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Human Bites

  • Author: Jeffrey Barrett, MD; Chief Editor: John L Brusch, MD, FACP  more...
 
Updated: Mar 22, 2016
 

Background

Approximately 10%-15% of human bite wounds become infected owing to multiple factors. The bacterial inoculum of human bite wounds contains as many as 100 million organisms per milliliter and is made up of as many as 190 different species. Many of these are anaerobes that flourish in the low redox environment of tartar that lies between human teeth or in areas of gingivitis. Most injuries due to human bites involve the hands. Hand wounds, regardless of the etiology, have a higher rate of infection than do those in other a locations. (See Pathophysiology and Etiology.)

Infections associated with human bites are often far advanced by the time they receive appropriate care. Patients often wait until infection is well established before seeking medical treatment. These wounds are frequently more extensive than estimated on initial examination by the inexperienced observer and are frequently managed inadequately. (See Prognosis, Presentation, Treatment, and Medication.)

Human bites have been shown to transmit hepatitis B, hepatitis C, herpes simplex virus (HSV), syphilis, tuberculosis, actinomycosis, and tetanus.

Evidence suggests that it is biologically possible, but quite unlikely, to transmit human immunodeficiency virus (HIV) through human bites. (See Pathophysiology, Presentation, and Workup.)

The goals of therapy are to minimize possible soft tissue deformity and to prevent or appropriately treat infection. Recognition of the high risk of infectious complications and early aggressive treatment are mandatory to prevent serious wound infection and its associated complications.[1, 2] (See Prognosis, Treatment, and Medication.)

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Pathophysiology

Human bite wounds occur as 2 separate entities: clenched-fist injuries and occlusive bites.

Clenched-fist injury

Clenched-fist injuries are the most common and have the greater clinical significance. They occur as the closed fist strikes the teeth of another individual with sufficient force to create a small wound, usually 3-8 mm in length. The injury usually occurs over the dorsal surface of the third and fourth metacarpophalangeal (MCP) or proximal interphalangeal joints of the dominant hand. Because of the thinness of the skin in these areas, potential injuries include joint penetration, metacarpal fracture, and extensor tendon laceration. Injury to the digital nerve or artery is rare.

As the fingers extend following injury, the bacterial inoculum may be carried proximally with the extensor tendons. This makes adequate irrigation of the wound more difficult. These are the most serious human bite wounds, and they require the most aggressive treatment.

Occlusive bites

Occlusive bites occur when there is sufficient force to break the skin. Such injuries to the hand have a higher infection rate than similar bites to other parts of the body because of the thinness of the skin in this area.

When a finger is bitten, such as in a chomping-type injury, tendons and their overlying sheaths are in close proximity to the skin. The wound may appear to be a minor abrasion-type injury, but careful inspection is required to rule out deep injury.

Occlusive human bite wounds of the head and neck result in avulsion, laceration, and crushing of the tissues. Even so, when a tooth strikes the head, even a deep puncture wound may appear innocuous. However, deep, subgaleal, bacterial contamination is possible. This is especially true in young children who have relatively thin, soft scalp and forehead tissue.

Disease transmission

Regardless of the mechanism and anatomic location of the bite wound, the composition of the bacterial inoculum is the same. Cultures of human bite wounds are commonly polymicrobial in nature, and aerobes and anaerobes are represented almost equally. Beta-lactamase production occurs frequently. Commonly isolated aerobes include Eikenella corrodens and Staphylococcus, Streptococcus, and Corynebacterium species. Staphylococcus aureus is isolated in up to 30% of infected human bite wounds and is associated with some of the most severe infections.

E corrodens is a slow-growing, facultative, anaerobic, gram-negative bacillus. It is frequently associated with chronic infection and abscess formation. This pathogen is isolated in 30% of human bite wounds. Other commonly isolated anaerobes include Bacteroides, Fusobacteria, Prevotella, and Peptostreptococcus species.

