Initiate early broad-spectrum antibiotics as soon as possible. Providing coverage for gram-positive, gram-negative, aerobic, and anaerobic bacteria is essential. Penicillins and beta-lactamase inhibitors or triple antibiotics are potential choices.
Vancomycin is a potent antibiotic directed against gram-positive organisms and active against enterococcal species. It is useful for the treatment of septicemia and skin structure infections.
Vancomycin is indicated for patients who cannot receive or have failed to respond to penicillins and cephalosporins or for those who have infections with resistant staphylococci. For abdominal penetrating injuries, combine with an agent active against enteric flora and/or anaerobes.
To avoid toxicity, assay of vancomycin trough levels after the third dose drawn 0.5 h prior to next dosing currently is recommended. Dose adjustment may be necessary in patients with renal impairment; follow creatinine clearance (CrCl).
Ampicillin-sulbactam sodium (Unasyn)
This is a drug combination that uses a beta-lactamase inhibitor with ampicillin; covers skin, enteric flora, and anaerobes; not ideal for nosocomial pathogens.
Ticarcillin and clavulanate potassium (Timentin)
This antipseudomonal penicillin plus beta-lactamase inhibitor provides coverage against most gram-positive and gram-negative organisms and most anaerobes. It contains 4.7-5 mEq of sodium per gram. Ticarcillin inhibits biosynthesis of bacterial cell wall mucopeptide and is effective during the active growth stage.
Piperacillin and tazobactam (Zosyn)
This combination of an antipseudomonal penicillin and a beta-lactamase inhibitor inhibits biosynthesis of bacterial cell wall mucopeptide and is effective during the stage of active multiplication.
An aminoglycoside antibiotic used for gram-negative bacterial coverage, gentamicin is commonly used in combination with both an agent against gram-positive organisms and one that covers anaerobes. Consider using gentamicin when penicillins or other less toxic drugs are contraindicated, when bacterial susceptibility tests and clinical judgment indicate use, and in mixed infections caused by susceptible strains of staphylococci and gram-negative organisms.
Dosing regimens are numerous and are adjusted on the basis of CrCl and changes in the volume of distribution. Gentamicin may be administered IV or IM.
Metronidazole is an imidazole ring-based antibiotic that is active against anaerobes. It is usually given in combination with other antimicrobial agents, except when used for Clostridium difficile enterocolitis, in which case monotherapy is appropriate.
Metronidazole is active against various anaerobic bacteria and protozoa. It appears to be absorbed into cells of microorganisms that contain nitroreductase; then, unstable intermediate compounds are formed that bind DNA and inhibit synthesis, causing cell death.
Clindamycin is a lincosamide useful in treatment against serious skin and soft-tissue infections caused by most staphylococci strains; it is also effective against aerobic and anaerobic streptococci, except enterococci. This agent inhibits bacterial protein synthesis by inhibiting peptide chain initiation at the bacterial ribosome, where it preferentially binds to the 50S ribosomal subunit, causing bacterial growth inhibition.