Animal Bites in Emergency Medicine Medication

This is one of most controversial subjects in wound care. Remember that proper wound care (inspection, debridement, irrigation, closure, if indicated) reduces infection more than antibiotics. In general, low-risk wounds do not require prophylactic antibiotics. However, therapy is recommended for high-risk wounds (eg, cat bites that are a true puncture, bites to the hand, massive crush injury, late presentation, poor general health).^[15]

The goal of initial therapy is to cover staphylococci, streptococci, anaerobes, and Pasteurella species. Prophylactic antibiotics may be given for a 3- to 5-day course. The first-line oral therapy is amoxicillin-clavulanate. For higher risk infections, a first dose of intravenous antibiotic may be given (ie, ampicillin-sulbactam, ticarcillin-clavulanate, piperacillin-tazobactam, or a carbapenem). Other combinations of oral therapy include cefuroxime plus clindamycin or metronidazole, a fluoroquinolone plus clindamycin or metronidazole, sulfamethoxazole and trimethoprim plus clindamycin or metronidazole, penicillin plus clindamycin or metronidazole, amoxicillin plus clindamycin or metronidazole and less effective azithromycin or doxycycline plus clindamycin or metronidazole.^{[16, 6, 7]} If the wound is infected on presentation, a course of 10 days or longer is recommended.

For monkey bites, postexposure prophylaxis valacyclovir or acyclovir should be given for 14 days.

Class Summary

Empiric antimicrobial therapy must be comprehensive and should cover all likely pathogens in the context of the clinical setting.

Levofloxacin

For pseudomonal infections and infections due to multidrug resistant gram-negative organisms.

Metronidazole

Imidazole ring-based antibiotic active against various anaerobic bacteria and protozoa. Used in combination with other antimicrobial agents (except for C difficile enterocolitis).

Ampicillin and sulbactam (Unasyn)

Drug combination of beta-lactamase inhibitor with ampicillin. Interferes with bacterial cell wall synthesis during active replication, causing bactericidal activity against susceptible organisms.

Ticarcillin and clavulanate potassium (Timentin)

Inhibits biosynthesis of cell wall mucopeptide and is effective during stage of active growth. Antipseudomonal penicillin plus beta-lactamase inhibitor that provides coverage against most gram-positive organisms, most gram-negative organisms, and most anaerobes.

Piperacillin and tazobactam sodium (Zosyn)

Antipseudomonal penicillin plus beta-lactamase inhibitor. Inhibits biosynthesis of cell wall mucopeptide and is effective during stage of active multiplication.

Imipenem and cilastatin (Primaxin)

For treatment of multiple organism infections in which other agents do not have wide-spectrum coverage or are contraindicated due to potential for toxicity.

Ertapenem (Invanz)

Bactericidal activity results from inhibition of cell wall synthesis and is mediated through ertapenem binding to penicillin-binding proteins. Stable against hydrolysis by a variety of beta-lactamases including penicillinases, cephalosporinases, and extended-spectrum beta-lactamases. Hydrolyzed by metallo-beta-lactamases.

Meropenem (Merrem IV)

Bactericidal broad-spectrum carbapenem antibiotic that inhibits cell-wall synthesis. Effective against most gram-positive and gram-negative bacteria.

Has slightly increased activity against gram-negatives and slightly decreased activity against staphylococci and streptococci compared to imipenem.

Amoxicillin and clavulanate (Augmentin)

Drug combination that extends antibiotic spectrum of penicillin to include bacteria normally resistant to beta-lactam antibiotics. Indicated for skin and skin structure infections caused by beta-lactamase–producing strains of Staphylococcus aureus.

Cefuroxime (Ceftin, Kefurox, Zinacef)

Second-generation cephalosporin maintains gram-positive activity that first-generation cephalosporins have; adds activity against P mirabilis, H influenzae, E coli, K pneumoniae, and M catarrhalis. Condition of patient, severity of infection, and susceptibility of microorganism determine proper dose and route of administration.

Ciprofloxacin (Cipro)

Fluoroquinolone with activity against pseudomonads, streptococci, MRSA, S epidermidis, and most gram-negative organisms, but no activity against anaerobes. Inhibits bacterial DNA synthesis and, consequently, growth.

Clindamycin (Cleocin)

Lincosamide for treatment of serious skin and soft tissue staphylococcal infections. Also effective against aerobic and anaerobic streptococci (except enterococci). Inhibits bacterial growth, possibly by blocking dissociation of peptidyl tRNA from ribosomes, causing RNA-dependent protein synthesis to arrest.