In addition to the acute risk of localized infection, human bites pose the potential for the transmission of systemic infections, which can be life threatening. Hepatitis B transmission via human bites is well documented. In approximately 75% of patients with hepatitis B, the antigen is detectable in their saliva, and it is approximately 100 times more infectious than HIV.

Less likely is the transmission of HIV, although several cases in the literature suggest this as a mode of transmission.[3, 4] HIV is found in the saliva of affected patients, although at lower levels than in the blood. In addition, salivary inhibitors render the virus noninfective in most cases. As a result, the risk of transmission of HIV via human bites is exceedingly low.[5]

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Etiology

The causes of human bite wounds include the following:

  • Aggressive behavior, often in combination with alcohol (the cause of most clenched-fist injuries)
  • Rough sexual play or sexual assault
  • Domestic violence
  • Child abuse
  • Occupational injury to dental personnel
  • Seizure-related tongue lacerations
  • Nose biting (punishment for adultery in several cultures [6] )
  • Accidents during sporting events
  • Aggressive play of children in daycare centers
  • Self-inflicted wounds in persons who are emotionally disturbed or mentally handicapped - Lesch-Nyhan syndrome is an uncommon disorder that includes self-mutilation through biting

Institutionalized patients with poor impulse control create a high-risk environment for human bite wounds.

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Epidemiology

Occurrence in the United States

Human bites are ranked as the third leading cause of all bites seen in hospital emergency departments (after dog and cat bites), accounting for 3.6-23% of bite wounds. However, the true frequency is difficult to estimate because most human bites are probably unreported or patients fail to seek medical attention. Of those reported, approximately 60% occur in an upper extremity (most frequently the dominant one), while 15% occur in the head and neck region, most commonly the ears, nose, or lips. The remainder occur on the breasts, genitals, thighs, and other areas.

International occurrence

In a 4-year retrospective review in the United Kingdom, 421 (13%) human bites were identified out of 3136 case notes. The majority of those bitten were young males, with 44% of the males aged 16-25 years. The male-to-female ratio was 3:1.[7]

Sex- and age-related demographics

Clenched-fist infections are predominantly found in men, presumably owing to their more aggressive behavior. Occlusive bite wounds occur with equal frequency in males and females.

The peak incidence of human bites, including occlusive bites and clenched-fist injuries, occurs in individuals aged 10-34 years.

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Prognosis

The prognosis is excellent in patients who promptly seek medical attention following injury. However, patients frequently present days to weeks after injury, when the infectious process is well established. Conversely, the severity of a human bite injury may initially be underestimated, especially by an inexperienced observer, resulting in a significant delay of appropriate therapy.

Morbidity of human bites is primarily related to the degree of permanent function and/or cosmetic impairment.

Bite infections of poorly vascularized structures, such as ear cartilage, are particularly difficult to cure. In particular, in ear infections, plastic surgery is often needed to achieve an acceptable cosmetic result.

The morbidity of human bites is also related to infection and its sequelae. Prior to the era of antibiotics, up to 20% of hand bites required amputation of a finger. While amputation is seldom required today, residual scarring may result in permanent functional and/or cosmetic impairment; complications include the following:

  • Cosmetic deformity resulting from wound contraction
  • Permanent hand disability secondary to stiffness and/or chronic pain
  • Infectious tenosynovitis
  • Septic arthritis
  • Abscess formation
  • Amputation (rare)
  • Transmission of disease (eg, hepatitis B or C, HIV) [4]
  • Osteomyelitis
  • Necrotizing fasciitis

Occlusive bite injuries among toddlers placed in crowded daycare centers are usually superficial and rarely become infected.

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Patient Education

Patients must clearly understand the signs and symptoms of wound infection that signal a need to return for immediate reevaluation. These include, but are not limited to, the following:

  • Fever
  • Odor
  • Drainage
  • Purulence
  • Swelling
  • Cellulitis
  • Warmth
  • Pain
  • Decreased mobility

Patients must also clearly understand the importance of early and regular follow-up care for this seemingly minor injury, as well as the rationale for providing antibiotics and the importance of compliance with this recommendation.

