What is a complicated Urinary Tract Infection (UTI)?

From the Guidelines

A complicated urinary tract infection (UTI) is an infection of the urinary system that occurs with underlying conditions that increase the risk of treatment failure or serious complications, such as structural or functional abnormalities of the urinary tract, presence of foreign bodies like catheters, immunosuppression, pregnancy, diabetes, or infection with antibiotic-resistant organisms. These conditions can lead to increased morbidity, mortality, and decreased quality of life if not properly managed. According to the most recent guidelines, the treatment of complicated UTIs should involve a combination of antibiotics, such as amoxicillin plus an aminoglycoside, a second-generation cephalosporin plus an aminoglycoside, or an intravenous third-generation cephalosporin as empirical treatment for complicated UTI with systemic symptoms 1.

Some key points to consider in the management of complicated UTIs include:

• The use of ciprofloxacin and other fluoroquinolones should be avoided for empirical treatment of complicated UTI in patients from urology departments or when patients have used fluoroquinolones in the last 6 months, unless the local resistance rate is <10% and the patient does not require hospitalization 1.
• Managing any urological abnormality and/or underlying complicating factors is crucial to prevent recurrence and improve patient outcomes 1.
• Treatment should be guided by urine culture results whenever possible, and patients should complete the full antibiotic course, increase fluid intake, and follow up to ensure resolution.
• Addressing underlying anatomical or functional abnormalities is essential to prevent recurrence, which may involve removing obstructions, managing diabetes, or replacing long-term catheters.

In terms of specific antibiotic regimens, the European Association of Urology guidelines recommend using a combination of antibiotics, such as amoxicillin plus an aminoglycoside, or a second-generation cephalosporin plus an aminoglycoside 1. For severe cases requiring hospitalization, initial intravenous antibiotics like ceftriaxone 1-2g daily, piperacillin-tazobactam 3.375g every 6 hours, or carbapenems may be necessary. It is essential to note that the treatment of complicated UTIs should be individualized based on the patient's specific underlying conditions, local resistance patterns, and urine culture results 1.

From the FDA Drug Label

Urinary Tract Infections, both complicated and uncomplicated, caused by Pseudomonas aeruginosa; Enterobacter spp.; Proteus spp., including Proteus mirabilis and indole-positive Proteus; Klebsiella spp. ; and Escherichia coli. Uncomplicated and Complicated Urinary Tract Infections (including pyelonephritis) caused by Escherichia coli or Klebsiellapneumoniae, when the infection is severe, or caused by Escherichia coli, Klebsiellapneumoniae, or Proteus mirabilis, when the infection is mild to moderate, including cases associated with concurrent bacteremia with these microorganisms Complicated Urinary Tract Infection is an infection of the urinary tract that involves the upper urinary tract (kidneys) or is associated with significant complications, such as:

• Infection caused by certain bacteria, including Pseudomonas aeruginosa, Enterobacter spp., Proteus spp., Klebsiella spp., and Escherichia coli
• Presence of underlying medical conditions, such as urinary tract abnormalities or immunocompromised state
• Severity of the infection, such as presence of systemic symptoms (e.g., fever, chills) or significant laboratory abnormalities (e.g., elevated white blood cell count) The exact definition and criteria for complicated urinary tract infection may vary depending on the specific clinical context and guidelines being followed 2, 3.

From the Research

Definition of Complicated Urinary Tract Infection

• Complicated urinary tract infection occurs in individuals with functional or structural abnormalities of the genitourinary tract 4.
• It is associated with a higher risk of recurrence or chronification, progression, or severe outcome than uncomplicated urinary tract infections 5.

Characteristics of Complicated Urinary Tract Infection

• Many urological abnormalities may be associated with complicated urinary infection 4.
• There is a wide spectrum of potential infecting organisms, and isolated bacteria tend to be more resistant to antimicrobial therapy 4.
• Morbidity and infection outcomes in subjects with complicated urinary infection are principally determined by the underlying abnormality rather than the infection 4.

Management of Complicated Urinary Tract Infection

• Principles of management include uniform collection of a urine specimen for culture before antimicrobial therapy, characterization of the underlying genitourinary abnormality, and non-treatment of asymptomatic bacteriuria except before an invasive genitourinary procedure 4.
• The antimicrobial regimen is determined by clinical presentation, patient tolerance, renal function, and known or anticipated infecting organisms 4.
• If the underlying abnormality contributing to the urinary infection cannot be corrected, then early post-treatment recurrence of infection is anticipated 4.
• The management of complicated urinary infection is individualized depending on patient variables and the infecting organism 4.

Treatment Options

• Treatment options for complicated urinary tract infections include fluoroquinolones, cephalosporins, and beta-lactams 6.
• The choice of treatment depends on the severity of the infection, the underlying abnormality, and the susceptibility of the infecting organism to antimicrobial agents 6.
• New antimicrobial agents, such as ceftazidime-avibactam and meropenem/vaborbactam, may be effective against complicated urinary tract infections caused by multidrug-resistant organisms 6.