A/45-49 GENERAL PATHOLOGY OF INFECTIOUS DISEASES (Tamer) Flashcards
Name the main taxonomic categories of infectious agents
“President Putin Has Very Few Badass Competitors”
- *P**rions
- *P**rotozoa
- *H**elminths
- *V**iruses
- *F**ungi
- *B**acteria
- *C**hlamydia , rickettsias, mycoplasmas
AND
Ectoparasites
prions are infectious agents that cause transmissible diseases.
what are they composed of ? where are they found ? describe their mechanism of action
- composed entirely of a protein material (PrP) found in high levels in neurons.
- cause transmissible spongiform encephalopathies
- Prp (Prion protein) undergoes conformational change and becomes Protease resistant. this resistant Prp causes Sensitive Prp’s to become protease resistant as well . that’s what makes them transmissible.
Name few features of Viruses
- Obligate intracellular, uses Host cells
- 20-300 nm
- usually seen in EM but may aggregate in infected cell and form inclusion bodies seen by LM
-consist of nucleic acid surrounded by capsid
(protein coat) and sometimes a lipid membrane (from host)
-Transient (C.C ,influenza )OR Persistent that may replicate (chronic EBV) or may not (latent infection by herpes zoster)
Some Viruses can transform host cell into … ?
neoplastic cells.
Examples :
-Adenovirus
- upper/lower RTI’s
- conjunctivits
- diarrhea
-Rotavirus
- childhood diarrhea
- EBV
- infectious mononucleosis
give the general characteristics of Bacteria
- Prokaryotes, have cell membrane and Wall ,some have flagella/pilli ,different locations (intra/extra)
- classfied GRAM +/- according to thickness of peptidoglycan in cell wall , shape, form of respiration
- synthesize DNA,RNA, use host for nutrition
- some are considered normal flora
- Strep.Mutans (teeth)
- Staph. Epidermidis (skin)
- GI
Chlamydia, Rickettsia and Mycoplasma are considered Atypical Microorganisms. HAWCUMDIS ?
-similar to bacteria but lack structures/metabolic capabilities
-Chlamydia (Obli.Intra) - can’t synthesize ATP
,cause female infertility , blindness
-Rickettsia (Obli.Intra) -transmitted by lice,ticks,mites
cause hemorrhagic vasculitis , pneumonia , hepatitis ,CNS injuries, DEATH
-Mycoplasma - tiniest , lack cell wall
cause atypical pneumonia
Pathogenic Fungi Have shit-load of properties.
mention few of them.
- Eukaryotes
- Chitin in cell wall and ergosterol in cell membrane
- grow as
- budding yeast
- hyphae (septate/aseptate)
-thermal dimorphism :
- hyphae at room temp
- yeast at body temp
-sexual/ asexual spores
there are 2 types of infection caused by fungi. what are these ?
1) superficial infections: skin,hair,nails can cause abscesses/granulomas in subcutaneous tissue
2) deep infections that are dormant and spread in immunocompromised individuals e.g. candida, aspergillus,cryptococcus
Protozoa are …
- Single cell Eukaryotes
- replicate
-
intra-celluary (malaria in RBC)
OR - extra-cellularly (UG system ,intestine,blood)
-major cause of morbidity/mortality in developing countries
name the features of helminth
- highly differentiated multicellular parasitic worms
- generate eggs/larvae
- disease proportional with number of organisms and usually due to inflammatory responses against egg/larvae
- reproduction
- sexual multiplication -in definitive host
- asexual multiplication- in intermediate host/vector
Name the 3 classes of Helminths.
**_1) Roundwarms_** collagenous tegument (cover), non-segmented structure
2) Flatworms
gutless , head and ribbon of flat segments , absorptive tegument
3) Flukes
leaf-like , primitive ,syncytial integument
what are Ectoparasites ?
Insects - lice, bedbugs, fleas
OR
Arachnids- mites, ticks, spiders
- Cause disease by biting /attaching to and living on or in the skin
- arthopods can cause direct/indirect (vector for infectious agent) damage
mention few possible routes of infection
- inhalation
- ingestion (fecal-oral)
- sexual transmission
- bites (vectors)
- zoonotic
- injection
the skin and mucosal surface are the 1st line of defence against infectious agents. explain how they do so .
- skin kertainized layer has low pH (5.5) and fatty acids prevent the growth of microbes. skin sheds and renews.
- humid skin is more penetrable as well as breaks in skin e.g. cuts , wounds , burns , few microbes penetrate unbroken skin (schistosoma)
- intravenous catheters ,needles ,bites can also cause infections
Name few agents that impair the mucociliary clearance
- smoking -metaplasia
- intubation
- Cystic Fibrosis -hyperviscous mucus
- B.pertussis -toxin mediated Cilliostasis
- Influenza - lower mucus viscosity ,loss of ciliated epithelium
- TB-escape phagocytosis
- immunosupression
- gastric acid aspiration
Most of intestinal tract pathogens are transmitted by …
food and drink contaminated with fecal material
what are some of the defense mechanisms of the GI tract ?
1) Acidic pH , Viscous mucus
2) Lytic pancreatic enzymes , bile
3) defensins, IgA
4) Normal Flora
How do infections occur in the GI ?
- when defense mechanisms are either supressed (fungi) /organism developes resistance against them(protozoa) .
(e. g. non-enveloped virus may be resistant to defense mechanisms)
pathogens cause disease by :
- entero/exo-toxins
- invade and cause hemorrhage (shigella,salmonella)
- invade and travel through layers into blood stream
- *-**protozoa travel in cyst resistant to stomach acid
the Urogenital tract is usually sterile because its flushed many times per day . how do infections occur then ?
- by pathogens that adhere to urothelium
- more frequent in women - shorter urethra
- catheters increase risk
if a Urogenital Tract infectious agent travels to the kidney it may lead to …
Chronic pyelonephritis
spreading of microorganisms can be
locally
OR
spread to other areas via blood,lymphatics ,nerves
-invasion to blood is rapidly supressed (tooth brushing)
but if sustained causes fever, hypotension ,sepsis
-If reached blood either :
- travel freely -EBV,poliovirus
- intracellularly -herpes in wbc’s , HIV
name the few possible routes in which pathogens exit the host
1) skin shedding
2) coughing
3) sneezing
4) urination
5) defecation
6) placentofetal/vertical transmission
7) insect vectors
-following (second) transmission depends on badassness of the microbe
- bacteria form spores
- protozoa travel in cyts
- helminths make eggs
Steps in microbial pathogenesis
- Attachment to host cell , colonisation
- invasion
- local/wide spread , multiplication
- cell/tissue damage
