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American Critter Bites and Stings
Kalpesh Patel, MD
Department of Pediatric Emergency Medicine
June 14, 2006
2
Objectives
By the end of this lecture you should be able to: Describe the management and treatment for
• Marine invertebrate injuries• Insect envenomations• Reptile envenomations• Mammalian bites and common associated
infections Understand and perform initial management of
these injuries, such as• Local wound care• Venom specific antidotes• Stinger and tick removal
3
Marine Invertebrates
Irritants• Hydras• Anemones• Common purple jellyfish• Sea nettle
Toxin producers• Portuguese man-of-war• True jellyfish• Lion’s mane
Handle with care• Corals• Sea Urchins
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Irritants
Hydras• Maine to Florida and Texas coastline• Attaches to solid objects• Causes mild sting• Requires local care
Anemones• US tidal zones• Mildly toxic at worst – skin irritation
Sea nettle and common purple jellyfish• Atlantic coast• Mildly toxic - skin irritation
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Irritants - Treatment
Wash copiously with sea water or normal saline Benadryl Topical/Oral Steroids
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Toxin Producers
Nematocysts• Specialized organelles
which have toxin-coated barbed threads that fire when a tentacle is touched.
• Cannot penetrate human skin
• May discharge even when the creature is dead and washed up on the beach
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Toxin Producers
Size matters• Man of war can have tentacles
up to 75 feet long with 750,000 nematocysts each
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Toxin Producers
Toxin causes severe pain• Made of polypeptides and degradative enzymes• Causes release of inflammatory mediators,
histamine and histamine-releasing agents, serotonin
• May cause systemic symptoms N/V, abdominal rigidity Respiratory distress Arthralgias Hemolysis, renal failure Coma Severe envenomation can cause death
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Toxin Producers
Lion’s mane• Found on both coasts• Highly toxic
Instrument of death in Sherlock Holmes classic Adventure of the Lion’s Mane
• Causes severe burning• Prolonged exposure causes
muscle cramps and respiratory failure
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Toxin Producers - Treatment
3 goals:• Control shock – IV, fluids, etc.• Control venom effects
Remove tentacles from skin– Inactivate unexploded nematocysts with vinegar,
meat tenderizer, or baking soda slurry– Apply this to patient as well
• Pain relief Immobilize the wound area Codeine, Morphine, or Demerol Treat muscle spasms with 10% Calcium
gluconate 0.1ml/kg IV Topical/Oral steroids, Benadryl
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Handle with Care
Corals, Sea Urchins, Starfish• Have jagged edges or hard spines• Cause deep puncture wounds or sea lacerations• Easily leave foreign bodies• Stinging sensation, wheal formation, itching• Wound infection very common
Vibrio species, Erysipelothrix rhusiopathiae, Mycobacterium marinum
Fever Cellulitis Lymphangitis
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Handle with Care - Treatment
Copious irrigation with saline X-ray for foreign bodies
• Soak affected area in warm water• Use local anesthetic and explore sterilely
Wounds should be left open or loosely approximated
Antibiotics please• >8 y/o: Tetracycline for 10 mg/kg/dose QID• <8 y/o: Keflex or Bactrim• Add staphylococcal coverage for foreign bodies
Don’t forget tetanus prophylaxis
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Marine Vertebrates
Stingrays Catfish Scorpaenidea Sharks!
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Stingrays
Most common marine vertebrate injury Flat fish, bottom feeders, buried under sand or mud Easily stepped on causing reflex envenomation
• Venom apparatus is a serrated, retro-pointed caudal spine on the tail
• Coated in venom sheath which ruptures on skin penetration Heat labile toxin Can depress medullary respiratory centers Interfere with cardiac conduction PAINFUL
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Stingrays - Treatment
PreHospital:• Irrigate copiously with cold salt water• Flushing can help remove toxin• Control bleeding with pressure
ED:• IV fluids, Morphine 0.1mg/kg/dose for pain• Make an attempt to remove the spine• Soak extremity in hot water (104-113F) to
inactivate the venom until pain relieved• X-ray for foreign body (spine fragments)• Re-explore wound after soaking• Tetanus prophylaxis• No prophylactic antibiotics
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Scorpaenidae
Zebrafish, scorpionfish, stone fish Non-migratory, slow swimming, buried in sand Envenomation occurs when handling fish on fishing
trips Venom delivered by many small spines like the
stingray Venom also heat-labile Symptoms
• Pain, N/V• Hypotension• Tachypnea leading to apnea• MI with EKG changes
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Scorpaenidae - Treatment
Copious irrigation with saline Hot water immersion until pain relieved Morphine 0.1mg/kg/dose Close cardiopulmonary monitoring Admit to PICU if having significant systemic effects
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Catfish
Spines in the dorsal and pectoral fins• Puncture wounds and laceration• Easily break off as foreign body• Venom causes local inflammation, pain, edema,
hemorrhage, tissue necrosis Treatment
• Irrigation• Hot water immersion• Morphine 0.1mg/kg/dose• Antibiotics for gram negatives• Delayed primary closure
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Sharks!
