Human Bites Treatment & Management

Updated: Mar 04, 2021
  • Author: Jeffrey Barrett, MD; Chief Editor: John L Brusch, MD, FACP  more...
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Treatment

Approach Considerations

Wound cleaning

Meticulous wound care is the cornerstone of human bite wound management. Copious irrigation decreases the incidence of wound infection. Use isotonic sodium chloride solution, dilute povidone-iodine (Betadine), or dilute hydrogen peroxide to thoroughly cleanse the wound. Cleansing is best performed with a 10-mL syringe with an 18-gauge angiocatheter attached. Take care to avoid injection of the tissues and to prevent additional trauma.

Careful debridement of devitalized tissue, particulate matter, and clot is also necessary to reduce the infection risk and to improve the cosmetic result. Faster wound healing and better scarring result from clean, surgically created wound margins.

Wound closure

Wound closure is a source of controversy in the management of patients with human bite wounds. In general, do not close hand wounds, puncture wounds, infected wounds, or wounds more than 12 hours old. Allow such wounds to heal by secondary intention. They may be closed secondarily or revised at a later date.

Head and neck wounds, being in a cosmetically sensitive area, may be closed if they are less than 12 hours old and are not obviously infected. These wounds have been closed with a low incidence of infection, probably because of excellent blood supply and infrequency of edema.

The following points deserve specific mention:

  • Antibiotic prophylaxis is mandatory in these patients. [16]

  • 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 and still allow for drainage.

Tetanus prevention

Although rare, human bites have been shown to transmit Clostridium tetani. Assess all patients for tetanus immune status and update as appropriate. According to the recommendations of the US Centers for Disease Control and Prevention (CDC), [17] tetanus immune globulin and the 3-dose vaccine series should be administered to patients with an unknown tetanus vaccine history or those who have received fewer than 3 doses. It is also indicated for patients who received the complete tetanus series, but whose booster administration was more than 5 years ago. For patients with a history of 3 or more doses of tetanus and diphtheria vaccine who received a booster less than 5 years ago, no tetanus booster is required.

These wounds are often several days old and are heavily contaminated or even infected upon first presentation. Bites with no significant skin penetration (abrasions or contusions) require no further care.

Antibiotic use

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). The clinician should be aware that the Infectious Diseases Society of America (IDSA) clinical practice guidelines state that all human bite wounds require antibiotic prophylaxis. [18] However, a large clinical trial showed that prophylaxis of human bites that do not penetrate the epidermal layer or are not in high-risk areas is probably unnecessary. [19]

Additional considerations

A fully informed patient may make appropriate choices regarding viral prophylaxis when risks and benefits are clearly explained and understood.

Surgical intervention is frequently necessary. Procedures range from simple wound exploration and debridement to repair of complex structures under magnification.

Human bite wounds at risk for transmission of life-threatening disease require individualization of therapy.

Activity

After initial immobilization of hand injuries in a position of function and elevation, provide instruction regarding resumption of activity. Continue elevation until edema resolves.

In general, early mobilization (ie, 48-72 h postinjury), once improvement is noted, prevents one of the most common and difficult complications of hand injuries, the stiff joint.

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Surgical Care

Prehospital care

Recovery of avulsed tissue parts (eg, ear, finger) is an important consideration for prehospital providers. Otherwise, human bite wound management generally is uncomplicated and involves temporary dressing and transport.

Avulsed parts should be wrapped in sterile gauze dressing that is soaked with normal saline and placed in a plastic bag that is, in turn, placed in a container of ice water.

Emergency department care

Closed-fist injuries

An underlying fracture dictates consultation and potentially the need for inpatient treatment under certain circumstances. After appropriate anesthesia, explore the wound for joint space violation or tendon injury. Involvement of the joint space indicates that the patient should be admitted to the hospital. Also consider patients with tendon injuries, which usually are present, for admission.

