Emery Haley, PhD, Scientific Writing Specialist
Escherichia coli
Clinical Summary
- E. coli is a gram-negative, biofilm-forming, motile bacillus classically recognized as the primary uropathogen causing UTIs.
- E. coli is associated with all types of UTIs, from acute uncomplicated cystitis to complicated, catheter-associated, and hospital-acquired UTIs with life-threatening complications, in adults and children.
- In symptomatic UTI patients, E. coli:
- 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 E. coli UTI include pyelonephritis, bacteremia, infective endocarditis, urosepsis, and death.
- Multidrug-resistant E. coli is a significant and global health threat.
Bacterial Characteristics
Gram-stain
Gram-negative
Morphology
Bacillus
Growth Requirements
Non-fastidious (grows well in standard urine culture conditions)
Facultative anaerobe
Nitrate Reduction
Yes
Urease
Negative
Biofilm Formation
Yes
Pathogenicity
Colonizer or Pathobiont
Clinical Relevance in UTI
E. coli is a gram-negative, biofilm-forming, motile bacillus classically recognized as the primary uropathogen responsible for most UTIs. E. coli is associated with all types of UTIs, from acute uncomplicated cystitis to complicated, catheter-associated, and hospital-acquired UTIs with life-threatening complications, in adults and children.[1,2]
In preclinical models of UTI, E. coli has been shown to form biofilms, subpopulations of dormant persister cells,[3] and intracellular bacterial reservoirs within epithelial cells of the urinary tract,[4,5] abilities presumed to underlie persistent and recurrent UTIs.[6] For example, transurethral exposure of bladder cells to G. vaginalis triggers immune activation, urothelial exfoliation, and recurrent UTI due to the emergence of uropathogenic E. coli from bladder reservoirs.[7,8] More broadly speaking, in polymicrobial UTI models, E. coli exhibits both synergistic and antagonistic interactions with other uropathogenic species, including Enterococcus species, C. albicans, K. pneumoniae, M. morganii, P. aeruginosa, P. mirabilis, P. stuartii, and S. agalactiae.[1]
In a study of older adult males and females with clinically suspected complicated UTI, E. coli 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.[9] Furthermore, elevated markers of immune system activation in the urinary tract have been measured from the same clinical urine specimens in which E. coli was detected, indicating that the presence of E. coli was associated with an immune response to urinary tract infection.[10–12]
Although not considered one of the six highest priority “ESKAPE” pathogens, The World Health Organization (WHO) has included this organism in the 2024 Bacterial Priority Pathogens List (BPPL).[13] Severe reported complications of E. coli UTI include pyelonephritis, [14,15] bacteremia, infective endocarditis,[16–19] urosepsis and death [20,21]. The tendency of this organism to travel up the urinary tract toward the kidney results in a significant risk for progression to pyelonephritis and potentially bacteriuria.[15] Indeed, due to the high prevalence of E. coli UTIs, E. coli is also the number one cause of urosepsis, [20,21] which accounts for about 25% of sepsis cases overall.
Together, these findings indicate that E. coli should be seriously considered as a uropathogen and demonstrate the value of detecting this organism in any individual with symptoms of UTI.
Treatment
Evidence of Efficacy (Checkmarks): Amoxicillin/Clavulanate, Ampicillin, Ampicillin/Sulbactam, Cefaclor, Cefazolin, Cefepime, Ceftazidime, Ceftriaxone, Ciprofloxacin, Doxycycline, Fosfomycin, Gentamicin, Levofloxacin, Meropenem, Nitrofurantoin, Piperacillin/Tazobactam, Sulfamethoxazole/Trimethoprim, and Trimethoprim.