In general, empiric treatment of necrotizing infection should consist of broad-spectrum antimicrobial therapy, including activity against gram-positive, gram-negative, and anaerobic organisms .
Antibiotic therapy should be initiated
promptly after obtaining blood cultures .
Acceptable empiric antibiotic regimens include :
A carbapenem or beta-lactam-beta-lactamase inhibitor plus
An agent with activity against methicillin-resistant S. aureus(MRSA; such as vancomycin or linezolid) .
In neonates and children, vancomycin (15 mg/kg/dose every six to eight hours) is the usual empiric antibiotic for MRSA; the six-hour dosing interval is employed for sicker children, plus
Clindamycin, for its antitoxin effects against toxin-elaborating strains of streptococci and staphylococci (600 to 900 mg intravenously [IV] every eight hours in adults; 40 mg/kg per day divided every eight hours in children and neonates)
For patients who have particular exposures that may suggest infections with specific organisms, such as trauma in fresh water (Aeromonas) or sea water (V. vulnificus), it is appropriate to ensure that empiric therapy includes antimicrobial agents with activity against such organisms.
Options for carbapenems include :
imipenem, meropenem, or ertapenem. Meropenem (20 mg/kg per dose every eight hours) is the appropriate carbapenem for use in children and neonates with a postnatal age >7 days.
Options for beta-lactam–beta-lactamase inhibitors include; piperacillin-tazobactam, ampicillin-sulbactam, or ticarcillin-clavulanate.
Patients with hypersensitivity to these agents may be treated either with an aminoglycoside or a fluoroquinolone, plus metronidazole.
Antibiotic treatment should be tailored to Gram stain, culture, and sensitivity results when available :
Group A streptococcal or other beta-hemolytic streptococcal infection – Penicillin (4 million units IV every four hours in adults >60 kg with normal renal function or 300,000 units/kg per day divided every six hours in children) plus clindamycin (600 to 900 mg IV every eight hours in adults or 40 mg/kg per day divided every eight hours in neonates and children) .
Use of clindamycin is beneficial for its anti-toxin effect, regardless of in vitro susceptibility.
Clostridial infection : Penicillin plus clindamycin (dosing as above).
Aeromonas hydrophila – (See “Aeromonas infections”.)
Vibrio vulnificus – (See “Vibrio vulnificus infections”.)
Polymicrobial infection – Vancomycin plus a beta-lactam-beta-lactamase inhibitor.
Antibiotics should be continued until no further debridement is needed and the patient’s hemodynamic status has normalized; this duration must be tailored to individual patient circumstances .