Proper wound assessment includes using a tourniquet and extending the wound as needed to improve visualization. Provide outpatient treatment of these wounds (careful wound cleansing, antibiotic coverage, bulky dressing or splint, elevation) only in consultation with hand or orthopedic service. Early, mandatory follow-up care is essential. [20]

Treat noninfected wounds that appear to violate the tendon apparatus in the same manner as noninfected closed-fist injuries.

Puncture wounds

These most commonly are encountered about the head. Such wounds are difficult to clean adequately unless extended to allow for effective irrigation. Even in the absence of infection, such wounds are best left open and closed secondarily, if cosmetically necessary.

Bites to the ear or nose

When associated with tissue loss, these wounds require consultation with plastic surgery or ear, nose, and throat (ENT) service. Seeking consult for a bite that violates cartilage in these areas also is prudent because of poor blood supply to cartilage and difficulties in treating chondritis. [21]

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Antibiotic Prophylaxis

The literature regarding prophylaxis of human bite wounds is sparse. Only 2 randomized, controlled trials directly address the question. The first study indicated that prophylactic antibiotics are very effective in preventing infection. Patients with acute, noninfected human bites to the hand were randomized to prophylaxis with placebo, an oral cephalosporin, or a parenteral cephalosporin plus penicillin. Bites involving joints or tendons were excluded from the study. The results were dramatic, with infection developing in 47% of the placebo group but in none of the patients treated with antibiotics. [22]

In a larger, subsequent trial involving patients with “low-risk” human bites, no statistically significant difference was found in the placebo group compared with the group treated with antibiotics. In the study, patients were randomized to placebo or an oral cephalosporin plus penicillin. This trial excluded patients with bites to the hands, feet, or cartilaginous structures, and no patient in this trial had a bite wound that penetrated deep to the epidermis. [19]

A large, retrospective series examining human bite wounds in children found that none of the bites manifesting as abrasions became infected, while the rate of infection was much higher in bite wounds that caused punctures or lacerations. [23]

One can draw the following conclusions from these data:

  • Acute human bites that do not penetrate the epidermal layer probably do not need antibiotic prophylaxis as long as they do not involve the hands, feet, or joints or cartilaginous structures

  • Human bites that completely penetrate the epidermal layer, as well as bites that involve joints or cartilaginous structures, probably merit antibiotic prophylaxis, but the evidence is not strong.

  • Human bites to the hand are at high risk for infection and should be given antibiotic prophylaxis

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Treatment of Infected Human Bite Wounds

The current recommendations from the IDSA call for the use of amoxicillin/clavulanate or ampicillin/sulbactam in patients with an infected human bite wound. Cephalexin, which is commonly used for skin and soft-tissue infections, is ineffective against E corrodens, an important pathogen in infected human bites. Trimethoprim-sulfamethoxazole (TMP-SMZ) or a quinolone such as levofloxacin or moxifloxacin in addition to clindamycin is an acceptable alternative in the penicillin-allergic patient. [18]

Infected closed-fist injuries are a special case because of the deep nature of these infections and the relatively poor vascular supply to the tendons and other connective tissue. Admitting patients for IV antibiotic therapy is generally considered appropriate is these cases. Surgical debridement and drainage also may be necessary

Hepatitis B

Offer the patient a single dose of hepatitis B immunoglobulin (HBIG), as well as an accelerated course of hepatitis B vaccine with doses at 0, 1, and 2 months (unless the patient is known to be immune).

If the assailant's hepatitis B status is unknown but is considered high risk and the assailant is unavailable for testing, again offer an accelerated course of the hepatitis B vaccine to the patient.

If the assailant's status is unknown but is considered low risk and the assailant is unavailable for testing, the accelerated course of the hepatitis B vaccine may be offered to the patient with the understanding that the likelihood of disease transmission is low.

Human immunodeficiency virus

HIV transmission has been noted only rarely after a human bite. Exposure to saliva alone is not considered a risk factor for HIV (or hepatitis) transmission. Transmission requires HIV-infected blood mixed in the saliva of the biter and a skin break on the victim. The reverse consideration also is important in that blood drawn from an HIV-infected victim would come in contact with the mucous membranes of the biter. A 2005 recommendation from the Centers for Disease Control and Prevention (CDC) states that postexposure prophylaxis with a 28-day course of highly active antiretroviral therapy (HAART) should be used in either of these 2 scenarios. [24]

Draw a baseline specimen from the patient to determine preexposure HIV status, and retest him or her at 3 and 6 months. Failure to convert to HIV-positive status at 6 months makes transmission highly unlikely.