1 in 5,000,000 chance of attack in North America Gray reef, great white, blue, mako sharks Risk factors:
• Swimming near sewer outlets• Swimming in the late afternoon/early evening• Murky warm water• Increased commotion• Deep channels• Wearing bright objects• Surfers – boards are mistaken for elephant seals,
the shark’s usual diet in California
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Sharks!
Two types of bites:• Tangential injury
Close pass slashing movement teeth of open shark mouth
• Definitive bite Vary according to the part of the body bitten
– Lacerations– Soft tissue loss– Amputation of limb– Comminuted fractures– Hemicorpectomy
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Sharks!
Hypovolemic shock• Control bleeding with pressure• DON’T EXPLORE WOUNDS PREHOSPITAL• IV fluids, blood products as soon as available• Warmth• Oxygen• Surgery• Prophylactic antibiotics – 3rd gen cephalosporin
or bactrim• Tetanus prophylaxis• Admit to PICU for significant injury
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Bugs
Largest phylum in the animal kingdom Terrestrial Invertebrates
• Centipedes/Millipedes• Ticks• Spiders• Scorpions
Insects• Bees• Hornets• Yellow Jackets• Wasps• Fire Ants
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Centipede/Millipede
Centipedes• Bites with jaws that act like stinging pincers• Extremely painful• Toxin is innocuous – local reaction only
Millipedes - harmless Treatment
• Local anesthetic at wound site• Local wound care
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Ticks
Transmit many other infectious diseases:• Spirochetes – Lyme Disease, relapsing fever• Viruses – Colorado tick fever• Rickettsiae – Rocky Mountain spotted fever• Bacteria – tularemia, ehrlichiosis, babesiosis• Protozoa
Tick paralysis – wood tick, dog tick, deer tick• Tick releases neurotoxin producing cerebellar
dysfunction and ASCENDING Weakness• Latent period for 4-7 days• Restlessness, irritability, ascending flaccid
paralysis, respiratory paralysis, death
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Tick Paralysis - Management
Diligently search for the tick Remove using blunt forceps Do not squeeze – can release infective agents Admit to hospital for ascending paralysis, PICU if
worried about respiration
Ticks – The Movie
Ticks – The Sequel
Revenge of the Tick
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Brown Recluse Spider
Southern and mid-western states
Brown violin shaped mark on dorsum of cephalothorax
Usually outdoors, but make indoor nests in closets
Shy and will only attack when provoked
Venom is cytotoxic and contains hyaluronidase like factor
Loxosceles reclusa
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Brown Recluse – Clinical Signs
2-8 hours• Local reaction with mild-moderate pain• Erythema, central blister or pustule
24 hours• Fever, chills, malaise weakness, N/V, rash with
petechiae, joint pain, DIC, hematuria, renal failure
• Subcutaneous discoloration that spreads over 3-4 days
• Spreads to 10-15 cm• Pustule drains leaving ulcerated crater that scars
Scar formation is rare after 72 hrs Reaction varies according to amount of
envenomation
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Brown Recluse - Management
Unless spider is brought for ID, definitive diagnosis cannot be made
Good local wound care If systemic symptoms, then CBC with platelets,
U/A, BUN, creatinine• Vigorous supportive care in PICU
Surgical excision and skin grafting after necrosis is demarcated
Steroids, heparin, and hyperbaric O2 don’t work
No Dapsone for kids – methemoglobinemia No antivenom available Have wound rechecked daily for progression
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Black Widow
Shiny black spider with brilliant red hourglass marking on abdomen
Only the female bite is dangerous• Male spiders are ¼ the size of
females and bite cannot penetrate human skin
