Chapter 15 Micro

-Disrupts host cell function -Uses host cells nutrients (such as iron) -Produces waste products -Multiplies in host cells and causes ruptures (after rupture they can spread to other tissues in greater numbers)

How can bacterial pathogens damage host cells by direct damage?

Microbes attach to host cells by adhesins. The interaction triggers signals in the host cell that activates factors that can result in the entrance of some bacteria. -the host's cytoskeleton contains a protein called actin, which is used by some microbes to penetrate the host cells or move through the host cells The microbes produce surface proteins called INVASINS that rearrange actin filaments of the host's cytoskeleton and cause MEMBRANE RUFFLING

How can pathogens penetrate into the host cell cytoskeleton?

Using the host nutrients: siderophores ***Siderophores are proteins produced and secreted by pathogens. They are released into the medium, where they take iron away from iron-transport proteins by binding with the iron even more tightly than the host cells*** -Iron is required for the growth of most pathogenic bacteria, but there is not much free iron available because it is bound to iron-transport proteins. -To obtain iron, some pathogens secrete siderophores -Once the iron-siderophore complex is formed, it is taken up by siderophore receptors on the bacterial surface and then brought into the bacterium. In some cases the iron is brought in as part of the complex. Alternative ways: -some pathogens have receptors that directly bind to iron-transport proteins and then these are taken into the bacterium directly along with the iron. -some bacteria produce toxins when iron levels are low to kills the host cells so they release their iron and bacteria can take it.

How do siderophores cause damage to the host by using it's nutrients?

Waxy Lipids- (mycolic acids) -makes up the cell wall of mycobacterium tuberculosis and RESISTS DIGESTION -increases virulence by resisting digestion by phagocytes -bacteria can even multiply inside phagocytosis -wants to be eaten, because it has mechanisms to avoid being digested and can even multiply inside phagocytes

How do waxy lipids contribute to the cell wall components in evading host defenses?

M PROTEIN -a heat-resistant and acid-resistant protein found on both the cell surface and fimbriae -mediates the attachment of the bacterium to epithelial cells of the host and helps the bacterium RESIST PHAGOCYTOSIS by white blood cells. -made by STREPTOCOCCUS PYOGENES - increase virulence of of the microorganism -immunity to S. pyogenes depends on the bodies production of an antibody specific M-protein

How does M-protein contribute to the cell wall components in evading host defenses?

OPA -the outer membrane protein that allows attachment to host cells -the attachment of opa and fimbriae allows the host to take in bacteria Ex: Neisseria gonorrhoae causes gonorrhea and is good at attaching to mucous membranes

How does Opa contribute to the cell wall components in evading host defenses?

The blood of the horseshoe crab contains white blood cells called AMEBOCYTES, which have large amounts of a protein (LYSATE) that causes clotting. In the presence of endotoxin, amebocytes in the crab blood lyse and liberate their clotting protein The resulting gel-clot (precipitate) is a positive test for the presence of endotoxin -degree of reaction is measured by a spectrophotometer

How does the Limus Amebocyte Lysate (LAL) test work?

1. A macrophage ingests a gram-negative bacterium 2. the bacterium is degraded in a vacuole, releasing endotoxins that induce the macrophage to release cytokines, interleukin 1, and TNF 3.Cytokines are released into the blood stream by macrophages and travel to the HYPOTHALAMUS (the temperature control system of the brain) 4. Cytokines induce the hypothalamus to produce prostaglandins which reset the bodys "thermostat" to a high temp producing fever.

How is fever caused by endotoxins?

genotoxins

Toxins produced by some gram-negative bacteria that damage DNA are called____

Toxemia

presence of toxins in the blood

it changes characteristics of a microbe due to the incorporation of a prophage ( viruses that infect bacteria incorporate their DNA into the bacterial chromosome) -bacteria are not pathogenic until they have the specific gene or endotoxin -There are lysogenic viruses (or phage) that incases of specialized transduction takes apart of the bacterium - as result of lysogenic conversion, the bacterial cell is immune to infection by the same type of phage. -mechanism for transferring genes that encode toxins to a new bacterium E.COLI was not pathogenic until undergoing lysogenic conversion

!!!!!!!!!!!!!!how does lysogenic conversion increase pathogenicity of bacteria?

