Cefoxitin: Antibiotic Coverage and Indications
Cefoxitin is a second-generation cephalosporin (cephamycin) antibiotic with broad-spectrum coverage against gram-positive, gram-negative, and anaerobic bacteria, indicated for serious infections including intra-abdominal, gynecological, respiratory, skin/soft tissue, bone/joint infections, and septicemia. 1
Antimicrobial Spectrum
- Effective against gram-positive organisms including Staphylococcus aureus (including penicillinase-producing strains), Staphylococcus epidermidis, Streptococcus pneumoniae, and Streptococcus pyogenes 1
- Active against gram-negative aerobes including Escherichia coli, Klebsiella species, Proteus mirabilis, Morganella morganii, Proteus vulgaris, and Providencia species 1, 2
- Provides excellent coverage against anaerobic bacteria, particularly Bacteroides species (including B. fragilis), Clostridium species, Peptococcus niger, and Peptostreptococcus species 1, 3
- Notable gaps in coverage include Pseudomonas aeruginosa, Enterobacter species, and enterococci (e.g., Enterococcus faecalis) 1, 2
Clinical Indications
FDA-Approved Indications 1
- Lower respiratory tract infections (pneumonia, lung abscess)
- Urinary tract infections
- Intra-abdominal infections (peritonitis, intra-abdominal abscess)
- Gynecological infections (endometritis, pelvic cellulitis, pelvic inflammatory disease)
- Septicemia
- Bone and joint infections
- Skin and skin structure infections
Specific Use in Pelvic Inflammatory Disease (PID)
- Recommended as part of first-line inpatient treatment regimens for PID: cefoxitin 2g IV every 6 hours plus doxycycline 100mg orally/IV every 12 hours 4
- For outpatient PID treatment: cefoxitin 2g IM with probenecid 1g orally as a single dose, followed by doxycycline 100mg orally twice daily for 14 days 4
- Important note: Cefoxitin has no activity against Chlamydia trachomatis, requiring addition of doxycycline when treating PID 1
Mixed Aerobic-Anaerobic Infections
- Particularly valuable for polymicrobial infections involving both aerobic gram-negative rods and anaerobic bacteria 2, 3
- Can be used as a single-agent alternative to combination therapy (such as cephalosporin plus aminoglycoside) in appropriate mixed infections 2, 5
Dosing Considerations
Intravenous Administration
- Standard dosing: 2g IV every 6-8 hours for most infections 1
- For severe infections: up to 12g daily in divided doses 1
- For PID: 2g IV every 6 hours until clinical improvement (at least 48 hours), then transition to oral therapy 4
Intramuscular Administration
- 1-2g IM with lidocaine for dilution to reduce injection pain 6
- For PID outpatient treatment: 2g IM with probenecid 1g orally 4
Clinical Pearls and Caveats
- Cefoxitin is highly resistant to beta-lactamases, making it effective against many penicillinase-producing organisms 2, 3
- Treatment failures with cefoxitin are most commonly associated with abscess formation requiring surgical drainage rather than antimicrobial resistance 3, 7
- When treating PID, cefoxitin must be combined with doxycycline to provide coverage against C. trachomatis 1
- While cefoxitin has better anaerobic coverage than many cephalosporins, some clinicians add metronidazole for enhanced anaerobic coverage in severe mixed infections 4
- For post-cesarean infections, cefoxitin may be considered, but other regimens like clindamycin plus gentamicin or ampicillin-sulbactam are also recommended 8
Treatment Duration
- For most infections: 5-14 days depending on severity and site of infection 1
- For PID: at least 48 hours of IV therapy after clinical improvement, followed by oral therapy to complete 14 days total 4
- Patients should demonstrate substantial clinical improvement within 72 hours; if not, reevaluation of diagnosis and treatment is warranted 4