11.1 Flashcards by MARIANNE JOYCE TAYAG

growth and multiplication of a microbe in or on the body with or without the production of disease

infection

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abnormal state in which all or part of the body is not functioning properly

disease

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it is the measure of the pathogenicity of a microorganism

virulence

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it is the ability/capacity of a bacterium to cause disease

pathogenicity

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refers both to the mechanism of infection and to the mechanism by which disease develops

pathogenesis

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degree of pathogenicity

virulence

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Are molecules produced by pathogens that contribute to their ability to cause disease

Virulence factors

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Examples of virulence factors

• Adhesion factors
• Biofilms
• Extracellular enzymes
• Toxins
• Antiphagocytic factors

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disease causing organism

pathogen

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scientific study of disease

pathology

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causative agent of disease

etiology

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organism that shelters and supports the growth of pathogenic organisms

host

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it is the ability of a microorganism to enter, survive, and multiply within a host

infectivity

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more virulent and can cause diseases in a normal person

strict pathogens

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typically member of normal flora and cause diseases when introduced into unprotected sites, usually occur in people with underlying conditions

opportunistic pathogens

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Portals of Entry

Pathogens must:

Gain access to host
Adhere to host tissue
Penetrate or evade host defenses
Damage host tissue

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Routes microorganisms can penetrate the body:

Mucuous membranes
Skin
Parenteral route
Preferred portal of entry

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– Easiest and most frequent route of
infection
– Inhaled through nose or oral cavity
– Dust particles, moisture droplets

Respiratory tract

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Enumerate 5 diseases that can enter through the respiratory tract

CPTIS

Common cold
Pneumonia
Tuberculosis
Influenza
Smallpox

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pathogens are ingested through food or water, contaminated fingers
pathogens are inactivated by stomach acid, enzymes, bile

gastrointestinal tract

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4 diseases that enter the body through the gastrointestinal route

CHAP

cholera
hepatitis A
amoeboid dysentery
poliomyelitis

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mucous membrane entry route where infections are sexually transmitted

genitourinary tract

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Contracted sexually, intact or broken
mucous membranes

Genitourinary tract

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Enumerate 5 sexually transmitted infections (STIs) that enter via the genitourinary tract.

HIV
genital warts
genital herpes
syphilis
gonorrhea

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Barrier to microorganisms

Unbroken skin

2 natural openings in the skin that can serve as entry points for pathogens.

hair follicles and sweat gland ducts

parasite that can penetrate normal, unbroken skin to cause infection

hookworm larva

fungal infection that grows on the keratin layer of the skin

ringworm

2 conditions of damaged skin that can allow microbial entry

abscesses and burns

route of entry where microorganisms are deposited directly below the skin

parenteral route

Enumerate 5 examples of parenteral entry points for microorganisms.

Puncture wounds, injections, bites, wounds, surgery

Enumerate 4 diseases transmitted through the parenteral route

MRHT malaria rabies hepatitis B tetanus

• Some organisms must enter via preferred route to cause disease • Some organisms may cause disease with many different routes of entry

Preferrend Portal of Entry

Virulence of a microbe or the potency of its toxin is often expressed as the

LD 50 (lethal dose for 50% of hosts)

amount of toxin/pathogen necessary to kill 50% of the population

LD50

Measures potency of toxins

LD50

LD50 Botulinum toxin =

0.03 ng/kg

LD50 Staphylococcal enterotoxin =

1350 ng/kg

LD50 Shiga toxin =

250 ng/kg

dose required to produce infection in 50% of test animals

ID50 (infectious dose for 50% of hosts)

Measures virulence of a microorganism

ID50

Anthrax ID50: • Cutaneous = • Inhalation = • Gastrointestinal =

• Cutaneous = 10–50 endospores • Inhalation = 10,000–20,000 endospores • Gastrointestinal = 250,000–1,000,000 endospores

attachment of microorganisms after entry to host

Adherence

Examples of surface molecules

• **Ligands and adhesins** bind specifically for receptors on host cells. • **Glycocalyx, pili, fimbriae**

Receptors of host cells

Mannose (a sugar)

Altering receptor that alters ability for infection to occur

Adhesin (together with mannose)

Attaches to teeth by its glycocalyx

*Streptococcus* *mutans*

have fimbriae that adhere that to glycocalyx of *Streptococcus* *mutans*

*Actinomyces*

Involved in dental caries (cavities)

*Actinomyces*

have adhesins on fimbriae, attach to specific regions of small intestine

*Escherichia* *coli*

Communities of microorganisms and their extracellular products that attach to non living and living surfaces

