Is Levaquin (levofloxacin) effective against Morganella infections?

Levofloxacin Efficacy Against Morganella morganii Infections

Levofloxacin (Levaquin) is effective against Morganella morganii infections, with studies showing 100% susceptibility of M. morganii isolates to levofloxacin. 1

Susceptibility Profile and Evidence

Morganella morganii is an opportunistic Gram-negative bacillus that can cause various infections, particularly in healthcare settings. The evidence regarding levofloxacin's efficacy against this organism is compelling:

• A multicentre study in Switzerland examining clinical isolates from intensive care and hematology/oncology patients found 100% susceptibility of Morganella morganii (16 strains) to levofloxacin 1

• Levofloxacin demonstrates a broad spectrum of activity against Gram-negative bacteria, including Morganella species, with good tissue penetration and maintenance of adequate concentrations at infection sites 2

Dosing Considerations

For optimal efficacy against Morganella infections:

• Higher doses of levofloxacin (750 mg daily) are recommended to overcome potential resistance mechanisms and improve efficacy 3, 4

• The pharmacokinetic profile of levofloxacin is compatible with once-daily administration and allows for sequential intravenous to oral therapy 5

Clinical Applications

Levofloxacin can be used for various Morganella-associated infections:

• Urinary tract infections: 750 mg once daily for 5 days or 250-500 mg once daily for 10 days, with higher doses preferred to prevent resistance development 4

• Complicated skin and skin structure infections: Sequential therapy with levofloxacin 750 mg once daily for 7-14 days 6

• Respiratory infections: When Morganella is identified as the causative pathogen, levofloxacin has demonstrated efficacy 5

Important Considerations and Precautions

1. Resistance monitoring:

   • Always check local resistance patterns before empiric therapy, as fluoroquinolone resistance rates can vary by region 4
   • Rising rates of levofloxacin resistance should be taken into account when selecting therapy 3

2. Alternative options:

   • For patients with penicillin allergy, levofloxacin represents a viable alternative 3
   • After failure of first-line treatments, levofloxacin-containing regimens may be appropriate 3

3. Special populations:

   • In immunocompromised patients, such as those with cancer, levofloxacin can be considered for infections caused by gram-negative bacteria like Morganella 4

When to Consider Alternative Therapies

• If antimicrobial susceptibility testing shows resistance to levofloxacin
• After failure of second-line therapy, treatment should be guided by antimicrobial susceptibility testing 3
• In cases of severe infections or sepsis where combination therapy might be warranted 7

Levofloxacin's excellent activity against Morganella morganii makes it an appropriate choice for treating infections caused by this organism, particularly when supported by susceptibility testing.