Animal bites, arthropod bites and zoonoses: SAQ

This pairing tests the two highest-stakes paediatric bite decisions in one encounter. The brother has an established infected cat bite of the hand, which carries high risk of deep structure involvement from Pasteurella and oral anaerobes inoculated through a deep puncture over a joint, and he needs irrigation, a hand-surgery assessment for septic arthritis and tenosynovitis, intravenous amoxicillin-clavulanate, and a tetanus review. The sister has a bat scratch in Australia, which is an Australian bat lyssavirus exposure until public health clears it, and she needs urgent post-exposure prophylaxis with wound washing, rabies immunoglobulin, and vaccine, begun without waiting for confirmation. [1]

Question 1 (10 marks)

Outline your immediate management of the 8-year-old boy's infected cat bite of the hand. In your answer address: (a) the likely causative organisms and why a cat bite over the proximal interphalangeal joint is high-risk; (b) your wound care, closure, and surgical decisions; (c) your antibiotic choice, route, and rationale; and (d) your tetanus and disposition plan. [1]

Marking points: recognise Pasteurella multocida plus oral anaerobes and streptococci as the polymicrobial inoculum from cat oral flora, and that the cat's long narrow teeth produce a deep puncture that seeds the tendon sheath or joint and seals over. Describe copious irrigation without primary closure of a hand bite, examination for septic arthritis and tenosynovitis with pain on passive movement, and urgent hand-surgery review with exploration if deep structure involvement is confirmed. State intravenous amoxicillin-clavulanate for an established infected hand bite with systemic features, covering Pasteurella and anaerobes, with a clear tetanus review and admission for a febrile child with a deep hand infection and twenty-four to forty-eight-hourly review. [3]

Question 2 (10 marks)

Detail your management of the 5-year-old sister's bat scratch, including the reasoning behind the urgency. In your answer address: (a) the pathogen and its natural history; (b) the specific post-exposure prophylaxis regimen and why it is begun before public health confirmation; and (c) the counselling and public health responsibilities. [2]

Marking points: identify Australian bat lyssavirus as the pathogen, clinically indistinguishable from rabies and almost universally fatal once symptomatic but virtually entirely preventable with prompt prophylaxis. Describe thorough wound washing, infiltration of rabies immunoglobulin into and around the wound, and a rabies vaccine course on days zero, three, seven, and fourteen, with immunoglobulin given only on the first visit and critical for a previously unvaccinated child. Explain that prophylaxis is never delayed for confirmation because of the incubation window and the lethality once symptomatic, and note the public health notification, documentation of the vaccine schedule, and family counselling about the rationale and the remaining doses. [2]