Flashcards in Respiratory Pathogens Deck (70)
Name 6 pathogens that contribute to lower respiratory tract infections
- haemophilus influenza
- strep. Pneumoniae
- legionella pneumophila
- mycobacterium tuberculosis
- mycoplasma pneumonia
- chlamydia pneumonia
What are the two factors that affect the degree of pathogenicity of a disease causing organism?
- the proteins it expresses
- how effectively it can integrate environmental information
What does bacterial adhesion involve?
Surface interactions between specific receptors on the mammalian cell membrane (usually carbohydrates) and ligands (usually proteins) on the bacterial surface
What is bacterial invasion?
Bacteria invasion refers to the penetration of host cells and tissues, and is mediated by a complex array of molecules called invasins
What molecules mediate bacterial invasion?
Mechanisms that result in the evasion of host defences (x5)
- immunity at mucosal surfaces
- destruction of immune cells
- interference with inflammatory response
- evasion of innate immunity
- overcome acquired immune responses
How does the bacteria overcome acquired immune responses?
Phase/Antigen variation - switching between on and off forms of a gene / allowing the bacterium to change the sequence of a gene
What are endotoxins?
Lipopolysaccharides complexed to proteins that occur in the outer membrane of the envelope of gram negative bacteria
Principal antibody type produced at mucosal surfaces? What molecules cleave these immunoglobulin?
Incubation period of Diphtheria
What does corynebacterium diphtheria cause/what is it characterised by?
Infects mucous membranes (tonsils) - toxin produces acute inflammation and formation of pseudomembrane
Early symptoms of corynebacterium diphtheria
Swollen neck glands
Late symptoms of corynebacterium diphtheria (x3)
Shock -> hypotension, tachycardia, pale, cold skin, sweating, anxious
What are diphtheria outbreaks associated with? (X2)
Immunity gaps, vaccination failure
Is corynebacterium diphtheria
I) gram positive or gram negative
II) cocci or bacilli
III) aerobic or anaerobic
IV) motile or non-motile
V) growth medium
Grows in tellurite agar, which is toxic for other throat flora
How is corynebacterium diphtheria transmitted?
Direct contact droplets/skin
Indirect via contaminated object
Treatment of Diphteria (x2)
- immediate inoculation with diphtheria anti-toxin
- administer penicillin or erythromycin to eliminate the bacteria
Prevention of diphtheria
Diphtheria Formal Toxoid (DFT Vaccine) - part of multiple vaccine - given at 2,3,4 months ; booster jab at 5 years
How does diphtheria enters the cell?
Endocytosis - proteolytic cleavage takes place in the cell, resulting in 2 fragments
Which bacteria causes whooping cough?
Describe the appearance of B. Pertussis (x3)
Transmission of Bordetella Pertussis
Infection by exposure to infected individual
Clinical features of B. Pertussis infection (x4)
- insidious onset
- catarrhal stage with common cold symptoms
- paroxysmal coughing
- residual cough
What may adults suffering from bordetella pertussis experience? (X4)
- shortness of breath during coughing
- nocturnal coughing
- tingling sensation in back of throat
- post-tussive vomitting
Route of infection of B. Pertussis
The organism infects the ciliated epithelial layer of the respiratory tract without invading deeper, resulting in an acute tracheobronchitis
What mediates the action of B. Pertusis? (X2)
- filamentous hemagglutinin (FHA)
- cell bound pertussis toxin (PTx)
What is pertactin (PRN)?
The outer membrane protein that promotes the attachment of B. Pertussis to tracheal epithelial cells
What is the outer membrane protein that promotes the attachment of B. Pertussis to tracheal epithelial cells
Name 4 toxins involved with bordetella pertussis
1. Pertussis toxin
2. Adenylate cyclase/hemolysin
3. Tracheal cytotoxin (TCT)
4. Lipopolysaccharide (endotoxin)