eMedicine Specialties > Otolaryngology and Facial Plastic Surgery > Trauma

Human Bites: Treatment & Medication

Author: Ian K McLeod, MD, Assistant Professor, Department of Surgery, Uniformed Services University of the Health Sciences; Chief, Otolaryngology Service, DeWitt Army Community Hospital
Coauthor(s): Daniel J Gallagher III, MD, Attending Surgeon, Department of Otolaryngology, Walter Reed and DeWitt Army Hospitals; Don R Revis Jr, MD, Consulting Staff, Department of Surgery, Division of Plastic and Reconstructive Surgery, University of Florida College of Medicine; Michael Brent Seagle, MD, Associate Professor, Division of Plastic Surgery, University of Florida College of Medicine; Consulting Staff, Florida Surgical Center
Contributor Information and Disclosures

Updated: May 21, 2008

Treatment

Medical Care

Meticulous wound care is the cornerstone of human bite wound management.

Copious irrigation decreases the incidence of wound infection. Use normal saline, diluted Betadine, or diluted hydrogen peroxide to cleanse the wound thoroughly. This cleansing is best performed by using a 10-mL syringe with an 18-gauge angiocatheter sheath attached. Avoid the injected tissue and prevent additional trauma.

Careful debridement of obviously devitalized tissue, particulate matter, and clot is also necessary to reduce infection risk and improve cosmesis. Surgically created wound margins speed wound healing and decrease scarring.

Wound closure is a source of controversy. In general, do not close wounds that are older than 12 hours, infected, or due to puncture. Allow these wounds to heal by means of secondary intention, and consider secondary closure or revision at a later date.

Head and neck wounds occur in cosmetically important areas and may be closed if less than 12 hours old and not obviously infected. Closure of these wounds has a low incidence of infection, probably because of the excellent blood supply and infrequency of edema. However, several points deserve specific mention. Perform closure in a simple interrupted fashion, avoiding layered closure with buried sutures. The objective is to provide wound edge approximation that is not watertight, which allows for drainage. Antibiotic prophylaxis is mandatory in these patients.

• Bite wounds are often several days old and heavily contaminated or overtly infected on first presentation.
• On rare occasions, human bites have been shown to transmit Clostridium tetani. All patients should be assessed for tetanus immune status and updated appropriately. Administer tetanus toxoid or tetanus immunoglobulin when immunity is in question.
• Bites with no substantial skin penetration (eg, abrasions, contusions) and without injury to underlying structures require no further care.
• Human bite wounds at risk for transmission of disease (eg, hepatitis, HIV) require therapy individualization. A fully informed patient (ie, risks and benefits are clearly explained and understood) may be allowed to choose appropriate viral prophylaxis.
• Offer the patient a single dose of hepatitis B immunoglobulin (HBIG) and an accelerated course of hepatitis B vaccine with doses at 0, 1, and 2 months if the assailant is known to have hepatitis B, unless the patient is known to be immune.
• Offer the patient an accelerated course of hepatitis B vaccination if the assailant has unknown hepatitis B status, is considered at high risk, and is unavailable for testing.
• The accelerated course of hepatitis B vaccine may be offered to the patient if the assailant has an unknown hepatitis B status, is considered low risk, and is unavailable for testing, with the understanding that the likelihood of disease transmission is low.
• The Centers for Disease Control and Prevention recommend that patients be offered zidovudine and possibly lamivudine chemoprophylaxis if the assailant is known to be infected with HIV or considered at high risk and unavailable for testing.
• Draw a baseline specimen to determine preexposure HIV status. Retest at 3 and 6 months. Failure to seroconvert at 6 months makes the transmission of HIV highly unlikely.
• Considerable debate occurs over which patients require antibiotic therapy. Antibiotics cannot prevent or eradicate infections in the face of poor wound care, reflecting the importance of meticulous wound care as the cornerstone of therapy. Administering antibiotics is preferred when their use is in question; the risk of antibiotic therapy is minimal, whereas the potential complications of bite wound infections are considerable.
• Superficial noninfected wounds may be treated without antibiotics if left open to heal by secondary intention when evaluated early in compliant patients with no significant comorbidity.
• Infected wounds and wounds of the head and neck closed primarily require antibiotic therapy.
• Wounds managed on an outpatient basis may be treated with oral antibiotics, whereas wounds requiring admission to the hospital should be treated with intravenous antibiotics.
• Antibiotic prophylaxis is warranted if the wound is believed to be at higher risk for infection (eg, significant contamination is present; bone, tendon, or joint space is involved; the bite is on the hand; deep puncture wounds are present; or bites occurring in high-risk patients).
• Continue prophylaxis in the noninfected wound for 3-5 days. Administer therapeutic antibiotics for 10-14 days.
• Selection of the appropriate antibiotic involves multiple factors, including culture results, drug sensitivities, patient age, drug interactions, expected compliance, and renal and hepatic function.
• All patients should be re-examined in 48-72 hours in the emergency department or by the primary care provider.