Biofilms

Is resistant to disinfectants and antibiotics

Biofilms

Examples of biofilms

Medical catheters Algae Dental plaque

Enumerate 5 mechanisms which assist bacterial survival in the host

Capsule Production Capsular antigen M protein production Resistance to oxidative damage Coagulase production

* Impair phagocytosis - preventing phagocytic cell from attaching to microorganism * and it is made by glycoclayx

Capsule

Frederick Griffith’s experiment of genetic transformation

*Streptococcus* *pneumoniae*

3 Components of Cell Wall

M protein Opa protein Mycolic acid

- mediates attachment to epithelium - resists phagocytosis

M protein

Organism which has an M protein that resists phagocytosis

*Streptococcus* *pyogenes*

- an outer membrane — encoded by Opa genes - helps in attachment - inhibits T helper cells

Opa protein

organism which has an Opa protein that inihibits T helper cells

*Neisseria* *gonorrheae*

- resists digestion by phagocytes

Mycolic acid

organism which has mycolic acid that resists digest by phagocytes

*Mycobacterium* *tuberculosis*

extracellular enzyme

exoenzymes

dissolve material between cells, form or dissolve clots

extracellular enzymes

- converts fibrinogen to fibrin clot - isolates microorganism from host defenses

Coagulase

Protect bacteria from phagocytosis from WBCs and other host defenses

Blood clot

are often coagulase positive and associated with boils and abscesses

*Staphylococci*

enzyme that breaks down fibrin

*Kinases*

kinase enzyme specifically produced *Streptococci*

Streptokinase

kinase enzyme specifically produced by *Staphylococci*

Staphylokinase

Enzyme that breaks down cell to cell adhesions in connective tissue

Hyaluronidase

Enzyme that breaks down hyaluronic acid (found in connective tissues)

Hyaluronidase

has a “spreading factor” mixed with a drug to help spread drug thru a body tissue

Hyaluronidase

Enzyme produced by *Clostridium* *perfringens*

Collagenase

bacterial species that produces collagenase and causes gas gangrene

*Clostridium* *perfringens*

Identify the type of infection where Clostridium perfringens uses collagenase to spread through muscle tissue

Gas gangrene

*Clostridium* *perfringens* uses this to spread itself thru muscle tissue

Collagenase

Breaks down protein collagen

Collagenase

Destroy antibodies

IgA proteases

Causes death (necrosis) to tissue cells

Necrotizing factor

Identify the disease caused by bacteria that produce necrotizing factors and destroy soft tissues rapidly.

Necrotizing fasciitis

Common name of the bacteria that causes necrotizing fasciitis

Flesh eating bacteria

- the process by which pathogens alter their surface proteins - new antibodies must be produced

Antigenic variation

Identify the surface protein in Neisseria gonorrhoeae that has several versions due to antigenic variation

Opa protein

3 diseases where the pathogen uses antigenic variation

Gonorrhea Sleeping sickness Influenza

- Bacterial proteins that trigger rearrangement of actin filaments (cytoskeleton) in host cells to promote invasion - Facilitates movement of microorganism into host cells

Invasins (sounds like invasion)

How Pathogens Damage Host Cells

1. Utilize host’s nutrients 2. Direct damage in immediate vicinity of infection 3. Toxin production

Bind iron away from host’s iron binding proteins

Siderophores

Enumerate 3 types of pathogens that can cause direct damage by multiplying inside host cells.

Viruses Bacteria Protozoa

general term for poisonous substances produced by certain microorganisms that contribute to disease symptoms.

Toxins

2 main types of toxins

Exotoxins and Endotoxins

type of toxin that is secreted by bacteria and is often **protein-based**

Exotoxins

type of toxin that is a component of the outer membrane of Gram-negative bacteria

Endotoxins

type of toxin primarily responsible for causing fever and shock due to its release during bacterial cell lysis

endotoxins

7 possible harmful effects of bacterial toxins

– Fever – Cardiovascular abnormalities – Diarrhea – Shock – Destroy blood cells – Destroy blood vessels – Disrupt nervous system

Specific for a structure or function in host cell

Exotoxins

Synthesized by specific bacteria that often have plasmids or prophages bearing the exotoxin genes

Exotoxins

Exotoxins are heat-labile proteins which are inactivated at what temp

60-80 deg Celsius

One of the most lethal substances known, effective in microgram-per-kilogram doses. Give specific example

Exotoxin (e.g. botulinum toxin)

Exotoxins are highly immunogenic and they stimulate the production of NEUTRALIZING ANTIBODIES called

Antitoxins

Exotoxins are easily inactivated by? To form what?

