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Questions and Answers
Why is routine laboratory culturing of Francisella tularensis discouraged?
Why is routine laboratory culturing of Francisella tularensis discouraged?
- The organism is an obligate anaerobe, making standard aerobic culturing techniques ineffective.
- Growth requires specific media supplemented with cysteine and poses a biosafety risk. (correct)
- The organism's rapid growth kinetics and minimal nutritional requirements lead to overgrowth in cultures, obscuring results.
- It only grows on blood agar and inhibits the growth of other organisms.
Which factor primarily dictates the variance in clinical manifestations of tularemia, ranging from mild to fulminant?
Which factor primarily dictates the variance in clinical manifestations of tularemia, ranging from mild to fulminant?
- The specific antibiotic administered during the initial treatment stages.
- The patient's age and pre-existing immunity levels.
- The route of exposure, host immune response, and the virulence of the _Francisella tularensis_ strain. (correct)
- Environmental factors, such as humidity and temperature, during the infection period.
How does Francisella tularensis' intracellular lifestyle contribute to its virulence and pathogenicity?
How does Francisella tularensis' intracellular lifestyle contribute to its virulence and pathogenicity?
- By infecting cells involved in the immune response, such as macrophages and dendritic cells, the bacteria can evade immune clearance. (correct)
- By replicating within host cells, the bacteria efficiently disseminate to other susceptible hosts through direct contact.
- Intracellular survival enables the bacteria to enhance expression of antibiotic-resistance genes.
- Intracellular localization facilitates direct horizontal gene transfer between bacteria, accelerating adaptation.
Why is Francisella tularensis considered a potential biological weapon?
Why is Francisella tularensis considered a potential biological weapon?
What is the significance of the pleomorphic nature of Francisella tularensis in the context of diagnostic microbiology?
What is the significance of the pleomorphic nature of Francisella tularensis in the context of diagnostic microbiology?
In regions such as Arkansas and Missouri, why are most cases of tularemia observed during wet summers?
In regions such as Arkansas and Missouri, why are most cases of tularemia observed during wet summers?
Why might tetracycline be added to a treatment regimen including Streptomycin or gentamicin for Tularemia?
Why might tetracycline be added to a treatment regimen including Streptomycin or gentamicin for Tularemia?
Which of the following statements accurately characterizes the geographical distribution and prevalence of Francisella tularensis?
Which of the following statements accurately characterizes the geographical distribution and prevalence of Francisella tularensis?
Which aspect of the immune evasion strategy employed by Francisella tularensis most directly facilitates its systemic spread within an infected host?
Which aspect of the immune evasion strategy employed by Francisella tularensis most directly facilitates its systemic spread within an infected host?
How might a laboratory diagnose Francisella tularensis, given that routine cultures aren't commonly performed?
How might a laboratory diagnose Francisella tularensis, given that routine cultures aren't commonly performed?
Flashcards
Francisella tularensis
Francisella tularensis
A zoonotic pathogen that causes rabbit and deerfly fever. Carried by rabbits, deer, and rodents.
Type A F. tularensis
Type A F. tularensis
More virulent strain of Francisella tularensis, found in the U.S.
Type B F. tularensis
Type B F. tularensis
Less virulent strain of Francisella tularensis, found in Europe.
Infectious Nature of F. tularensis
Infectious Nature of F. tularensis
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Cells Primarily Infected by F. tularensis
Cells Primarily Infected by F. tularensis
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Growth Requirements of F. tularensis
Growth Requirements of F. tularensis
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Risk Groups for Tularemia
Risk Groups for Tularemia
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Vectors of Francisella tularensis
Vectors of Francisella tularensis
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Ulceroglandular Tularemia
Ulceroglandular Tularemia
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Pneumonic Tularemia
Pneumonic Tularemia
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Study Notes
- Francisella tularensis is a zoonotic pathogen.
- It is the causative agent of rabbit and deerfly fever.
- Rabbits, deer and various rodents are carriers of this bacterium.
- Type A is more virulent and is present in the U.S.
- Type B is less virulent and is found in Europe.
- F. tularensis is gram-negative, pleomorphic coccobacilli.
- F. tularensis is an obligate aerobe, non-motile, and intracellular pathogen.
- It is one of the most infectious pathogenic bacteria known.
- Inhalation or inoculation of as few as 10 organisms can cause disease.
- This bacterium is a dangerous potential biologic weapon.
- It primarily infects reticuloendothelial cells such as macrophages, dendritic cells, and hepatocytes
- F. tularensis has complex/fastidious growth requirements (requires cysteine).
- It requires 3+ days before growth is detected in the culture.
- Lab diagnosis not normally done due to high contagious nature and cysteine-containing medium requirement.
- Cultures are typically performed only in specialized biosafety level 3 (BSL-3) laboratories.
- F. tularensis is enzootic in all states.
- Most cases are found in rural areas of Arkansas and Missouri.
- Risk groups include hunters, laboratory personnel, and those exposed to ticks and biting arthropods.
- Vectors include ticks, mites, and lice.
- It's transmitted to humans through the skin, causing ulceroglandular tularemia and swelling of axillary and cervical lymph nodes.
- It's transmitted to humans through ingestion of infected meat, causing GI tularemia.
- It's transmitted to humans through inhalation, causing pneumonia.
- It's transmitted to humans through tick bites which is most common in the U.C., tick-borne tularemia from a rabbit reservoir.
- Most infections occur during wet summers.
- Bacteria arrive to local lesion or regional lymph nodes and the lymph nodes enlarge.
- Lymph nodes become tender, and may suppurate.
- The bacteria then spread via the lymphatic system to various organs and tissues (skin, lungs, liver, spleen, kidneys, and CNS).
- The spectrum of symptoms varies from mild to fulminant and fatal.
- Most common symptoms are flu-like with chills, fever, headache, malaise, loss of appetite, and fatigue.
Forms of Tularemia
- Ulceroglandular tularemia is the most common presentation.
- It develops through contact with contaminated animal products or through insect bites.
- It causes formation of lesions and lymphadenopathy.
- Glandular tularemia leads to lymphadenopathy without evidence of ulceration.
- Oculoglandular tularemia occurs when the organism gains entry through the conjunctiva, which becomes inflamed.
- Pharyngeal tularemia occurs when the organism gains entry through the pharynx and causes severe sore throat.
- Pneumonic tularemia occurs through inhalation of infectious aerosols or through bacteremia spread, causing pneumonia.
- Typhoidal tularemia is caused by ingestion of undercooked meat and causes nausea, vomiting, diarrhea, and abdominal pain.
- Diagnosis includes clinical presentation and history for potential exposure.
- An agglutination test and fluorescent-antibody stain of infected tissue can be performed.
- Treatment includes Streptomycin or gentamicin + tetracycline.
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