Module 9

Chapter 15 Microbial Mechanisms of Pathogenicity

  • Pathogenicity: the ability of a pathogen to ______by overcoming the defenses of the host
  • Virulence: the ______of pathogenicity
  • A pathogenic organism is ______
  • A pathogen that is highly virulent causes ______

How microorganisms enter a host

Portals of entry

  • ______of entry: avenues that pathogens can use ______into the human body

Mucous membranes

  • ______tract, ______(GI) tract, ______(GU) tract, conjunctiva (eyes)
  • Most common portals are ______, ______tracts
  • ______through nose, mouth
  • ______
  • ______is portal for pathogens that cause ______

Skin

  • Largest organ, ______of defense
  • ______is ______to most microbes
  • Some gain access through ______in skin
  • Some fungi can ______

Parenteral route

  • Access through ______
  • From ______
  • All microbes have ______portal of entry
  • Some microbes have ______portals of entry

Numbers of invading microbes

  • Likelihood of disease ______as ______of pathogens ______
  • ______can be overwhelmed by immune system
  • ______of a disease expressed as ______: infectious dose for ______of a ______
  • Expression of relative virulence under experimental conditions - can be ______for ______portals
  • Potency of ______expressed as ______: ______for 50% of a test population

Virulence Factors

  • ______or ______that a pathogen uses to ______
  • Many virulence factors exist

Adherence

  • Means of ______
  • ______for pathogenicity in most pathogens
  • Interfere with ______, interfere with ______
  • ______(______)bind to complementary ______
  • Adhesins may be located on ______, ______structures
  • Adhesins usually ______
  • Binding is ______for certain host ______, ______

How pathogens penetrate host defenses

  • Most pathogens must ______to ______
  • Several factors contribute to the ability of pathogens to invade a host

Capsules

  • Capsules impair ______(being ______)
  • Prevents ______to pathogen
  • Capsules ______a bacterium is virulent

Cell wall components

  • Some cell walls contain chemicals that ______
  • ______resists phagocytosis
  • Streptococcus pyogenes
  • ______inhibits T helper cells
  • Neisseria gonorrhoeae
  • ______(waxy lipid)resists digestion
  • Mycobacterium tuberculosis

Enzymes

  • ______: coagulates fibrinogen
  • ______: digest fibrin clots
  • Hyaluronidase: hydrolyzes hyaluronic acid
  • Collagenase: hydrolyzes collagen
  • ______: destroy IgA antibodies

Antigenic variation

  • During pathogenesis, body produces ______to fight infection
  • Bind to ______on surface of bacteria
  • Antigenic variation: ability to ______
  • Changes ______over time
  • By the time body produces antibodies, surface antigen has changed
  • Influenzavirus, N. gonorrhoeae, Trypanosomabrucei(African sleeping sickness)

How bacterial pathogens damage host cells

  • Bacteria can damage host by:
  • Using host’s nutrients
  • Direct damage
  • The production of toxins

Using host’s nutrients

  • ______: proteins that tightly bind ______
  • ______is required for growth
  • Iron in human body is ______
  • Some pathogens release ______to ______from host

Direct damage

  • A number of ways that microbes can damage cells
  • Grow ______cells, multiply and ______cell
  • ______to host cell and cause damage as pathogen uses host ______
  • ______host by ______

Toxins

  • Toxins: ______that are produced by some microbes
  • Toxigenicity: ability of microbes to ______
  • Two types of toxins
  • ______
  • ______

Exotoxins

  • ______toxins made ______bacterium and secreted to its surroundings
  • Many are ______, so small amounts harmful
  • Why? ______
  • ______in body fluids, can be transported ______
  • Diseases caused by bacteria that produce toxins are a ______of toxin
  • Staphylococcal food poisoning is an ______
  • ______: antibodies produced by the body that ______toxins

Types of toxins

  • ______toxins: consist of two parts, “A” and “B”
  • A part is ______(______) component
  • B part is the ______component
  • Diptheria toxin is A-B toxin
  • Membrane-disrupting toxins
  • ______host cells by making ______in plasma membranes
  • Disrupts ______bilayer

Superantigens

  • Provoke ______immune response
  • Stimulate ______(division) of ______(immune cells)
  • Release chemicals, ______, that regulate immune response
  • Too many cytokines in blood can lead to ______

Endotoxins

  • Part of ______of ______bacteria
  • ______portion of outer membrane
  • Endotoxin is the lipid portion, called ______
  • Endotoxins are released when Gram-negative bacteria ______and cells ______
  • ______endotoxins
  • Antibiotics can cause ______ release LPS
  • All endotoxins produce the ______signs and symptoms
  • ______, ______, weakness, aches, ______, death
  • Disseminated intravascular clotting
  • Shock: life threatening ______
  • Endotoxic shock – shock produced by ______

Plasmids and pathogenicity

  • R factors carry ______
  • Others can carry ______
  • Toxins - tetanus neurotoxin, staphylococcal enterotoxin
  • Fimbriae, adhesions, enzymes (coagulase)

Lysogeny and Pathogenicity

  • Prophage: ______incorporated into ______
  • Prophage can provide ______to bacteria
  • ______conversion: change in ______due to a ______
  • Can transfer virulence genes to ______

Pathogenic properties of viruses

  • Viruses have a number of mechanisms to ______
  • Can grow ______of host cells
  • Some can “______” attachment sites
  • HIV has attachment sites ______for antibodies to bind
  • Some attack ______
  • HIV

Cytopathic effects of viruses

  • ______effects (CPE): ______of viral infection
  • CPE used to ______many viral infections

Pathogenic properties of Fungi

  • Fungal ______may cause symptoms
  • ______infections provoke an ______response
  • Tichothecene:______that inhibit ______synthesis
  • ______that modify host membranes, allow ______
  • Candida, Trichophyton
  • ______prevents ______
  • Cryptococcus

Pathogenic properties of Protozoa

  • ______of protozoa and their ______often produce symptoms
  • Some (Plasmodium) invade ______(red blood cells) and rupture them
  • Others (Giardia lamblia) attach to host cells by a “______” and digest cells and tissue fluids
  • Some can undergo ______(Giardia, Trypanosomas)

Pathogenic properties of Helminths

  • ______ofhelminths causes disease
  • Some (Wuchereriabancrofti) use ______for growth, reproduction (elephantitis)
  • Block lymphatic circulation, leads to accumulation of lymph, grotesque swelling

Pathogenic properties of Algae

  • Some produce ______
  • Paralytic shellfish poisoning
  • (Alexandrium, a dinoflagellate)

Portals of exit

  • Specific routes that microbes use to ______
  • In secretions, excretions, discharges, tissue that’s been shed
  • In general, portals of exit are ______
  • Respiratory tract
  • Gastrointestinal tract
  • Genitourinary tract
  • Skin
  • Blood