are critical to preserving the kidneys' full, healthy functioning.

How is a kidney infection diagnosed?

A kidney infection diagnosis is based on physical symptoms and urine testing. Most typically, a general practitioner, urgent care physician, or emergency room physician will make the diagnosis.

Kidney infection is a type of urinary tract infection, so symptoms will typically include symptoms of a bladder infection (cystitis), such as pain over the pubic area, frequent urination, and cloudy urine. The healthcare professional will look for specific symptoms of a kidney infection in addition to the UTI symptoms:

• Pain in the side (flank pain) or lower back pain

• Costovertebral angle tenderness, which is pain caused by tapping the back above the kidney

• Fever

• Chills

• Nausea

Fever, flank pain, and nausea are the strongest indicators of kidney infection.

The diagnosis is confirmed with a urinalysis and a urine culture. The urine test confirms the diagnosis by identifying white blood cells and other substances indicating infection. The urine culture is used to identify the type of bacteria responsible for the infection and determine its resistance to antibiotics. Both are critical in determining the most effective antibiotic therapy.

Blood tests are not usually ordered for patients with an uncomplicated kidney infection, but blood will be tested for hospitalized patients.

Imaging tests are not required for uncomplicated kidney infections. If complications occur, however, a physician may order a CT scan of the abdomen and pelvis to assess the structural health of the kidneys. A contrast dye might be taken orally or injected directly into the bloodstream to make kidney structures show up better in the scan.

Kidney infection treatment options

Kidney infections are treated with antibiotics, pain relievers, and fever reducers. A general practitioner can treat uncomplicated kidney infections and a few complicated kidney infections on an outpatient basis, but people with complicated kidney infections likely require hospitalization and intravenous antibiotics. Pregnant women may require additional consultation with an obstetrician or gynecologist.

Outpatient treatment

Patients with an uncomplicated kidney infection can be treated on an outpatient basis with a one- to two-week course of oral antibiotics. The doctor will prescribe an antibiotic specific to the type of bacteria found in the urine culture. In some cases, the doctor will start treatment with a single, antibiotic injection. A follow-up visit will be scheduled one or two days after starting antibiotic treatment. By that time, most symptoms will markedly fade. If symptoms do not improve in that time, the physician will order more tests and possibly admit the patient to a hospital.

Hospitalization

Patients with complicated kidney infections or patients who are not improving on oral antibiotics are often admitted to a hospital. They are treated daily with intravenous infusions of antibiotics and regularly monitored by healthcare professionals. When the infection is under control, patients are sent home to complete their regimen on an oral antibiotic.

Surgery

In some cases, the kidney infection may be complicated by kidney stones, structural problems with the kidneys, or an enlarged prostate in men. These conditions may need to be treated with surgery or other procedures, such as shockwave therapy, to remove the complication. Severe kidney infections with abscesses or tissue death may require surgical incision and drainage, scraping away dead tissue, or the total removal of the kidney (nephrectomy).

Kidney infection medications

Medical treatment for kidney infection involves antibiotics, pain relievers (analgesics), and fever-reducing medications (antipyretics). The physician tailors the antibiotics based on the bacteria cultured from the urine sample and its drug resistance. Acetaminophen is used to provide both fever and pain relief.

Antibiotics

Antibiotics are the treatment of choice for kidney infections. First-line therapy will usually involve a five to seven-day course of an oral fluoroquinolone (ciprofloxacin or levofloxacin) or two weeks of trimethoprim-sulfamethoxazole (TMP-SMX).

Depending on the symptoms, treatment may start with an initial injection of an antibiotic. For patients admitted to a hospital, patients will usually be started on intravenous antibiotics such as ciprofloxacin, levofloxacin, ceftriaxone, imipenem-cilastatin, or piperacillin-tazobactam.

Depending on the isolated bacteria and its drug resistance profile, the antibiotic will ideally be streamlined to an oral option for outpatient completion with another week or more of therapy. Sometimes, an oral antibiotic is not possible, but patients may receive intravenous antibiotics outside of the hospital.

Pain killers

NSAIDs, such as aspirin or ibuprofen, may risk kidney damage or kidney failure in patients with kidney problems, so healthcare professionals discourage their use in patients with a kidney infection. Instead, both pain relief and fever reduction can be managed with prescription or over-the-counter acetaminophen.

What is the best medication for a kidney infection?

Kidney infections are treated with antibiotics. The “best” antibiotic will be the one most suitable for the bacteria causing the condition, its resistance to specific antibiotics, and taking into account any patient allergies.

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Best medications for a kidney infection