10. 11. Infection I & II Flashcards
What are the 6 classifications of infectious organisms?
• Bacteria
• Virus
• Protozoan
• Fungus
• Intracellular bacteria
• Helminth
Bacteria causes tissue injury by ...
that aid ...
and break down tissue (...
, ...
and ...
. Gram +ve bacteria also releases ...
that inhibit cellular functions, including ...
. Gram -ve bacteria releases ...
(LPS = ...
), which have detrimental effects on cell function. Bacteria can initiate ...
.
Bacteria causes tissue injury by releasing enzymes
that aid invasion
and break down tissue (collagenase
, coagulase
and hyaluronidase
. Gram +ve bacteria also releases exotoxins
that inhibit cellular functions, including phagocytosis
. Gram -ve bacteria releases endotoxins
(LPS = lipopolysaccharides
), which have detrimental effects on cell function. Bacteria can initiate later hypersensitivity response
.
Viruses produces ...
that invade cells, and can evade ...
. Viruses replicate by using ...
. Cell damages result from ...
of the cell membranes to release new ...
. Virus replication changes ...
(MHC 1) and also invokes ...
(NK and CD8+ cells, extracellular viral antigens). Intracellular virtual replication disrupts ...
and therefore causes ...
. Some viruses can cause ...
, causing ...
and damage to surrounding tissues.
Viruses produces virions
that invade cells, and can evade immune surveillance
. Viruses replicate by using cell machinery
. Cell damages result from rupturing of the cell membranes to release new virions
. Virus replication changes cell's antigenic properties
(MHC 1) and also invokes inflammatory/ immune response
(NK and CD8+ cells, extracellular viral antigens). Intracellular virtual replication disrupts cell function
and therefore causes cell death
. Some viruses can cause unrestricted cell replication/ differentiation
, causing neoplasia
and damage to surrounding tissues.
Similar to viruses, this pathogen enter cells in order to replicate in the cytoplasm → ...
;
Protozoans, such as ...
release enzymes, causing ...
influx and cell lysis. ...
causes excessive ...
response. Both microorganisms try to avoid immune response through ...
; ...
can initiate excessive inflammatory and immune responses. There are also ...
within the ...
that can cause inflammation;
Fungi releases ...
and provoke excessive immune response.
Similar to viruses, this pathogen enter cells in order to replicate in the cytoplasm → Chlamydia
;
Protozoans, such as Acanthamoeba
release enzymes, causing calcium
influx and cell lysis. Toxoplasma
causes excessive immune
response. Both microorganisms try to avoid immune response through encystment
; Helminths
can initiate excessive inflammatory and immune responses. There are also endosymbiotic bacteria
within the helminth
that can cause inflammation;
Fungi releases proteases
and provoke excessive immune response.
Most bacteria cannot penetrate an intact corneal/ conjunctival surface, but which bacteria can? And how?
Pseudomonas aeruginosa releases proteases that can slowly penetrate the epithelium in 3 hours. Breakage in the epithelium promotes adhesion and invasion.
Endotoxins released can also affect epithelial tight junctions. With sufficient bacterial load, toxins can provoke inflammatory response and epithelial damage, this increases bacterial access, particularly in the conjunctiva.
What are the innate immune receptor and cells involved in innate immunity?
Toll-like receptors and Corneal dendritic cells
What action of the bacteria causes inflammatory responses and continued tissue damages?
Bacterial replication in the stroma and continual release of exotoxins damages epithelium and causes inflammatory responses. Neutrophil enzymes can also cause further tissue damage.
Name a long term complication resulting from acute infectious keratitis.
Loss of sensory nerves in the cornea, corneal scarring as a result of ulceration/ perforation.
Contact lens wear increases susceptibility with ...
. Contact lenses causes tear film to become immobile, therefore prevents bacteria from being ...
. Contact lenses causes ...
of the corneal epithelium, therefore disrupts the ...
and promotes ...
to epithelium. Overnight contact lens wear ...
, therefore promote a ...
environment.
