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Questions and Answers
Which bacterium causes whooping cough?
Which bacterium causes whooping cough?
- Brucella abortus
- Brucella suis
- Brucella melitensis
- Bordetella pertussis (correct)
What is the major attachment factor produced by virulent Bordetella species?
What is the major attachment factor produced by virulent Bordetella species?
- Pertussis toxin (PTx)
- Filamentous heamagglutinin (FHA) (correct)
- Adenylate cyclase toxin
- Tracheal cytotoxin
Brucella is a zoonotic disease.
Brucella is a zoonotic disease.
True (A)
The Bordetella species causing whooping cough is Bordetella ____________.
The Bordetella species causing whooping cough is Bordetella ____________.
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Study Notes
Bordetella
- Small, Gram-negative, aerobic, encapsulated coccobacilli
- Most important species: Bordetella pertussis
- Virulence factors:
- Attachment factors: Filamentous hemagglutinin (FHA), Pertussis toxin (PTx)
- Factors mediating tissue damage: PTx, Adenylate cyclase toxin, Tracheal cytotoxin, Endotoxin
- Causes whooping cough
- Culture characteristics:
- Enriched medium (blood)
- Bordet-Gengou agar (blood agar + growth factor)
- Charcoal blood agar
- Slow grower (6-7 days at 37°C)
- Colonies characterized by mercury droplets appearance
Whooping Cough
- Incubation period: 1-2 weeks
- Acute respiratory disease (mainly affects children)
- Transmitted via inhalation of droplets
- Non-invasive organism
- Stages:
- Catarrhal stage (1-2 weeks): attachment and adhesion, virulence factors: FHA, PTx
- Paroxysmal stage (3 weeks): tissue damage, virulence factors: PTx, Adenylate cyclase toxin, Tracheal cytotoxin, Endotoxin
- Convalescent stage (3 weeks): slow recovery, no organism
Diagnosis
- Can be diagnosed clinically
- Specimens: Nasopharyngeal secretion swab, Aspiration of Nasopharyngeal secretion, Cough plate
- Direct detection: Direct Fluorescent Assay (DFA), Polymerase Chain Reaction (PCR)
- Culture: Bordet-Gengou agar, Charcoal agar
- Identification: Oxidase +ve, Catalase +ve, Morphology: mercury droplets appearance
Treatment and Prevention
- Treatment: Erythromycin
- Prevention: Whooping cough vaccine (killed whole cell vaccine, part of DPT vaccine), Acellular vaccine (genetically inactivated PTx) (DTaP)
- Chemoprophylaxis: Erythromycin
Brucella
- Named after David Bruce (1855-1931)
- Characteristics: Short, Gram-negative, aerobic, non-motile, non-capsulated, facultative intracellular pathogen
- Zoonotic disease: primary infection in animals
- Members of the genus: Brucella abortus, Brucella melitensis, Brucella suis
Brucellosis
- Undulant fever or malt fever
- Zoonotic
- Mode of transmission: ingestion of animal secretion, direct contact with infected animal, inhalation of animal secretion
- Pathogenesis: Endotoxin is the major virulence factor
- Clinical manifestation: Fever, chill, sweating, headache, malaise, weakness, undulant fever, body ache, enlarged lymph nodes, liver, spleen, osteomyelitis, meningitis
- Lab diagnosis:
- Specimens: blood, bone marrow (invasive), other samples (according to site of infection)
- Direct detection and cultivation (dangerous)
- Serology: Standard tube agglutination test, ELISA, Brucellin Test
Treatment and Prevention
- Combination therapy for long time: Doxycycline & Rifampicin
- Prevention: Control of infected animal, Live attenuated vaccine for cattle, Pasteurization of milk
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