microbiology Chapter 15 and 16

Gastrointestinal Tract

Feces/fecal matter

Mycolic acid

(waxy lipid) resists digestion by phagocytes; can multiply inside phagocytes Mycobacterium tuberculosis

Portal of Exit

specific routes by which a particular pathogen leaves the body

Urine flow

sterile - helps clear the urethra from microorganisms

Blood Serum

straw-colored liquid remaining after the blood is allowed to clot

invasins

surface proteins that rearrange the actin filaments of the cytoskeleton causing membrane ruffling in host cell allowing bacteria to move through and between host cells.

example of toxoid

tetanis shot

Pathogenic Properties of Protozoa

-Protozoan waste products may cause disease symptoms

Coagulase

-coagulates fibrin in blood to form a clot -clot provides protection

Second Line of Defense

-phagocytic WBCs -inflammation -fever -antimicrobial substances

Genitourinary Tract

Urine, vaginal secretions

Leukocytosis

- increase of WBCs due to a microbial infection

Saliva

- washes microbes off teeth and mucus membranes of the mouth -contains lysozyme an enzyme capable of breaking down the peptidoglycan of bacterial cell walls of g+ bacteria and to a lesser extent those of g- bacteria - contains an antibody (Immunoglobulin A) that prevents attachment of microbes so that they cannot penetrate the mucous membrane.

2nd Line of Defense: Fever

-Abnormally High Body Temperature (Systemic Response) -Most frequent cause is infection from bacteria and their toxins or viruses -Hypothalamus normally set at 37ºC (98.6ºF) -Gram-negative endotoxin causes phagocytes to release the cytokine interleukin 1 (IL-1) IL-1 causes the hypothalamus to release prostaglandins that reset the hypothalamus to a higher temperature, thereby causing fever -Up to a certain point fever is considered a defense mechanism after that it can be a threat

Pathogenic Properties of Algae

-Alexandrium produces a neurotoxin associated with Paralytic shellfish poisoning

2nd Line of Defense: Antimicrobial Substances; Interferons

-Antiviral proteins produced by certain animal cells such as lymphocytes and macrophages after viral stimulation -protects uninfected host cells from viral infection by interfering with viral replication -cytokine messengers

examples of specialized lymphocytes

-B cells (antibody production via plasma cells) -T cells (T helper cells, Cytotoxic T Lymphocytes, T regulatory cells)

example of Gastrointestinal tract pathogen

-Brucella spp.(Brucellosis) -Hepatitis A virus

Bacterial Evasion of the Complement System

-Capsules prevent Complement activation -Some g- surface lipid-carbohydrates prevent membrane attack complex (MAC) formation. -G+ cocci release an enzyme that breaks down the C5a

Function of Inflammation

-Destroy and remove infective agent -limit its effects by confining/walling off the agent and its by-products -Repair/replace damaged tissue

Line of Defense: Mucous Membrane Secretions chemical factors

-Earwax -Gastric juice -Saliva

Pathogenic Properties of Fungi

-Fungal waste products may cause symptoms -allergic response -produce toxins -Capsule prevents phagocytosis -Aflatoxin; carcinogenic (Aspergillus found on peanuts)

CPE effects observed in viral infected cells

-Halts macromolecular synthesis -Causes the cell's lysosomes to release enzymes resulting in cell death -Forms inclusion bodies in host cell containing viral parts -Causes host cells to fuse into a multinucleate cell (syncytium) -Cause changes in host cell functions -Induce cells to produce interferons -Induce antigenic changes on the surface of the host cell -Induce chromosomal changes in the host cell -Loss of contact inhibition resulting in unregulated cell growth

example of parenteral route pathogen

-Hepatitis B -Lyssa virus(rabies)

Deficiencies in complement proteins can cause

-Increased susceptibility to recurrent infections with pyogenic (pus forming) microbes (S.aureus) -Increased susceptibility to Neisseria meningitidis and N. gonorrhoeae infections

TLRs bind to the following microbial structures

-Lipoteichoic acid in g+ -Lipopolysaccharide in g- -Flagellin in flagella of motile bacteria -DNA of bacteria -DNA or RNA in viruses -Various components of fungi and parasites

example of Respiratory tract pathogen

-Mycobacterium tuberculosis (TB) -Varcella Zoster virus (Chicken pox)

2nd Line of Defense: Antimicrobial Substances;Antimicrobial Peptides

-Peptides produced by nearly all plant and animal cells used to destroy various microorganisms -destroy bacterial cells

example of skin route pathogen

-Plasmodium spp(malaria) -Ricketsia rickettsii(Rocky mountain spotted fever)

Examples of microorganisms with capsule

-Streptococcus pneumoniae - pneumococcal pneumonia -Haemophilus influenzae - bacterial meningitis in young children -Bacillus anthracis - anthrax -Klebsiella pneumoniae - bacterial pneumonia -Yersinia pestis - plague

