Infectious disease Flashcards
define infectious disease
disease caused by bacterium, virus, protozoan, or fungus
define infection
occurs when infectious agent enters the body and begins to reproduce
define pathogen
infectious agent that causes disease
define host
an organism infected by another organism
define virulence
relative ability of agent to cause rapid and severe disease
categories of infectious agents
-prion
-viruses
-bacteria
-fungi
-protozoa
-helminths
-ectoparasites
prions are characterized by …
spongiform change caused intracellular vacuoles in neurons and glia
prions are composed of
abnormal forms of host protein
prions cause what type of disease
transmissible spongiform encephalopathies (neurodegenerative disorder)
creutzfeldt Jakob disease has symptoms of
loss of cognitive ability, decrease in ability to move and memory loss
what is seen in Creutzfeldt Jakob disease
prions build up and cause brain to shrink and tissue fills with holes
viruses are defined as
obligate cellular parasites that replicate inside living cells
viruses replicate by doing what
by replicating nucleic acid and synthesis of viral protein
how are bacteria classified
- by gram staining
- by shape
- by need of O2
gram positive bacteria have
thick wall that retains crystal violet stain
gram negative bacteria have
thin cell wall surrounded by an outer membrane
types of bacteria are
- cocci
- bacilli
- spiral
characteristics of cocci bacteria
- round shaped and cause pneumonia and sepsis
characteristics of bacilli bacteria
- rod shaped
- single, pairs, or in chains
- causes serious diseases
characteristics of spirila bacteria
- shaped like spirals
- very motile
- need moist atmosphere
- live in reproductive tract
- leptospirosis
what different methods can bacteria damage hosts
- producing enzymes that destroy tissue
- producing poisonous toxins
- exotoxins released into surroundings
what can exotoxins cause
- inhibit protein synthesis
- damage cell membrane
- interfere with normal nerve function
what are the different types of fungal infections (Mycoses)
- superficial mycoses
- subcutaneous mycoses
- systemic mycoses
- allergic mycoses
- endemic mycoses
what area do superficial mycoses affect
affect skin, hair, nails
what area do subcutaneous mycoses affect
affect muscle and connective tissue below skin
what area do systemic mycoses affect
involve internal organs
what area do allergic mycoses affect
affect lungs or sinuses
- have chronic asthma, cystic fibrosis or sinusitis
what are endemic mycosis
infections restricted to certain areas (histoplasma in Ohio river valley)
histoplasmosis and blastomycosis are endemic to which region
Mississippi river
paracoccidiodes brasiliensis endemic to which region
south america especially Brazil
coccidiodes immitis is endemic in which region
southwestern USA and north mexico
what are the morphological classification of protozoa
- amoebas
- flagellates
- cliliophroa
- coccidian
diseases caused by protozoans include
-malaria, dysentery, giardiasis, sleeping sickness, toxoplasmosis
characteristics of helminths
- macroscopic, multicellular and eukaryotic
- lack digestive system and locomotion
- reduced nervous system
two major phyla of helminths are
- nemathelminthes (roundworms)
- Platyhelminthes (flatworms)
- Trematoda (flukes)
- Cestoda (tapeworms)
what location in the body are helminths common and what places
common in intestinal tract and places with poor sanitation
ectoparasites are what
insects or arachnids that attach to and live on the skin
what can ectoparasites cause
itching and excoriations
patterns of infection include
- localized infection
- systemic infection
- focal infection
patterns of transmission are
- horizontal (infected person to person)
- vertical transmission (parent to offspring)
define localized, systemic, and focal infection
localized: microbes enter body and stay at confined space
systemic: infection spreads by the bloodstream
focal: infectious agent breaks and from local infection and carried to other tissues
bacteria damage to host cells depends on what
ability to adhere to host cells, invade cells, or deliver toxins
LPS is what
toxin found in gram negative bacteria
MTB causes what
granulomatous inflammation -> delayed hypersensitivity to prevent spread of bacilli
HBV and HCV cause what
liver damage due to infected hepatocyte
what are the mechanisms that help microorganisms resist immune system
- antigenic variation
- resistance to innate defenses
- impairment of T cell response
- resistance to phagocytosis
- resistance to ROS
- resistance to complement activation
- resistance to antibiotics
what are the five major histological patterns tissue reaction to infections
- suppurative inflammation
- mononuclear/granulmatous
- cytopathic cytoproliferative reaction
- tissue necrosis
- chronic inflammation and scarring
suppurative or purulent inflammation is characterized by
production of large amounts of pus consisting of neutrophils, necrotic cells and edema fluid
what bacteria induces suppurative inflammation
staphylococci
