HOW TO TREAT 31
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HOW TO TREAT 31
Figure 5 . Teeth and claw marks on woman ’ s leg as a result of an attack by a domestic cat .
Figure 6 . Toddler ’ s bite marks on a mother ’ s arm . their vaccination status ), the nature of the wound ( and any contamination ), and any delays to wound care and definitive management . Dog bites result in infection 2-25 % of the time , cat bites have a higher rate of infection of 30-50 % and human bites get infected 2-47 % of the time . 6 The broad ranges reflect the variability in wounds and their complexity in different studies .
When considering both prophylaxis and treatment ( if a wound presents clinically infected ), it is important to consider the oral flora of the biter , and the organisms that commonly cause infections from bite wounds from that species . Infections can relate to oral flora from the biter ( see table 1 ) or skin flora from the patient . Oral flora are by nature polymicrobial , so the table indicates some , but not all , of the possible organisms present . Standard practice for bite wounds is to treat for both aerobes and anaerobes when providing antimicrobial prophylaxis and treatment .
INVESTIGATION
IN addition to history and examination , diagnostic tests include imaging modalities for underlying tissue damage — including for fractures , vascular , neurological and tendon and muscle injuries . Swabbing wounds for culture is not helpful unless there are clinical signs of infection ( cultures of uninfected wounds will not correlate with subsequent infection ). Ultrasound ( see figure 8 ) can be considered if there is suspicion of an underlying collection associated with an infected wound . Consider a CT scan to assess for penetrating head trauma in any injury of unknown depth on the scalp . Consider an abdominal CT scan if a penetrating injury of the abdomen may have occurred . Blood tests are usually only indicated if there is active evidence of infection ,
Box 2 . High-risk bite injuries that require antimicrobial prophylaxis
• Delayed presentation ( eight hours or more ).
• Puncture wounds unable to be debrided adequately .
• Cat bites .
• Wounds on the hands , feet , face or genitals .
• Deep tissue involvement ( bones , joints , tendons ).
• Immunocompromised host , including asplenia and those with diabetes .
• Comorbid host with increased risk of infection , including cirrhosis and diabetes .
• Crush injury with devitalised tissue .
• Wound involving an open fracture .
Box 3 . Wounds that may require surgical / specialist referral
• Wounds at high risk of infection requiring washout and debridement ( cat and human bites are at greater risk than wounds from dog bites ).
• Wounds requiring interventions to assess and repair damaged or exposed structures such as vascular , nerve , tendon , muscle or bony injuries .
• Wounds with cosmetic consequences may need plastic surgery referral .
• Consider a delay in closure to reduce the infective risk in wounds other than those needing closure for cosmetic reasons ( such as facial wounds ).
• Complex or large wounds .
• Paediatric patients .
• Tissue loss or avulsion injuries .
• Bites involving deep structures ( joints , bones , tendons or blood vessels ).
• Bites over prosthetic material such as knee replacements .
• A delayed presentation , that is longer than 8-10 hours after injury .
• High-risk patients , for example those with significant immunosuppression .
if the patient is systemically unwell or has life-threatening injuries .
MANAGEMENT
Minor bite injuries
MINOR bite injuries are frequent , particularly in children . Minor injuries can be managed with exploration , debridement and irrigation . Antibiotics are only indicated for high-risk bite injuries ( see box 2 ). Bite injuries that do not penetrate the skin or have a small break in skin ( common from school or day-care injuries ), merely require wound assessment and care including examining for any underlying structural injury ( such as a crush injury ), ensuring up-to-date tetanus vaccination and that the patient is returning to a safe environment .
Wound care
Thoroughly clean the wound with saline irrigation , including any associated puncture wounds , and remove any foreign material such as teeth . Undertake debridement of any devitalised tissue . If there has been a delay of longer than 24 hours before medical review , or signs of infection are present , do not perform primary closure . However , facial injuries are often closed for cosmetic reasons and because they have a lower risk of infection .
The decision with reference to closure of wounds is made by weighing up functional consequences , cosmetic consequences , and risk of infection . Small wounds can be left open to heal
Table 1 . Specific organisms to consider in mammalian bites , according to species of biter
Biter
Organisms
Dog Capnocytophaga spp . ( 2 %) Pasteurella dagmatis Pasteurella canis ( 50 %) Pasteurella multocida ( 30 %) Staphylococci Streptococci Moraxella spp . Neisseria spp . Clostridium spp . ( including Clostridium tetani ) Anaerobes
Cat Pasteurella multocida ( 50 %) Streptococci Staphylococci Neisseria Moraxella Anaerobes Bartonella henselae ( cat-scratch disease )
Rodent Streptobacillus moniliformis ( rat-bite fever ) Spirillum minus ( rat-bite fever ) Salmonella spp . Actinobacillus
Human
Cow , horse and camel
Pig
Monkey ( see figure 7 )
Bat
Eikenella corrodens Haemophilus Viridans streptococci Streptococcus pyogenes Streptococcus anginosus Staphylococcus aureus Anaerobic bacteria Consider the risk of bloodborne viruses such as hepatitis B and C and HIV
Actinobacillus Polymicrobial
Polymicrobial Pasteurella spp . Actinobacillus spp . Pseudomonas aeruginosa Anaerobes
Polymicrobial Streptococci Haemophilus influenza Neisseria spp . Herpes B virus
Australian bat lyssavirus
Source : Abrahamian FM et al 2011 7 , Murphy J et al 2021 8