Complications of fever

-Tachycardia - rapid heart rate,affects elderly persons with cardiopulmonary disease -Increased metabolic rate, produce acidosis -Dehydration -Electrolyte imbalances -Seizures in young children -Delirium and coma

example of genitorinary tract pathogen

-Treponema pallidum(syphilis) -Herpes Simplex Virus 2(genital herpes)

Pathogenic Properties of Helminths

-Uses host tissue for growth-metabolic waste can also contribute to the symptoms

Ways bacteria destroy host cells

-Using the host's nutrients - Causing direct damage in the immediate vicinity of the invasion -Producing toxins transported by blood and lymph that damage sites far removed from the original site of invasion -Inducing hypersensitivity reactions

When does a decline in the efficiency of phagocytosis occur

-With increased age - recipients of heart or kidney transplants have impaired nonspecific defenses as a result of receiving drugs that prevent the rejection of the transplant.

Differential WBC count

-a calculation of the percentage of each kind of WBC in a blood sample -determines Leukocyte increase or decrease

Line of Defense: Intact Skin mechanical factors

-a mechanical form of defense -top layer of epidermal cells is dead,dryness of skin inhibits microbial growth -endothelial cells that line blood and lymphatic vessels are not closely packed as those of the epidermis allowing defensive cells and microbes to move into and out of the blood and lymph

macrophages

-a phagocytic cell -mature monocyte

dendritic cells

-a type of antigen-presenting cell characterized by long fingerlike extensions -found in lymphatic tissue and skin

Vaginal secretions

-acidic due to lactic acid by Lactobacillus -resultant acidic environment is antibacterial to other introduced bacteria into the vagina

2nd Line of Defense: Phagocytic WBCs

-beginning of an infection, both granulocytes (especially neutrophils) and monocytes migrate to the infected area -monocytes leave the blood and enter the infected tissue -monocytes enlarge and develop into actively phagocytic macrophages - number of granulocytes increases dramatically; -as the infection progresses, the macrophages dominate which is reflected by an increase in monocytes. -In viral and fungal infections, macrophages predominate in all phases of defense.

Adhesins/ligands

-bind to receptors on host cells -typically glycoproteins or lipoproteins; whereas, the receptors on the host cell are typically sugars

Lectin pathway

-liver produces lectin -lectin combines with sugar monnose on surface of bacteria -triggers complement protein and starts cascade -triggers C3

Chronic inflammation:

-longer lasting inflammatory response to a chronic infection such as tuberculosis caused by M. tuberculosis

2nd Line of Defense: Antimicrobial Substances;The Complement System

-defense system consisting of over 30 proteins in circulatory system -helps WBC -activate C3 protein -covers bacteria with proteins

2nd Line of Defense: Inflammation

-defensive response due to local damage to the body's tissues -Damage can be caused by microbial infections, physical agents, or chemical agents -activation and increased concentration of acute-phase proteins (complement, cytokine, fibrinogen for clotting, and kinins for vasodilation

Natural Killer Cells

-destroy a variety of infected body cells and certain tumor cells via cytolysis and apoptosis -released intact microbes are destroyed by phagocytes

Vasodilation

-dilation of blood vessels -increases blood flow to the damaged area -responsible for the redness and heat associated with inflammation.

C3 protein

-final activation protein -activated by stimulation -starts cascade of protein that activates cytolysis -initates opsonization (enhance phagocytosis) -inflamation

Pathogenic Properties of Viruses

-get into host cell and invade host's immune system -obligate intracellular parasites -Cytopathic Effects (CPE) of Viruses

Perspiration

-helps maintain body temperature, and flush microorganisms. contains lysozyme. -Lysozyme is also found in tears, saliva, nasal secretions, and tissue fluids

Line of Defense: Mucous membranes mechanical factors

-mechanical form of defense -epithelial layer and an underlying connective tissue layer -provides less protection than intact skin -epithelial layer secretes a glycoprotein fluid called mucus which maintains the membranes moist -Lines the gastrointestinal, respiratory, and genitourinary tracts -mucus traps many microorganisms

Line of Defense: Normal Microbiota

-microbial antagonism, competing with pathogens for nutrients -normal microbiota are considered commensalistic -may cause disease if their environmental conditions change (opportunistic pathogens)

Innate Immunity

-non specific -defenses that protect against any pathogen

Using the host's nutrients

-pathogenic bacteria require iron for growth -obtain iron from host by secreting siderophores

prevent phagosome-lysome fusion

-plasmodium -HIV -Mycobacterium -Chlamydia

Sebum

-produced by the skin's oil glands, forms a protective film over the skin -unsaturated fatty acid in the sebum inhibits the growth of certain pathogenic bacteria and fungi -Bacteria that metabolize sebum form free fatty acids that cause the inflammatory response associated with acne

