Infectious Diseases Flashcards Preview

Gen Path 300 > Infectious Diseases > Flashcards

Flashcards in Infectious Diseases Deck (63):
1

Infections

A disease caused by microorganisms, especially those that release toxins or invade body tissues

2

Colonization

Harmless inhabitation by microbes in the body

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Virus

a pathogen made of a nucleic acid inside a protein shell

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Bacteria

a unicellular organism without a true nucleus or organelles

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Helminthes

worms

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Mycobacteria

A type of bacteria with fungal-type properties

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Prions

A small proteinaceous infectious particle.

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Routes of infection

Contact
Airbourne
Droplet
Vehicle (common source -- i.e. food, water)
Vector (carried by intermediate source)

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Pathogenicity

The number of organisms and amount of time required to start a new infectious process

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Chain of Transmission

Pathogen or Agent
Reservoir
Portal of Exit
Transmission
Modes of entry
Susceptible host

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What are the lines of defence?

First: mechanical barriers
Second: inflammation
Third: acquired immune response

12

Defence against infection relies on what two thing?

1. Mechanical integrity of epithelial surfaces
2. Decontamination (removal of pathogen)

13

Three patterns of infections

1. Local damage (wart)
2. Toxic to host (botulism)
3. Widespread effects (HIV)

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How does infection spread within a host?

1. Directly
2. Via natural channels (membranes, vessels)
3. Through nerves or phagocytes

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Pathogen's Mode of Action

How the organism produces a pathologic process

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What factors affect the occurrence and spread of infection?

1. Pathogenic factors
2. Host factors

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Pathogen factors affecting occurrence and spread

1. Virulence (degree of pathogenicity)
2. Dose
3. Site of infection
4. Synergy between different pathogens

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Host factors affecting occurrence and spread of infection.

Resistance to infection
Immune competency
Leukocyte count
Necrosis/Ischemia of tissue

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Opportunistic infection

Takes advantage of compromised/defective immune system

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Staphylococcal Infections

One of the most common bacteria to reside on the skin

Over 30 subtypes

Leading cause of nosocomial and community acquired infections.

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S. aureus

Staphyloccus aureus
Most common staph infection

Nonmotile, anaerobic, hardy. Includes MSRA

Infection can result in: osteomyelitis, respiratory tract infection, infectious arthritis, septicemia, endocarditis, TSS, cellulitis, mastitis

22

S. pyogenes

Streptococcal pyogenes

One of the most common bacterial pathogens.
Suppurative and non-suppurative

Transmission: contact, droplets, foodborne

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Strep throat

Caused by S. pyogenes
Common cause of sore throat.
Pustulant

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Scarlet fever

Caused by S. pyogenes

Usually follows untreated strep throat

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Impetigo

Caused by S. pyogenes
Skin infection. Usually in children, in hot weather.

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Cellulitis

Caused by S. pyogenes

Acute skin infection

27

S. agalactiae

Streptococcus agalactiae
Normal part of GI flora

Leading cause of neonatal pneumonia, meningitis, sepsis

Infrequent cause of pyrogenic (purulent -- pus -- but not related to S. pyogenes. sigh) disease in adults

Pregnant women routinely screened.

28

Necrotizing fasciitis

Caused by S. pyogenes

Serious, potential fatal, spreads quickly along fascial lines.

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Pneumococcal infections

Streptococcus pneumonia

Can cause pneumonia, sepsis, otitis media, meningitis

Most common cause of community acquired pneumonia, and of bacterial meningitis

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Meningococcal Infections

Can cause meningitis and septicaemia

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Anaerobic infections

Not big oxygen fans. Suppurative.

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Diptheria

C. diphteria.
Anaerobic

Pseudomembranous pharyngitis

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Plague

Y. pestis
Anaerobic

Severe pneumonia, massive lymphadenopathy, high fever --> can progress to septicaemia

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Buboes

Enlarges lymph nodes; pathognomic for plague

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Botulism

C. botulinum (spore)
Anaerobic

Food borne or wound borne
Interferes with release of ACh at peripheral nerve endings

36

Spore

Cell produced by bacillus to withstand extreme conditions. Can remain viable for decades

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Cholera

V. cholerae
Anaerobic

Diarrhea --> dehydration, oliguria, shock

38

Spirochete

Slender, spiral, motile bacteria that lives off dead and decaying matter in soil and water.

Ex. Lyme disease, syphylis

39

Lyme disease

B. burgdorferi

Vector borne disease (deer tick).
Bull's eye rash (erythemia migrans), nausea, vomiting, neurological and arthritis-type symptoms

40

Mycobacteria

Small, slow growing aerobic bacteria
Complex lipid-rich envelope

Tuberculosis
Leprosy

41

Tuberculosis

Mycobacterium tuberculosis

Leading infectious disease cause of death
1/3 world's preventable deaths

Systemic, inflammatory
Affects lungs and may disseminate to lymph nodes and other organs.

Characterized by granulomas and then casseous necrosis

42

Virus

Smallest microorganism
Always pathogenic
Can only reproduce in host cells.

Protein cover.

43

Herpes virus

Family of virus that can cause

Herpes Simplex 1
Herpes Simplex 2
Varicella-zoster virus
Epstein-Barr
Cytomegalovirus

44

Herpes Simplex

HSV 1 -- typically oral
HSV 2 -- genital

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Varicella-Zoster Virus

Causes chicken pox and shingles

Can develop into life threatening pneumonia or encephalitis

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Herpes Zoster

Shingles

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Epstein-Barr Virus

Infectious mononucleosis

48

Cytomegalovirus

CMV
Symptoms similar to mono

Can cross placenta and cause congenital defects

49

Enterovirus

Member of picornavirus (small RNA virus)

Includes hand/foot/mouth, poliomyelitis

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Post polio syndrome

In 25-50% of people who have had polio, 15-30 years later.

Symptoms like chronic fatigue but progressive

51

Influenza

Fever, cough, headache. Possibly fatal

52

Rhinovirus

Common cold
URTA
Acute, afebrile, self-limiting

53

Mycosis

Any disease caused by fungus

Can be superficial or systemic

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Fungal pneumonia

Pneumocystis carinii or jirovecli

Extremely serious form of pneumonia

55

Yeast infections

Candida albicans

GI tract, mouth (thrush), genitals (candidiasis)

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Genital warts

Human papillovirus

Higher incidence of cervical, anorectal and bladder cancers.

57

Chlamydia

Chlamydia trachomatus

3 million new cases/year

Most common bacterial STI

No symptoms, or pain with intercourse, dysuria, bleeding

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Gonorrhea

Neisseria gonorrhoeae

650,000 new cases/year

In men: urethritis, urgency, paining
In women: no symptoms, or slight pain with urination, intercourse

59

Hepatitis B

Hep B Virus

Can be passed through breastfeeding

77,000 new cases/year
Jaundice, arthralgias, rash, dark urine, anorexia ...

Can relapse at the end of treatment.
Cannot be eliminated.

60

Syphillis

70,000 new cases a year

Treponema pallidum

Unprotected sexual contact, contact with skin and mucous membranes, transplancental, blood transfusions

61

Primary, secondary and tertiary syphilis

Primary: Chancre at site of infections
3-8 weeks after

Secondary: flu like symptoms and rash 6 weeks to 2 years

Tertiary: severe, CV and CNS up to 20 years later.

62

Vaccination

Any suspension containing antigenic molecules derived from microorganism given to stimulate an immune response to infectious disease.

63

Most common cause of bacterial meningitis is non-teens.

Pneumococcus infection.