Surgical Care

Surgical intervention is frequently necessary in treating human bite wounds. Surgical interventions range from simple wound exploration and debridement to the repair of complex structures under magnification. Certain patients (eg, children, those who are emotionally unstable or mentally disabled) may require anesthesia to permit adequate surgical examination of the wound.

Indications for surgical intervention include presence of the following:

• Severe soft tissue infection
• Abscess
• Joint penetration
• Underlying fracture
• Osteomyelitis
• Foreign body
• Neurovascular compromise or injury to a complex structure (eg, facial nerve, parotid duct)

The goal of treating human bites to the head and neck region is the restoration of the patient's facial appearance and function. Years ago, these wounds were routinely left open because of the high rate of wound infection. However, care of these patients has undergone marked changes with the introduction of broad-spectrum antibiotics and the evolution of microsurgical techniques. The development of broad-spectrum antibiotics gradually led to general acceptance of the idea that patients who presented early and without obvious infection were candidates for primary wound closure.

Once surgeons became familiar with and accepted this approach because of its good clinical results, aggressive reconstructive techniques evolved in the acute setting. These techniques have proven to be safe and effective, yielding an acceptably low rate of morbidity, and they do not leave the patient with a potentially significant facial deformity while awaiting reconstruction. More importantly, the ultimate results of primary reconstruction are clearly superior to those of delayed reconstruction.

Many options are available to the surgeon, including primary closure, skin grafting, composite grafting, use of local flaps, and microsurgical replantation.

• Lip wounds are among the most common facial bite wounds.  
  • Vermillion defects may be reconstructed with mucosal advancement flaps. Wounds measuring up to a third of the length of the lip may be closed by using a wedge or chevron excision and approximating the two cut edges. Perform muscular reapproximation of the orbicularis oris with interrupted buried absorbable sutures to assure continuity of the sphincteric muscular ring.
  • Small (<1.5 cm²) lip segments have been successfully replanted as composite grafts when a segment of lip has been amputated and is available for reattachment. However, the survival of such grafts is often questionable. Patients with small tissue loss may benefit more from primary wound closure or from using one of the available local flaps.
  • Larger defects may require a local flap (eg, Bernard advancement flap, Gillies fan flap, Karapandzic myocutaneous flap) or a lip switch procedure (eg, with an Abbé or Estlander flap).
  • Large amputated lip segments have been successfully replanted by using microvascular techniques, and successful results are unmatched by any other reconstructive technique. No other donor tissue matches replanted lip regarding symmetry, contour, shape, color, texture, or motion. Return of muscle function and protective sensation is fairly predictable. Although this approach is reliable, it is not universally applicable. The surgeon must have adequate experience in microvascular techniques, and the treating facility must have microsurgical equipment. Caution patients against smoking in the postoperative period to avoid the vasoconstrictive effects of nicotine.
  • An artery may be anastomosed to the remaining labial artery if it is identifiable in the severed lip.
  • Veins are small and often unidentifiable. Veins may be repaired primarily or by using a vein graft. When no vein is found and when 2 arteries are located in the severed segment, 1 of the arteries may be anastomosed to a facial vein; this creates an arteriovenous fistula that aids venous drainage of the amputated part through retrograde flow.
  • Venous congestion is the most likely cause of failure in lip replantation. In general, when no venous anastomosis is performed, patients require venous decompression for 4-6 days until the wound is adequately revascularized from surrounding tissue.
  • Venous drainage may be achieved in several ways. All methods involve notable bleeding and frequently require administration of blood transfusions, which increase the risk of disease transmission. Some recommend systemic anticoagulation with heparin, while others advocate local injection of heparin into reattached tissue. Bleeding occurs from the suture line, which should be kept free of clot or crusting to allow the egress of venous blood. Leeches actively remove blood and may be applied to the suture line. Passive oozing from the leech bite continues to provide artificial venous outflow after they are removed. An anticoagulant (hirudin) in leech saliva that is injected when it bites enhances venous egress. Give patients undergoing leech therapy appropriate antibiotic prophylaxis against infection by Aeromonas hydrophila, which is found in the GI tract of the leech.
• Ear wounds are also common facial bites because of the prominent position of the ears on the head.  
  • Coverage of exposed cartilage and restoration of shape are the primary concerns.
  • Similar to lip bites, small bites on the ears can be closed primarily and may require wedge excision.
  • Alternatives for covering exposed cartilage in the presence of skin deficits are the use of postauricular flaps or temporoparietal fascial flaps covered with thick split-thickness skin grafts. Helical advancement may be performed to reconstruct helical defects.
  • Small amputated parts may be replaced as composite grafts. If the composite graft fails, débride the wound, close the skin over the cartilage, and delay definitive reconstruction until infection or inflammation subsides.
  • Salvaged denuded cartilage can be preserved by placing it in an abdominal or cervical pocket or under postauricular skin.
  • Larger amputated segments may be replanted by using microvascular techniques similar to those described for the lip. However, these procedures tend to fail because of the small caliber of the vessels. Reanastomosing the veins may be difficult or impossible; alternative techniques for ensuring venous drainage may be needed.
  • In the absence of microvascular capabilities, amputated cartilage may be skeletonized and placed in a subcutaneous pocket for use during later reconstruction.
  • Delayed reconstruction may be performed by using a retroauricular flap, helical advancement, or cartilage or composite grafting, depending on the residual defect.
• Cheek wounds are frequently amenable to primary closure. Injuries with great tissue loss may be closed with cervicofacial, nasolabial, or other locoregional flaps.
• Bites to the eyelid are infrequent but pose a particular threat in terms of eye closure and corneal protection.  
  • A full-thickness graft from the contralateral lid may be used when only a skin deficit is encountered.
  • A composite graft from the contralateral lid may be used for defects of the tarsal plate.
• Nose wounds and resultant nose reconstruction can be challenging, and details of the procedure are beyond the scope of this discussion.  
  • Briefly, cartilaginous defects may require cartilage grafts from the septum, ear, or costal cartilages. A composite cartilage graft harvested from the ear may also be necessary.
  • Soft tissue coverage may require a dorsal nasal flap for small defects of the nasal dorsum.
  • A nasolabial flap (either pedicle or island), forehead flap, or Washio flap may be required for larger defects.