ID50

infectious dose for 50% of a sample population Measures virulence of a microbe

LPS (lipopolysaccharide)

-part sugar part fat -inherently toxic, but we are not exposed until the cell dies -when the body is exposed, it releases cytokines

Antigen

Any substance that induces an immune response in the body against that substance, especially the production of antibodies. ex: toxins, bacteria, viruses, foreign substances

blood

Arthropods provide a portal of exit for microbes via the____

Adherence (adhesion)

Attachment of a pathogen to the tissue of a host; a necessary step in the process of pathogenicity

Kinase enzyme ex: fibrinolysin (streptokinase) which is produced by streptococcus pyogenes

Bacterial enzyme used to evade host defenses by breaking down fibrin clots and DIGESTING them to isolate the infection. -the prevention of coagulation helps the bacterium get further into the body by thinning the blood

Collagenase enzyme ex: produced by several species of clostridium and facilitates the spread of gas gangrene.

Bacterial enzyme used to evade host defenses by breaking down protein collagen-which forms connective tissue of muscles and other body organs/tissues.

Coagulases (enzyme) ex; produced by some members of the staphylococcus genus

Bacterial enzyme used to evade host defenses by coagulating (clotting) the fibrinogen in the blood. -fibrinogen is converted to fibrin, the fibrin may protect the bacterium from phagocytosis and isolate it from other defenses of the host -if the virus is surrounded by clots it is less likely to get detected

IgA proteases (enzyme) ex: N. gonnorhoeae and and N. meningitidis have this ability

Bacterial enzyme used to evade host defenses by destroying IgA antibodies. -IgA antibodies are produced by the body as a defense against adherence of pathogens to mucosal surfaces

Hyaluronidase enzyme ex: produced by some clostridia that causes gas gangrene positive(therapeutic) example: hyaluronidase may be mixed with a drug to promote the spread of the drug through the body tissue

Bacterial enzyme used to evade host defenses by digesting polysaccharides that hold cells together (usually cells of connective tissue) -helps bacteria get through the tissues and spread further from it's initial site of infection

Biofilms

Communities of microbes that cling to surfaces and share available nutrients are called______

•Ergot are alkaloid toxins that cause hallucinations •Often on grains •Similar to LSD •Causes gangrene (restricts capillaries / blood flow) •Aflatoxin is a carcinogenic toxin produced by Aspergillus •Mycotoxins are produced by mushrooms and are neurotoxic •Phalloidin and amanitin -shrooms producing hallucinations, can be fatal

Describe Three fungal toxins

Disseminated Intravascular Coagulation (DIC)

Endotoxins cause the formation of abnormal activation of the proteins involved in blood coagulation, causing small blood clots to form in vessels and cutting off the supply of oxygen to distal tissues

Mycotoxins

Fungal toxin •are produced by mushrooms and are neurotoxic •Phalloidin and amanitin

Aflatoxin

Fungal toxin •is a carcinogenic toxin produced by Aspergillus

•Respiratory tract- -Coughing and sneezing (TB, pneumonia, influenza) •Gastrointestinal tract -Feces and saliva (cholera, shigellosis, amebic dysentry) •Genitourinary tract -Urine; secretions from the penis and vagina(STI's) •Skin- can shed through skin/warts(impetigo, ringworm warts) •Blood(biting insects or needles) -Arthropods that bite; needles or syringes

Identify the portals of exit and give examples:

-changes the properties of a host -can penetrate and grow inside host cells -

In general, how do viruses damage a host?

-microbes leave the body via specific routes called portals of exit in secretions, excretions, discharges, or tissue that has been shed. -In general, portals of exit relate to the infected part of the body, with microbes tending to use the same portal for entry and exit. - the most common portals of exit are the respiratory and GI tracts

Is there always a portal of exit for microbes? Is the portal of exit always the same as the portal of entry? Is it ever the same?

Streptolysins

Membrane-disrupting toxins (Exotoxins) produced by streptococci. can cause lysis of RED and WHITE blood cells

Hemolysins

Membrane-disrupting toxins (Exotoxins) that destroy erythrocytes (red blood cells) by forming protein channels

Leukocidins

Membrane-disrupting toxins (Exotoxins) that kill phagocytic leukocytes (white blood cells) -act by forming protein channels

Biofilms -they don't start as biofilms, they must attach first -biofilms develop when microbes adhere to a particular surface that is typically moist and contains organic matter -biofilms represent another method of adherence and are important because they resist disinfection and antibiotics ex: plaques on teeth, algae on the walls of swimming pools

Microbes have the ability to come together in masses, cling to surfaces, and take in available nutrients in communities called ______ Give examples of these

siderophores

Proteins secreted by pathogens that bind iron are known as_____

True ex: for bacillus anthracis, it only takes 10-15 endospores entered in the skin to cause disease. When the same bacteria is inhaled, it causes 10,000 to 20,000 endospores to cause disease

