Is Levofloxacin or Moxifloxacin a better empirical choice for prostatitis caused by Enterococcus Faecalis resistant to Enrofloxacin?

Levofloxacin is the Better Empirical Choice for Enterococcus Faecalis Prostatitis

For prostatitis caused by Enterococcus faecalis with resistance to enrofloxacin but sensitivity to pradofloxacin, levofloxacin is the better empirical choice compared to moxifloxacin due to its superior prostatic penetration and established efficacy against enterococcal prostatitis. 1, 2

Rationale for Choosing Levofloxacin

• Levofloxacin has excellent prostatic penetration with a penetration ratio of 2.96-4.14 (prostate:plasma concentration), ensuring adequate drug levels at the site of infection 3
• Studies specifically examining E. faecalis strains from prostatic secretions show lower resistance rates to levofloxacin (4.8%) compared to other fluoroquinolones like norfloxacin (26.8%) 4
• Levofloxacin 500 mg once daily for 28 days has demonstrated clinical efficacy in chronic bacterial prostatitis, including cases caused by E. faecalis 5
• Levofloxacin is specifically recommended as the first-choice fluoroquinolone for bacterial prostatitis due to better prostatic penetration compared to ciprofloxacin while maintaining similar efficacy 1

Fluoroquinolone Selection for Enterococcal Infections

• When selecting a fluoroquinolone for enterococcal infections, cross-resistance between different fluoroquinolones should be considered, but individual susceptibility patterns may vary 6
• Resistance to enrofloxacin does not necessarily indicate resistance to all fluoroquinolones, particularly newer generations like levofloxacin and pradofloxacin 4
• The MIC of 2.0 for marbofloxacin suggests moderate susceptibility, while sensitivity to pradofloxacin indicates that some fluoroquinolones remain effective against this strain 4

Treatment Duration and Dosing

• For chronic bacterial prostatitis, levofloxacin should be administered at 500 mg once daily for 28 days 5
• The once-daily dosing of levofloxacin (compared to twice-daily for moxifloxacin) may improve patient adherence during the extended treatment course required for prostatitis 2
• For severe cases or complicated infections, consider initial parenteral therapy with levofloxacin 750 mg daily 6

Why Not Moxifloxacin?

• While moxifloxacin has broad-spectrum activity, there is less clinical evidence specifically supporting its use in enterococcal prostatitis compared to levofloxacin 1, 2
• Moxifloxacin has not been as extensively studied for prostatic penetration as levofloxacin has 3
• Levofloxacin has been directly compared to ciprofloxacin in randomized controlled trials for bacterial prostatitis, showing equivalent efficacy with more convenient dosing 5

Alternative Options if Fluoroquinolones Fail

• If treatment fails or resistance develops, consider ampicillin (the drug of choice for enterococcal infections) possibly combined with an aminoglycoside for synergistic effect 6, 7
• Fosfomycin has in vitro activity against E. faecalis and is FDA-approved for UTIs caused by this organism, though its prostatic penetration is less established 6, 7
• For multidrug-resistant enterococci, linezolid or high-dose daptomycin may be considered, though these should be reserved for documented resistant cases 6

Clinical Pearls and Pitfalls

• Always obtain cultures and susceptibility testing before initiating therapy when possible, as enterococci have variable resistance patterns 6, 4
• Cephalosporins (including cefuroxime) should not be used for enterococcal infections as enterococci have intrinsic resistance to this class 7
• Consider the possibility of a complicated infection with anatomic abnormalities or foreign bodies that may require additional interventions beyond antimicrobial therapy 6
• Monitor for treatment failure and be prepared to adjust therapy based on clinical response and culture results 1