From the FDA Drug Label
Ciprofloxacin has been shown to be active against most strains of the following microorganisms, both in vitro and in clinical infections... Aerobic gram-positive microorganisms ... Staphylococcus saprophyticus ... Aerobic gram-negative microorganisms ... Pseudomonas aeruginosa
The following in vitro data are available, but their clinical significance is unknown ... Ciprofloxacin exhibits in vitro minimum inhibitory concentrations (MICs) of 1 μg/mL or less against most (≥ 90%) strains of the following microorganisms; however, the safety and effectiveness of ciprofloxacin in treating clinical infections due to these microorganisms have not been established in adequate and well-controlled clinical trials ... Aerobic gram-positive microorganisms ... Staphylococcus haemolyticus
Most strains of Burkholderia cepacia and some strains of Stenotrophomonas maltophilia are resistant to ciprofloxacin as are most anaerobic bacteria, including Bacteroides fragilis and Clostridium difficile.
For testing aerobic microorganisms other than Haemophilus influenzae , Haemophilus parainfluenzae, and Neisseria gonorrhoeaea: MIC (μg/mL)Interpretation ≤ 1 Susceptible (S) 2 Intermediate (I) ≥ 4 Resistant (R)
Ciprofloxacin is active against Pseudomonas aeruginosa. However, for MRSA (Methicillin-resistant Staphylococcus aureus), ciprofloxacin's effectiveness is not established as the provided drug label only mentions activity against methicillin-susceptible strains of Staphylococcus.
- Ciprofloxacin may be used for coverage of Pseudomonas.
- Doxycycline may be used for coverage of MRSA, but this information is not found in the provided ciprofloxacin drug label. The combination of ciprofloxacin and doxycycline may provide coverage for severe cellulitis with possible MRSA versus Pseudomonas, but the FDA drug label for ciprofloxacin does not directly answer the question regarding the use of this combination for this specific purpose 1.
From the Research
Ciprofloxacin and doxycycline together may not provide optimal coverage for severe cellulitis with possible MRSA versus Pseudomonas. For severe cellulitis with concern for both pathogens, a more appropriate regimen would be vancomycin (15-20 mg/kg IV every 8-12 hours) plus either piperacillin-tazobactam (4.5g IV every 6-8 hours) or cefepime (2g IV every 8 hours) 2. While ciprofloxacin offers good Pseudomonas coverage, and doxycycline has some activity against MRSA, this combination has limitations. Doxycycline's MRSA coverage is inconsistent for severe infections, and resistance to fluoroquinolones is increasing in both organisms. Additionally, the FDA has advised that fluoroquinolones should be reserved for infections lacking alternative options due to serious side effects. For severe skin infections with these specific concerns, the vancomycin plus anti-pseudomonal beta-lactam approach provides more reliable coverage of both pathogens and follows current practice guidelines for complicated skin and soft tissue infections. Some studies suggest that combination antibiotic treatment for MRSA infections may be beneficial, but the evidence is not yet conclusive 3. However, vancomycin remains an acceptable treatment option, with moves toward individualized dosing to a pharmacokinetic/pharmacodynamic (PK/PD) target 2. Once culture results are available, therapy should be narrowed to target the specific pathogen identified. It's also worth noting that other antibiotics, such as linezolid, may be effective against MRSA, but their use should be reserved for specific cases 2. In general, the choice of antibiotic regimen should be guided by the severity of the infection, the suspected pathogens, and the patient's individual characteristics. The use of amikacin sulfate has been reported to be effective in treating Pseudomonas cellulitis in certain cases, but its use is not commonly recommended for human patients 4. Overall, the most appropriate treatment regimen for severe cellulitis with possible MRSA versus Pseudomonas should be determined on a case-by-case basis, taking into account the latest evidence and guidelines.