Complicated UTI

Complicated urinary tract infection (cUTI) is a syndrome that is diagnosed by the presence of a microbial pathogen in the urine or blood, as well as pyuria. These pathogens are often gram-negative bacteria (such as the non-fermenting gram-negative bacteria we have been looking at during this course).

The inclusion criteria for cUTI are as follows:

• All patients with cUTI must have evidence of pyuria (the presence of more than 10 white blood cells per ml³ or a positive dipstick analysis for leukocyte esterase)
• Patients must have at least 2 of the following symptoms:
  • Fever (body temperature ≥38°C)
  • Nausea or vomiting
  • Dysuria or urinary frequency/urgency
  • Costovertebral angle tenderness on physical examination
  • Flank pain or pelvic pain
• Patients must have a history of at least one of the following:
  • Obstructive uropathy
  • Urinary retention of ≥100ml
  • Azotemia caused by intrinsic renal disease
  • Urinary retention caused by benign prostatic hypertrophy
  • An indwelling urinary catheter or recent instrumentation of the urinary tract

Once cUTI is clinically diagnosed, identification of the pathogen is vital to provide suitable and effective treatment to the patient.

These infections are very dangerous as they can lead to septic shock or sepsis. Additionally, if cUTI is caused by NFGNB, their ever-increasing antibiotic resistance makes it more difficult to treat.

Treatment of cUTI depends on the particular NFGNB species identified in the patient. Largely, Pseudomonas and Acinetobacter species are the most common NFGNB that cause cUTIs. However, other species such as Burkholderia, Stenotrophomonas and Alcaligenes have also been shown to cause cUTIs.

As previously discussed on this course, the treatment may be a single antibiotic therapy or a combination of different antibiotic therapies. However, for cUTI, the most commonly used class of antibiotics are fluoroquinolones, followed by cephalosporins, aminoglycosides, and penicillins. This is dependent on the species detected and whether resistance to particular antibiotics is known.