Morganella

Morganella

The genus Morganella belongs to the tribe Proteeae. The genus Morganella has only one species, Morganella morganii with twosubspecies, morganii and sibonii. M. morganii was classified ear-lier under the genus Proteus as Proteus morganii. M. morganii are small, Gram-negative, motile bacilli, but unlike Proteus species do not produce swarming on the solid media. They are faculta-tively anaerobic and nonencapsulated. They grow on blood agar or on MacConkey agar. They are oxidase negative and catalase and indole positive. M. morganii ferments glucose and mannose but not lactose. The bacteria decarboxylate ornithine, hydrolyze urease, and reduce nitrates. They do not liquefy gelatin and do not produce hydrogen sulfide. M. morganii is commonly found in human and animal feces and rarely causes severe invasive dis-eases. It is most often found as an opportunistic pathogen in patients who are hospitalized, particularly those on prolonged antibiotic therapy. M. morganii causes UTIs, which are often associated with an alkaline urine pH. The bacteria have also been occasionally reported to cause sepsis, pneumonia, wound infections, pericarditis, chorioamnionitis, endophthalmitis, empyema, spontaneous bacterial peritonitis, and CNS infec-tions. Nosocomial M. morganii strains are usually susceptible to cefepime, imipenem, meropenem, piperacillin, aminoglycosides, and fluoroquinolones. These have also shown resistance to ceftazidime and other third-generation cephalosporins. ESBL-producing strains of M. morganii have been reported recently.