Leg ulcer infection

Mild case: flucloxacillin 500mg po qds with or without metronidazole 400mg po tds 

Moderate or severe: 

• flucloxacillin 1g iv qds (increase to 2g iv qds for severe infection or in obese patients) PLUS metronidazole 400mg po tds (500mg iv tds if iv is required) 
• For cases with sepsis: ADD gentamicin 5mg/kg iv single dose. If creatinine clearance less than 30 ml/min reduce dose to 3mg/kg.  

For pregnant patients:

cefalexin 1g po tds or erythromycin 500mg po qds

For penicillin allergy (Non-severe):

Mild cases: cefalexin 1g po tds with or without metronidazole 400mg po tds 

Moderate or severe (including MRSA positive patients):

•  cefazolin 1g iv tds (increase to 2g iv tds for severe infections) PLUS metronidazole 400mg po tds (500mg iv tds if iv is required) 
• For cases with sepsis: ADD gentamicin 5mg/kg iv single dose. If creatinine clearance less than 30 ml/min reduce dose to 3mg/kg.

For Penicillin allergy (Severe): 

Mild cases: doxycycline 100mg po bd with or without metronidazole 400mg po tds 

Moderate or severe (including MRSA positive patients):

• co-trimoxazole 960mg po or iv bd (can be increased to 1.44g iv or po bd for severe cases) PLUS metronidazole 400mg po tds (500mg iv tds if iv is required) 
• For cases with sepsis: ADD gentamicin 5mg/kg iv single dose. If creatinine clearance less than 30 ml/min reduce dose to 3mg/kg.

Consider penicillin allergy assessment and delabelling

Principles are based upon: NICE guideline 152

1. Be aware that:

• there are many causes of leg ulcers: underlying conditions, such as venous insufficiency and oedema, should be managed to promote healing
• most leg ulcers are not clinically infected but are likely to be colonised with bacteria
• antibiotics do not help to promote healing when a leg ulcer is not clinically infected.

2. Do not take a sample for microbiological testing from a leg ulcer at initial presentation, even if it might be infected.

3. Only offer an antibiotic for adults with a leg ulcer when there are symptoms or signs of infection (for example, redness or swelling spreading beyond the ulcer, localised warmth, increased pain or fever). When choosing an antibiotic (see the recommendations on choice of antibiotic above) take account of: 

• the severity of symptoms or signs
• the risk of developing complications
• previous antibiotic use.

4. Give oral antibiotics if the person can take oral medicines, and the severity of their condition does not require intravenous antibiotics.

5. If intravenous antibiotics are given, review by 48 hours and consider switching to oral antibiotics if possible.

6. When prescribing antibiotics for an infected leg ulcer in adults, give advice to seek medical help if symptoms or signs of the infection worsen rapidly or significantly at any time, or do not start to improve within 2 to 3 days of starting treatment.

7. Reassess an infected leg ulcer in adults if:

• symptoms or signs of the infection worsen rapidly or significantly at any time, or do not start to improve within 2 to 3 days
• the person becomes systemically unwell or has severe pain out of proportion to the infection.

8. When reassessing an infected leg ulcer in adults, take account of previous antibiotic use, which may have led to resistant bacteria.

9. Be aware that it will take some time for a leg ulcer infection to resolve, with full resolution not expected until after the antibiotic course is completed.

10. Consider sending a sample from the leg ulcer (after cleaning) for microbiological testing if symptoms or signs of the infection are worsening or have not improved as expected.

11. When microbiological results are available: 

• review the choice of antibiotic(s), and
• change the antibiotic(s) according to results if symptoms or signs of the infection are not improving, using a narrow spectrum antibiotic if possible.

12. Consider referring to plastic surgery department for adults with an infected leg ulcer if they:

• have a higher risk of complications because of comorbidities, such as diabetes or immunosuppression
• have lymphangitis
• have spreading infection that is not responding to oral antibiotics