Gas Gangrene in Emergency Medicine Medication

Antibiotics may not penetrate the ischemic muscle but are important adjuncts to surgery.

Class Summary

Clostridial species are exquisitely sensitive to a combination of penicillin G and clindamycin. However, because it is difficult initially to distinguish gas gangrene from other soft tissue infections, such as necrotizing fasciitis, which is caused by a broad spectrum of pathogens, empiric first-line antibiotic therapy should be broad.^{[1, 2, 3, 14]} Clindamycin, tetracycline, and other inhibitors of bacterial protein synthesis may, however, have some increased utility as they halt the production of bacterial toxin. Low-level clostridial resistance occurs to clindamycin, and, as such, this agent should not be used as monotherapy.

Antibiotic treatment should include gram-positive (penicillin or cephalosporin), gram-negative (aminoglycoside, third-generation cephalosporin, or ciprofloxacin), and anaerobic coverage (clindamycin or metronidazole). In addition, vancomycin or linezolid should be considered in those at risk for methicillin-resistant Staphylococcus aureus (MRSA). In some communities, MRSA infections are now being isolated even in those without risk factors (8-25%); the risk factors traditionally associated with MRSA are a history of hospitalization, surgery, dialysis, residence in a long-term care facility, presence of a permanent indwelling catheter or percutaneous medical device (eg, tracheostomy tube, gastrostomy tube, Foley catheter), or previous isolation of MRSA.^{[1, 2, 3, 14]}

Antibiotics should be administered IV since absorption by other routes is inconsistent given the hypotension and suboptimally performing gastrointestinal tract of seriously ill patients.

Tetracycline

Semisynthetic antibacterial agent derived from Streptomyces cultures. Treats gram-positive and gram-negative organisms and mycoplasmal, chlamydial, and rickettsial infections. Inhibits bacterial protein synthesis by binding with 30S and, possibly, 50S ribosomal subunit(s).

Penicillin G (Pfizerpen)

DOC for use with infections by clostridial species. Interferes with synthesis of cell wall mucopeptide during active multiplication, resulting in bactericidal activity against susceptible microorganisms.

Clindamycin (Cleocin)

Lincosamide useful as treatment against serious skin and soft tissue infections caused by most staphylococcal strains. Also effective against aerobic and anaerobic streptococci, except enterococci. Inhibits bacterial protein synthesis by inhibiting peptide chain initiation at bacterial ribosome where it preferentially binds to 50S ribosomal subunit, causing bacterial growth inhibition. Will also halt bacterial production of toxin.

Ceftriaxone (Rocephin)

Third-generation cephalosporin that has broad-spectrum activity against gram-negative organisms, lower efficacy against gram-positive organisms, and higher efficacy against resistant organisms. Arrests bacterial cell wall synthesis and inhibits bacterial growth by binding to one or more penicillin-binding proteins.

Metronidazole (Flagyl)

Active against various anaerobic bacteria and protozoa. Appears to be absorbed into cells; intermediate-metabolized compounds that are formed bind DNA and inhibit protein synthesis, causing cell death.

Linezolid (Zyvox)

Prevents formation of functional 70S initiation complex, which is essential for bacterial translation process. Bacteriostatic against enterococci and staphylococci and bactericidal against most strains of streptococci. Used as alternative in patients allergic to vancomycin and for treatment of vancomycin-resistant enterococci.

Gentamicin (Gentacidin, Garamycin)

Aminoglycoside antibiotic used for gram-negative bacterial coverage. Commonly used in combination with an agent with activity against gram-positive organisms and one that covers anaerobes.

Not antibiotic of first choice. Consider using when penicillins or other less toxic drugs are contraindicated, when bacterial susceptibility tests and clinical judgment indicate its use and in mixed infections caused by susceptible strains of staphylococci and gram-negative organisms.

Dosing regimens are numerous and are adjusted based on CrCl and changes in volume of distribution. Gentamicin may be administered IV/IM.

Vancomycin (Vancocin)

Potent antibiotic directed against gram-positive organisms and active against enterococci species. Useful to treat septicemia and skin structure infections. 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. May need to adjust dose in patients diagnosed with renal impairment (use CrCl).

Class Summary

Hyperbaric oxygen (HBO) produces a tissue level of 300 mm Hg of oxygen. This is approximately 50 mm Hg greater than the partial pressure necessary to induce bacteriostasis and halt toxin production. This then decreases the extent of debridement and possible amputation needed to control infection.^[15]

Hyperbaric oxygen (HBO)

Use is controversial but can be used to supplement surgical debridement and antibiotics. This modality may be particularly helpful in areas where complete surgical resection of necrotic tissue is difficult such as the paraspinal muscles or abdominal wall. Potential benefits include improved neutrophil-mediated killing of bacteria, direct bactericidal effect on anaerobes, improved activity of some antibiotics, and enhanced wound healing. Given its aerotolerance, gas gangrene caused by C septicum may be less amenable to HBO therapy.

Class Summary

Toxoids are used to induce active immunity.

Tetanus toxoid adsorbed or fluid

Used to induce active immunity against tetanus in selected patients. Immunizing agents of choice for most adults and children >7 y are tetanus and diphtheria toxoids. Necessary to administer booster doses to maintain tetanus immunity throughout life.

Pregnant patients should receive only tetanus toxoid not a diphtheria antigen-containing product.

In children and adults, may administer into deltoid or midlateral thigh muscles. In infants, preferred site of administration is mid thigh laterally.

Class Summary

Immunoglobulins are used to induce passive immunity.

Tetanus immune globulin (TIG)

Used for passive immunization of any person with a wound that may be contaminated with tetanus spores.

Class Summary

Pain control is essential to quality patient care. Analgesics ensure patient comfort, promote pulmonary toilet, and have sedating properties, which are beneficial for patients who have sustained trauma or have sustained injuries.

Morphine sulfate (Astramorph, MS Contin, MSIR, Oramorph)

DOC for analgesia due to reliable and predictable effects, safety profile, and ease of reversibility with naloxone.

Various IV doses are used; commonly titrated until desired effect obtained.

Fentanyl citrate (Duragesic, Sublimaze)

A synthetic opioid that is 75-200 times more potent and has a much shorter half-life than morphine sulfate. Has less hypotensive effects and is safer in patients with hyperactive airway disease than morphine because of minimal-to-no associated histamine release. By itself, it causes little cardiovascular compromise, although addition of benzodiazepines or other sedatives may result in decreased cardiac output and blood pressure.

Highly lipophilic and protein-bound. Prolonged exposure leads to accumulation in fat and delays weaning process.

Consider continuous infusion because of the short half-life of fentanyl.

Parenteral form is DOC for conscious sedation analgesia. Ideal for analgesic action of short duration during anesthesia and immediate postoperative period.

Excellent choice for pain management and sedation with short duration (30-60 min) and easy to titrate. Easily and quickly reversed by naloxone.

After initial parenteral dose, subsequent parenteral doses should not be titrated more frequently than q3h or q6h thereafter.

Transdermal form is used only for chronic pain conditions in patients with tolerance to opioids. When using transdermal dosage form, most patients are controlled with 72-h dosing intervals; however, some patients require dosing intervals of 48 h.

Easily and quickly reversed by naloxone.