Cephalosporins with Anaerobic Coverage

Cefoxitin is the primary cephalosporin with reliable anaerobic coverage, followed by cefotetan as an alternative option. 1, 2

Primary Options

Second-generation cephalosporin with established anaerobic coverage 1
FDA-approved for intra-abdominal infections, gynecological infections, and skin/soft tissue infections caused by anaerobes including Bacteroides species 2
Effective against many anaerobic bacteria resistant to some penicillins and other cephalosporins 2
Dosing: Typically administered every 6-8 hours intravenously 1
Has high stability in the presence of bacterial beta-lactamases, both penicillinases and cephalosporinases 2

Second-generation cephalosporin with anaerobic activity 3
FDA-approved for intra-abdominal infections and gynecological infections involving anaerobes 3
Longer half-life (176 min) compared to cefoxitin (49 min), allowing for less frequent dosing (every 12 hours) 4
Despite higher protein binding (85% vs 50% for cefoxitin), free cefotetan serum concentrations at 12 hours post-dose remain higher than free cefoxitin at 6 hours post-dose 4

Both cefoxitin and cefotetan are recommended for moderate to severe intra-abdominal infections involving anaerobes 1
Particularly useful when Bacteroides species are suspected pathogens 2, 3
For polymicrobial infections with both aerobic and anaerobic components 1

Both agents are effective for pelvic inflammatory disease, endometritis, and other gynecological infections 2, 3
When used for pelvic inflammatory disease involving potential Chlamydia trachomatis, additional anti-chlamydial coverage should be added 2, 3

Effective for mixed aerobic-anaerobic skin and soft tissue infections 1
Particularly useful for animal and human bite wounds with potential anaerobic contamination 1

Active against gram-positive aerobes (Staphylococcus aureus [methicillin-susceptible], Streptococcus species) 2, 3
Active against gram-negative aerobes (E. coli, Klebsiella species, Proteus species) 2, 3
Active against anaerobes (Bacteroides fragilis, Clostridium species, Peptostreptococcus) 2, 3
Not active against Pseudomonas aeruginosa, MRSA, or Enterococcus species 2, 3

Cefoxitin requires more frequent dosing (every 6-8 hours) compared to cefotetan (every 12 hours) 4
For surgical prophylaxis in procedures with risk of anaerobic contamination, both agents are effective options 1, 2, 3
Neither agent penetrates the cerebrospinal fluid adequately for CNS infections 5
Dosage adjustment required in patients with renal impairment 5

When cephalosporins cannot be used, alternatives for anaerobic coverage include:
- Combination therapy with metronidazole plus another agent 1, 6
- Amoxicillin-clavulanate (oral option with anaerobic coverage) 1, 6
- Carbapenems (broader spectrum including anaerobes) 1

Increasing resistance among Bacteroides species has been reported in some regions 7
Local susceptibility patterns should guide therapy choices 7
Neither cefoxitin nor cefotetan has activity against extended-spectrum beta-lactamase (ESBL)-producing organisms 8