T or F; the area of the body that is exposed to microorganisms effects how many endospores are required to develop infection/disease

respiratory tract

Sneezing is a portal of exit of microbes from the_____

interferons

Substances produced by virus-infected cells that protect neighboring uninfected cells from infection are called____

True A lower ID50 means you are more virulent because it takes less endospores to make more of an impact

T or F: The lower the ID50 the more virulent

True ex: the LD50 number of Botulinum is 0.03 ng/kg and the LD50 number for shiga toxin is 250 ng/kg. Botulinum is more toxic because it requires less of the toxin to make an effect.

T or F: The lower the LD50 number the more potent

True ex: brain eating ameba needs to go through the nose in order to get to the brain in order to infect as badly as it can. If they gain access to the body by another portal, disease may not occur. ex: salmonella typhi, (causes typhoid fever) produces all signs and symptoms of the disease when swallowed. If the bacteria is rubbed on skin no reaction or only slight inflammation will occur

T or F: most pathogens have a preferred portal of entry

1. adhesins/ligands 2. surface receptors

The attachment between pathogen and host is accomplished by means of surface molecules on the pathogen called 1.___________ that bind specifically to complementary 2.______ _____on the cells of certain host tissues

antitoxins

The body produces antibodies called __________ that provide immunity to exotoxins.

virulence

The degree of pathogenicity of an organism is known as the____

respiratory tract

The easiest and most frequently traveled portal of entry for infectious microorganisms is the _____

endotoxins

The outer portion of Gram-negative cell walls contain_____

Adaptive immunity

The specific defensive response of the body to an infection or to antigens. the ability to recognize and remember specific antigens

Ergot

Type of Fungal toxin: •alkaloid toxins that cause hallucinations •Often on grains •Similar to LSD •Causes gangrene (restricts capillaries / blood flow)

Toxins

Various poisonous substances produced by some microorganisms (bacteria and viruses).

EXOTOXIN: Protein that contains two subunits: enzyme component (A part) that includes the toxin!! and binding component (B part) that only allows binding of a very SPECIFIC cell type -Ex: Diptheria toxin

What are characteristics of A-B toxins? (Exotoxins)

-endotoxins are located within the bacterial cells -they are part of the outer membrane portion of he cell wall of gram-negative bacteria (of LPS) -The lipid portions of LPS is called Lipid A and is an endotoxin. thus, endotoxins are lipopolysaccharides -exert their effects by stimulating macrophages to release cytokines in very high concentrations -all endotoxins produce the same signs and symptoms as varying degrees; fever, weakness, general aches, possibly death -Released during bacterial multiplication(cell division) and cell death

What are characteristics of ENDOTOXINS?

-proteins produced and secreted by pathogenic bacteria as part of their growth and metabolism. -exotoxins are secreted outside of the bacterial cells that produce them and secreted into surrounding medium during log phase -Can be produced by gram + and gram -. but primarily gram +!!! -are soluble in body fluids and can easily diffuse into the blood and are rapidly transported -VERY harmful and lethal -work by destroying particular parts of the host's cells or inhibiting metabolic functions -only few bacteria produce them!

What are characteristics of EXOTOXINS?

(are EXOTOXINS) -cause an intense immune response due to the release of CYTOKINES from host T-CELLS -stimulate a rapid increase of immune T-cells (types of white blood cells) that act against foreign organisms. -T-cells release an enormous amount of chemicals called cytokines -Cytokines are protein molecules that regulate the immune responses and mediate cell to cell communication -High levels of cytokines in the blood stream give rise to a number of symptoms including fever, nausea, vommitting, diarrhea, shock, and sometimes even death. The body starts killing itself bc when it comes across the superantigen it thinks theres tons of them so it increases the antibody numbers and symptoms.

What are characteristics of Superantigens?

Membrane disruption toxins, a type of exotoxin, cause lysis of host cells by disrupting plasma membranes by forming protein channels in the plasma membrane or disrupting the phospholipid portion of the membrane. -The three types are: -Leukocidins, Hemolysins, Streptolysins

What are characteristics of membrane disruption exotoxins? what are the three types?

