12. pathogenesis II Flashcards
the quantitative ability of an agent to cause disease. these agents cause disease when introduced into the host in small numbers. involves adherence, persistence, invasion and toxigenicity
virulence
the process by which bacteria stick to the surfaces of host cells. after bacteria have entered the body, this is a major initial step in the infection process
adherence
the process by which bacteria, parasites and fungi and viruses enter host cells or tissues and spread in the body
invasion
the ability of a microorganism to produce a toxin that contributes to the development of disease
toxigenicity
these are the objective changes in the body, such as fever, rash, that can be directly observed
signs
these are subjective changes, such as pain and loss of appetite, that are experienced by the patient
symptoms
what are the four stages of the infectious process?
- the incubation period
- the prodromal stage
- the illness period
- the convalescence (recovery) period
this period of the infectious process is the time between pathogen entry and development of signs and symptoms. the pathogen is reproducing but has not reached a sufficient level to cause clinical manifestation. this periods length varies with the pathogen
the incubation period
this period of the infectious process occurs with an onset of signs and symptoms that are not yet specific enough to make a clear diagnosis. however, the patient is often contagious
the prodromal period
this period of the infectious process occurs when the disease is the most severe and displays characteristic signs and symptoms. the host immune response is typically triggered at this stage
the illness period
this period of the infectious process is the period of decline, the signs and symptoms begin to disappear
the convalescence (recovery) period
pathogens adhere with a ______ degree of specificity to particular tissues
high
the cell surfaces of both bacteria and host cells are ________
hydrophobic
in general, the more hydrophobic the bacterial cell surface the ________ the adherence to the host cell
greater
is gram positive or gram negative bacteria more hydrophobic?
gram neg
examples of this are pili and fimbrae, membrane and capsular materials (glycocalyx, capsule or S layer), and specialized adhesion molecules on the surface of the invading microbe
adherence factors/adhesions
these are the main adherence virulence factors that mediate ligand-receptor mechanisms to adhere to host cell surfaces
pili (or fimbrae)
______ strains have type 1 pili, which adhere to epithelial cell receptors
E.coli
E.coli organisms that cause urinary tract infections commonly have _____
P-pili
these have fimbrae that consist partly of protein F, and M protein and are covered by lipoteichoic acids (LTA)
group A streptococci e.g. Streptococcus pyogenes
_____ and ________ cause adherence of the Streptococci to buccal epithelial cells (e.g. cause sore throat)
LTA and protein F
during this step of a pathogen infecting a host, the bacterial pathogens actively penetrate the hosts mucous membranes and epithelium. this is accomplished by secreting lytic substances or enzymes such as coagulase, collagenase, hemolysins
invasion
how do hyaluronidase and collagenase work?
1, attacking the extracellular matrix and basement membranes of body surfaces (integuments) and intestinal linings
2. degrading carbohydrate-protein complexes between cells or on the cell surface
- some pathogens may penetrate to deeper tissue and continues disseminating through the body of the host
in this type of pathogen, after adherence occurs, conformational changes in the cytoskeleton of the host cell allow the uptake of the bacteria
intracellular pathogen
