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Bite, Animal, Emergency Medicine

Basics

Description

- Catscratch disease (CSD): - 3 of the following 4 criteria: - Cat contact, with presence of scratch or inoculation lesion of the skin, eye, or mucous membrane - Positive CSD skin test result - Characteristic lymph node histopathology - Negative results of lab studies for other causes of lymphadenopathy

- Catscratch disease: - From the bite/scratch of a cat, dog, or monkey - Small macule or vesicle that progresses to a papule: - Begins several days (3-10) after inoculation - Resolves within several days or weeks - Regional lymphadenopathy occurs 3 wk postinoculation - Tender - Nonsuppurative - Resolves after 2-4 mo

- S. minus - Incubation period from 1-3 wk - More common in Asia - Arthritis not common

- Antibiotic indications: - Infected wounds - Cat bites - Hand injuries - Severe wounds with crush injury - Puncture wounds - Full-thickness puncture of hand, face, or lower extremity - Wounds requiring surgical d ©bridement - Wounds involving joints, tendons, ligaments, or fractures - Immunocompromised patients - Wounds presenting >8 hr after the event

- Catscratch disease: - Analgesics - Apply local heat to affected nodes. - Avoid lymph node trauma. - Disease usually self-limiting - Antibiotics controversial, consider if severe disease is present or immunocompromised victim

- All bites: - Infected wounds at presentation - Severe/advancing cellulitis/lymphangitis - Signs of systemic infection - Infected wounds that have failed to respond to outpatient (PO) antibiotics

  • Most bites are from provoked animals.
  • Dog bite wounds:Large dogs inflict the most serious wounds (pit bulls cause the most human fatalities).Most fatalities in children (70%) due to bites to face/neckDogs of family or friends account for most bites.
  • Cat bite wounds:Majority from pets known to victim50% infection rate in those seeking carePuncture wounds most frequent due to sharp thin teeth causing deep inoculation of bacteria
  • Catscratch disease (CSD):3 of the following 4 criteria:Cat contact, with presence of scratch or inoculation lesion of the skin, eye, or mucous membranePositive CSD skin test resultCharacteristic lymph node histopathologyNegative results of lab studies for other causes of lymphadenopathy
  • Rat bite wounds:Occur in lab personnel or children of low socioeconomic classRat-bite fever (RBF), rare in US but high mortality rateRat bites rarely transmit rabies, and prophylaxis not routine

Etiology

  • Dog and cat bites:Pasteurella multocida is the major organism in both:Twice as likely to be found in cat bites than dog bitesGram-negative aerobe found in up to 80% of cat infectionsInfection appears in <24 hrStaphylococcus or Streptococcus:Infection appears in >24 hrOther organisms include anaerobes and Capnocytophaga canimorsus (dogs).
  • Catscratch disease:Caused by Bartonella henselae
  • Rat bites:Caused by Spirillum minus and Streptobacillus moniliformis (RBF)

Diagnosis

Signs and Symptoms

  • Distribution of mammalian bites:Dog bites represent 80-90% of all bites.Cat bites represent 5-15% of all bites.Human bites represent 2-5% of all bites (see "Human Bite" chapter).Rat bites represent 2-3% of all bites.
  • Dog bites:Appearance:Crush injuries (most common), tears, avulsions, punctures, and scratchesLow rates of infection compared with cat and human bitesInfections usually present with:cellulitismalodorous gray dischargefeverlymphadenopathy
  • Cat bites:Appearance:Puncture wounds (most common)AbrasionsLacerationsHigh infection rates (30-50%) due to deeper puncture wounds
  • Catscratch disease:From the bite/scratch of a cat, dog, or monkeySmall macule or vesicle that progresses to a papule:Begins several days (3-10) after inoculationResolves within several days or weeksRegional lymphadenopathy occurs 3 wk postinoculationTenderNonsuppurativeResolves after 2-4 moLow-grade fever, malaise, headache
  • Rat-bite fever:Does not have to involve a bite. Can occur from handling of ratsS. moniliformis:Begins several days (2-10) after exposureCommon in USFever, rigors, migratory polyarthralgias, headaches, nausea, and vomitingS. minusIncubation period from 1-3 wkMore common in AsiaArthritis not common

History

  • Animals behavior, provocation, location, ownership
  • Time since attack
  • Past medical history: Conditions compromising immune function, allergies, and tetanus status

Physical Exam

  • Record the location and extent of all injuries.
  • Document any swelling, crush injuries, or devitalized tissue.
  • Note the range of motion of affected areas.
  • Note the status of tendon and nerve function.
  • Document any signs of infection, including regional adenopathy.
  • Document any joint or bone involvement.