Visible effects of viral infection on a cell!! 1. stopping cell synthesis: herpes simplex virus irreversibly stop mitosis 2. causing cell lysosomes to release enzymes-resulting in destruction of intracellular contents and host cell death 3. Creating inclusion bodies in the cell cytoplasm- Inclusion (something that is not supposed to be there) 4. Fusing cells to create syncytium- several adjacent infected cells fuse to form a very large multinucleate cell (called a syncytium) such giant cells are produced from infections by viruses that cause measles, mumps, and common cold. 5. changing host cell function or inducing chromosomal changes 6. Loss of contact inhibition: in the cell, leading to cancer. Transformation results in abnormal, spindle-shaped cell that does not recognize contact inhibition (meaning it won't stop growing when they come inclose contact with other cells) the loss of contact inhibition results in unregulated cell growth, resulting in the change of a normal cell into cancer/tumor 7. Producing interferons to protect uninfected cells-

What are cytopathic effects of viruses? give examples

Microorganisms gain access to the GI tract in food, water, and contaminated hands. Those that can survive stomach acid and bile can cause poliomyelitis, Hep A, typhoid fever, amebic dysentery, and cholera.

What are examples of diseases that are commonly contracted by pathogens that invade the Gastrointestinal tract? How do they enter?

Microorganisms gain access to the genitourinary tract via sexual contact. Some microbes that cause STI's can penetrate unbroken mucous membranes. Others require cuts or abrasions and may cause HIV, genital warts, chlamydia, herpes, syphilis, and gonorrhea.

What are examples of diseases that are commonly contracted by pathogens that invade the genitourinary tract? How do they enter?

Microorganisms gain access to the body via the parenteral route when they are deposited directly into the tissues beneath the skin or into mucous membranes when barriers are penetrated or injured. These include punctures, bites, cuts, wounds, surgery. Mosquitos and needle injections are examples. Examples of diseases are HIV, Hepatitis, bacteria that can cause tetanus, rabies, malaria.

What are examples of diseases that are commonly contracted by pathogens that invade the parenteral route? how do they enter?

Common cold, pneumonia, TB, influenza, measles

What are examples of diseases that are commonly contracted by pathogens that invade the respiratory tract?

Invasions are surface proteins produced by bacteria that rearrange ACTIN filaments of the host's cytoskeleton. -invasins of the microbe cause MEMBRANE RUFFLING (the host cell membrane to resemble a splash of liquid hitting a solid surface) which is a result of disruption in the cytoskeleton on the host cell. -once inside the cell certain bacteria can use ACTIN to propel themselves through the host cell cytoplasm and from one to host cell to another. (the bacteria use the condensation of actin on one end of it to propel through the cytoplasm. Ex: Shigella and Listeria *side note- bacteria can manipulate aspects of the human body to get what they want

What are invasins and how do they help penetrate the host cell's cytoskeleton? give examples of specific bacteria

1) By using the host's nutrients. 2) By causing direct damage in the immediate vicinity of the invasion. 3) By producing toxins, transported by blood and lymph, that damage sites far removed from the original site of invasion. 4) By inducing hypersensitivity reactions.

What are the four basic ways bacterial pathogens can damage host cells?

D-inclusion bodies

What are the granules found in the cytoplasm or nucleus of some virus-infected cells? a)Syncytia b)Endotoxins c)Lysosomes d)Inclusion bodies

•Use host tissue for growth •Produce large masses; cause cellular damage •Produce waste products •Produce waste products that cause symptoms -can absorb nutrients from the host, causing starvation/damage -have damage causing abilities via mouths and anuses -mass of worms in the heart

What are the pathogenic properties helminths? (type of animals)

Complex pathogenesis. Usually a combination of •Toxic metabolic products •Provoke an allergic response •toxins inhibit protein synthesis •Proteases modify host cell membranes •Capsules prevent phagocytosis **Have some virulence factors but not typically pathogenic

What are the pathogenic properties of Fungi?

•Some produce a neurotoxin called saxitoxin (a neurotoxin) -typically infect the nervous system •Paralytic shellfish poisoning- when humans eat dinoflagellates that produce saxitoxin, symptoms are similar to botulism -cant really see algae in the ocean,

What are the pathogenic properties of algae?

•Presence of protozoa and their waste products causes symptoms -can cause direct damage •Avoid host defenses by: -Digesting cells and tissue fluids -Growing in phagocytes -Antigenic variation-(anything foreign that can bind to an antibody, cause an immune response) -some antigens reproduce every few weeks so the body cannot clear the infection bc immune response takes weeks. ex: plasmodium (causes malaria) invades the host cells and reproduce within them, causing their rupture

What are the pathogenic properties of protozoans?

