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