Morganella Infections Treatment & Management

Updated: Oct 05, 2015
  • Author: James R Miller, MD; Chief Editor: Pranatharthi Haran Chandrasekar, MBBS, MD  more...
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Treatment

Medical Care

M morganii strains are naturally resistant to penicillin, ampicillin, ampicillin/sulbactam, oxacillin, first-generation and second-generation cephalosporins, erythromycin, tigecycline, colistin, and polymyxin B.

Most strains are naturally susceptible to piperacillin, ticarcillin, mezlocillin, third-generation and fourth-generation cephalosporins, carbapenems, aztreonam, fluoroquinolones, aminoglycosides, and chloramphenicol.

The widespread use of third-generation cephalosporins has been associated with the emergence of highly resistant M morganii, as follows:

  • Many hospital-acquired strains express derepressed chromosomal ampC beta-lactamases (Bush group 1) similar to those produced by Pseudomonas aeruginosa and Enterobacter species. [19]
  • These strains may be resistant to ceftazidime and other third-generation cephalosporins, but they are usually susceptible to cefepime, imipenem, meropenem, piperacillin, the aminoglycosides, and fluoroquinolones.
  • The beta-lactamase inhibitors (ie, clavulanic acid, sulbactam) are ineffective against these enzymes; however, the combination of piperacillin and tazobactam is more effective than piperacillin alone.
  • Rare isolates of M morganii produce extended-spectrum beta-lactamases (ESBLs). These enzymes hydrolyze drugs such as ceftazidime, cefotaxime, and aztreonam but have little effect on the cephamycins (ie, cefoxitin, cefotetan). ESBLs are inhibited by clavulanic acid.
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Surgical Care

Drain any abscesses. Aggressive surgical drainage is required for brain abscesses caused by M morganii.

Debride any surgical wounds.

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Consultations

Consultations with a microbiologist, an infection control specialist, and/or an infectious diseases specialist may be warranted.

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