Antimicrobial prescribing: NHS Lothian
- Collect pus in a universal container for culture during incision and drainage of the abscess
- Send a swab only if you cannot collect pus in a sample container
- Blood cultures if febrile or evidence of sepsis.
Peri-anal abscess
Antibiotics are not an alternative to surgical drainage and should only be used as an adjunctive treatment for patients with the following:
- Significant peri-anal cellulitis
- Diabetes or other significant immunocompromise
- Sepsis
See here if Fournier’s gangrene suspected.
Recommended total duration: Stop 24 hours after surgical drainage.
Recommended total duration: Stop 24 hours after surgical drainage.
- If cellulitis present 5 days (total duration = IV + oral)
| Recommended antibiotics |
Flucloxacillin 2g every 6 hours IV PLUS Gentamicin (use NHS Lothian Calculator AMT intranet page) PLUS Metronidazole 400mg every 8 hours orally (or 500mg every 8 hours IV if oral route unavailable) |
| Penicillin-allergy OR previous MRSA |
Vancomycin IV (use NHS Lothian Calculator AMT intranet page) - target trough level 10-15mg/L PLUS Gentamicin IV (use NHS Lothian Calculator AMT intranet page) PLUS Metronidazole 400mg every 8 hours orally (or 500mg every 8 hours IV if oral route unavailable) |
| Preferred |
Co-trimoxazole 960mg every 12 hours orally PLUS Metronidazole 400mg every 8 hours orally |
| Alternative |
Co-amoxiclav 625mg every 8 hours orally Suitable for those ≤ 65 years old with a low risk of C.diff infection. |
Likely organisms: Bacteroides, Staphylococcus aureus, Streptococcus spp., E.coli
- Metronidazole has excellent oral bioavailability – only give IV in severe illness, suspected malabsorption or oral route compromised.
- Dual-anaerobe cover: adding Metronidazole to Co-amoxiclav: is not usually required.