Francisella

Tularaemia takes several forms depending on the route of entry. Ulceroglandular disease, the commonest, follows a tick or deerfly bite or handling an infected rabbit and produces a punched-out skin ulcer with tender regional lymphadenopathy. Glandular disease has adenopathy without an ulcer; oculoglandular follows conjunctival inoculation; oropharyngeal follows ingestion of contaminated meat or water; and pneumonic tularaemia, from inhalation during lawn mowing over an animal carcass or from deliberate aerosol release, is the most lethal form. The organism requires cysteine-enriched media such as buffered charcoal yeast extract or Thayer-Martin with cysteine, and the microbiology laboratory must be warned because of the risk of laboratory-acquired infection; diagnosis is usually serological rather than by culture. It survives within macrophages, so treatment is with an aminoglycoside, streptomycin or gentamicin, and beta-lactams fail. Doxycycline and ciprofloxacin are alternatives with a higher relapse rate.