Emery Haley, PhD, Scientific Writing Specialist
Pseudomonas aeruginosa
Clinical Summary
- P. aeruginosa is recognized as a classical, urease-variable, gram-negative, biofilm-forming, motile uropathogen.
- P. aeruginosa is associated with complicated, persistent, and recurrent UTI (the same population for which the Guidance UTI assay is indicated).
- In symptomatic UTI patients, P. aeruginosa:
- Is not a contaminant (is found in catheter-collected urine specimens).
- Is viable (can grow out on culture).
- Is pathogenic (associated with elevated urine biomarkers of infection).
- Reported severe complications of P. aeruginosa UTI include pyelonephritis, bacteremia, infective endocarditis, urosepsis, and death.
- Multidrug-resistant P. aeruginosa is an “ESKAPE” pathogen and a well-studied significant global health threat.
Bacterial Characteristics
Gram-stain
Gram-negative
Morphology
Bacillus
Growth Requirements
Non-fastidious (grows well in standard urine culture conditions)
Obligate anaerobe
Nitrate Reduction
Yes
Urease
Variable
Biofilm Formation
Yes
Pathogenicity
Pathobiont or Pathogen
Clinical Relevance in UTI
P. aeruginosa is a gram-negative, urease-variable,[1] motile bacillus with potent biofilm-forming capabilities. It is a classically recognized as a common uropathogen, particularly well-known for its association with catheter-associated UTIs (CAUTIs) and hospital-acquired UTIs (HAUTIs). This organism’s tendency to form biofilms on urinary catheters and to travel up the urinary tract toward the kidney, as well as its intrinsic and acquired resistance to several classes of antibiotics makes this uropathogen particularly challenging to treat.[2] Indeed, P. aeruginosa is one of the six so-called “ESKAPE pathogens” identified as critical multidrug-resistant bacteria requiring urgent development of effective therapeutics.[3]
P. aeruginosa and Enterococcus species have been found to act synergistically in polymicrobial infections, increasing the formation of biofilms, causing increased kidney histopathology, and resulting in higher antibiotic resistance.[4] In contrast, P. aeruginosa exhibits antagonism with other gram-negative uropathogens, including P. mirabilis and E. coli.[4]
Thanks to its ability to form both biofilms and intracellular reservoirs in epithelial cells of the urinary tract, P. aeruginosa is associated with persistent and recurrent UTIs.[5,6] P. aeruginosa is also commonly associated with complicated UTIs in older adults, immunocompromised individuals, and individuals with urinary tract abnormalities. For example, P. aeruginosa is reported to be the most frequent cause of pyelonephritis in children with vesicoureteral reflux (VUR).[7] In a study of older adult males and females with clinically suspected complicated UTI, P. aeruginosa was detected in both midstream voided and in-and-out-catheter collected specimens indicating that it was truly present in the bladder, not simply a contaminant picked up during voiding.[8] Furthermore, elevated markers of immune system activation in the urinary tract have been measured from the same clinical urine specimens in which P. aeruginosa was detected, indicating that the presence of P. aeruginosa was associated with an immune response to urinary tract infection.[9–11]
Reported severe complications of P. aeruginosa UTI include pyelonephritis, bacteremia, infective endocarditis, urosepsis, and death.[12–14]
Together, these findings indicate that P. aeruginosa should be seriously considered as a uropathogen and demonstrate the value of detecting this organism, particularly in individuals with indwelling catheters or other risk factors for complicated UTI.
Treatment
Evidence of Efficacy (Checkmarks): Cefepime, Ceftazidime, Ciprofloxacin, Levofloxacin, Meropenem, and Piperacillin/Tazobactam.