Ch1 Flashcards
(28 cards)
What is Brucella?
Gram-negative, nonencapsulated coccobacilli that cause brucellosis, a zoonotic disease affecting both animals and humans.
What are alternative names for brucellosis?
Undulant fever and Malta fever.
What are the distinguishing features of Brucella?
Gram-negative coccobacilli, slow-growing, strictly aerobic (some strains require CO₂), facultative intracellular, smooth and rough colony types, lack exotoxins but have less toxic endotoxin, zoonotic, culture is hazardous, potential bioterrorism agent.
Which Brucella species are associated with humans and their hosts?
B. abortus: Mild, rare suppuration, from cattle; B. melitensis: Severe, abscesses/osteomyelitis, from goats/sheep; B. suis: Chronic, destructive, from swine/hares/reindeer/rodents; B. canis: Mild, relapsing fever, from dogs and canids.
What are the key virulence factors of Brucella?
Endotoxin with O chain of LPS; Intracellular survival inside macrophages; Disseminates to spleen, liver, bone marrow, lymph nodes, kidneys; Granuloma formation with central necrosis.
What are the epidemiological highlights of brucellosis?
> 500,000 cases/year worldwide. Endemic in Latin America, Africa, Mediterranean, Middle East, and Western Asia. Palestine had only 2 cases in 2023.
Who are high-risk groups for brucellosis?
Animal handlers, veterinarians, lab personnel, consumers of unpasteurized dairy, and people in endemic regions.
What are the modes of transmission of brucellosis?
Direct contact (animal handling), ingestion (unpasteurized dairy), inhalation (lab exposure), and less commonly through conjunctiva, blood transfusion, or transplacental transmission.
What is the incubation period and symptoms of brucellosis?
1–3 weeks. Symptoms include undulant fever, malaise, fatigue, sweats, myalgia, arthralgia, weight loss, nonproductive cough, and possibly GI or respiratory symptoms in advanced cases.
How is brucellosis diagnosed?
Hazardous culture, serum agglutination test (>1:160), or PCR. Fourfold rise in antibody titers is diagnostic.
What is the treatment for brucellosis?
First-line: Doxycycline + Rifampin for 6+ weeks; Children: Rifampin + Cotrimoxazole; Not effective: Penicillins, cephalosporins, macrolides, fluoroquinolones; Note: High relapse rate if treatment is inadequate.
How can brucellosis be prevented and controlled?
Vaccinate animals (RB51 for B. abortus); Eliminate infected herds; Avoid unpasteurized dairy; Lab safety, protective gear; No human vaccine currently.
What is Bartonella?
Gram-negative, facultative intracellular bacteria (35 species), causes recurrent fevers and vasoproliferative lesions.
What are the 3 major human pathogens in Bartonella?
B. bacilliformis, B. henselae, B. quintana.
What are the transmission routes of Bartonella species?
B. bacilliformis: Sandfly (Phlebotomus); B. quintana: Human body lice; B. henselae: Cat scratches, bites, fleas.
Describe the phases of Carrión’s disease (B. bacilliformis).
Acute: Oroya fever – hemolytic anemia, fever, myalgia; Chronic: Verruga peruana – angioproliferative skin nodules.
What are the clinical features of B. quintana (trench fever)?
Severe headache, relapsing 5-day fevers, tibia pain, weakness, and bone pain. May lead to bacillary angiomatosis and endocarditis in immunocompromised patients.
What are the clinical features of B. henselae (cat scratch disease)?
Regional lymphadenopathy (self-limited), and in immunocompromised: bacillary angiomatosis, endocarditis, peliosis hepatis, splenic peliosis, Parinaud’s oculoglandular syndrome.
How does Bartonella evade the immune system?
Invades endothelial cells and erythrocytes; Suppresses host immunity; Upregulates VEGF (angiogenesis); Hides in RBCs (no MHC expression); Type IV secretion system.
How is Bartonella diagnosed?
Blood culture (2–6 weeks); Serology (IgM/IgG titers); PCR; Histopathology with Warthin-Starry stain.
What are treatment options for Bartonella infections?
B. bacilliformis: Chloramphenicol or ciprofloxacin; B. henselae: Azithromycin (mild), Doxycycline + Rifampin (severe); B. quintana: Doxycycline, erythromycin, or azithromycin; Supportive care for complications.
How can Bartonella infections be prevented?
Personal hygiene (lice), avoid cat scratches/bites, vector control (sandfly, flea), early diagnosis and treatment.
What is Streptobacillus moniliformis?
Gram-negative, pleomorphic rod. Long, thin, poor staining, forms granules, bead-like chains, and long filaments. Found in rats’ nasopharynx.
How is Streptobacillus transmitted?
Mainly through rat bites/scratches. Also via contaminated food/water (Haverhill fever). Risk groups: children with pet rats, lab workers, pet shop employees.
