Emery Haley, PhD, Scientific Writing Specialist
Morganella morganii
Clinical Summary
- M. morganii is recognized as a classical, urease-positive, gram-negative, biofilm-forming, motile uropathogen.
- M. morganii is primarily associated with complicated UTIs in children and older adults with risk-factors such as immunocompromising comorbidities and urinary tract abnormalities.
- In symptomatic UTI patients, M. morganii:
- 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 M. morganii UTI include pyelonephritis, bacteremia, urosepsis, and death.
- Multidrug-resistant M. morganii is a significant 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
Positive
Biofilm Formation
Yes
Pathogenicity
Colonizer or Pathobiont
Clinical Relevance in UTI
M. morganii is a urease-positive,[1]gram-negative, biofilm-forming, motile bacillus classically recognized as a uropathogen.[2] M. morganii is associated with both community -acquired and hospital-acquired complicated UTIs,[3] primarily among older adults [4] and children[5,6] with immune-compromising comorbidities and/or urinary tract abnormalities.
In preclinical studies, M. morganii was shown to exhibit synergism with Enterococcus species for biofilm formation.[7] In contrast, the presence of M. morganii decreased the urease activity, catheter encrustation, and cytotoxicity of P. mirabilis.[7,8]
In a study of older adult males and females with clinically suspected complicated UTI, M. morganii 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 M. morganii was detected, indicating that the presence of M. morganii 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 M. morganii UTI include pyelonephritis, bacteremia, urosepsis, and death.[4,6,14]
Together, these findings indicate that M. morganii should be seriously considered as a uropathogen and demonstrate the value of detecting this organism, particularly in individuals with urinary tract abnormalities, immunocompromise, or other risk factors for complicated UTI.
Treatment
Evidence of Efficacy (Checkmarks): Ampicillin/Sulbactam, Cefepime, Ciprofloxacin, Doxycycline, Gentamicin, Levofloxacin, Meropenem, Piperacillin/Tazobactam, Sulfamethoxazole/Trimethoprim, and Trimethoprim.