Females not aggressive unless provoked or guarding egg sac
Produces a neurotoxin
Latrodectus mactans
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Black Widow – Clinical Signs
No local symptoms 1-8 hours after bite
• Generalized pain and muscle rigidity Cramping pain to abdomen, flanks, thighs,
chest• Chills• Urinary retention• Priapism• Death from cardiovascular collapse
Mortality 50% in young children
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Black Widow - Management
Children < 40kg: Antivenin given as soon as bite confirmed• Dose: 2.5ml (one vial)
Children >40kg: not as urgent to give immediately unless having respiratory difficulty or significant hypertension
Morphine or Demerol Calcium gluconate 10% solution 0.1ml/kg IV over 5
minutes for muscle cramps• Robaxin doesn’t work as well• Valium can be used, but is short lived with
variable effects Admit to PICU
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Other Spiders
Tarantulas• Do not bite unless provoked• Venom is mild and not a problem
Wolf Spider and Jumping spider• Mild venom only causes local reaction
Treatment is good local wound care
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Bees, Hornets, Yellow Jackets, & Wasps
Bees have a barbed stinger next to a venom sac which can remain in the victim’s skin
Bees die after the stinger is dislodged
The stinger must be removed if seen – don’t delay, move venom is released with time• Scraping works best, don’t pull
or squeeze Wasps, Yellow Jackets, and
Hornets can sting multiple times
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Insects
Venoms contain protein antigens which elicit an IgE antibody response
Major problem is allergic reactions and anaphylaxis• Group I – local response• Group II – Mild systemic reactions
Generalized itching and urticaria• Group III – Severe systemic reactions
Wheezing, angioneurotic edema, N/V• Group IV – Life threatening reactions
Laryngoedema, hypotension, shock Occurs in 0.5-5% of the population from insects
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Insect - Management
Group I – cold compresses Group II – Benadryl 4-5 mg/kg/day divided QID Group III
• Epinephrine 1:1000 0.01 ml SQ (max 0.3ml)• Benadryl PO
• H2 blockers
• No steroids• Admit to hospital for 23 hr obs
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Insects - Management
Group IV – may need intubation• All of the above, plus• Wheezing refractory to epinephrine may need
aminophylline 6mg/kg bolus over 20 minutes, then 1.1 mg/kg/hr infusion
• Hypotension Fluid bolus IV epinephrine 1:10,000 IV Hydrocortisone 2mg/kg Q6h
• Admit to PICU
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Insects - Management
Group III or IV reactions need referral to an allergist for hyposensitization
After obs, D/C home with EpiPen Jr.• Spring loaded autoinjectors self-administered in
the thigh• Always write for the twin pack
Contains practice syringe and 2 loaded syringes
• Parents should give this in the field AND seek further care
Avoid wearing bright colored clothing, perfumes Wear long sleeved garments, gloves when
gardening and hats Medical alert bracelets or necklaces
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Fire Ants
Common in the South Bites with jaws and pivots
head to give multiple stings Venom is an alkaloid with
direct effect on mast cell membranes
Solenopsis richteri and Solenopsis invicta
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Fire Ants – Clinical Presentation
Immediate – wheal and flare
4 hrs – vesicle 8-10 hours – vesicle
becomes umbilicated pustule
24 hrs – vesicle surrounded by painful erythematous area that lasts 3-10 days
43
Fire Ants - Treatment
Symptomatic care• Ice• Cleansing• Antihistamines for itching• Steroids, antibiotics and antihistamines don’t
have an effect on the lesions Systemic reactions are rare
44
Scorpions
