That Bites!Back to Basics

Review

Jason R. Frank MD MA(Ed) FRCPC

Presented and modified by Avik Nath

Dept of Emergency Medicine

Bites & the MCC

• According to the MCC, what are the bites that every doctor should know something about?

NEW SLIDE : MCC Objectives

MCC Key Objectives:

• Examine the patient completely to document the presence/absence of more than one wound

• Search for evidence of infection (e.g., fever, cellulitis, discharge), or joint penetration.

NEW SLIDE – Animal Bites Microbiology• COMMON BACTERIA IN ANIMAL BITES

– Pasteurella species– Staphylococci– Streptococci– Anaerobic bacteria

• Dog bites– Capnocytophaga canimorsus– Causes sepsis (esp asplenic)

• Cat bites– Bartonella henselae (organism responsible for cat scratch

disease)

• Human bites– Eikenella corrodens

Important Medical Bites

MCC List:

1. Dog bites

2. Cat bites

3. Human bites

4. Insect stings

5. Snake bites

• Other list:

1. Spider bites

2. Jellyfish stings

3. Scorpion stings

4. Tick bites

5. Bat bites

Case 1

• A 20 woman presents with this bite• Delivering fliers• Neighbourhood dog• Unsure of owner• 12 hours ago

Case 1

1. Diagnostic issues?

2. Management issues?

3. Plan for this case?

4. Epidemiology?

5. Medicolegal?

Dog Bites

• Many MD visits (12,000 bites/day US)• Usually child <5• 10-20 deaths per year US• Dx Issues:

– 6 incisors, straight, large deep punctures– Circumstances; dog ownership; safety– Nature of each wound– r/o rabies– Bacteria: anaerobes, Strep, Staph, etc

• 5-6% dog bites get infected• Rare sepsis: Capnocytophaga canimorus

Dog Bites • Tx issues:

– Abx: Clavulin; Clinda + Cipro– Tetanus– Wound management – ?Closure– Pain management– Rabies prophylaxis– Public health reporting– Safety for all

• Medicolegal– Documentation– Testimony

NEW SLIDE - Dog Bites

• Primary Closure:– Clinically uninfected– Less than 12 hours old (24 hours on the face)– NOT located on the hand or foot

• Most cat and human bites leave open

NEW SLIDE - Dog Bites • Wounds at high risk for the development of infection

– Crush injuries– Puncture wounds (cats worse than dogs)– Bites involving the hands and feet– Wounds more than 12 hours old (24 hours old on face)– Cat or human bites, except those to the face– Bite wounds in compromised hosts (eg,

immunocompromised, absent spleen or splenic dysfunction, venous stasis, diabetes mellitus [adults])

NEW SLIDE - Rabies• Rabies:

– animals uniformly begin to sicken and die within 10 days (usually five to seven days) of spread of rabies virus from the CNS to the salivary glands

– a healthy domestic dog, cat, or ferret should be confined and observed for 10 days

– If the animal remains healthy for the full 10 days, then it did not have rabies virus in its saliva at the time of exposure.

– Post-exposure prophylaxis should be given immediately if an exposing animal is rabid or suspected to be rabid

• Passive immunization – rabies immune globulin• Active immunization – rabies vaccination

– Contact public health– Unprovoked attacks are more likely by rabid than non-rabid

animals

NEW SLIDE - Rabies• Rabies:

– If the animal is available for observation, immediate prophylaxis is indicated when the animal develops clinical signs of illness.

– In addition, prophylaxis should be started if the person's significant exposure is to the head or neck, since incubation periods as short as four days have been reported in bites this close to the central nervous system

– If the animal remains well for 10 days, the regimen can be discontinued at that time.

Case 1 – Your Management?

• A 20 woman presents with this bite• Delivering fliers• Neighbourhood dog• Unsure of owner• 12 hours ago

Case 2

• 75 F• Her cat startled watching Senators win on CBC• Bit her forearm• 3 hours ago• Pain worse • What should she do?

Cat Bites

1. Diagnostic issues?

2. Management issues?

3. Plan for this case?

4. Epidemiology?

5. Medicolegal?

Cat Bites• Similar to dog bites• 60-80% infection rate• Bacteria: esp Pasturella multocida• Very rapid cellulitis• Cat-scratch LN: Bartonella

• Rx Clavulin or Doxycyline• Splint• Re-check

Case 2 – Your Plan?

• 75 F• Her cat startled watching Senators loss on CBC• Bit her forearm• 3 hours ago• Pain worse • What should she do?

Case 3

• 19 male, HBD• “Minding his own business” at a bar• Assaulted• He “won”• Punched in face• Punched the other guy – cut his knuckle on tooth• Feeling hung over• Wants to leave

Case 3

• Diagnostic issues?• Management issues?• Plan for this case?• Epidemiology?• Medicolegal?

Human Bites• Bacterial Infections

– mouth bugs, including anaerobes, Staph, Strep– Eikenella– Rx Clavulin; Pip-tazo– Tetanus

• Viral infections– HIV, Hep B, Hep C; HSV– PEP

• Wound management• “Closed fist injuries” / “Fight bites”• Other sites: ears, etc• Four incisors, oval

Case 3 – What is Your Plan?

• 19 male, HBD• “Minding his own business” at a bar• Assaulted• He “won”• Punched in face• Punched the other guy – cut his knuckle on tooth• Feeling hung over• Wants to leave

Case 4

• Bad field trip to woods• Multiple kids with “bug bites”

Case 4 continued• Hymenoptera (honeybees, bumblebees, wasps, ants)

– Anaphylaxis (IgE, non)– Remove stinger– 2’ infections (Staph, Strep)

• Tick bites– Ixodes Lyme disease (Borrelia burgdorferi)– RMSF, Ehrichiosis, babesiosis, tularemia, etc– Rx Doxycycline

• Mosquito bites– Symptomatic (NSAIDS, antihistamines)– West Nile Virus

Case 4 continued - Spiders

• Black widow spider– Aggressive females– Rare systemic– Rx antivenom if severe

• Brown Recluse / “Fiddleback”– More common– Necrotic arachnism– DIC, death– Supportive

Case 5

• 50 diabetic man bit by a snake at a petting zoo

Case 5

• Diagnostic issues?• Management issues?• Plan for this case?• Epidemiology?• Medicolegal?

Case 5 – Snake Bites

• Wound care• Identify snake• In Canada: Massasauga rattler

• Antivenom (Rx CroFab)

That Bites! - Summary

• Clear history of events, timing• Identify all wounds• Wound care• Punctures • Foreign bodies• Tetanus• Abx• Other PEP: HIV, Hep B, Hep C, Rabies• Public health• Documentation

That Bites! - Summary

MCC List:

1. Dog bites

2. Cat bites

3. Human bites

4. Insect stings1. Hymenoptera

2. Mosquitoes

5. Snake bites

• Other list:

1. Spider bites1. Black widow

2. Brown recluse

2. Tick bites1. Lyme disease

That Bites!Back to Basics

Review

Jason R. Frank MD MA(Ed) FRCPC

Presented by Avik Nath

Dept of Emergency Medicine