2 - Pathogenesis of Microbial Disease 1 & 2 - FBS
Pandemic
Term: if infections has a worldwide distribution (e.g., COVID-19).
Endemic infection
Term: infection that is constantly present at a low level in a specific population (e.g., Malaria in West Africa)
Incubation period
Term: interval between the initial infection and the first appearance of any signs or symptoms (hours/days/weeks).
Infectious dose
Term: number of pathogens that will infect 50% of an experimental group of hosts in a specified time.
lethal dose
Term: number of pathogens that will kill 50% of an experimental group of hosts in a specified time.
Invasiveness
Term: plays a critical role in pathogenesis; it is dependent upon secreted bacterial enzymes.
Pyogenic inflammation (pus producing)
Term: primarily characterized by the presence of neutrophils, is commonly associated with pyogenic bacteria such as Streptococcus pyogenes, Staphylococcus aureus, and Streptococcus pneumoniae.
Acute specific illness (period of illness)
Term: the disease is most severe. The person exhibits overt signs and symptoms of disease.
Recovery period (Period of convalescence)
Term: the illness subsides and the patient returns to health
An infection
Term: the successful colonization of a host by a microorganism.
Gram-negative
Are Diarhhoea, Cholera, and Whooping cough diseases from gram-positive, or gram-negative bacteria?
Gram-positive
Are diphtheria, tetanus, gas gangrene, and toxic shock diseases from gram-positive, or gram-negative bacteria?
Bacterial neurotoxin
Tetanus toxins are what type of neurotoxin?
Endotoxin
Clinical effects from this toxin are fever and/or shock.
Exotoxin
Clinical effects from this toxin are variable.
adherence
What is the first step in infection?
biofilm
Dental plaque is a classic example of what?
Endotoxin
Disease from this toxin can include Sepsis by gram-negative rods
Exotoxin
Diseases from this toxin include cholera, tetanus, or diphtheria.
Lipopolysaccharide-lipoprotein complexes
Endotoxins are made primarily from which biomolecule?
Bacterial chromosomees
Endtoxins are where on location of genes?
polypeptides
Exotoxins are made of ____________________, whose genes are frequently located on plasmids or lysogenic bacterial viruses.
Proteins
Exotoxins are made primarily from which biomolecule?
Plasmid, or bacteriophage
Exotoxins are where on location of genes?
bacterial enzymes
Invasiveness plays a critical role in pathogenesis; it is dependent upon secreted ________________________.
plasmid
The genes for both E. coli toxins are carried on a what?
Gas gangrene
Mode of action for this disease: Alpha-toxin: a lecithinase destroys eukaryotic cell membranes
Toxic Shock
Mode of action for this disease: Binds to class II MHC protein; induces IL-1 and IL-2
Diphtheria
Mode of action for this disease: Elongation factor inactivated by ADP-ribosylation
Diarrhoea
Mode of action for this disease: Labile toxin stimulates adenylate cyclase by ADP-ribosylation; stable toxin stimulates guanylate cyclase.
Cholera, as well as Whooping cough.
Mode of action for this disease: Stimulates adenylate cyclase by ADP-ribosylation
Tetanus
Mode of action for this disease: Tetanospamin blocks release of the inhibitory neurotransmitter glycine at motor nerve ends.
Endotoxin
Origin of this toxin comes from cell wall constituent
Exotoxin
Origin of this toxin is secreted from the cell
Endotoxin
Primary chemistry that makes up this toxin are lipopolysaccharides.
Exotoxin
Primary chemistry that makes up this toxin are polypeptides.
incubation period
Some bacteria are more contagious during which period?
invasive period
Some bacteria are more infectious during which period?
Endotoxin
Source of this toxin is from cell walls of gram-negative bacteria.
Exotoxin
Source of this toxin is from some species of gram-positive and gram-negative bacteria.
Contagious diseases
Term: A disease that is easily spread from person to person.
Tetanus Toxin (Tetanospasmin)
Term: A neurotoxin from Clostridium tetani that hinders glycine release, resulting in muscle spasms and neurological disturbances.
Exotoxin
Term: A potent, often heat-labile protein toxin secreted by certain bacteria, causing specific toxic effects on the host's cells or tissues.
Endotoxin
Term: A toxic component of the cell wall of certain gram-negative bacteria, released when the bacteria die, that can trigger harmful immune responses in the host.
Zoonotic disease
Term: Disease transmitted from animals to humans. E.g. Rabies
Nosocomial diseases
Term: Diseases acquired in hospital settings
Iatrogenic diseases
Term: Diseases that are contracted as the result of a medical procedure.
Epidemic
Term: Infection occurs much more frequently than usual (e.g., an epidemic of influenza in the winter).
Communicable diseases
Term: Infections that spread from host to host.
Granulomatous inflammation (granuloma forming)
Term: Inflammation characterized primarily by the presence of macrophages and T cells, with notable instances caused by organisms like Mycobacterium tuberculosis, leading to the formation of granulomas.
Bacterial cytotoxins (Miscellaneous exotoxins)
Term: Produced by gas gangrene-causing Clostridium welchii and other clostridia, these toxins, including α-toxin, collagenase, protease, hyaluronidase, and DNAase, harm cells and connective tissue through multiple actions, some with hemolytic and necrotizing effects.
