Kachur - Topic 1 - Immunity to Bacterial Pathogens Flashcards
Human microbiome
all the microbes that call us home
pathogen
microbes that can cause disease
infection
infection replicates in/on host
disease
microbial infection damages host
pathogenicity
- ability of an organism to cause disease
- either a yes or no
Virulence
extent to which a microbe can cause disease
- how bad something effects
Virulence factors
adaptations and traits that promote virulence in a pathogen
What are the two types of pathogens
- opportunistic pathogens
- true pathogens
What is a opportunistic pathogen
- result from opportunistic conditions:
- compromised immune system (immunodeficiency)
- disruption in the balance of normal microbes
What are the two types of true pathogens
obligate and facultative pathogens
What are obligate pathogens
pathogen must cause disease to be transmitted
What is a facultative pathogen
can cause disease but doesn’t require host to complete life cycle
How does the establishment of infection work
- presence of microorganism on host doesn’t lead to disease
- interactions between host + microbe contribute to final outcome
What is the establishment of infection influenced by?
- virulence of the microbe
- defense mechanism of host (innate vs adaptive)
What are the steps to establishment of infection
- pathogen encounter/exposure
- host entry
- adhesion + invasion
- immune system evasion
- host damage
- each step requires unique evasion strategies
What is staphylococcus epidermis
- an opportunistic pathogen
- normal component of the skin + important in protecting skin from unwanted pathogens
How do we encounter S. epidermis
- its very hardy and a ubiquitous component of human skin
How does S. epidermis enter the host
- nosocomial (hospital-borne)
- spread through catheters, pacemakers, + plastic implants
How does S. epidermis adhere to the host
- can tolerate changing osmolarity
- attaches via hydrophobic interactions
- teichoic acid associates with plastic
- bacterial components bind ECM components of host
How does S. epidermis evade the immune system
- biofilms provide resistance to antibiotics + protection from AMPs
- AMP resistance through efflux pumps (extensive antibiotic resistance genes)
- PGA-poly-gamma-glutamic acid production in capsule-like exopolymer (protects against phagocytosis + AMPs)
How does S. epidermis damage the host
- PSMs (phenol-soluble modulins)
- allows access to host cell resources
What is Yersinia pestis
- gram negative bacilli
- discovered by Alexandre Yersin in 1894
- causative agent of bubonic plague
How does yersinia pestis cause bubonic plague
- route of infection: flea bite
- replicate in macrophages
- macrophages migrate to lymph nodes -> buboes form
Who was Roberta Koch
- studied the theory that microorganism cause human disease (showed cause and effect relationship between pathogen + disease)
- developed Koch’s postulates
What are the 4 Koch’s postulates
- pathogen must be present in all cases of disease + absent from health animals
- pathogen must be grown in pure culture
- cause disease from culture
- be reisolated + shown to be same as original
