Pathogens with Respiratory Transmission Flashcards by Bryan Edwards

Three primary bacteria discussed in this packet

Mycobacterium
Mycoplasma
Corynebacterium

How well did you know this?

Not at all

Perfectly

Staining used for mycobacterium?

Acid-Fast

How well did you know this?

Not at all

Perfectly

Describe the growth of mycobacteria?

Very Slow (18hours)
Growth from one pole

How well did you know this?

Not at all

Perfectly

Significance of mycobacteria growth time?

Culturing is too slow for diagnosis

How well did you know this?

Not at all

Perfectly

mycobacterial structure associated with virulence?

Serpentine Cord Formation

How well did you know this?

Not at all

Perfectly

Describe the mycobacterial cell wall

Made with mycolic acids (very hydrophobic

Waxy part of outer layer

How well did you know this?

Not at all

Perfectly

Significance of mycolic acids in mycobacterium? (2)

Acid-Fastness

Prevents lysozyme or complement attack

How well did you know this?

Not at all

Perfectly

What is Freund’s Adjuvant?

The waxy part of the outer layer of mycobacteriua

Antigenic

How well did you know this?

Not at all

Perfectly

What is LAM? Why do we care?

Lipoarabinomannan

Stimulates cytokine production by mammalian host

How well did you know this?

Not at all

Perfectly

TB promotes what other disease?

HIV

How well did you know this?

Not at all

Perfectly

Symptoms of mycobacterium tuberculosis?

Fatigue, Fever, Night Sweats, Weight Loss, Hemoptysis

How well did you know this?

Not at all

Perfectly

Primary presentation of mycobacterium tuberculosis?

Exudative lesion (edema, inflammation)
Usually Unnoticed

How well did you know this?

Not at all

Perfectly

Three potential responses to exudative lesions?

Healing
Necrotizes lung
Productive Lesion

How well did you know this?

Not at all

Perfectly

A productive lesion will cause a _____ to occur. This can cause these two responses.

Granuloma

Encasing or Spreading (via lymph, bronchi, or blood)

How well did you know this?

Not at all

Perfectly

Encases granulomas run the risk of

Reactivation

Leads to multiple granulomas, fibrination of lung

How well did you know this?

Not at all

Perfectly

Mycobacterium tuberculosis spread in the blood can lead to …

Miliary TB

How well did you know this?

Not at all

Perfectly

What is caseum?

Necrotic tissue damaged by inflammatory response and lack of vascularization

How well did you know this?

Not at all

Perfectly

Why are caseum especially bad in mycobacterial infection?

The hollowed areas they leave behind may allow encapsulated TB to escape

How well did you know this?

Not at all

Perfectly

Prevalence of TB?

2B people in the world infected (30%)

How well did you know this?

Not at all

Perfectly

TB at risk populations in the US? (5)

Minorities and Immigrants
Co-Existing Infection (esp. HIV)
Homeless
Very Young or Old
Travelers in High Risk Areas

How well did you know this?

Not at all

Perfectly

How is TB spread?

Person-to-Person via respiratory droplets

How well did you know this?

Not at all

Perfectly

What does TB do when in the body?

Attach to alveolar macrophages and invade
Prevent Phagolysosome fusion
Cytotoxicity from cord factor
Cytokine-mediated inflammation

How well did you know this?

Not at all

Perfectly

T or F. TB always presents with primary symptoms of the lungs.

False. Rarely primary extrapulmonary symptoms will occur.

How well did you know this?

Not at all

Perfectly

Two sites where long term TB retention may occur.

Granulomas and Bone Marrow.

How well did you know this?

Not at all

Perfectly

Two tests used to detect TB?

Mantoux (PPD) Test | QuantiFERON-Gold assay (IGRA)

How does a Mantoux (PPD) Test work?

Intradermal Protein Injection | Sensitivity within 72 hours indicates that Tmem cells were present

How does a QuantiFERON-Gold assay work?

Tests for releave of IFN-g from peripheral lymphocytes when exposed to TB antigen

Best method of diagnosing TB?

PCR

Two ineffective means of diagnosing TB?

Culture (too slow) | Acid-fast sputum stain (requires massive inf. to detect)

What does a IGRA+ or PPD+ patient with no symptoms and normal X ray indicate? What should you do?

Latent TB | Latent TB MUST be treated

Drug therapy commonly used to treat tuberculosis patients?

INH, Rifampin, Pyrazinamide, Ethambutol daily for 6-9 months

Drug therapy commonly used for latent TB?

Just INH

What non-chemical treatment method is important in some patients?

Directly Observed Therapy

Why might someone except to see TB+ patients very commonly in other countries?

Other parts of the world vaccinate for TB

How do you treat XDR-T patients? (3)

Meropenem + Clavulanate Linezolid is effective, but almost always causes adverse events Bedaquiline

Two manifestations of mycobacterium leprae?