-Skin (skin is a portal of entry when it is damaged via wounds. some microbes gain access to the body through openings in the skin such as hair follicles, pores, and sweat glands) exception: larvae of the hookworm can actually bore through intact skin) -Mucous membranes (many bacteria and viruses gain access to the body by penetrating mucous membranes lining the respiratory tract gastrointestinal tract, genitourinary tract, and conjunctiva of the eye. The respiratory tract is the easiest and most frequent portal of entry for infectious microorganisms. Mucous membranes are not as easy to invade due to being sticky/thick. -Parenteral route (direct deposits underneath the skin or into mucous membranes when barriers are penetrated or injured). Occurs when there are punctures, injections, bites, cuts, wounds, surgery, or splitting of the skin. Examples are also mosquitos, needle injections

What are the three portals of entry? How do they enter? Give examples

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

What are the three types of exotoxins?

-Coagulases: coagulate fibrinogen -Kinases-digest fibrin clots -Hyaluronidase- digest polysaccharides that hold cells together -Collagenase- breaks down collagen -IgA proteases- destroy IgA antibodies

What enzymes are used by pathogens to evade host defenses?

Antigenic Variation is when pathogens alter their surface antigens so that antibodies are not effective and cannot inactivate or destroy them. -in the presence of antigens, the body produces proteins called anitbodies, which bind to antigens and inactivate or destroy them. -However, some pathogens can alter their surface antigens via antigenic variation -Thus, by the time the body can exhibit an immune response against a pathogen, the pathogen has already altered it's antigens and is unaffected by the antibodies

What is antigenic variation? how is it used to evade host defenses?

-The pathogen must gain access to the host, adhere to the host tissues, penetrate or evade host defenses, and damage host tissues -Some microbes don't cause disease by directly damaging host tissue, instead disease is due to accumulation of microbial waste products

What is required for a pathogen to cause a disease?

C-to break down fibrin

What is the action of bacterial kinases? a)To coagulate fibrinogen b)To hydrolyze hyaluronic acid c)To break down fibrin d)To break down collagen

a)Genitourinary tract

What is the preferred portal of entry for chlamydia? a)Genitourinary tract b)Gastrointestinal tract c)Skin d)Respiratory tract

-Some bacteria make glycocalyx material that forms capsules around their cell walls which increases the virulence of the species. The capsule resists host defenses by impairing phagocytosis, the process by which certain cells of the body engulf and destroy microbes. -Capsules are an important virulence factor bc they act as slimy shields that let the bacterium flow through our blood without being detected. examples of bacteriums that use capsules: streptococcus pneumoniae- pneumonia haemophilus influenzae- pneumonia and meningitis bacillus anthracis- anthrax Yersinia pestis-plaque

What is the role of capsules in evading host defenses?

The cell wall of certain bacteria contain chemical substances that contribute to virulence. M PROTEIN -resists phagocytosis -made by STREPTOCOCCUS PYOGENES OPA -outer membrane protein that allows attachment to host cells -Neisseria gonorrhoae WAXY LIPID (mycolic acid) - resists digestion -Mycobacterium tuberculosis

What is the role of the cell wall components in evading host defenses? Give examples.

adhesins (ligands) may be located on a microbes glycocalyx or on other microbial surface structures such as pili, fimbrae, or flagella.

Where are adhesins located?

a)By using antigenic variation

Which one of the following is NOT a way fungi cause disease? a)By using antigenic variation b)By producing toxins c)By secreting protease d)By provoking an allergic response

A- conjunctiva

Which one of the following is NOT an example of the parenteral route of entry? a)Conjunctiva b)Surgery c)Injection d)Bite

C- cytopathic effects

Which one of the following refers to the visible effects of a viral infection? a)Lysogenic conversion b)Lysogenic effects c)Cytopathic effects d)Cytopathic conversion

b)Ergot alkaloid

Which one of the following toxins is an alkaloid that can cause hallucinations resembling those produced by LSD? a)Aflatoxin b)Ergot alkaloid c)Phalloidin d)Amanitin

Toxigenicity

capacity to produce toxins at the site of multiplication

Virulence

degree of pathogenicity

Pathogenesis

how a pathogen actually causes a disease

toxoids

inactivated exotoxins used in vaccines; stimulates the production of antitoxins in the body so immunity is produced

LD50

lethal dose (of a toxin) for 50% of the test population measures the potency of a toxin

Pathogenicity

the ability to cause disease by overcoming host defenses

-Type of EXOTOXINS -Damage DNA causing mutations, disrupting cell division, and leading to cancer -Damages Eukaryotic DNA

what are genotoxins?

A-B toxin action

what does this chart show?