Moreover, patients need to be informed of potential complications that may develop even with complete compliance with the care plan, and they should understand that wound revision for cosmetic or functional purposes may be desirable at a later date.

For patient education information, see the First Aid and Injuries Center and the Infections Center, as well as Human Bites and Tetanus.

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Contributor Information and Disclosures
Author

Jeffrey Barrett, MD Associate Professor of Emergency Medicine, Department of Emergency Medicine, Temple University School of Medicine

Jeffrey Barrett, MD is a member of the following medical societies: American Academy of Emergency Medicine, Society for Academic Emergency Medicine

Disclosure: Nothing to disclose.

Coauthor(s)

Don R Revis, Jr, MD Consulting Staff, Department of Surgery, Division of Plastic and Reconstructive Surgery, University of Florida College of Medicine

Don R Revis, Jr, MD is a member of the following medical societies: American College of Surgeons, American Society for Aesthetic Plastic Surgery, American Society of Plastic Surgeons, American Medical Association

Disclosure: Nothing to disclose.

Chief Editor

John L Brusch, MD, FACP Assistant Professor of Medicine, Harvard Medical School; Consulting Staff, Department of Medicine and Infectious Disease Service, Cambridge Health Alliance

John L Brusch, MD, FACP is a member of the following medical societies: American College of Physicians, Infectious Diseases Society of America

Disclosure: Nothing to disclose.

References
  1. Kennedy SA, Stoll LE, Lauder AS. Human and Other Mammalian Bite Injuries of the Hand: Evaluation and Management. J Am Acad Orthop Surg. 2015 Jan. 23 (1):47-57. [Medline].

  2. Aziz H, Rhee P, Pandit V, Tang A, Gries L, Joseph B. The current concepts in management of animal (dog, cat, snake, scorpion) and human bite wounds. J Trauma Acute Care Surg. 2015 Mar. 78 (3):641-8. [Medline].

  3. Khajotia RR, Lee E. Transmission of human immunodeficiency virus through saliva after a lip bite. Arch Intern Med. 1997 Sep 8. 157(16):1901. [Medline].

  4. Vidmar L, Poljak M, Tomazic J, Seme K, Klavs I. Transmission of HIV-1 by human bite. Lancet. 1996 Jun 22. 347(9017):1762. [Medline].

  5. Smoot EC, Choucino CM, Smoot MZ. Assessing risks of human immunodeficiency virus transmission by human bite injuries. Plast Reconstr Surg. 2006 Jun. 117(7):2538-9. [Medline].

  6. Okimura JT, Norton SA. Jealousy and mutilation: nose-biting as retribution for adultery. Lancet. 1998 Dec 19-26. 352(9145):2010-1. [Medline].

  7. Harrison M. A 4-year review of human bite injuries presenting to emergency medicine and proposed evidence-based guidelines. Injury. 2009 Aug. 40(8):826-30. [Medline].

  8. Welbury RR, Murphy JM. The dental practitioner's role in protecting children from abuse. 3. Reporting and subsequent management of abuse. Br Dent J. 1998 Feb 14. 184(3):115-9. [Medline].

  9. American Academy of Pediatrics Committee on Child Abuse and Neglect, American Academy of Pediatric Dentistry. Guideline on oral and dental aspects of child abuse and neglect. Pediatr Dent. 2005-2006. 27(7 Suppl):64-7. [Medline].

  10. Freeman AJ, Senn DR, Arendt DM. Seven hundred seventy eight bite marks: analysis by anatomic location, victim and biter demographics, type of crime, and legal disposition. J Forensic Sci. 2005 Nov. 50(6):1436-43. [Medline].

  11. Stevens DL, Bisno AL, Chambers HF, Dellinger EP, Goldstein EJ, Gorbach SL, et al. Practice guidelines for the diagnosis and management of skin and soft tissue infections: 2014 update by the infectious diseases society of America. Clin Infect Dis. 2014 Jul 15. 59 (2):147-59. [Medline].

