Park lec 3 Flashcards
1
Q
List different classes of pathogens.
A
prions
Viruses
Bacteria
Fungi
parasites
2
Q
what are viruses
A
- Obligate intracellular pathogens
- Capsid (protein coats) and genome (RNA or DNA)
- Some are enclosed within an envelope derived from the cytoplasmic membrane of the host cells
- Cause lysis and death of the host cell during replication
- Some remain in a latent, nonreplicating state for long periods without causing disease
–> Varicella zoster virus - Some cause cancer
–> Human papillomavirus
3
Q
what are bacteria
A
- Prokaryotic
- Microscopic shapes
- Spherical
–> Diplococci, staphylococci, streptococci
- Elongated
–> bacilli
- Helical
–> Spirilla (spirochete)
4
Q
what is spirochetes
A
- type of bacteria
- anaerobic
- Ex: borrelia burgdorferi (lyme disease), treponema pallidum (syphilis)
5
Q
what is mycoplasmas
A
- Much smaller than other bacteria
- No cell wall - resistant to cell-wall inhibiting antibiotics (ex. penicillins)
- Ex: mycoplasma pneumoniae (pneumonia)
6
Q
what is rickettsiaceae
A
- type of bacteria
- Obligate intracellular pathogens
- Transmitted via arthropod vectors (mites, fleas, ticks, lice)
- Ex: rickettsia rickettsia (Rocky Mountain spotted fever)
7
Q
what is chlamydiaceae
A
- type of bacteria
- Obligate intracellular pathogens
- Transmitted via person-to-person contact
- Ex: chlamydia trachomatis - sexually transmitted; cause conjunctivitis in newborns
8
Q
what are the two types of fungi
A
superficial mycoses and systemic mycoses
9
Q
what is superficial mycoses
A
- dermatophytosis
- Ringworm, athletes foot (tinea pedis), and jock itch (tinea cruris)
- caused by dermatophytes whose infection is limited to the cooler cutaneous surfaces
10
Q
what is systemic mycoses
A
- Serious fungal infections of deep tissue (rare)
- Candidiasis (yeast infection) - opportunistic infection of candida albican, which is commensal flora in skin, mucous membranes, and GI tract
- aspergillosis - a lethal form of pneumonia caused by aspergillus, a common mold in people with lung diseases or immunocompromised patients
11
Q
what is fungi
A
- Intact immune mechanisms and competitions for nutrients provided by the bacterial flora normally keep colonizing fungi in check
- A disease or an antibiotic therapy can upset the balance, permitting opportunistic infections
12
Q
what are the 3 types of parasites
A
protozoa, helminths, and parasitic arthropods
13
Q
what are protozoa
A
- Unicellular animals
- Ex: plasmodium (malaria) - vector-bone (mosquito)
- Ex: entamoeba histolytica (amebic dysentery, or amoebiasis), giardia duodenalis (giardiasis) - contaminated water and food
14
Q
what are helminths
A
- Wormlike parasites
- Ex: roundworms, tapeworms, flukes
- Transmission primarily through ingestion of fertilized eggs (ova) or the penetration of infectious larval stages through the skin
15
Q
what are parasitic arthropods
A
- Ectoparasites - mites ( scabies ), chiggers, lice (head,body,pubic) and fleas
- May serve as vectors of other infectious diseases, such as bubonic plague (fleas)
16
Q
what are the different modes of transmissions from pathogens
A
penetrations, direct contact, indigestion, inhalation
17
Q
describe penetrations
A
- Any disruption may allow the invasion of pathogens, which normally cannot penetrate intact skin or mucous membranes
- Ex: abrasions, burns, needles, insect, and animal bites
18
Q
what are the two routes of direct contact
A
sex and congenital infections
19
Q
describe sexually transmitted infections
A
- Transmitted by the exposure of the intact skin or membrane to pathogens
- Ex: gonorrhea, syphilis, chlamydia, and genital herpes
20
Q
describe congenital infections
A
- Infection of a child during gestation or birth from mother (vertical transmission)
- Ex: Toxoplasmosis, Others (syphilis, varicella zoster, parvovirus B19), Rubella, Cytomegalovirus infection, and Herpes simplex virus (TORCH infection) and HIV
21
Q
describe ingestion
A
- Cholera, typhoid fever, amoebic dysentery, food poisoning, etc.