Consultations

A hand surgeon should be consulted for hand wounds involving bone, tendon, or joint space because of the higher risk for infection and potential need for admission and exploration. Likewise, consultation with either an otolaryngologist-head and neck surgeon or facial plastics and reconstructive surgeon should be obtained for all avulsion bites involving the face or neck. 

Medication

The goals of pharmacotherapy are to reduce morbidity and prevent complications.

Antibiotics

Several antibiotics are commonly used in cases of human bite wounds.

Amoxicillin and clavulanic acid (Augmentin)

Most effective and economical choice for outpatient therapy unless contraindicated.

Doxycycline (Doryx, Vibramycin, Vibra-Tabs)

Broad-spectrum, synthetically derived bacteriostatic tetracycline antibiotic. Almost completely absorbed, concentrates in bile, and excreted in urine and feces as a biologically active metabolite in high concentrations. Inhibits protein synthesis and thus bacterial growth by binding to 30S and possibly 50S ribosomal subunits of susceptible bacteria. May block dissociation of peptidyl t-RNA from ribosomes, arresting RNA-dependent protein synthesis. Alternative oral therapy in patients with penicillin allergy.

Ceftriaxone sodium (Rocephin)

Third-generation cephalosporin with broad-spectrum, gram-negative activity; low efficacy against gram-positive organisms, high efficacy against resistant organisms. Inhibits bacterial cell-wall synthesis by binding 1 or more penicillin-binding proteins. Antimicrobial effect by interfering with synthesis of peptidoglycan (major structural component of bacterial cell wall). Bacteria lyse because of ongoing activity of cell-wall autolytic enzymes while cell-wall assembly arrested. Highly stable in presence of beta-lactamases (penicillinase, cephalosporinase) of gram- and gram-positive bacteria.
About 33-67% of dose excreted unchanged in urine; rest secreted in bile and ultimately in feces as microbiologically inactive compounds. Reversibly binds to human plasma proteins; binding reported to decrease from 95% bound at plasma concentration <25 mcg/mL to 85% bound at 300 mcg/mL.
Noncompliant patients may benefit from once-daily IM dosing; also may be used as IV antibiotic in inpatients.

Cefoxitin sodium (Mefoxin)

Second-generation cephalosporin with activity against some gram-positive cocci, gram-negative rods, and anaerobic bacteria. Inhibits bacterial cell-wall synthesis by binding to 1 or more penicillin-binding proteins; inhibits final transpeptidation step of peptidoglycan synthesis, resulting in cell-wall death.

Infections caused by cephalosporin- or penicillin-resistant gram-negative bacteria may respond.

Ampicillin sodium and sulbactam (Unasyn)

Drug combination of beta-lactamase inhibitor with ampicillin. Interferes with bacterial cell-wall synthesis during active replication, resulting in bactericidal activity against susceptible organisms. Alternative to amoxicillin in patients unable to take oral medication.

Ticarcillin disodium and clavulanic acid (Timentin)

Inhibits biosynthesis of cell-wall mucopeptide and effective during stage of active growth.

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