bite injuries

Question 1

what are dog bites commonly associated with?

Answer 1

puncture, crush and tearing type injuries

Question 2

what are cat bites associated with more commonly?

Answer 2

more likely to penetrate and thus more likely to cause osteomyelitis and septic arthritis
therefore cat bites are more associated with infection than dog bites.

Question 3

How do we assess bite injuries?

Answer 3

1. document location, depth, description (include damage to underlying structures), time of bite and by which organism.
2. assess infection risk in individual: tetanus status, risk of rabies (bats in UK, dogs abroad), HIV infection in biter or unknown status, immunisation in patient (hep B/C). Inform public health of any rabies infections
3. assess wound for infection (pus, red, swelling, localised cellulitis, fever, lymphadenopathy)
4. assess NV damage and tendon damage
5. Xray to rule out fracture, any foreign bodies
6. check drug history and allergies.

Question 4

How do we manage bite injuries?

Answer 4

remove debris
encourage wound to bleed if it has just occurred
irrigate with warm water
take swabs esp if looks infected and send for culture
Abx prophylaxis for bites <72 hours old
Tetanus prophylaxis - HATI if not immunised or if high risk regardless of immunisation
Rabies prophylaxis if risk
HIV prophylaxis if risk
ensure full debridement, splinted and elevated
advice on analgesia
encourage movement once infection resolved.
tendon damage dealt with after issues healed.

Question 5

what antibiotic prophylaxis is recommended for bite injuries?

Answer 5

Non pen allergy: Co-amoxiclav TD oral for 5 days
penicillin allergy:
- animals: metronidazole and doxycycline 5 days
- human bite: metronidazole and erythromycin 5 days

Question 6

If a bite does become infected, what antibiotic treatment is advised?

Answer 6

7 days co-amoxiclav
if pen allergy 7 days metronidazole and doxycycline/erythromycin

if systemically unwell IV Abx

with infected wounds need to ensure debridement and wash out. also that cultures have been sent.

Question 7

what are the common organisms that are associated with human bites?

Answer 7

alpha and beta haemolytic streptococcus
S.aureus
S. epidermis
cornybacterium

Question 8

what organism is most commonly associated with animal bites? what type of organisms is this and what does it commonly cause?

Answer 8

Pasteurella Multocida

- gram negative coccobacillus 
- causes abscess's, cellulitis and joint infections and may cause tenosynovitis in hand bites

other organisms in animal bites: streptococci, staphylococci , Neisseria and morexella

Question 9

what antibiotic is Pasteurella Multocida resistant to? what does this mean about treatment of animal bites?

Answer 9

erythromycin and flucoxacillin

Therefore for penicillin resistant individuals don’t give erythromycin must instead give metrondizaole and DOXYCYCLINE

Question 10

what are the risk factors to infection after a bite injury?

Answer 10

immunocompromised
peripheral vascular disease
diabetes 
alcohol 
age >50 
delayed treatment 
bite to feet, hand or major joint