Lecture 1 8/31/23 Flashcards by Danika Boltz

What are the possible bacteria shapes?

-cocci
-bacilli
-coccobacilli
-spiral
-spirochete

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What are the general characteristics of bacteria?

-prokaryotic
-unicellular
-singular cellular chromosome
-complex cell wall
-asexual repro. through binary fission

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What is etiology?

cause of disease

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What is a pathogen?

microbe that can cause disease

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What is transmission?

spread of infectious agents from one host to another susceptible host

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What is colonization?

presence of microbes in the body without any disease

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What is infection?

invasion or growth of disease-causing microbes in the body

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What is pathogenesis?

mechanisms by which pathogens causes disease

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What is pathogenicity?

ability of a pathogen to cause disease

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What are virulence factors?

properties found in isolates that cause disease not in isolates of the same species that do not cause disease

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What is virulence?

pathogen’s ability to cause disease/damage

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What is predisposition?

condition of the host that makes it susceptible to infections

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What are the potential outcomes of infection?

-disease followed by recovery
-disease followed by death or disability
-disease followed persistence of subclinical/chronic infection

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What are the characteristics of obligate pathogens?

-highly virulent
-small # enough to cause infection
-distinct disease presentation
-host does not need any predisposition factors

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What are the characteristics of primary pathogens?

-moderately virulent
-moderate numbers to cause infection
-distinct disease
-host needs some level of predisposition

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What are the characteristics of opportunistic pathogens?

-no virulence
-non-specific disease
-host has many and/or severe predisposing factors

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What is the sequence of events in bacterial pathogenesis?

-entry into host
-evasion of host defenses
-colonization of host systems
-multiplication
-exertion of damage in host
-transmission to other hosts

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What is the disease “triangle of tragedy?”

-host: factors that impact susceptibility
-pathogen: factors that impact ability to infect/damage
-environment: factors that impact exposure

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What types of damage can infection result in?

-changes in normal physiology
-depletion of nutrients
-inflammation/damaging immune response
-combination

What is the microbiome?

collection of all microbes that naturally live on and inside of a body

What are the characteristics of gram positive bacteria?

-thick peptidodglycan
-contain lipoteichoic acid
-no outer membrane

What are the characteristics of gram negative bacteria?

-thin peptidoglycan
-have outer membrane containing lipopolysaccharide

What are the characteristics of acid-fast bacteria?

-thin peptidoglycan
-no outer membrane
-considered gram pos.
-have mycolic acid

What happens when gram negative bacteria die?

-release lipid A/endotoxin into bloodstream
-results in stimulated immune system and endotoxic or septic shock

What are the two types of bacteria without a cell wall?

-mollicutes: genetically have no cell wall -L-forms: once had cell wall but it has degraded

Why can gram-staining not be used on bacteria without cell walls?

cell walls are what keep the gram-staining dyes in the cell

What must be considered when treating an infection caused by cells lacking cell walls?

antibiotics that act by damaging the cell wall will not work on these bacteria

What are the characteristics of flagella?

-filamentous structures used for motility -number and arrangement can be used for ID

What are endoflagella?

flagella inside the cell surface (like in spirochetes)

What are the characteristics of pili/fimbriae?

-small, thread-like -virulence factor -facilitate adherence -contribute to antigenicity/protection

What are the characteristics of the capsule?

-outer polysaccharide coating on some bacteria -helps with evading phagocytosis -significant virulence factor

What are the characteristics of endospores?

-dormant forms -highly resistant -produced when bacteria are exposed to adverse conditions -essential when nutrients are depleted -survival mechanism

What are exotoxins?

proteins produced inside bacteria and secreted into the surrounding medium

What are endotoxins?

constitutive elements of the bacteria membrane that are liberated when bacteria die

What are the characteristics of exotoxins?

-heat labile -exert action on specific target cells

What are the characteristics of endotoxins?

-heat stable -induce inflammation

What do super antigens do?

-bind and cross link to MHC classical II on APCs and T helper cell receptor -result in T cell activation and massive cytokine release -end result is symptoms of shock

How do super antigens differ from conventional antigens?

super antigens can activate any T cell, while conventional antigens only activate antigen-specific T cells

What are the characteristics of biofilms?

-extracellular polymeric substances -bacteria in masses -increased clinging to surfaces -promote chronicity -reduce antimicrobial penetration/susceptibility

What is quorum sensing?

molecular communication system that synchronizes expression of certain genes

What are plasmids?

circular extrachromosomal elements containing virulence factors that are transferred via conjugation

What are bacteriophages?

virus particles that attack bacteria and transfer or mutate virulence factors via transduction

What are the three bacterial locations?

-extracellular (most common) -obligate intracellular -facultative intracellular

What properties are used to classify bacteria?

-staining properties -metabolic properties -biochemical characteristics -fatty acid profile -DNA sequencing

What DNA sequence is most often used for bacteria classification?

16s ribosomal gene