Morganella morganii

RANK: Species

TAXONOMY: Bacteria -> Proteobacteria -> Gammaproteobacteria -> Enterobacteriales -> Enterobacteriaceae -> Morganella -> Morganella morganii


Morganella morganii is a species of Gram-negative bacteria. It has a commensal relationship within the intestinal tracts of humans, mammals, and reptiles as normal flora. Although M. morganii has a wide distribution, it is considered an uncommon cause of community-acquired infection and it is most often encountered in postoperative and other nosocomial infections such as urinary tract infections. M. morganii can produce the enzyme catalase, so is able to convert hydrogen peroxide to water and oxygen. This is a common enzyme found in most living organisms. In addition, it is indole test-positive representing this organism can split tryptophan to indole, pyruvate, and ammonia. Although a rare human pathogen, M. morganii has been reported as a cause of urinary tract infections, nosocomial surgical wound infections, peritonitis, central nervous system infection, endophthalmitis, pneumonia, chorioamnionitis, neonatal sepsis, pyomyositis, necrotizing fasciitis, and arthritis. Numerous cases of nosocomial infection have been described, usually as postsurgical wound infections or urinary tract infections. Patients in whom bacteremia develops are typically immunocompromised, diabetic, or elderly, or have at least one serious underlying disease. M. morganii is a member of the tribe Proteeae (normal fecal flora that often causes infection in patients whose normal flora have been disturbed by antibiotic therapy) of the family Enterobacteriaceae, with two species: M. morganii and M. sibonii. M. morganii has been regarded as a harmless opportunistic pathogen, but some strains carry "antibiotic-resistant plasmids" and have been associated with nosocomial outbreaks of infections. Several reports indicate M. morganii causes sepsis, ecthyma, endophthalmitis, and chorioamnionitis, and more commonly urinary tract infections, soft tissue infections, septic arthritis, meningitis, and bacteremia, often with fatal consequences. Identified as constituent of vaginal microbiome. [PMID:23282177]

This species has been identified as a resident in the human gastrointestinal tract based on the phylogenetic framework of its small subunit ribosomal RNA gene sequences.[PMC 4262072]

Histamine producer
Gut associated
Catalase producer
Type species
Vaginal microbiome