Diagnosis Tests & Interpretation

Lab

  • Aerobic and anaerobic cultures from any infected bite wound
  • Cultures not routinely indicated if wounds not clinically infected
  • Catscratch disease:Presence of elevated titers of B. (Rochalimaea) henselae, orPositive reaction to catscratch antigen (CSA):Inject 0.1 mL CSA IMInduration at the site 48-72 hr later equal to or exceeding 5 mm is positive

Imaging

Plain radiograph indications:

  • Fracture
  • Suspect foreign body (e.g., tooth)
  • Baseline film if a bone or joint space has been violated in evaluating for osteomyelitis
  • For infection in proximity to a bone or joint space

Differential Diagnosis

  • Human bite injuries: Human teeth cause crush injuries and animal teeth cause more punctures and lacerations.
  • Bite injuries from other animals
  • CSD-caused lymphadenopathy:Reactive hyperplasia (leading cause of lymphadenopathy in children <16 yr)Infection, chronic lymphadenitis, drug reaction, malignancy, and congenital conditions

Treatment

Pre-Hospital

Apply pressure to any bleeding wound

Initial Stabilization/Therapy

  • Achieve hemostasis on any bleeding wound.
  • Airway stabilization if bite located on face or neck

Ed Treatment/Procedures

  • Wound irrigation:Copious volumes of normal saline irrigation with an 18G plastic catheter tip aimed in the direction of the puncture.Avoid injection of saline through tissue planes due to force of irrigation.
  • D ©bridement:Remove foreign material, necrotic skin tags, or devitalized tissues.Do not d ©bride puncture wounds.Remove any eschar present so underlying pus may be expressed and irrigated.
  • Wound closure:Closing wounds increases risk of infection and must be balanced with scar formation and effect of leaving wound open to heal secondarily.Do not suture infected wounds or wounds >24 hr after injury.Repair of wounds >8 hr: ControversialClose facial wounds (warn patient of high risk of infection).Infected wounds, those presenting >24 hr after the event, and deep hand wounds should be left open.May approximate the wound edges with Steri-Strips and perform a delayed primary closure.
  • Antibiotic indications:Infected woundsCat bitesHand injuriesSevere wounds with crush injuryPuncture woundsFull-thickness puncture of hand, face, or lower extremityWounds requiring surgical d ©bridementWounds involving joints, tendons, ligaments, or fracturesImmunocompromised patientsWounds presenting >8 hr after the event
  • Elevate injured extremity
  • Tetanus prophylaxis
  • Rabies immunoprophylaxis:Not required if rabies not known or suspectedRodents (squirrels, hamsters, rats, mice) and rabbits rarely transmit the disease.Skunks, raccoons, bats, and foxes represent the major reservoir for rabies.See "Rabies" chapter for treatment guidelines.
  • Catscratch disease:AnalgesicsApply local heat to affected nodes.Avoid lymph node trauma.Disease usually self-limitingAntibiotics controversial, consider if severe disease is present or immunocompromised victim
  • Rat-bite fever:High mortality (10%)IV penicillin or doxycycline

Medication

First Line

  • Amoxicillin/clavulanic acid (Augmentin): 500/125 mg (peds: 40 mg/kg/24h) q8h PO
  • Ampicillin-sulbactam (Unasyn): 3 g q6h IV
  • Penicillin 1-2 million units q6h IV (peds 20,000-50,000 U/kg/d div. q4h IV)
  • Piperacillin-Tazobactam (Zosyn): 4.5 g q8h IV
  • Ticarcillin-clavulanate (Timentin): 3.1 g q4h IV
  • Ceftriaxone (Rocephin): 1 g/d plus Metronidazole (Flagyl): 500 mg q8h