Very few are dangerous to humans in North America• Centruroides sculpturatus
Grasps prey by pincers and then stings with tail Nocturnal
• Crawl into sleeping bags and unoccupied clothing
Injects an excitatory neurotoxin affecting autonomic and skeletal nervous systems• Pain, restlessness, hyperactivity, roving eye
movements, respiratory distress• Convulsions, drooling, wheezing, fever, cyanosis,
respiratory failure
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Scorpions - Management
Cryotherapy at sting site and supportive care Antivenin if symptoms persist after supportive care
• Tachycardia• Fever• Severe hypertension• Agitation
Phenobarbital or other sedative/anticonvulsants for persistent hyperactivity, convulsions or agitation
Calcium gluconate 10% 0.1ml/kg for muscle contractions
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Snakes
US has 120 different species of snakes• Only 15% poisonous
Two families:• Crotalidae (pit
vipers) 99% of snakebites
• Elapidae 1% of snakebites
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Identifying Poisonous Snakes
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Include Cottonmouth, Rattlesnake, Water moccasin, and Copperhead
Venom is a combination of necrotizing, hemotoxic, nephrotoxic and cardiotoxic substances• Mojave rattlesnake has a large fraction of
neurotoxin• Neurotoxin prevents depolarizating action of
acetylcholine (paralytic)• Proteolytic enzyme acts like hyaluronidase
causing local tissue destruction• Hemotoxic effects include hemolysis,
thrombocytopenia and fibrinogen proteolysis leading to bleeding diathesis
Crotalids
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Crotalids
Small children are more susceptible to venom given their size compared to adults causing more systemic symptoms
Bites on the head, neck or trunk hasten systemic absorption
Most bites are on the extremities Measure the distance between the two fang marks
to estimate snake size• 8mm = small snake• 8-12mm = medium snake• >12mm = large snake
10-20% of bites are “dry bites” (no venom)
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Crotalid Bites - Symptoms
5-10 min – Intense burning pain and erythema Perioral numbness Metallic taste N/V, chills, weakness, syncope, sweating Neuromuscular symptoms after a few hours:
• Diplopia, difficulty swallowing, lethargy, progressive weakness
Next 8 hours – Progressive edema at wound site Vesicles and Hemorrhagic blebs by 24 hours Edema may lead to compartment syndrome and
necrosis Secondary infection – gram-negative bacteria
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Crotalid - Management
Pre-Hospital • ABC’s• Rest• Take off jewelry and clothing from affected
extremity• Immobilize extremity and keep below level of
heart• Keep warm• NPO• Venous tourniquet (experienced hands only)• Incision and Suction kit if available (must use
within 5-10 minutes of bite)• Rapid transport to medical facility
52
Snake Bite Kits
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Crotalid - Management
ED• IV access, fluids, (Central line & CVP?) Morphine• If snake is brought to ED, treat it with respect
Many people bitten by “dead” snake Decapitated snakes bite reflexively for up to 1
hour• Measure circumference of extremity at leading
point of edema and 10 cm proximal Q30min X 6 hours, then Q4 for 24 hours
• CBC with platelets, Coags, Type and Cross, U/A • If moderate or severe poisoning, then also get
BMP, fibrinogen and ABG• Repeat labs Q4-6 hours
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Crotalid Antivenin
AVCP polyvalent antivenom• Horse serum, highly antigenic – needs skin
testing prior to giving• Don’t use it if you can get CroFAB
CroFAB• Sheep derived antibody with cleaved Fc portion
Cleared from kidneys fast• Less adverse reactions
For maximal binding, use antivenom within 4 hours of bite. Use after 12 hours is questionable. Don’t use after 24 hours.