Formaldehyde and Iodine Toxoids

True or False Exotoxins are able to produce fever in the host directly

False

Identify the naming convention often used for exotoxins.

They are named after the disease they cause (e.g., diphtheria toxin)

Produced inside some bacteria as part of their growth and metabolism and released into the surrounding medium

Exotoxins

Most bacteria that produce exotoxins are gram positive or negative?

Gram positive

They carry the genes for exotoxins

Plasmids or Phages

Are soluble in body fluids, so can easily diffuse into the blood and are rapidly transported throughout the body.

Exotoxins

Function of exotoxins

Work by destroying particular parts of the host’s cells or by inhibiting certain metabolic functions

3 types of Exotoxins

1. A-B toxins 2. Membrane disrupting toxin 3. Superantigens

A-B toxins are also called

Type III toxins

Most exotoxins fall into this category/type

A-B toxins

2 components of A-B toxins (type III toxins)

A component (active enzyme component) B component (binding component)

A-B toxins are released by?

Bacteria

Inhibits protein synthesis and kills cell

A component

Component of A-B toxins that bind to receptor of host cell

B component

Membrane disrupting toxin is also called

Type II toxins

Causes lysis of cells by disrupting cell membrane

Membrane disrupting toxin

membrane-disrupting exotoxin that forms protein channels

*Staphylococcus* *aureus* toxin

membrane-disrupting exotoxin that disrupts phospholipids

*Clostridium* *perfringens* toxin

Membrane disrupting toxins that kill phagocytic WBCs

Leukocidins

Membrane disrupting toxins that kill RBCs

Hemolysins

Superantigens are also called

Type I toxins

Provoke intense immune response Protein in nature (antigens)

Superantigens

Stimulate T cells

Superantigens

Superantigens release cytokines (too much), leading to

Fever Nausea Vomiting Diarrhea

- Attack nerve cells - Target the nervous system, and can interfere with normal nerve impulse transmission

Neurotoxins

2 examples of diseases caused by neurotoxins

Tetanus (Clostridium tetani) Botulism (Clostridium botulinum)

Toxins that attack cardiac cells

Cardiotoxins

Toxins that attack liver cells

Hepatotoxins

Toxins that attack lining of GI tract

Enterotoxins

Toxins that attack variety of cells

Cytotoxins

Name the bacterium responsible for producing diphtheria toxin.

*Corynebacterium* *diphtheriae*

Toxin that requires lysogenic phage carrying tox gene

Diphtheria toxin

inhibits protein synthesis in eukaryotic cells

Cytotoxins

Organism responsible for producing Erythrogenic toxins

*Streptococcus* *pyogenes*

damage plasma membranes of capillaries under skin causing rash

A,B,C toxins

Diseases associated with Erythrogenic toxins

Scarlet fever

Organism responsible for producing Botulinum toxin

*Clostridium* *botulinum*

– Acts on neuromuscular junction

Botulinum toxin

– Prevents nerve impulse transmission • Inhibits release of neurotransmitter acetylcholine Thus, causing ____ ____

Botulinum toxin flaccid paralysis

Organism responsible for producing tetanus toxin

*Clostridium* *tetani*

specific name of the tetanus neurotoxin

Tetanospasmin

What part of the nervous system is affected by tetanospasmin?

Central nervous system (CNS)

What is the clinical result of tetanospasmin (tetanus toxin) interfering with inhibitory neurons?

Uncontrollable muscle contractions

classic symptom of tetanus involving jaw muscles?

Lockjaw (trismus)

Organism responsible for producing vibrio enterotoxin

*Vibrio cholerae*

Produces cholera toxin

Vibrio enterotoxins

2 sub units of vibrio enterotoxins

Sub unit B - attaches epithelim of intestinal tract Sub unit A - causes cells to secrete large amounts of electrolytes causing diarrhea

Organism responsible for producing *Staphylococcal* enterotoxin

*Staphylococus* *aureus*

*Staphylococcal enterotoxin* is similar to what toxin?

Cholera toxin

3 ways on how bacterial enterotoxins affect human host

• (1) ingestion of preformed exotoxin • (2) colonization of a mucosal surface followed by exotoxin production • (3) colonization of a wound or abscess followed by local exotoxin production

Where are endotoxins located in bacterial cells?

outer membrane of Gram-negative bacteria

What is the chemical nature of endotoxins?

