Member of the enterobacteriaciae (obsolete: Proteus morganii), it is also a member of the Proteus-Providencia group and a gram-negative inhabitant of the GI-tract. Implicated as a causative agent of diarrhea (summer diarrhea). Can cause severe infections in immunosuppressed and COPD patients. Recently, M morganii was reported as the causal agent in a case of fatal neonatal sepsis. M. morganii is a common gram-negative nosocomial agent in wounds and bacteremia (article).
Biochemical
- Indole +
- oxidase -
- H2S -
- urease +
- ornithine decaboxylase +
- motility: variable
M. morganii subspecies sibonii is indole-variable and may only be distinguished by the ability to ferment trehalose.
Susceptibility
Like the indole-positive members of the Proteus genus, Morganella morganii has a chromosomally encoded class C betalactamase: AmpC, which is a cephalosporinase conferring resistance to penicillins and the early cephalosporins. The majority of chromosomal Amp C betalactamases is inducible by betalactamantibiotics. Imipenem, ampicillin and cefoxitin belonging to the strongest inducers. Stably derepressed mutants have decreased susceptibility to most betalactams except cefoxitin and imipenem (article).
Other relevant mechanisms of resistance include resistance conferred by extended spectrum betalactamases or ESBLs (article).
Antibiogram of a clinical isolate of M. morganii:
Detail of AmpC induction:
Therapy
Morganella susceptibility follows general patterns of enterobacteriaciae. Eucast breakpoints (excel) remarks that Morganella is a poor target for imipenem and tigecycline has limited activity against Morganella.
Yes, I will help to keep The Retroscope add-free! donate.
Related posts:
Loading ...