Contact lens wear increases susceptibility with ocular bacterial infection
. Contact lenses causes tear film to become immobile, therefore prevents bacteria from being swept away by the lids
. Contact lenses causes chronic mild hypoxia
of the corneal epithelium, therefore disrupts the homeostatsis
and promotes bacterial adhesion
to epithelium. Overnight contact lens wear alters tear levels of pro-inflammatory cytokines
, therefore promote a pro-inflammatory
environment.
Extended wear CLs stimulates ...
migration to ...
cornea. These are ...
, so if infection occurs, ...
will become more agressive than normal ...
response. Therefore damage is more extreme. Placing a contact lens on a healthy cornea can cause a ...
of T cells.
Extended wear CLs stimulates Langerhans cell
migration to central
cornea. These are antigen presenting cells
, so if infection occurs, inflammation
will become more agressive than normal neutrophils
response. Therefore damage is more extreme. Placing a contact lens on a healthy cornea can cause a loss of a number
of T cells.
Chronic dry eyes induces ...
. The accelerated cell death causes ...
and improves ...
. Reduced tears results in reduced ...
.
Chronic dry eyes induces epithelial apoptosis
. The accelerated cell death causes epithelial erosion
and improves bacterial adhesion
. Reduced tears results in reduced antibacterial activity
.
WIth an intact cornea and normal tear film, ...
for bacteria is insufficient for ...
.
In a compromised cornea, bacteria can adhere and replicate, allowing release of ...
and ...
, breaks down the corneal barrier further. Bacterial proliferation occurs in the ...
. Injured epithelial cells release ...
. Early neutrophil ...
from limbal vessels and anterior uvea. Release of ...
and ...
. Later chemotaxis of ...
from limbus. Corneal ...
can occur if not treated soon.
WIth an intact cornea and normal tear film, adhesion time
for bacteria is insufficient for invasion
.
In a compromised cornea, bacteria can adhere and replicate, allowing release of toxins
and enzymes
, breaks down the corneal barrier further. Bacterial proliferation occurs in the corneal stroma
. Injured epithelial cells release interleukins
. Early neutrophil chemotaxis
from limbal vessels and anterior uvea. Release of proteases
and reactive oxygen species
. Later chemotaxis of lymphocytes
from limbus. Corneal perforation
can occur if not treated soon.
What are the clinical signs of protozoal infections?
Extreme pain
Acanthamoeba is a ...
and exist as two different forms: ...
(motile form) or ...
(cellulose wall). They can evade the ...
and ...
. They undergo ....
, and thus can go undetected. Acanthamoeba can form ....
in the ...
for ...
. They preferentially attacks ...
, therefore causes ...
. They causes the formation of ...
made out of mostly ...
.
Acanthamoeba is a protozoa
and exist as two different forms: trophozoites
(motile form) or encysted
(cellulose wall). They can evade the immune system
and anti-amoebal drugs
. They undergo dormancy
, and thus can go undetected. Acanthamoeba can form cysts
in the corneal stroma
for protection
. They preferentially attacks corneal nerves
, therefore causes pain
. They causes the formation of perineural/ radial infiltrates
made out of mostly neutrophils
.
The intracellular bacterium ...
causes trachoma, which is the world’s most common ...
. Trachoma can manifest as an aggressive ...
. This bacterium also causes ...
, but with less aggressive presentations. Infective particles are transmitted by ...
. They can form ...
in host cells, which then grows to form ...
. This bacterium triggers ...
involving ...
and ...
T cells. These responses causes formation of ...
or ...
.
The intracellular bacterium Chlamydia
causes trachoma, which is the world’s most common infective blindness
. Trachoma can manifest as an aggressive keratoconjunctivitis
. This bacterium also causes sexually-transmitted adult inclusion conjunctivitis
, but with less aggressive presentations. Infective particles are transmitted by flies or sexual interactions
. They can form small elementary inclusion bodies
in host cells, which then grows to form large intial bodies
. This bacterium triggers marked cellular immune responses
involving CD4+
and CD8+
T cells. These responses causes formation of follicular hyperplasia of tarsal conjunctiva
or follicular infiltrates of bulbar/ limbal conjunctiva
.