Is oral ciprofloxacin (Cipro) effective for treating Enterobacter cloacae infections?

Oral Ciprofloxacin for Enterobacter cloacae Infections

Oral ciprofloxacin is effective for treating Enterobacter cloacae infections when the organism is documented as susceptible, but third-generation cephalosporins should not be used due to high resistance rates, and fourth-generation cephalosporins or carbapenems are preferred for empiric therapy in serious infections. 1

Ciprofloxacin Activity Against Enterobacter cloacae

• Ciprofloxacin demonstrates in vitro activity against Enterobacter species, including E. cloacae, and is FDA-approved for treating infections caused by this organism 2, 3
• The drug achieves therapeutic concentrations in most tissues and body fluids, making it suitable for various infection sites 4
• Oral ciprofloxacin dosing for systemic infections: 20-40 mg/kg per day divided every 12 hours in children (maximum 750 mg per dose), or standard adult dosing of 500-750 mg every 12 hours 1

Critical Resistance Considerations

• First and second-generation cephalosporins are generally not effective against Enterobacter infections 1
• Third-generation cephalosporins are not recommended due to increased likelihood of resistance, particularly for E. cloacae 1
• Oral isolates of E. cloacae from Hong Kong populations showed 88% resistance to cephalothin, but most strains remained sensitive to ciprofloxacin 5
• Resistance rates to ciprofloxacin in oral E. cloacae isolates are generally lower than in isolates from urine, skin, and soft tissues 5

When to Use Ciprofloxacin

For documented susceptible E. cloacae infections:

• Urinary tract infections where oral therapy is appropriate 1, 2
• Skin and skin structure infections 3
• Bone and joint infections 3
• Sequential therapy after initial intravenous treatment for serious infections 6

Clinical efficacy data:

• Overall clinical response rate of 93% in serious infections treated with IV ciprofloxacin (with or without oral follow-up) 6
• Bacteriologic response rate of 84% against Enterobacteriaceae 6
• Organisms typically eradicated from cultures within 1 day of starting therapy 7

Preferred Alternatives for Empiric Therapy

For serious infections or when susceptibility is unknown:

• Fourth-generation cephalosporins (e.g., cefepime) if Extended-Spectrum beta-lactamase (ESBL) is absent 1
• Carbapenems (meropenem or imipenem) represent valid therapeutic options for multidrug-resistant Enterobacter infections 1
• For carbapenem-resistant Enterobacter: polymyxins, tigecycline, fosfomycin, or double carbapenem regimens 1

Common Pitfalls to Avoid

• Never use third-generation cephalosporins empirically for suspected E. cloacae infections due to high resistance rates and risk of treatment failure 1
• Always obtain culture and susceptibility testing before initiating therapy, as resistance patterns vary significantly by institution 2, 3
• Do not assume susceptibility based on in vitro activity alone—confirm with actual susceptibility testing for the specific isolate 2
• For intra-abdominal infections involving E. cloacae, combine ciprofloxacin with metronidazole for anaerobic coverage 3
• Monitor for emergence of resistance during treatment, particularly in Pseudomonas co-infections, though this is less common with Enterobacter species 7

Sequential IV-to-Oral Therapy

• Ciprofloxacin is one of the few broad-spectrum antibacterials available in both IV and oral formulations 4
• Sequential IV-to-oral therapy offers potential cost savings and may allow early hospital discharge in appropriately selected patients 4
• Mean duration of IV therapy in clinical trials was 9 days, followed by oral therapy at 500-750 mg every 12 hours 6