Francisella tularensis

Zoonontic infection carried on rodents and rabbits and transmitted by biting insects
Presentation depends on route of entry: (ulcero)glandular, oculoglandular, pharyngeal, typhoidal, or pneumonic
Treatment is streptomycin

Background

Zoonotic infection whose main animal reservoirs are rodents and rabbits
Essentially worldwide Northern Hemisphere distribution, especially in the US, Japan, Russia, and Scandinavian countries
Transmission:
- Bite of ticks, biting flies, or mosquitoes (Europe)
- Exposure to animal products, including skinning, dressing, and eating wild game
- Also from animal stool or bites, including cats that have killed infected rodents

Ulceroglandular: ulcer develops at site of inoculation with tender lymphadenopathy and systemic symptoms
Glandular: ulcer is undetectable or healed, only lymphadenopathy and systemic illness remains
Oculoglandular: entry through the conjuctiva
Pharyngeal: entry through the oropharynx, with exudative pharyngitis/tonsillitis
Typhoidal: febrile illness without lymphadenopathy or ulcer, sometimes with diarrhea; patient often has an underlying chronic disease
Pneumonic: direct inhalation, often from sheep shearing, landscaping, and microbiology laboratory work

Culture
- Grows slowly on standard culture media, needs cystine-rich media (e.g. chocolate agar, BHI, or cystine media)
- Looks bacillary in logarithmic growth phase (small Gram-negative rod), slow-growing only on chocolate agar
Serology (EIA) can be used in the right context
PCR

For severe disease, streptomycin 10 mg/kg (max 1 g) IM q12h for 7 to 10 days
- Alternatives include gentamicin or amikacin
For mild to moderate disease, alternatives include:
- Doxycycline 100 mg po bid for 14 to 21 days
- Ciprofloxacin 500 mg po bid for 10 to 14 days
For meningitis, use an aminoglycoside (as above) plus either IV ciprofloxacin, doxycycline, or chloramphenicol for 14 to 21 days
- Aminoglycosides have poor CNS penetration