Infected Bite Wounds (Animal and Human)

• Surgery may be required for severe and penetrating injuries involving joints and tendons, and severe infection or poor response to treatment.
• If an animal bite from overseas consider rabies virus – urgent Infectious Diseases consult required.

Pathogens

• Usually multiple including anaerobes, S. aureus, Streptococcus spp, Pasteurella multocida (cats and dogs), Eikenella corrodens (humans).

Drug Treatment

• Duration: At least 5 days.

Empiric

Mild infection

amoxicillin+clavulanic acid HMLSchedNZFPMLnoids Amoxicillin+Clavulanic Acid F: 0.9 / 0.5 Half life: 2 hours / 1 hour Elimination: renal fe: 0.9 / 0.5

PO 500 mg/125 mg three times a day

• fe (amoxicillin) = 0.9, fe (clavulanic acid) = 0.5, consider adjusting dose if CrCl reduced.

Penicillin allergy

metronidazole HMLSchedNZFPMLnoids Metronidazole F: 1 Half life: 8 hours Elimination: oxidation, glucuronidation fe: 0.1

PO 600 mg twice a day

• Metabolised by CYP3A. (fe < 0.1).

AND EITHER

trimethoprim+sulfamethoxazole HMLSchedNZFPMLnoids Trimethoprim+Sulfamethoxazole F: 0.8 Half life: 9 hours / 12 hours Elimination: CYP2C8/9 acetylated fe: 0.3 / 0.7 (co-trimoxazole)

PO 160 mg/800 mg twice a day

• fe (trimethoprim) = 0.7, fe (sulfamethoxazole) = 0.3, consider adjusting dose if CrCl reduced.
• Sulfamethoxazole is metabolised by CYP2C8/9 and conjugation.

OR

doxycycline HMLSchedNZFPML Doxazosin F: 0.7 Half life: 12 hours Elimination: CYP3A fe: 0.1

200 mg on day 1 then 100 mg once a day

• Metabolised by unknown pathways. (fe = 0.4).
• Avoid in pregnancy and breastfeeding.

Severe infection

• fe (amoxicillin) = 0.9, fe (clavulanic acid) = 0.5, consider adjusting dose if CrCl reduced.

Mild penicillin allergy

• High oral availability – prescribe orally unless GI absorption is compromised or patient is nil by mouth.
• Metabolised by unknown pathways. (fe = 0.1).

AND

cefuroxime HMLSchedNZFPMLnoids Cefuroxime F: 0.4 Half life: 2 hours Elimination: renal fe: 0.9

IV 1.5 g every eight hours

• fe = 0.9, consider adjusting dose if CrCl is reduced.

Severe penicillin allergy

Consult Infectious Diseases/Clinical Microbiology

Topic Code: 99259

must be prescribed or recommended by a consultant.