RT4 by Like Mike Flashcards
bordatella toxins
TCT = tracheal cytotoxin; PT = pertussis toxin; ACT = adenylate cyclase toxin; DNT = dermonecrotic toxin; LOS = lipooligosaccharide FhA = Filamentous haemagglutinin
advantage of FhA
Multiple binding sites enables attachment to multiple cell types such as ciliated epithelial cells and macrophages
Stages in B. pertussis pathogenesis
- transmission
- adhesion (using virulence factors FHA, PT, Fimbriae)
- growth and toxin release (using virulence factors PT, ACT and TCT)
- Local and systemic pathology (using virulence factors TCT, PT, DNT, LOS)
- Bacterial clearance
Whooping cough stages (symptom based)
- incubation (0-1 days)
- catarrhal (signs of common cold, 1-2.5 days)
- paroxysmal (cough, vomiting, trouble breathing due to constriction, bacterial growth. difficulty INHALING (get whooping inspirational noise)
can cough so hard they vomit
can be fatal due to respiratory insufficiency, 2-4 days) - convalescence (~4-7 days)
culturing and identifying B. pertussis
take sample from nasopharyngeal swab or secretions
don’t due throat swab
is sensitive to lipids which are in cotton swabs so don’t use cotton swabs
so use alginate/special bordatella swab
is nutritionally fastidious so use charcoal blood agar + cephalosporin (slows growth of background bacteria). example media: bordet-gengou
DaPT vaccine for Pertussis
“aP” in DaPT vaccine
use accelular components, e.g. Fha, PT. lower rate of side effects than whole cell vaccine
viral agents for infectious bronchitis and bronchiolitis
influenza virus
adenovirus
respiratory syncitial virus
bacterial agents for infectious bronchitis and bronchiolitis
bordatella pertussis
mycoplasma pneumonia
chlamydophilia pneumonia
most common infectious agents causing bronchiolitis are bordatella and mycoplasma
Bordatella pertussis (general info)
clinical syndrome: whooping cough (chronic bronchitis)
small, gram -ve coccobacillus
typically occurs in unvaccinated children
adults important as reservoir
highly communicable
HPIV (general info)
clinical syndromes: laryngotracheobronchitis (croup), bronchitis
virus family: paramyxoviridae
enveloped
glycoprotein with Hemagglutinin-Neuraminidase (HN) activity
fusion factor (F): involved in viral entry. ABs against F protein are neutralizing
Paramyxoviridae overview
2 subfamilies:
-paramyxoviriniae: has genera respirovirus and rubulavirus. respirovirus has species HPIV-1 and HPIV-3. Rubulavirus has species HPIV-2 and HPIV-4
-pneumoviriniae: has genera RSV, mPV (metapneumovirus )
Genetic material of HPIV
Linear ss (-) sense RNA Release of nucleocapsid into cytoplasm occurs following fusion of viral and host cell envelopes
Key Viral Proteins of HPIV
P/F proteins: Immune evasion
F Proteins (fusion proteins): role in syncitium formation
HN Protein Structural: Hemagglutinin and Neuraminidase activity
L Protein: Multifunctional Polymerase
M Protein Matrix: Structural Protein
Croup aka laryngotracheobronchitis (important)
commonly caused by respiratory viruses (HPIV, Pneumovirus, RSV)
most common in young children and infants
swelling and narrowing of airway, distinctive cough (sounds like seal barking)
rarely can be fatal
seasonal variability of RSV
peaks around december through january