Dosage NOT based on weight. Kids need more
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Crotalid - Management
CroFAB• Initial dose is 4-6 vials• Repeat initial dose if there is progression of
symptoms• Once there is no progression, then give either:
2 vials Q6h for 3 doses OR 2-6 vials if progression of symptoms recur
• Admit to PICU• All patients must be reexamined in 2-5 days after
bite• Watch for serum sickness up to 3 weeks out
CroFAB2
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Crotalid - Management
Local wound care Tetanus prophylaxis NO ICE to wound Watch for signs of compartment syndrome, call
surgery Debridement needed in 3-6 days
• Oxygen, Aluminum acetate 1:20 solution, triple dye
Blood products for coagulopathy No prophylactic antibiotics
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Elapids
Only 2 poisonous Elapids in US:• Eastern Coral Snake –
Found in Georgia• Arizona Coral Snake• “Red on yellow, kill a
fellow; Red on black, venom lack”
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Elapids
Uses a potent neurotoxin Local signs are minimal with little pain Several hours later, pt will develop malaise, N/V,
muscle fasciculations and weakness Neurologic signs include diplopia, difficulty talking
or swallowing, bulbar dysfunction, and generalized weakness
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Elapids - Management
Venous tourniquet, Incision and suction don’t work for coral snakes
If eastern coral snake is suspected, give antivenin• Horse serum derived, requires skin testing before
giving• Dosage is 3-5 vials IV• Repeat if signs of venom toxicity continue
No antivenin available for Arizona coral snake Admit to PICU
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Exotic Snakes
Consult a medical herpetologist or poison control (1-800-222-1222)
Contact your local zoo• Required by law to carry antivenin for the snakes
they have Report illegally possessed reptiles to the police
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Mammalian Bites
Dog bites account for 80-90% of all mammal bites Cats 5-10% Rodents 2-3% Humans 2-3% Other wild or domestic animals make up the rest
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Mammal Bites
Dogs generate strong forces and cause local crush injuries
Only 5-10% of bites become infected because wound is easily cared for and not very deep
Cat bites cause deep puncture wounds with 50% infection rate• May penetrate fascial compartments, tendons,
vessels and bones Most common bacteria: Staphylococcus &
Pasturella species Human bites are Strep viridans or Staph aureus Also many anaerobes are mixed in: Bacteroides,
Peptostreptococcus, Eikenella corrodens
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Dog Bites
Usually attack head and neck in most victims Cause lacerations of lips, nose and cheek May penetrate the skull and cause depressed skull
fracture
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Cat Bites
Usually attack upper extremities Pasturella infections are very aggressive
• Symptoms begin at 12-24 hours with erythema, significant edema and intense pain
Cats also scratch, especially the face Consider corneal abrasions Bartonella henselae
• Papule at site of scratch with later regional lymphadenopathy
• Self limited, resolves in 2-3 months• May have unusual manifestations:
encephalopathy, hepatitis, atypical pneumonia
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Human Bites
Typically involve the hand when punching someone in the mouth• Wound overlies the MCP joint, consider Boxer’s
fracture• Mild swelling in 1-2 days to site• If there is pain with active or passive finger
motion, then consider tendonitis or deep compartment syndrome
• Also consider Hepatitis B and syphilis being spread by bites
66
Rodent Bites and Other Mammals
Ratbite fever (10% infection rate) Pet owners and lab workers
• 2 forms: Haverhill fever (Streptobacillus moniliformis) Sodoku (spirullum minus)
• 1-3 week incubation period• Chills, fever, malaise, rash, headache• Both forms responsive to IV penicillin
Rabbits – tularemia
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Mammal Bites - Treatment
Meticulous and prompt wound care• Scrubbing with soft sponge and 1% povidone-
iodine solution Stronger solutions retard wound healing
• Pressure irrigation Facial wounds require primary closure for cosmesis Hand wounds should have delayed primary closure
or heal by secondary intention due to infection rate• Place a few deep sutures to bring wound
together• Skin sutures placed in 3-5 days
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Mammal Bites - Treatment
Antibiotic prophylaxis• No perfect drug, but Augmentin is close• If allergic, then a combination of clindamycin
AND a 2nd or 3rd gen cephalosporin OR Bactrim• First dose should be given in the ED
Infected bites require aggressive drainage and debridement• Obtain aerobic and anaerobic deep would
cultures• Leading edge would culture for cellulitis• Admit for IV antibiotics
Tetanus prophylaxis
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Rabies
Rabies virus• Virus transmitted through scratches, abrasions
and animal saliva contact with mucous membranes
• Causes an progressive, irreversible encephalopathy traveling up peripheral nerves to the brain Anxiety, insomnia, confusion, agitation,
hypersalivation, hydrophobia• Unprovoked attacks• Wild carnivorous animals, BATS• Rodents, squirrels and rabbits are considered
no-risk
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Rabies
If the animal can be observed, then prophylaxis can be delayed
If the animal shows signs of rabid behavior, then start the patient on prophylaxis immediately• Animal will be sacrificed and brain biopsy will be
done to look for rabies Prophylaxis is with passive antibody (RIG) and
vaccine HDCV• RIG is given once, half IM and the other half
infiltrated around bite• HDVC is given 1.0 ml IM on days 0,3,7,14, and
28 = 5 total doses.
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Questions?