Microbio 3 Flashcards
Shigella
[Px]
Invades GI mucosa via M cells that overlie Peyer’s patches – lyse containment vacuole, enter cytosol – apoptosis – spread to adjacent cells.
*Shiga toxin is a minor player since there are nontoxigenic strains that cause Shigellosis.
What is the importance of env gene in HIV replication?
env gene encodes gp160, which is cleaved and modified into gp120 and gp41.
>gp120: viral attachment binding to CD4 receptor of T cells (CCR5).
>gp41: transmembrane, fusion b/w virus and target cells.
Norovirus
disease, presentation, outbreaks where
MCC of viral gastroenteritis (adults).
>Watery diarrhea w/o blood or mucus.
>Outbreaks in crowded settings (schools, hospitals).
>Acute onset w/ quick resolution (2-3 days).
*Resistant to inactivation by acid, bile, pancreatic enzymes.
TB treatment drugs
[MOA]
> Rifampin: inhibits DNA-dependent RNAp.
Isoniazid: inhibits mycolic acid synthesis (cell wall structure and virulence).
Pyrazinamide: unclear MOA.
Ethambutol: inhibits arabinosyl transferase.
TB treatment drugs
[SE]
> Rifampin: rash, red-orange body fluids, cytopenias, GI side effects (vomiting).
Isoniazid: neurotoxic (give B6), hepatotoxic.
Pyrazinamide: hyperuricemia, hepatotoxic.
Ethambutol: optic neuropathy.
Pertussis (whooping cough)
[Cause, virulence factors, phases]
B. pertussis
>Virulence: adhesins, toxins (Pertactin, tracheal cytotoxin, adenylate toxin, pertussis toxin).
>3 phases: Catarrhal stage, Paroxysmal stage (severe coughing w/ whoop), Convalescent stage.
Pasteurella
[Disease, characteristic]
Mouths of dogs (cats).
Most skin infections (cellulitis, osteomyelitis) caused by dog bites
Infection w/in 24 hrs of inoculation.
>Mouse-like odor (indole-positive species)
What does H. influenzae type b virulence depend on?
Polysaccharide capsule made of polyribosylribitol phosphate (PRP).
PRP binds to Factor H, a complement control protein that prevents complement deposition on host cells – degrades C3b – no opsonization, no phagocytosis.
Aspergillus
[Diseases]
Widely distributed in environment, decaying veggies, monomorphic (mold form only).
>Invasive aspergillosis
>Aspergilloma (fungus balls)
>Allergic bronchopulmonary aspergillosis
What’s significant about compound muscle action potential in botulism?
Botulism presents w/ diplopia, dysphagia, and dry mouth.
These effects can be partially overcome by high-rate repetitive nerve stimulation to facilitate compound muscle muscle action potential (CMAP), since excitation at the NMJ is inhibited in botulism.
Nonbullous impetigo.
[Causes, ssx, complications]
May be caused by S. aureus or S. pyogenes (labs).
>Painful non-itchy pustules; Honey-crusted lesions (perioral).
>Can lead to PSGN – immune complex deposition on GBM, complement activation.
Bronchiolitis
[Cause, ssx, findings]
MCC is RSV; lower respi tract infection.
>Rhinorrhea, congestion –> cough, low-grade fever, inc. work of breathing.
>Findings: hypoxemia, tachypnea, retractions and nasal flaring (respi distress)
Why is it difficult to make a vaccine for Hepatitis C virus?
High mutation rate and no proofreading in its RNA-dependent RNAp – prone to errors during replication – can have several quasispecies or variant strains in one person.
Hypervariable genes can code for envelope – host can’t mount an effective immune response – antibodies for one variant but not others.
What contributes to Mycobacteria’s virulence?
Cord factor: a mycoside that inactivates neutrophils, damages mitochondria, induces TNF release.
*W/o cord factor, there would be no disease.