Necrotising Soft Tissue Infections

• Necrotising soft tissue infections are life-threatening and should be referred urgently to surgery.
• Risk factors – diabetes, obesity, immunocompromise, recent skin trauma, intravenous drug use (IVDU).
• Diagnosis and surgical management depends on findings at surgery and organism identification, and must be differentiated from pyomyositis.
• Consult Infectious Diseases/Clinical Microbiology and see Hospital HealthPathways.
• The LRINEC score is a predictive score for necrotising fasciitis - see Hospital HealthPathways.
• For post-operative infections, see Abdominal Wound Infection (Post-operative) and Limb Wound Infection (Post-operative).

Pathogens

• Common: Streptococcus pyogenes, mixed aerobes and anaerobes especially Clostridium perfringens

Drug Treatment

• Duration: 2 weeks or more

Empiric

Limb infection:

flucloxacillin HMLSchedNZFPMLnoids Flucloxacillin F: 0.9 Half life: 1 hour Elimination: renal fe: 0.7

IV 2 g every four hours

• fe = 0.7, consider adjusting dose if CrCl reduced.
• Risk of hepatotoxicity is increased in females, patients > 55 years old, high doses, and courses longer than 14 days duration.

AND

clindamycin HMLSchedNZFPMLnoids Clindamycin F: 0.9 Half life: 3 hours Elimination: CYP3A fe: 0.1

IV 600 mg every eight hours

• Metabolised by CYP3A. (fe < 0.1).
• Clindamycin suppresses toxin production and improves outcome.

Penicillin allergy

Consult Infectious Diseases/Clinical Microbiology

Abdominal/perineal infection:

piperacillin+tazobactam HMLNZFPMLnoids Piperacillin+Tazobactam F: n/a Half life: 1 hour Elimination: renal fe: 0.8/0.6

IV 4 g/500 mg every eight hours

• If still on piperacillin+tazobactam beyond 48 hours, consider measuring a trough concentration. Consult Infectious Diseases for interpretation.
• fe (piperacillin) = 0.8, fe (tazobactam) = 0.6, consider adjusting dose if CrCl reduced.

AND

• Metabolised by CYP3A. (fe < 0.1).
• Clindamycin suppresses toxin production and improves outcome.

Penicillin allergy

Consult Infectious Diseases/Clinical Microbiology

Pathogens Known

Streptococcus pyogenes, Clostridium perfringens

benzylpenicillin HMLSchedNZFPMLnoids Benzylpenicillin F: n/a Half life: 1 hour Elimination: hydrolysis fe: 0.9 (Penicillin G)

IV 2.4 g (4 mega units) every four hours

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

AND

• Metabolised by CYP3A. (fe < 0.1).
• Clindamycin suppresses toxin production and improves outcome.

Mild penicillin allergy

cefazolin HMLSchedNZFPMLnoids Cefazolin F: n/a Half life: 2 hours Elimination: renal fe: 0.9

IV 2 g every eight hours

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

AND

• Metabolised by CYP3A. (fe < 0.1).
• Clindamycin suppresses toxin production and improves outcome.

Severe penicillin allergy

Consult Infectious Diseases / Clinical Microbiology

Topic Code: 99266

must be prescribed or recommended by a consultant.