Tuberculoid Leprosy | Lepromatous Leprosy

Describe tuberculoid leprosy (paucibacillary).

Macular Lesions | Nerves on One Side (occasional bilateral) Involved

Describe lepromatous leprosy (multibacillary)

Progressive Nodular Lesions | Bilateral Nerve Death --> Bone Resorption/Extremity Loss

Which form of leprosy is rare in the modern era

Lepromatous

Describe the skin markings seen on patients with mycobacterium leprae

Whitened, anaesthetized skin area with red ring around it

Most mycobacterium leprae cases come from what parts of the world? How is it transmitted?

Asia and Africa | Long-term contact

What organisms can have mycobacterium leprae infections?

Humans and Armadillos

Describe the pathogenesis of mycobacterium leprae.

Inflammatory disease (like TB) Inflammation damages Nerve Endings Hyposensitivity can cause soft tissue damage and bone loss

How do you treat mycobacterium leprae?

Dapsone (sulfone) + Rifampin

Significance of M. avium-intracellulare?

Most common hospital-acquired bacterial infection of AIDS patients

Treatment for M. avium-intracellulare?

Clarithromycin + Ethambutol for life

How does M. kansasii present?

TB-like symptoms in IC patients

Describe the physical structure of mycoplasm bacteria

Probably the smallest possible free-living entity | No Cell Wall, Membrane Only with Sterols

How do mycoplasm generate sterols?

They don't. They take them from the host.

Describe what you would see in attempting to culture mycoplasm pneumoniae.

Grows Slowly | Tiny Colonies with Depressed centers (Fried Egg Appearance)

Describe the clinical presentation of mycoplasma pneumoniae

Mild atypical (wheeze+crackle) pneumonia tracheobronchitis Insidious Onset Mild Fever + Dry Cough

How is mycoplasma pneumoniae transmitted?

Transmitted via respiratory droplets

Circumstances in which mycoplasma pneumoniae is more common.

Schoolchildren | Winter

Describe the pathogenesis of mycoplasma pneumoniae.

Proline-rich adhesion protein forms elongated tip, binds epithelial cells. Protein M blocks the Ab Fab region Cyotoxic Effects

List cytotoxic effects of mycoplasma pneumonia

Production of H2O2, O2- | Competition for nutrients

How is mycoplasma pneumonia

Typically don't treat if mind | Tetracycline, Erythromycin

What drug are you a doof if you give to treat mycoplasma.

Penicilin | Mycoplasma don't have a cell wall

Mycoplasma genetalium manifest in what three ways?

Normal Flora Urethral Infections Genital Infections

Manifestations of mycoplasma hominis?

10% of salphingitis | Post-partum fever

Unique metabolic activity of ureaplasma urealyticum?

Requires 10% urea to grow

Long term effect of ureaplasma urealyticum metabolism?

Generates an alkalinized environment Causes bladder stones Bladder stones --> Non-gonococcal urethritis in males

Describe the physical structure of Corynebacterium diphtheriae

G+ with mycolic acids in outer mem Club Shaped Pleomorphic

Important diagnostic test for Corynebacterium diphtheriae.

Plate on tellurite blood agar, will reduce potassium tellurite to tellurium (turn it black)

Clinical presentation of Corynebacterium diphtheriae?

Throat Infection -- sore throat, fever "Bull-Neck" -- Swollen Lymph Nodes Pseudomembrane -- forms at back of throat and may obstruct airway Toxin

Effects of Corynebacterium diphtheriae toxin?

Absorbed in blood -- affects heart, liver, kidneys

How are toxigenic strains of Corynebacterium diphtheriae identified?

Elek immunodiffusion test Filter paper with antitoxin placed perpendicular to stain streaks Toxin and Anti-Toxin form precipitate

How is Corynebacterium diphtheriae spread?

Aerosolized droplets

When is Corynebacterium diphtheriae typically acquired?

Usually a childhood disease, most adults immune from subclinical exposure (except not really)

Mortality rate of Corynebacterium diphtheriae

10-25%

Describe the pathogenesis of Corynebacterium diphtheriae.

- AB toxin from beta-phage conversion. - B binds EGF-like receptor and it internalized. Low pH in vesicle allows hydrolysis, frees the A - A binds NAD and ADP, ribosylates EF-2 - NO PROTEIN SYNTHESIS

How does Corynebacterium diphtheriae work its tox genes.

High Fe turns off toxAB operon Free Fe is kept at low levels in the body Corynebacterium diphtheriae only releases the toxin in the body

How is Corynebacterium diphtheriae prevented?

DTaP or DPT | Booster before school and every 10 years

How is Corynebacterium diphtheriae treated?

Quarantine Equine anti-toxin in large dose Penicillin/Erythromycin to keep bacteria low