Toxigenicity
Term: The capacity of a microorganism to produce and release toxins that can cause harmful effects on the host's cells or tissues.
Biofilms
Term: a complex, functional community of one or more species of microbes, encased in an extracellular polysaccharide matrix and attached to one another or to a solid surface (such as a denture prosthesis or an intravenous catheter).
Pathogen
Term: a microorganism capable of causing disease
Virulence
Term: a quantitative measure of pathogenicity and is related to an organism's toxigenic potential and invasiveness.
Disease
Term: any condition in which the normal structure or functions of the body are damaged or impaired.
Prodromal period
Term: characterized by early, mild symptoms of disease, such as general aches and malaise.
Period of decline
Term: during this infection period, the signs and symptoms subside.
cell wall proteins
The ______________________ of the Gram-positive cocci, such as the M protein of the group A streptococci and protein A of the staphylococci, are also antiphagocytic.
Exotoxin
The antigenicity of this toxin induces high-titre antibodies called antitoxins.
-labile
The heat-____________toxin of E. coli (inactivated at 65°C in 30 min)
-stable
The heat-____________toxin of E. coli (not inactivated by boiling for 30 min)
gastrointestinal tract
What is the portal of entry for Cholera?
gastrointestinal tract
What is the portal of entry for Dysentery?
skin
What is the portal of entry for Hep-B?
gastrointestinal tract
What is the portal of entry for Infectious hepatitis?
respiratory tract
What is the portal of entry for Influenza?
respiratory tract
What is the portal of entry for Meningitis?
respiratory tract
What is the portal of entry for Pneumonia?
capsule
The polysaccharide ________________ of several common pathogens, such as Streptococcus pneumoniae and Neisseria meningitidis, prevents the phagocyte from adhering to the bacteria.
Exotoxin
The toxicity of this toxin is high (fatal dose of 1µg)
Endotoxin
The toxicity of this toxin is low (fatal dose in the order of 100s of µg's)
skin
What is the portal of entry for Tetanus?
respiratory tract
What is the portal of entry for Tuberculosis?
gastrointestinal tract
What is the portal of entry for Typhoid?
Genital tract
What is the portal of entry for gonorrhea, syphilis, AIDS, and Vaginitis?
respiratory tract
What is the portal of entry for mononucleosis?
gastrointestinal tract
What is the portal of entry for polio?
respiratory tract
What is the portal of entry for the common cold?
Bacterial Enterotoxins
These toxins act on the gut mucosa and cause gastrointestinal disturbances.
Collagenase, hyaluronidase.
These two enzymes degrade their respective intercellular substances, facilitating the spread of bacteria through tissues, and are significant in skin infections caused by Streptococcus pyogenes.
Coagulase
This enzyme accelerates fibrin clot formation, protecting organisms from phagocytosis by isolating the infected area and coating them with a fibrin layer; produced by Staphylococcus aureus.
Leukocidins
This enzyme causes can destroy both neutrophilic leukocytes and macrophages, with Aggregatibacter actinomycetemcomitans, a periodontal pathogen, harboring this enzyme, and less virulent mutants lacking its secretion.
Immunoglobulin A protease (IgA)
This enzyme degrades protective IgA on mucosal surfaces, enabling adherence of organisms like N. gonorrhoeae, H. influenzae, and S. pneumoniae to mucous membranes.
exotoxin
This toxin can cause disease in distant parts of the body as a result of diffusion or carriage of the toxin via systemic routes
Endotoxin
This toxin does not have toxoids or vaccines available.
Endotoxin
This toxin is poorly antigenic.
Exotoxin
This toxin is usually thermolabile (destroyed rapid at/above 60C)
Endotoxin
This toxin is usually thermostable at 100C for 1-hour.
Exotoxins
This toxin uses toxoids as vaccines
1. Trismus (Lock jaw) 2. Risus Sardonicus (Grin caused by facial spasms) 3. Opisthotonos (severe simultaneous spasm of ALL muscles)
What three things make up the "Tetanic Triad"?
Tetanus toxin
What toxin can lead to spastic paralysis?
Heat labile, Heat stable.
What two heat types are there of E. coli?
clostridia
Toxins with a hemolytic and necrotizing activity has been identified in ____________.
Exotoxic
Which toxin is highly toxic?
False - We now understand that biofilm-associated infections are challenging to eliminate because organisms within biofilms are more resistant to antimicrobials than their free-living counterparts
True or false - infections associated with biofilms are easy to eradicate.
1. Enterotoxins 2. Neurotoxins 3. Cytotoxins
What are three types of exotoxins?
adherence mechanisms
What do some bacteria and fungi have to facilitate their attachment onto host cells, which can thereby enhance their ability to multiply?
Endotoxins
___________ are lipopolysaccharides found in the cell walls of Gram-negative bacteria (both cocci and bacilli), and they are not intentionally released from the cell.
adherence mechanisms
________________________ are critical for organisms that attach to mucous membranes; mutants that lack these mechanisms are often non-pathogenic