From the Guidelines
Metronidazole and ciprofloxacin (Cipro) are typically used together to treat intra-abdominal infections, particularly complicated intra-abdominal infections such as peritonitis, diverticulitis, appendicitis with perforation, or abdominal abscesses. This combination is effective because it provides broad-spectrum coverage against both aerobic and anaerobic bacteria commonly found in the gastrointestinal tract. Ciprofloxacin targets gram-negative aerobic bacteria like E. coli and Pseudomonas, while metronidazole is effective against anaerobic bacteria such as Bacteroides fragilis 1.
The use of metronidazole and ciprofloxacin together is recommended for patients with high-severity community-acquired intra-abdominal infection, as defined by APACHE II scores ≥15 or other variables listed in Table 1 (Table 2) 1. However, quinolone-resistant E. coli have become common in some communities, and quinolones should not be used unless hospital surveys indicate ≥90% susceptibility of E. coli to quinolones 1.
Some key points to consider when using this combination include:
- The typical dosing regimen for adults with normal renal function would be ciprofloxacin 500-750 mg orally twice daily or 400 mg IV every 12 hours, along with metronidazole 500 mg orally or IV every 8 hours.
- Treatment duration generally ranges from 5-14 days depending on infection severity and clinical response.
- This combination may also be used for mixed aerobic-anaerobic infections in other sites, such as diabetic foot infections, pelvic inflammatory disease, or certain skin and soft tissue infections.
- Patients should be monitored for side effects including gastrointestinal disturbances, metallic taste (from metronidazole), and potential QT interval prolongation (from ciprofloxacin) 1.
It's worth noting that the empiric use of antimicrobial regimens with broad-spectrum activity against gram-negative organisms, including meropenem, imipenem-cilastatin, doripenem, piperacillin-tazobactam, ciprofloxacin or levofloxacin in combination with metronidazole, or ceftazidime or cefepime in combination with metronidazole, is recommended for patients with high-severity community-acquired intra-abdominal infection 1. However, the combination of metronidazole and ciprofloxacin is a viable option for the treatment of intra-abdominal infections, particularly complicated intra-abdominal infections.
From the FDA Drug Label
Complicated Intra-Abdominal Infections (used in conjunction with metronidazole) caused by Escherichia coli, Pseudomonas aeruginosa, Proteus mirabilis, Klebsiella pneumoniae, or Bacteroides fragilis The type of infection for which you would use metronidazole and ciprofloxacin (Cipro) together is Complicated Intra-Abdominal Infections.
- This includes infections caused by:
- Aerobic bacteria such as Escherichia coli, Pseudomonas aeruginosa, Proteus mirabilis, and Klebsiella pneumoniae
- Anaerobic bacteria such as Bacteroides fragilis 2
From the Research
Infection Type for Metronidazole and Ciprofloxacin Combination
The combination of metronidazole and ciprofloxacin is used to treat complicated intra-abdominal infections, as evidenced by several studies 3, 4, 5.
Key Findings
- A randomized, double-blind trial compared the efficacy of sequential IV-to-oral ciprofloxacin plus metronidazole with ceftriaxone plus metronidazole in adult patients with complicated intra-abdominal infections, and found that the two regimens were statistically equivalent 3.
- Another study compared intravenous/oral ciprofloxacin plus metronidazole with intravenous piperacillin/tazobactam in adults with complicated intra-abdominal infections, and found that the ciprofloxacin plus metronidazole regimen was clinically more effective 4.
- The combination of ciprofloxacin plus metronidazole was also found to be at least as effective as imipenem/cilastatin and clinically more effective than piperacillin/tazobactam therapy in patients with intra-abdominal infections 5.
Benefits of Combination Therapy
- The use of metronidazole and ciprofloxacin together provides broad-spectrum coverage against both aerobic and anaerobic organisms, making it an effective treatment option for complicated intra-abdominal infections 6, 7.
- The combination regimen also offers potential advantages over exclusively IV regimens, including the option of sequential IV/oral therapy, patient convenience, cost savings, and reduced hospital stay 5.