  12. Presutti RJ. Bite wounds. Early treatment and prophylaxis against infectious complications. Postgrad Med. 1997 Apr. 101(4):243-4, 246-52, 254. [Medline].

  13. Kretsinger K, Broder KR, Cortese MM, et al. Preventing tetanus, diphtheria, and pertussis among adults: use of tetanus toxoid, reduced diphtheria toxoid and acellular pertussis vaccine recommendations of the Advisory Committee on Immunization Practices (ACIP) and recommendation of ACIP, supported by the Healthcare Infection Control Practices Advisory Committee (HICPAC), for use of Tdap among health-care personnel. MMWR Recomm Rep. 2006 Dec 15. 55:1-37. [Medline].

  14. Stevens DL, Bisno AL, Chambers HF, Everett ED, Dellinger P, Goldstein EJ, et al. Practice guidelines for the diagnosis and management of skin and soft-tissue infections. Clin Infect Dis. 2005 Nov 15. 41(10):1373-406. [Medline].

  15. Henry FP, Purcell EM, Eadie PA. The human bite injury: a clinical audit and discussion regarding the management of this alcohol fuelled phenomenon. Emerg Med J. 2007 Jul. 24 (7):455-8. [Medline].

  16. Zubowicz VN, Gravier M. Management of early human bites of the hand: a prospective randomized study. Plast Reconstr Surg. 1991 Jul. 88(1):111-4. [Medline].

  17. Baker MD, Moore SE. Human bites in children. A six-year experience. Am J Dis Child. 1987 Dec. 141(12):1285-90. [Medline].

  18. Smith DK, Grohskopf LA, Black RJ, Auerbach JD, Veronese F, Struble KA, et al. Antiretroviral postexposure prophylaxis after sexual, injection-drug use, or other nonoccupational exposure to HIV in the United States: recommendations from the U.S. Department of Health and Human Services. MMWR Recomm Rep. 2005 Jan 21. 54:1-20. [Medline].

  19. Ruskin JD, Laney TJ, Wendt SV, Markin RS. Treatment of mammalian bite wounds of the maxillofacial region. J Oral Maxillofac Surg. 1993 Feb. 51(2):174-6. [Medline].

  20. Stucker FJ, Shaw GY, Boyd S, Shockley WW. Management of animal and human bites in the head and neck. Arch Otolaryngol Head Neck Surg. 1990 Jul. 116(7):789-93. [Medline].

  21. Donkor P, Bankas DO. A study of primary closure of human bite injuries to the face. J Oral Maxillofac Surg. 1997 May. 55(5):479-81; discussion 481-2. [Medline].

  22. Uchendu BO. Primary closure of human bite losses of the lip. Plast Reconstr Surg. 1992 Nov. 90(5):841-5. [Medline].

  23. Menard P, Bertrand JC, Philippe B. [Reconstruction of the lip vermillion using a myo-mucosal advancement flap]. Rev Stomatol Chir Maxillofac. 1991. 92(1):18-21. [Medline].

  24. Walton RL, Beahm EK, Brown RE, et al. Microsurgical replantation of the lip: a multi-institutional experience. Plast Reconstr Surg. 1998 Aug. 102(2):358-68. [Medline].

  25. Godwin Y, Allison K, Waters R. Reconstruction of a large defect of the ear using a composite graft following a human bite injury. Br J Plast Surg. 1999 Mar. 52(2):152-4. [Medline].

  26. Talan DA, Abrahamian FM, Moran GJ, Citron DM, Tan JO, Goldstein EJ. Clinical presentation and bacteriologic analysis of infected human bites in patients presenting to emergency departments. Clin Infect Dis. 2003 Dec 1. 37(11):1481-9. [Medline].

  27. Goldstein EJ. Bites. Mandell GL, Bennett JE, Dolin R, eds. Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases. 7th ed. Philadelphia, Pa: Elsevier Churchill Livingstone; 2009. chap 319.

 
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