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Surgical Indications

Surgical intervention is frequently necessary and ranges from simple wound exploration and debridement to repair of complex structures under magnification.

Certain patients (eg, children, persons who are emotionally unstable, persons who are mentally handicapped) may require surgical exploration under anesthesia to adequately examine the wound.

Indications for surgical intervention include the following:

  • Severe soft-tissue infection

  • Abscess

  • Joint penetration

  • Underlying fracture

  • Tendon laceration

  • Osteomyelitis

  • Tenosynovitis

  • Septic arthritis

  • Neurovascular compromise or injury to a complex structure (eg, facial nerve, parotid duct)

  • Foreign body

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Surgery for Head and Neck Wounds

The goals of treating human bites to the head and neck region are the restoration of the patient's facial appearance and function. [25, 26] In the past, 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 present early and without obvious infection are candidates for primary wound closure. [27]

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, the use of local flaps, and microsurgical replantation.

Lip wounds

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 2 cut edges. [28] 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 the use of 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). [29]

Large amputated lip segments have been successfully replanted using microvascular techniques, with the results being unmatched by any other reconstructive technique. [30] No other donor tissue matches replanted lip with regard to symmetry, contour, shape, color, texture, or motion. Return of muscle function and protective sensation is fairly predictable.

Although this approach is reliable, however, 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.

Vascular repair

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

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 gastrointestinal (GI) tract of the leech.

Ear wounds

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 by 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. [31]

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

Cheek wounds are frequently amenable to primary closure. Injuries with great tissue loss may be closed with cervicofacial, nasolabial, or other locoregional flaps.

Eyelid wounds

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

Nose wounds and resultant nose reconstruction can be challenging; reconstructive considerations include the following:

  • Cartilaginous defects may require grafts from the septum, ear, or costal cartilages; a composite cartilage graft harvested from the ear may also be necessary

  • For small defects of the nasal dorsum, soft-tissue coverage may require a dorsal nasal flap

  • A nasolabial flap (either pedicle or island), forehead flap, or Washio flap may be required for larger defects

Indications for hospitalization

Acutely, any patient with an injury severe enough to require operative exploration should be observed overnight postoperatively. Some may well require a longer stay, but this is dictated by the specific clinical situation. In certain high-risk situations, admission may also be reasonable (eg, noncompliant alcoholic patient with a bite wound to the hand).

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Outpatient Care and Monitoring

Patients evaluated early, without evidence of infection, and without hand wounds may be treated on an outpatient basis without antibiotics. However, it is generally recommended that patients return within 48-72 hours for reassessment. The development of any signs or symptoms of infection indicate a need for the patient to seek immediate medical attention.

Subacutely, patients with mild-to-moderate infections or hand wounds without infection may also be treated on an outpatient basis, with oral antibiotics, if they are likely to be compliant with the overall treatment plan. Some indications for admission include the following:

  • Evidence of systemic toxicity (fever, elevated WBC count, ill appearance)

  • Infected bite wounds of the hand

  • Failure of previously instituted outpatient treatment

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Consultations

A multidisciplinary approach can lead to maximum patient benefit in certain circumstances. Refer to a hand surgeon any hand injury with suspicion of tendon injury, fracture, joint-space violation, retained foreign body, injury to a nerve or vessel, or significant tissue loss. These have a significant risk for permanent disability and should be referred to a hand therapist.

Refer to a plastic surgeon, otolaryngological (ENT) surgeon, or maxillofacial surgeon any head or neck wound with suspicion of violation of cartilage, retained foreign body, or injury to nerves, vessels, or another complex structure. Also refer to the appropriate surgical subspecialist any wounds involving significant tissue loss that has created difficult closure.

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