What is the recommended treatment for a Morganella morganii (M. morganii) urinary tract infection (UTI)?

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Last updated: July 7, 2025View editorial policy

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From the Guidelines

The recommended treatment for a Morganella morganii urinary tract infection should be guided by antimicrobial susceptibility testing and typically involves fluoroquinolones or third-generation cephalosporins, with carbapenems reserved for resistant strains. When considering treatment options for M. morganii UTIs, it's crucial to note that this bacterium exhibits natural resistance to several antibiotics, including ampicillin, amoxicillin, first and second-generation cephalosporins, and tetracyclines, due to its chromosomally encoded AmpC beta-lactamase 1. Given the lack of clear recommendations for treating UTIs caused by multidrug-resistant organisms, including M. morganii, as noted in recent guidelines 1, the choice of antibiotic should be based on the organism's susceptibility profile. Key considerations include:

  • The use of fluoroquinolones such as ciprofloxacin or levofloxacin for their efficacy against M. morganii, provided susceptibility is confirmed.
  • Third-generation cephalosporins like ceftriaxone or cefotaxime as effective alternatives, especially for more severe infections.
  • Reserving carbapenems such as meropenem or imipenem for cases where resistance to other antibiotics is a concern. It is also important for patients to complete the full course of antibiotics, stay hydrated to help clear the infection, and follow up with their healthcare provider to confirm the infection has been fully treated, as suggested by general principles of UTI management 1.

From the Research

Morganella morganii UTI Contamination

  • Morganella morganii is a Gram-negative bacillus that can cause urinary tract infections (UTIs), among other types of infections 2, 3, 4, 5.
  • The recommended treatment for M. morganii UTIs is not explicitly stated in the provided studies, but the following antibiotics have been used to treat M. morganii infections:
    • Ceftazidime, imipenem, and amikacin have been shown to be effective against M. morganii 3.
    • Gentamicin is often used in combination with a third-generation cephalosporin or another antibiotic to which M. morganii is susceptible 3.
    • Carbapenems, aminoglycosides, ciprofloxacin, and colistin have also been used to treat M. morganii bacteremia 5.
  • It is essential to note that M. morganii can develop resistance to multiple antibiotics, making treatment challenging 3, 4, 5.
  • Source control measures, such as surgery, line removal, drainage, and tissue removal, may also be necessary in some cases 5.

Antibiotic Resistance and Treatment Outcomes

  • M. morganii has been shown to be resistant to various antibiotics, including first-generation cephalosporins, ampicillin-clavulanate, gentamicin, piperacillin-tazobactam, and ciprofloxacin 4.
  • The use of appropriate antibiotic therapy and source control measures can improve treatment outcomes for M. morganii infections 3, 5, 6.
  • However, the mortality rate for M. morganii bacteremia can be high, ranging from 14.7% to 41% in different studies 4, 5.

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

Clinical manifestations and prognostic factors of Morganella morganii bacteremia.

European journal of clinical microbiology & infectious diseases : official publication of the European Society of Clinical Microbiology, 2015

Research

Successful Treatment of PD Peritonitis Due to Morganella morganii Resistant to Third-Generation Cephalosporins - A Case Report.

Peritoneal dialysis international : journal of the International Society for Peritoneal Dialysis, 2017

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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