Francisella tularensis is a species of gram negative rods, which are non motile, non-spore forming aerobic bacteria, responsible for causing tularemia.
Portal of Entry Humans are accidental “death-end” hosts, bitten by vectors or skin contact with wild animals. Rarely ingested in infected meat, producing gastrointestinal tularemia. Also are inhaled producing pneumonia
There is no person-to-person spread.
Pathogenesis
- Form ulcers at the site of entry.
- Survive in macrophages and are transported to reticuloendothelial system
- Granulomas are formed, followed by necrosis and abscess formation.
- Endotoxin is produced, but no exotoxin.
Virulence Factors
Lipopolysaccharide serves as endotoxin.
Predisposing Factors • Contact with wild animals • Bitten by vectors • Ingestion of infected meats • Immunocompromised persons
• Cuts in skin
Clinical symptoms
Clinical symptoms depend upon the site of entry:
Handling infected animals
- Slow growing ulcer at the point of contact
- Swollen lymph nodes
Inhaled
- Sudden development of headache
- High fever
- Chills
- Body aches
- Fatigue
Ingested
- Sore throat
- Abdominal pain
- Diarrhea
- Vomiting
- Eye infections
- Ulcers
- Pneumonia
Lab- Diagnosis
Microscopy • Gram negative rods • Non motile • Non- spore forming
• Aerobic
Francisella tularensis
Culture
Rarely done because of:-
- High risk of transmission of infection to lab workers
- Special cysteine- containing medium is required for growth is not easily available
Serological tests • Agglutination test with acute and convalescent phase serum sample. • Fluorescent –antibody staining
• PCR
Francisella Tularensis – howMed
Francisella tularensis is a species of gram negative rods, which are non motile, non-spore forming aerobic bacteria, responsible for causing tularemia.
Portal of Entry Humans are accidental “death-end” hosts, bitten by vectors or skin contact with wild animals. Rarely ingested in infected meat, producing gastrointestinal tularemia. Also are inhaled producing pneumonia
There is no person-to-person spread.
Pathogenesis
Virulence Factors
Lipopolysaccharide serves as endotoxin.
Predisposing Factors • Contact with wild animals • Bitten by vectors • Ingestion of infected meats • Immunocompromised persons
• Cuts in skin
Clinical symptoms
Clinical symptoms depend upon the site of entry:
Handling infected animals
Inhaled
Ingested
Lab- Diagnosis
Microscopy • Gram negative rods • Non motile • Non- spore forming
• Aerobic
Francisella tularensis
Culture
Rarely done because of:-
Serological tests • Agglutination test with acute and convalescent phase serum sample. • Fluorescent –antibody staining
• PCR