- The low pH of the gastric acid acts as a barrier for many pathogens, but some are resistant to the low pH (ex: shigella and giardia) → differences in the infectious dose
- The normal bacterial flora of the bowel compete with pathogens
22
Q
describe inhalation
A
- Bacterial pneumonia, meningitis, and tuberculosis
- Viral infections such as measles, mumps, chickenpox, flu, common cold, and COVID
- The respiratory tract is equipped with multiple-tiered defense system (mucous membrane, coughing, antibodies, and enzymes, phagocytosis, etc)
- Smoking and diseases such as cystic fibrosis impair the defense system
23
Q
what are the types of sources for parasites to get in
A
endogenous, exogenous, person, fomites, animal, vector, place
24
Q
describe endogenous sources
A
Opportunistic infection acquired from the host’s own microbial flora
25
describe what the sources do
1. Location, host, object, or substance from which the infectious agent was acquired
--> Who, what, where, and when
26
describe exogenous sources
environment
-- water, food, soil, air
27
describe person sources
direct contact
28
describe fomites as sources
1. An inanimate object contaminated with infected body fluids
2. Rhinovirus through shared toys
3. HIV Hepatitis B virus by shared syringes
29
describe animals as sources
- Zoonoses - infectious diseases passed from other animal species to humans
- Ex: HIV, rabies, plague, flu, SARS, MERS, etc.
- 70% of emerging viral infections
30
describe vectors as sources
1. Biting arthropod
- Ex; lyme disease, west nile virus
31
describe place as a source
1. Healthcare associated infection (nosocomial infection)
2. Community acquired
32
what are the stages of disease courses
incubation period, prodromal stage, acute stage, convalescent stage, and resolution stage
33
describe the incubation period
Active replication of a pathogen without recognizable symptoms
34
describe the prodromal stage
1. Initial appearance of symptoms
2. Mild fever, myalgia, headache, and fatigue (somewhat nonspecific)
35
describe the acute stage
1. Max impact of the infectious process
2. Inflammation and tissue damage (more specific)
36
describe the convalescent stage
Progressive elimination of the pathogen
37
describe the resolution stage
Tool elimination of a pathogen
38
describe virulence factors
1. Substances or products generated by infectious agents that enhance their ability to cause disease
39
what pathological functions of does virulence factors have?
exotoxins, endotoxins, adhesion factors, evasive factors, invasive factors
40
describe exotoxins
1. Proteins released by pathogenic bacteria
2. Inactivate key cellular constituents (ex: diphtheria toxin inhibits protein synthesis)
3. Many are superantigens inducing excessive and nonspecific inflammatory responses
--> Bind to MHC of antigen-presenting cells and t-cell receptors
--> T cells are activated regardless of the antigen presented on MHC
41
describe endotoxins
1. Lipids and polysaccharides, not released (ex: lipopolysaccharides)
2. Can induce clotting, bleeding, inflammation, hypotension, and fever (endotoxic shock)
42
describe adhesion factors (adhesion)
1. Bind to macromolecules on surface of host cells
2. Adhesion is critical for the colonization of the pathogens
3. Some pathogens form a mucous layer (slime)
43
describe evasive factors
1. Inactivate host’s immune system
2. Ex: leukocidins form pores in the cell membrane of neutrophils and macrophages
3. Some pathogens survive and reproduce within phagocytes after phagocytosis by neutralizing lysosomal contents with evasive factors
44
describe invasive factors
1. Facilitate the penetration of anatomic barriers
2. Ex; pseudomonas aeruginosa collagenase breaks skin
45
what does commensalism mean
1. colonizing bacteria acquire nutrition and host is neither benefit nor are harmed
--> Commensal bacteria in a human body (normal flora) are 10x more than human cells
46
what does mutualism mean
1. both the microorganisms and the host derive benefits from the interaction
-> Infectious disease
-> Infectious agents
47
what does incidence mean
The number of new cases of an infectious disease that occur within a defined population ( ex: per 100,000 people ) over an established period of time ( ex: monthly, quarterly, yearly)
48
what does disease prevalance mean
The number of active cause at a given time in a population
49
what does endemic mean
Describes relatively stable incidence and prevalence in a particular geographical region
50
what does epidemic mean
Describes an abrupt and unexpected increase in the incidence of disease over endemic rates
51
what does pandemic mean
Refers to the spread of disease beyond continental boundaries
52
what do fomites mean
An animate object contaminated with infected body fluids
53
what do zoonoses mean
Infectious diseases passed from other animal species to humans
54
what do nosocomial infection mean
Healthcare associated infection
55
what does congenital infection mean
Infection of child during gestation or birth from mom
56
what does prodromal stage mean
Initial appearance of symptoms
57
what does acute stage mean
Max impact of infectious process
58
what does convalescent stage mean
Progressive elimination of the pathogen
59
what is a exotoxin
Proteins released by pathogenic bacteria
60
what is a endotoxin
Can induce a lot of things (endotoxic shock)
61
what is a superantigen
Induces excessive and nonspecific inflammatory responses