Sulfamethoxazole/trimethoprim (Bactrim, Bactrim DS, Septra, Septra DS)

Inhibits bacterial growth by inhibiting synthesis of dihydrofolic acid.

Amoxicillin (Trimox, Biomox, Amoxil)

Alone, this drug is effective against Pasteurella species. However, not indicated for skin and skin structure infections caused by beta-lactamase–producing strains of Staphylococcus aureus. A second antibiotic such as cephalexin is needed for Staphylococcus infections.

Azithromycin (Zithromax)

Inhibits bacterial growth, possibly by blocking dissociation of peptidyl tRNA from ribosomes, causing RNA-dependent protein synthesis to arrest. Treats mild-to-moderate microbial infections

Doxycycline (Doryx, Vibramycin, Bio-Tab)

Inhibits protein synthesis and thus bacterial growth by binding to 30S and possibly 50S ribosomal subunits of susceptible bacteria.

Class Summary

These agents inhibit viral replication.

Acyclovir (Zovirax)

Prodrug activated by phosphorylation by virus-specific thymidine kinase that inhibits viral replication. Herpes virus thymidine kinase (TK), but not host cells' TK, uses acyclovir as a purine nucleoside, converting it into acyclovir monophosphate, a nucleotide analogue. Guanylate kinase converts the monophosphate form into diphosphate and triphosphate analogues that inhibit viral DNA replication.

Has affinity for viral thymidine kinase and, once phosphorylated, causes DNA chain termination when acted on by DNA polymerase. Has activity against a number of herpesviruses, including herpes virus B. Primarily available in preparations for PO and IV use. Patients experience less pain and faster resolution of cutaneous lesions when used within 48 h from rash onset. May prevent recurrent outbreaks. Early initiation of therapy is imperative.

Valacyclovir (Valtrex)

Hydrochloride salt of the L-valyl ester of acyclovir. Rapidly converted into acyclovir after prompt absorption from the gut via first-pass intestinal or hepatic metabolism. An alternative to acyclovir for prophylaxis (or possibly treatment).

Class Summary

Tetanus results from elaboration of an exotoxin from Clostridium tetani. A booster injection in previously immunized individuals is recommended to prevent this potentially lethal syndrome. Patients who may not have been immunized against C tetani products (eg, immigrants, the elderly) should receive tetanus immune globulin.

Tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis vaccine (Tdap, Adacel, Boostrix)

Promotes active immunity to diphtheria, tetanus, and pertussis by inducing production of specific neutralizing antibodies and antitoxins. Indicated for active booster immunization for tetanus, diphtheria, and pertussis prevention for persons aged 10-64 y (Adacel approved for 11-64 y, Boostrix approved for 10-18 y). Preferred vaccine for adolescents scheduled for booster.

Tetanus toxoid

No longer available in the United States.

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

The CDC recommends Td for pregnant patients who have urgent indication tor tetanus toxoid or diphtheria toxoid vaccination.

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

Class Summary

Indicated in previously unvaccinated individuals to provide passive immunity to tetanus when individuals become exposed.

Tetanus immune globulin (HyperTET S/D)

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

Rabies Immune Globulin (Imogam Rabies-HT, HyperRab S/D)

Provides passive protection to individuals exposed to rabies virus. About 1/2 the dose should be administered into and around the bite wound as much as possible (given anatomic constraints), and the rest given intramuscularly at a site remote from the vaccine administration area in the gluteal or deltoid muscle.

Class Summary

Inactivated forms of virus that promote immunity by inducing an active immune response.

Rabies vaccine (Rabavert, Imovax Rabies Vaccine)

Inactivated form of virus grown in primary cultures of chicken fibroblasts; offers active immunity and, when used in combination with human rabies immune globulin (HRIG) and local wound treatment, protects postexposure patients of all age groups; also used for preexposure immunization in both primary series and booster dose.

Fourteen days after initiating immunization series, anti-rabies antibody titers reach levels well above minimal protective level of 0.5 IU/mL.

Vaccine must be injected IM and never SC, ID, or IV. In adults, inject into deltoid muscle area. In small children, administer into anterolateral zone of thigh.

Rabies vaccine adsorbed (RVA; BioPort Corp under US Department of Defense contract for military use only)

Inactivated virus vaccine, which promotes immunity by inducing active immune response. May be given IM only, never ID.