Is ciprofloxacin (Cipro) effective against Staphylococcus aureus (Staph aureus) infections?

From the Guidelines

Ciprofloxacin is not the preferred treatment for Staphylococcus aureus infections due to increasing resistance rates, and its use should be guided by susceptibility testing 1. When considering treatment options for Staphylococcus aureus infections, it's essential to prioritize antibiotics with a higher efficacy and lower resistance rates. According to the Infectious Diseases Society of America guidelines, antibiotics such as trimethoprim-sulfamethoxazole, clindamycin, doxycycline, or vancomycin are generally preferred for S. aureus infections, especially for serious infections 1. Some key points to consider when treating Staphylococcus aureus infections include:

• Methicillin-resistant S. aureus (MRSA) is often resistant to ciprofloxacin, and resistance can develop during treatment even with initially susceptible strains 1.
• Ciprofloxacin works by inhibiting bacterial DNA gyrase and topoisomerase IV, preventing DNA replication and ultimately killing the bacteria, but the high mutation rate of S. aureus allows it to develop resistance mechanisms relatively quickly 1.
• Susceptibility testing should be performed to confirm the organism's sensitivity to the drug before using ciprofloxacin for a S. aureus infection 1.
• For susceptible strains, typical adult dosing of ciprofloxacin is 500-750 mg orally twice daily or 400 mg IV every 8-12 hours, with treatment duration ranging from 7-14 days depending on infection severity and location 1. It's crucial to weigh the benefits and risks of using ciprofloxacin for Staphylococcus aureus infections, considering the potential for resistance development and the availability of alternative antibiotics with higher efficacy 1.

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 ... 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 ... Staphylococcus haemolyticus Staphylococcus hominis ... S. aureus ATCC 29213 0.12 – 0.5

Ciprofloxacin coverage for Staph aureus is variable. While ciprofloxacin has been shown to be active against some strains of Staphylococcus species, including Staphylococcus saprophyticus, its effectiveness against Staphylococcus aureus (Staph aureus) is not well established. The MIC values for S. aureus ATCC 29213 are 0.12 – 0.5 μg/mL, which suggests that ciprofloxacin may be effective against some strains of Staph aureus, but this is not a guarantee of clinical efficacy. Therefore, ciprofloxacin should be used with caution and only when susceptibility testing indicates that the specific strain of Staph aureus is susceptible to ciprofloxacin 2 2.

From the Research

Effectiveness of Ciprofloxacin against Staphylococcus aureus

• Ciprofloxacin has been studied as a potential treatment for Staphylococcus aureus infections, including methicillin-resistant S. aureus (MRSA) 3, 4.
• One study found that ciprofloxacin was effective in treating MRSA infections, with clinical cure or improvement in 91% of patients and bacteriologic cure in 60% of patients 3.
• However, another study found that ciprofloxacin was not effective in treating severe staphylococcal infections, with clinical failure in 5 patients and bacteriological failure in 12 patients 4.
• The effectiveness of ciprofloxacin against S. aureus may be limited by the emergence of resistant strains, as seen in 6 out of 37 patients in one study 3.

Comparison to Other Treatments

• Other antibiotics, such as vancomycin, linezolid, and daptomycin, are commonly used to treat S. aureus infections, including MRSA 5, 6, 7.
• These antibiotics have been shown to be effective in treating S. aureus infections, with vancomycin being a common choice for severe MRSA infections 6, 7.
• Ciprofloxacin is not typically recommended as a first-line treatment for S. aureus infections, but may be considered in certain cases, such as when other antibiotics are not effective or cannot be used 5, 6.

Current Recommendations

• The current recommendations for treating S. aureus bacteremia include the use of antibiotics active against MRSA, such as vancomycin or daptomycin, with adjustment of antibiotics based on susceptibility results 7.
• Cefazolin or antistaphylococcal penicillins may be used for methicillin-susceptible S. aureus (MSSA), while vancomycin, daptomycin, or ceftobiprole may be used for MRSA 7.
• Source control, including removal of infected devices and drainage of abscesses, is also an important component of treating S. aureus bacteremia 7.