Identify 4 bacterial or viral pathogens not discussed in class. For each list their species name, how they are transmitted, one major clinical presentation and one procedure for the treatment or prevention of each infection.
Please submit in Excel format. Use proper citation.
Assignment 5:
Identify 5 different careers for which utilize the field of microbiology. Describe how it is applied, but be very specific and concise in your description (less than 3 sentences for example). Use proper citation.
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Basic principles of infectious
disease I
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Pathogens and pathogenesis
pathos = sorrow
genesis = beginning
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“…the beginning of sorrow”
where does disease manifest?
…disease is an infection causing significant overt damage to the host
gain entry & colonize/invade
The course followed by all pathogens is:
context of
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Mechanical
Cellular injury/
death
Pharmacologic
alterations
Immunopatho-
logical
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Damage
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Mechanical
Occlusion of vital passages
ex. acute appendicitis
Occlusion and vital passages
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Acute appendicitis
Occlusion of vital passages
Occlusion of the lumen
Gallstones; tumor(s)
Infection & inflammation
Occlusion of intraluminal venous/arterial passages by
distension
Perforation/burst
Abscess
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Cellular injury/death
Toxins, replication, colonization & invasion
ex. AE lesion formation
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Intestinal AE lesions
Colonization of the gut by some E. coli leads to the formation of attaching/effacing (AE) lesions***a.k.a. “pedestals”
AE lesions damage the intestinal mucosa, interfere with membrane function (PMF) leading to cell death***
***also clinical manifestations of diarrhea, and hemorrhage
(Pierard et al 2012)
AE lesions
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Pharmacologic
alterations
Toxins
ex. ADP-ribosylation
any man-made, natural, or endogenous molecule which exerts a biochemical and/or physiological effect on the cell, tissue, organ, or organism.
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ADP-ribosylation
(adapted from Fishman PH 1980)
Enzymatic (ribosyl-transferase) addition of ADP-ribose to target protein(s)
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ADP-ribosylation, cont’d
(adapted from Fishman PH 1980)
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Immunopathological
Toxins, superantigens, inflammation & immune response
ex. Lymphadenopathy
Bubonic plague
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Acute appendicitis
Occlusion of vital passages
Occlusion of the lumen
Gallstones; tumor(s)
Infection & inflammation
Occlusion of intraluminal venous/arterial passages by
distension
Perforation/burst
Abscess
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Mechanical
Cellular injury/
death
Pharmacologic
alterations
Immunopatho-
logical
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Damage
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OBLIGATE vs. OPPORTUNISTIC pathogens
obligate pathogens are dependent on disease for transmission (reproduction)
…for opportunistic pathogens, disease is incidental*** often a consequence of immunologic compromisation
exogenously- vs. endogenously-acquired disease: the means by which microbiological disease is contracted
“primary”
“facultative”
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OBLIGATE vs. OPPORTUNISTIC?
exogenous vs. endogenous?
AE E. coli?
Y. pestis?
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any native/resident microorganism can cause
disease in a compromised individual
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Transmission
…Exchange of “infectious agent(s)” between individuals/groups…
vertical
sexual
oral
damage
aerosols
food/water
iatrogenic
fomites
vectors
DIRECT contact
INDIRECT contact
Intrapartum infections with S. agalactiae
S. agalactiae (Group B Streptococcus, GBS)
Vertical transmission during childbirth
leading infectious cause of neonatal morbidity/
mortality into the 1970s (CFR ≤50%)
carriage rate ≈20% healthy adults
ascending spread of GBS to the amniotic
sac & fluid
neonatal sepsis and meningitis
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Arthropod VECTORS & Lyme disease
Borrelia burgdorferi
Zoonotic spirochete transmitted by the bite
of deer ticks: (Ixodes scapularis and I. pacificus)
Prodrome of erythema migrans
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…tissues colonized by microbiota also serve as common routes
of entry for exogenously-acquired infectious agents…
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Portals of entry
The means by which a microorganism gains access to host tissues…
Entry by INGRESS
…entry w/o crossing epithelial barriers…
gastrointestinal tract
respiratory tract
genitourinary tract
Mucous membranes:
conjunctiva
Epidermis?
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…entry through a break in tissue(s)…
PARENTERAL entry
Vector (tick) transmission of
B. burgdorferi
Puncture/deep wounds
Burns
Any trauma which jeopardizes the
integrity of the epidermis (tissues)…
COLONIZATION factors
Adherence factors
Receptors for adherence factors:
cell surface expressed receptors
-glyco-proteins/-lipids
serum proteins
-plasminogen
extracellular matrix (ECM) type receptors
-fibronectin, collagen, & laminin
COLONIZATION factors
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…time lapsed between exposure to an infectious agent, and the presentation
of clinical symptoms…
incubation times dictated by:
low molecular weight nutrients and minerals (C, N, P, & Fe)
physiological/anatomical factors (pH, temperature, ROS, volatile fatty acids, mucin, peristalsis, etc.)
…clinical presentation of disease is rapid, and is often severe …
ACUTE infection
LATENT infection
…clinical presentation of disease is delayed/subclinical; manifestation of
symptoms is conditional…
immune response
MULTIPLICATION
incubation time
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Pathogen life-history
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SPREAD and DISSEMINATION
…lateral propagation from the point of entry to contiguous tissues…
SPREAD
…spread to distal tissues (metastasis)…
DISSEMINATION
erythematous rash
spread
annular lesions; meningitis;
musculoskeletal pain
hematogenous dissemination
acute illness
disseminated infection
1 week to 6 months
latent infection
6 months to 30 years
encephalopathy;
chronic arthritis
Lyme borreliosis
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portals of ESCAPE/EXIT
mucous membranes:
respiratory oropharynx (aerosolization)
gastrointestinal feces
urogenital contact
epidermis:
lesions
blood:
vectors (arthropods; needles)
hemorrhage
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context of
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Occlusion and vital passages
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AE lesions
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any man-made, natural, or endogenous molecule which exerts a biochemical and/or physiological effect on the cell, tissue, organ, or organism.
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