Febrile urinary tract infection (UTI) is a serious form of UTI accompanied by fever. Unlike simple UTIs localized to the bladder, a febrile UTI indicates the infection has progressed, often involving the kidneys. This escalation requires prompt medical attention to prevent widespread health issues. Recognizing the signs of a febrile UTI is important for timely intervention.
Understanding Febrile UTI
A febrile UTI is an infection within the urinary tract accompanied by a fever. This distinguishes it from a simple UTI, which usually affects only the lower urinary tract and may not cause a fever. The presence of fever suggests a systemic response to the infection.
Symptoms can vary depending on age. In infants under one year old, signs may be non-specific, including fever, vomiting, poor feeding, lethargy, or diarrhea. Children over five years old might experience more localized symptoms such as pain in the lower back or flank area, frequent or painful urination, and a persistent urge to urinate, along with fever. Adults with a febrile UTI may also report high fever, chills, back or side pain, nausea, and vomiting, in addition to typical UTI symptoms.
The most common cause of UTIs, including febrile ones, is bacteria, particularly Escherichia coli (E. coli), which originates from the gut. These bacteria ascend from the urethra into the bladder and, in cases of febrile UTI, continue to travel up the ureters to infect the kidneys. Factors increasing susceptibility include anatomical abnormalities in the urinary tract, a history of previous UTIs, or a weakened immune system. In children, vesicoureteral reflux (VUR), where urine flows backward from the bladder to the kidneys, can increase the risk of febrile UTIs and kidney involvement.
Diagnosing Febrile UTI
Diagnosing a febrile UTI involves a clinical evaluation, including medical history review and physical examination. Healthcare providers inquire about symptoms and their duration.
Urine tests are key for diagnosis. A urinalysis checks for indicators of infection, such as white blood cells, nitrites, or blood in the urine. A urine culture then identifies the specific bacteria causing the infection and determines its susceptibility to different antibiotics. To ensure accuracy, a clean-catch urine sample or catheterization may be necessary, especially in young children, to prevent contamination.
Blood tests are also ordered to assess infection severity and check for signs of a systemic response. These can include a complete blood count (CBC) to identify an elevated white blood cell count and inflammatory markers like C-reactive protein (CRP). Blood cultures might also be performed to determine if bacteria have spread to the bloodstream.
Imaging studies are not always part of the initial diagnostic process but are used in specific situations. An ultrasound of the kidneys and bladder may be performed, particularly in young children after their first febrile UTI, to identify any structural abnormalities or significant vesicoureteral reflux (VUR). Other imaging, such as a voiding cystourethrogram (VCUG) or a DMSA scan, might be considered for recurrent infections or concerns about kidney damage.
Treatment Approaches
Antibiotics are the primary treatment for febrile UTIs. Initially, broad-spectrum antibiotics are often prescribed to cover a wide range of common bacteria. Once urine culture results become available, the antibiotic regimen may be adjusted to a more targeted medication effective against the identified bacteria.
For severe cases, in infants, young children, or those unable to tolerate oral medications, intravenous (IV) antibiotics are administered in a hospital setting. This ensures rapid delivery and absorption of the medication. Once the fever subsides and the patient’s condition improves, treatment can transition to oral antibiotics to complete the course.
The duration of antibiotic treatment for febrile UTIs ranges from 7 to 14 days, depending on age and infection severity. It is important to complete the entire course of antibiotics, even if symptoms improve, to ensure the infection is fully eradicated and to prevent recurrence.
Supportive measures are also employed to manage symptoms. Over-the-counter medications like acetaminophen or ibuprofen can help reduce fever and alleviate pain. Maintaining adequate hydration by drinking plenty of fluids is also encouraged to help flush bacteria and support recovery. Hospitalization may be necessary for very young infants, individuals with severe symptoms, those unable to keep down fluids due to vomiting, or signs of widespread infection like sepsis.
Potential Complications and When to Seek Medical Attention
If a febrile UTI is left untreated or not adequately managed, it can lead to serious health complications. One concern is permanent kidney damage, including scarring and impaired kidney function, potentially progressing to end-stage renal disease. Untreated infections also increase the likelihood of recurrent UTIs.
The most severe complication is urosepsis, a life-threatening condition where the infection spreads from the urinary tract into the bloodstream. This requires immediate medical intervention.
Prompt medical attention is important if signs of a febrile UTI are present. Consult a doctor immediately if an infant or young child shows signs of a UTI accompanied by fever. Other urgent indicators include a high fever with chills or shaking, severe pain in the back or flank area, persistent nausea or vomiting, signs of dehydration, or changes in mental status such as confusion or lethargy. These symptoms suggest a serious infection requiring prompt evaluation and treatment to prevent further complications.