Second Line

  • 2 drug therapy: 1 of the following below + anaerobic coverage:Trimethoprim-sulfamethoxazole (Septra DS): 1 tablet q12h (peds: 8 mg/kg trimethoprim and 40 mg/kg sulfamethoxazole per day divided into 2 daily doses) POPenicillin (Penicillin VK): 500 mg (peds: 50 mg/kg/24h) PO q6hCiprofloxacin (Cipro): 500-750 mg q12h PO or 400 mg q12h IVDoxycycline: 100 mg PO BID
  • + (anaerobic coverage):Clindamycin (Cleocin): 150-450 mg (peds: 8-20 mg/kg/24h) PO q6h or 600-900 mg (peds: 20-40 mg/kg/24h) IV q8hMetronidazole (Flagyl): 500 mg PO TID (peds: 10 mg/kg/dose TID)

Follow-Up

Disposition

Admission Criteria

  • All bites:Infected wounds at presentationSevere/advancing cellulitis/lymphangitisSigns of systemic infectionInfected wounds that have failed to respond to outpatient (PO) antibiotics
  • Catscratch disease:Prolonged fever, systemic symptoms, and/or marked lymphadenopathy

Discharge Criteria

  • Healthy patient with localized wound infection:Discharge on antibiotics with 24-hr follow-up.
  • Noninfected wounds:

Follow-Up Recommendations

  • Hand specialist referral/follow-up for infected hand wounds.
  • Healthy patient with localized wound infection: Discharge on antibiotics with 24-hr follow-up.
  • 48-hr follow-up for noninfected wounds

Pearls and Pitfalls

Animal bites must be reported to authorities in many localities.

Additional Reading

  • Baddour L. Soft tissue infections due to dog and cat bites. UpToDate. 2009.
  • Brook I. Microbiology and management of human and animal bite wound infections. Prim Care. 2003;30(1):25-39.
  • Elliott SP. Rat bite fever and Streptobacillus moniliformis. Clin Microbiol Rev. 2007;20:13-22.
  • Galloway RE. Mammalian bites. J Emerg Med. 1998;6:325-331.
  • Griego RD, Rosen T, Orengo IF, et al. Dog, cat, and human bites: A review. J Am Acad Dermatol. 1995;33:1019-1029.
  • Klein JD. Cat scratch disease. Pediatr Rev. 1994;15(9):348-353.
  • Pickering L. Red Book: 2003 Report of the Committee on Infectious Diseases. 26th ed. Elk Grove Village, IL: American Academy of Pediatrics; 2003.
  • Smith PF, Meadowcroft AM, May DB. Treating mammalian bite wounds. J Clin Pharm Ther. 2000;25:85-99.
  • Trucksis M. Rat-bite fever. UpToDate. May 6, 2011.

See Also (Topic, Algorithm, Electronic Media Element)

Rabies

Codes

ICD9

  • 873.40 Open wound of face, unspecified site, without mention of complication
  • 874.8 Open wound of other and unspecified parts of neck, without mention of complication
  • 882.0 Open wound of hand except finger(s) alone, without mention of complication
  • V01.5 Contact with or exposure to rabies
  • 078.3 Cat-scratch disease
  • 879.8 Open wound(s) (multiple) of unspecified site(s), without mention of complication

ICD10

  • S01.80XA Unspecified open wound of other part of head, init encntr
  • S11.90XA Unsp open wound of unspecified part of neck, init encntr
  • S61.409A Unspecified open wound of unspecified hand, init encntr
  • Z20.3 Contact with and (suspected) exposure to rabies
  • A28.1 Cat-scratch disease

SNOMED

  • 399907009 Animal bite wound (disorder)
  • 283738008 Dog bite of face (disorder)
  • 283745008 Dog bite of neck (disorder)
  • 283782004 Cat bite - wound (disorder)
  • 283786001 Rat bite - wound (disorder)
  • 283809003 Animal bite of hand (disorder)
  • 406561001 Animal bite to human by potentially rabid animal (disorder)
  • 79974007 Cat scratch disease (disorder)