Lipopolysaccharides (LPS)

Component of LPS responsible for the toxic effects of endotoxins

Lipid A

Released when gram (-ve) bacteria undergo lysis and multiplication

Endotoxins

–Cause WBC to release cytokines • Toxic at these levels –Cause chills, fever, weakness, generalized aches, shock and death

Endotoxins

What clotting-related condition can be triggered endotoxins

Disseminated Intravascular Coagulation (DIC)

Can cause activation of blood clotting mechanisms causing tiny blood clots

Endotoxins

Routes that microbes use to exit host

Portals of Exit

5 portals of exit through which pathogens can leave the host.

Respiratory tract Gastrointestinal (GI) tract Urogenital tract Skin Blood

Portals of Exit (Preferred Ways to Leave the Body and Spread Infection) Respiratory tract: Gastrointestinal (GI) tract: Urogenital tract: Skin: Blood:

Respiratory tract: via cough or sneeze Gastrointestinal (GI) tract: via feces or saliva Urogenital tract: via urine, vaginal/penile secretions Skin: via open wounds Blood: Biting arthropods, needles or syringes, surgery

Enumerate disease caused by *Staphylococcus* *aureus*

Skin infections, pneumonia, septicemia, endocarditis, toxic shock syndrome

is part of the normal flora of the skin and nasal passages in many people. However, it can become infectious when the skin barrier is broken (e.g., through a wound, surgery, or catheter use

*Staphylococcus* *aureus*

The bacteria are highly contagious and can spread through direct contact with infected individuals or contaminated surfaces

*Staphylococcus* *aureus*

can be an opportunistic pathogen, infecting immunocompromised individuals or those with disrupted skin barriers.

*Staphylococcus* *aureus*

3 exotoxins produced by S. aureus

α-toxin exfoliative toxin Toxic Shock Syndrome Toxin-1 (TSST-1)

Forms pores in the membranes of host cells, leading to cell lysis.

Alpha toxin

Causes skin peeling in diseases like scalded skin syndrome.

Exfoliative toxin

A superantigen that causes widespread activation of T-cells, leading to systemic inflammation and shock.

Toxic Shock Syndrome Toxin 1 (TSST 1)

Promotes clot formation, allowing the bacteria to evade immune cells by creating a fibrin shield.

Coagulase

Breaks down connective tissue, facilitating the spread of infection.

Hyaluronidase

Binds to the Fc region of antibodies, preventing opsonization and phagocytosis by immune cells

Protein A

What term refers to the visible effects of viral infection on host cells?

Cytopathic effects (CPE)

What usually happens to host cells infected by animal viruses?

The host cell usually dies

3 mechanisms by which viruses can cause the death of host cells.

- Accumulation of multiplying viruses - Alteration of cell membrane permeability - Inhibition of host DNA or RNA synthesis

What are the two types of cytopathic effects?

Cytocidal (cell-killing) Noncytocidal (non-lethal but damaging)

Which virus is known to inhibit mitosis in host cells?

Herpes virus

What cellular organelles, when released by viral infection, can destroy cellular contents?

Lysosomes

What are inclusion bodies in virus-infected cells?

viral parts or nucleic acids

staining characteristics of inclusion bodies

Eosinophilic, Basophilic

What specific inclusion bodies are associated with Rabies virus?

Negri bodies

Adjacent infected cells fuse

Syncytium

What immune-signaling proteins may be produced by host cells in response to viral infection?

Interferons

Result of transformation of host cell

- Cause spindle shaped cells - Lack contact inhibition

Enumerate 9 Cytopathic Effects (CPEs) of Viruses

1. Inhibition of macromolecule synthesis 2. Release of lysosomal enzymes 3. Formation of inclusion bodies 4. Syncytium formation 5. Changes in host cell functions 6. Induction of interferon production 7. Antigenic changes on the plasma membrane 8. Chromosomal changes and activation of oncogenes 9. Transformation of host cells

What type of enzyme secreted by fungi helps them break down host tissues?

Proteases

What fungal structure helps evade phagocytosis by the host immune system?

Capsule

are toxic secondary metabolites produced by certain species of fungi (molds) that grow on crops, foodstuffs, and animal feed. These toxic compounds can contaminate various agricultural products, including grains (e.g., corn, wheat, barley), nuts, and dried fruits.

Mycotoxins

Name a mycotoxin associated with contamination of grains and can cause hallucinations or convulsions.

Ergot

Which mycotoxin is a known carcinogen often found in contaminated peanuts and corn?

Aflatoxin

11.1 Flashcards

(191 cards)