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66 Cards in this Set
- Front
- Back
infectious diseases are complex and involve a series of shifting interaction between _________and____________
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host and pathogen
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In a host-pathogen relationship, interaction with regards to pathogen depends on
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1. pathogens ability to evade or overcome host defense
2. pathogens ability to increase in numbers 3. pathogens ability to identify transmission mechanisms to new hosts |
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In a host-pathogen relationship, interaction with regards to host depends on
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1. host having useful functioning defenses
2. host's susceptibility to infection 3. degree of compromise found within the host immune system |
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pathogenicity
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for the pathogen, infection is a matter of survival
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opportunistic pathogens
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cause infection by taking advantage of a hosts' increased susceptibility to infection
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primary pathogens
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cause disease in healthy individuals
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characteristics of primary pathogens
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1. include viruses and bacteria
2. have evolved mechanisms that can overcome host defenses 3. once inside they can multiply rapidly 4. some primary pathogens are restricted to humans |
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pathogenic virulence
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refers to how harmful pathogen is to host, depends on pathogen's genetic factors - genetic elements are often turned on only in the host
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pathogens carry virulence genes in clusters called____________
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pathogenicity islands (can be located on plasmids)
ex. H.pylori |
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plasmids can be transferred between________
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cells - transfer genetic elements to other bacterial cells
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biofilms
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aggregated assemblies fo bacteria formed on a surface in response to various host factors (nutrition, antibiotics, recognition of attachment sites)
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biofilms consist of________________
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bacteria and self-produced matrix of extracellular polymeric substance (EPS) - DNA, proteins, polysaccharides
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characteristics of biofilms
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differential regulation of genes - immunity to host factors, antibiotics etc.
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biofilms communicate via________________
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quorum sensing
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biofilms are clinically important because
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1. can capture and retain nutrients (allowing continued growth)
2. they impede uptake of antibiotics and disinfectants 3. inhibit phagocytosis |
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biofilms can build up on medical devices such as
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catheters
heart valves prosthetic devices |
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biofilms are one of the causes of ____________on teeth
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plaque build-up
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quorum sensing
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when an organism senses their environment using special sensing proteins
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bacterial "language"
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sensor proteins are produced by bacteria, released from bacterial cells and interpreted by other bacterial cells (sensing based on population densities)
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it is important for the _________of bacteria to communicate and coordinate behavior with members of same species and other species
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survival
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certain genes are only turned on when there are enough_________present
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cells
ex. enterotoxin production in salmonella |
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glycocalyx is sticky substance composed of__________and___________or both
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polypeptides
polysaccharides |
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glycocalyx is produced in the_____________ and secreted to the outer pat of the______________
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cytoplasm
cell wall |
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glycocalyx provides a protective element against __________________ and can be used for ________________
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environmental stress
nutrition |
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Bacterial Cell wall: gram (+) bacteria
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theichoic acid
lipoteichoic acid M protein Mycolic acid |
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theichoic acid (gram positive bacteria)
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can cause colonization of the nasal epithelium
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lipoteichoic acid (gram positive bacteria)
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causes an inflammatory response
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M Protein (gram positive bacteria)
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required for infections
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Mycolic acid (gram positive bacteria)
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acts as a barrier against antibiotics and host defenses
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Gram negative cell wall is a complex structure involved in____________in may ways
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infection
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outer layer of gram negative cell wal is a barrier to ________________. Porin proteins exclude__________________
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antiseptics, disinfectants and antibiotics
lage molecules |
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the outer layer (LPS) of the gram negative cell wall functions as endotoxin with 2 parts having clinical relevance:_________________
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lipid A
O polysaccharide |
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if the glycocalix is loosely attached to the cell wall it is called a __________________
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slime layer - associated with some forms of dental decay
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if the glycocalyx is tightly attached to the cell wall it is called a____________________
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capsule
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functions of a capsule
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inhibits phagocytosis
many organisms are not infectious without a capsule capsule genes can be transferred between organisms |
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both slime layer and capsule variation of glycocalyx give an________________to the organism
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adherence capability
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3 structures (outside of bacterial cell wall) are primarily involved with adherence (staying in)
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glycocalyx
fimbrae pili |
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2 structures (outside of the bacterial cell wall) are primarily involved with motility (defeating host defenses and damaging host)
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flagella
axial filament |
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fimbrae and pili
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involved in adherence
appear as sticky projections (shorter than flagella) found on gram negative organisms composed of pilin protein subunits genes can be transfered from one organism o another |
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flagella used only for ____________
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motility: make it possible for bacteria to move from their point of origin to other places in the body ex. E. Coli can move from LI (harmless) to urinary tract where it can cause serious infection
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flagella consists of 3 parts
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filament - flagellin protein forms twisted helical chain
hook - links filaments to basal body basal body |
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clinical significance of fimbrae and pili
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help pathogens fulfill the staying in requirement through adherence
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fimbrae is only used for adherence, particularly in the_____________and_____________tracts
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urinary
intestinal |
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pili give bacteria motility in 2 ways
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twitching or gliding movements
through extension and retraction of pili |
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pili is involved in the development of_______________
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biofilms
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pili facilitate the transfer of genetic material from one bacterial cell to another through___________
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antibiotic resistance
toxin production defense against host defenses |
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clinical significance of flagella - allow movement which allows___________________
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opportunistic infections
escape from host defense (defeat host defense) systemic infection (damage to host) |
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axial filaments
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flagellum-like structures that are found on spirochets (gram negative bacteria)
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axial filament wrap around bacterial cell wall and are confined to the space between the_____________and _____________
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plasma membrane
and the cell wall |
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axial filaments are used for_____________ and cause he entire organism to rotate like a________________
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motility
corkscrew |
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the corkscrew motion gives the bacterium the ability to bore through____________(staying in). They allow organisms to get into the________ as well as___________ (damage the host)
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tissue
blood other tissues |
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six major structures found inside the bacterial cell wall:
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plasma membrane
nuclear region plasmids ribosomes inclusion bodies endospores |
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if a bacterium is pathogenic when it undergoes _______________, it will be pathogenic once it emerges
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sporogenesis
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endospores are resistant to almost all____________________
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disinfectants, antiseptics and antibiotics
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endospores are also resistant to_________ and can cause severe problems for the food industry. ex. ________________
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heat
Clostridium Botulinum |
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plasmids
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extra-chromosomal pieces of DNA that are separate from the main DNA structure
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some bacteria can carry_____________plasmids
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more than one
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plasmids often carry __________for toxins and ______________ resistance
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genes
antibiotic |
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plasmids can be transfered from one cell to another through___________during_______________
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pili
conjugation |
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lawsuit was filed against maker of_________________chili
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botulism-tainted
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bacterial structures that have direct clinical significance
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cell wall, glycocalyx, fimbrae, pili, axial filaments, flagella and endospores
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bacterial structures that target antibiotics
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cell wall, plasma membrane, DNA and ribosomes
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endospores are formed through the process of ______________
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sporulation
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endospores form when a bacterium is exposed to great_________________.
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environmental stress
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endospores characteristics
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1. confer a type of dormancy on the cell
2. extremely resistant to heta, desiccation, toxic chemicals, UV irradiation and antibiotics 3. bacteria can survie for extraordinary lengths of time in endospore state |
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endospore process is restricted to gram__________rods. with one exception:
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positive
exception: coxiella burnetti (gram negative coccus) |