Francisella tularensis: Difference between revisions

Revision as of 18:48, 16 August 2020

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

Microbiology

A fastidious Gram-negative coccobacillus
Multiple subspecies, including tularensis, holarctica, novocida, mediasiatica, and related species Francisella philomiragia and Francisella hispaniensis

History

Discovered in 1911 in Tulare county, California
Many names: deer fly fever, rabbit fever, etc...

Epidemiology

Zoonotic infection whose main animal reservoirs are rodents and rabbits
- In North America, the most important reservoirs are Sylvilagus species (especially Sylvilagus nuttalii, the cottontail rabbit) and Lepus species lagomorphs (rabbits), and a number of rodents including voles, squirrels, muskrats, and beavers
- In Europe, the reservoirs include voles, hamsters, mice, and hares
Essentially worldwide Northern Hemisphere distribution, especially in the US, Japan, Russia, and Scandinavian countries
Transmission:
- Vector-borne
  - In North America, by Amblyomma americanum ticks, Dermacentor variabilis ticks, Dermacentor andersoni ticks, Chrysops discalis deer flies
  - In Europe, Aedes cinereus and Ochlerotatus exrucians mosquitoes are more important, as well as Chrysops relictus deer flies and Haematopota pluvialis horse flies
- Direct contact with animal products, including skinning, dressing, and eating wild game
- Inhalation of aerosolized vectors (e.g. lawn-mowing), contact with contaminated water or mud, and animal bites of animals that have killed infected reservoir hosts (e.g. cats killing rodents)

Clinical Manifestations

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

Diagnosis

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

Management

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

@@ Line 1: / Line 1: @@
-* Zoonontic infection carried on rodents and rabbits and transmitted by biting insects
+*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
+*Presentation depends on route of entry: (ulcero)glandular, oculoglandular, pharyngeal, typhoidal, or pneumonic
-* Treatment is streptomycin
+*Treatment is streptomycin
-== Background ==
+==Background==
-=== Microbiology ===
+===Microbiology===
-* A fastidious [[Stain::Gram-negative]] [[Cellular shape::coccobacillus]]
+*A fastidious [[Stain::Gram-negative]] [[Cellular shape::coccobacillus]]
-=== History ===
+*Multiple subspecies, including ''tularensis'', ''holarctica'', ''novocida'', ''mediasiatica'', and related species ''Francisella philomiragia'' and ''Francisella hispaniensis''
-* Discovered in 1911 in Tulare county, California
-* Many names: deer fly fever, rabbit fever, etc...
-=== Epidemiology ===
+===History===
-* 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
+*Discovered in 1911 in Tulare county, California
-== Clinical Manifestations ==
+*Many names: deer fly fever, rabbit fever, etc...
-* '''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
-== Diagnosis ==
+===Epidemiology===
-* 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
+*Zoonotic infection whose main animal reservoirs are rodents and rabbits
-== Management ==
+**In North America, the most important reservoirs are [[Sylvilagus species]] (especially [[Sylvilagus nuttalii]], the cottontail rabbit) and [[Lepus species]] lagomorphs (rabbits), and a number of rodents including voles, squirrels, muskrats, and beavers
-* For severe disease, [[Is treated by::streptomycin]] 10 mg/kg (max 1 g) IM q12h for 7 to 10 days
+**In Europe, the reservoirs include voles, hamsters, mice, and hares
-** Alternatives include [[Is treated by::gentamicin]] or [[Is treated by::amikacin]]
+*Essentially worldwide Northern Hemisphere distribution, especially in the US, Japan, Russia, and Scandinavian countries
-* For mild to moderate disease, alternatives include:
+*Transmission:
-** [[Is treated by::Doxycycline]] 100 mg po bid for 14 to 21 days
+**Vector-borne
-** [[Is treated by::Ciprofloxacin]] 500 mg po bid for 10 to 14 days
+***In North America, by [[Vector::Amblyomma americanum]] ticks, [[Vector::Dermacentor variabilis]] ticks, [[Vector::Dermacentor andersoni]] ticks, [[Vector::Chrysops discalis]] deer flies
-* For meningitis, use an aminoglycoside (as above) plus either IV ciprofloxacin, doxycycline, or chloramphenicol for 14 to 21 days
+***In Europe, [[Vector::Aedes cinereus]] and [[Vector::Ochlerotatus exrucians]] mosquitoes are more important, as well as [[Vector::Chrysops relictus]] deer flies and [[Vector::Haematopota pluvialis]] horse flies
-** Aminoglycosides have poor CNS penetration
+**Direct contact with animal products, including skinning, dressing, and eating wild game
+**Inhalation of aerosolized vectors (e.g. lawn-mowing), contact with contaminated water or mud, and animal bites of animals that have killed infected reservoir hosts (e.g. cats killing rodents)
+==Clinical Manifestations==
+*'''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
+==Diagnosis==
+*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
+==Management==
+*For severe disease, [[Is treated by::streptomycin]] 10 mg/kg (max 1 g) IM q12h for 7 to 10 days
+**Alternatives include [[Is treated by::gentamicin]] or [[Is treated by::amikacin]]
+*For mild to moderate disease, alternatives include:
+**[[Is treated by::Doxycycline]] 100 mg po bid for 14 to 21 days
+**[[Is treated by::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
 {{DISPLAYTITLE:''Francisella tularensis''}}