Exotoxins

-produced inside the bacteria as part of their growth and metabolism -secreted into the surrounding medium or released following lysis -Produced by mostly gram positive bacteria and a few gram negative bacteria -Genes for most exotoxins are on bacterial plasmids or phages

capsule

-protective covering on bacterial cell -Gelatinous layer covering the entire bacterium; Composed of polysaccharide

2nd Line of Defense: Antimicrobial Substances;Iron-Binding Proteins

-proteins that provide an antimicrobial effect by inhibiting bacterial growth by reducing the amount of available iron.

siderophores

-proteins that take iron from the host's iron-transport molecules by binding the iron more tightly -taken up by bacterium

Adaptive Immunity

-resistance against a specific pathogen -humoral and cellular immunity

M protein

-resists phagocytosis -occurs on some strains of Streptococcus pyogenes

Plasmids

-segment of dna all by itself in bacteria -provides virulence factor -can produce toxins -antibiotic resistance (shares info w/ normal microbiota)

Acute inflammation

-short lasting inflammatory response -example boil caused by S. aureus.

cytokines

-small protein hormones that stimulate or inhibit normal cell functions -chemical message your body makes

what causes disease in a exotoxin producing bacteria

-the toxin and not by the bacteria -exotoxins produce specific signs and symptoms of the disease.

Limulus amoebocyte lysate (LAL) assay

-use of blood of the Atlantic horseshoe crab which contains WBCs called amoebocytes -amoebocytes contain large amounts of a protein (lysate) that causes clotting -In the presence of an endotoxin, amoebocytes lyse and release their clotting protein -resulting gel-clot (ppt) is a (+) test for the presence of endotoxin.

Gastric juice

-very high acidity destroy bacteria and most bacterial toxins -Many enteric pathogens are protected by food particles and can enter the intestines via the gastrointestinal tract -Helicobacter pylori neutralizes stomach acid, which allows it to grow resulting in ulcers and gastritis (inflammation of the lining of the stomach).

Endotoxins and the Pyrogenic Response

1. macrophage(WBC) digest G- bacterium 2.bacterium disassembled/degraded in vacuole 3.bacterium releases endotoxins(lipid A) in macrophage 4. in response to exposure to lipid A macrophage produces cytokines 5.cytokines released into blood stream by macrophage 6. cytokine travels to hypothalmus(temp. control center of brain) 7.cytokine induce hypothalmus to produce prostaglandins which reset the body's temperature causing a fever

Blood

Biting arthropods, needles/syringes

Classical pathway

Activated by contact between Ag-Ab complex that triggers the complement system

Alternative pathway

Activated by contact between certain complement proteins and a pathogen that triggers the complement system

when does a microorganism initially encounter phagocytes of the host

After a microorganism invades a body tissue

What organisms survive acid from gastric juices

Clostridium botulinum Staphylococcus aureus

examples of pathogenic bacterias that produce exotoxins

Clostridium botulinum - botulsim Staphylococcus aureus - food poisoning and TSS

Respiratory Tract

Coughing, sneezing

survive in phaolysosome

Coxiella burnetti

Adhesin on Streptococcus pyogenes

M protein

what cause the release of cytokines

Endotoxins

Adhesin on Escherichia coli

Fimbriae

Adhesin on Streptococcus mutans

Glycocalyx

Neutrophils

Highly phagocytic and motile; active in initial stages of infection

Toxoid

Inactivated toxin used in a vaccine

Lymphocytes

Involved in specific immunity; antibody production

lyse phagoctye membrane attack complex

Listeria monocytogenes

Examples of Portals of Entry

Mucous membranes Skin Parenteral Route

Inhibit adherence with M protein or capsule

P. pyogenes S. pneumoniae

Examples of mechanisms that expel microbes from the body

Peristalsis, defecation, vomiting, and diarrhea

Toxin

Poisonous substances produced by certain microorganisms that contribute to their pathogenicity

B Cells

Produce antibodies

Eosinphils

Produce toxic proteins against certain parasites (helminths), some phagocytosis

examples of Portal of Exits

Respiratory Tract Gastrointestinal Tract Genitourinary Tract Skin Blood

biofilms invade phagocytosis

S. aeruginosa

kill phagoctyes leukocidins

S. aureus

Line of Defense: Secretions chemical factors

Sebum Perspiration Urine flow Vaginal secretions

escape phagosome

Shigella Rickettsia

What is one factor responsible for swelling of lymph nodes during infection

The maturation and proliferation of macrophages along with lymphocytes

Virulence

The quantitative ability of an agent to cause disease

exoenzymes

The virulence of some bacteria aided by production of extracellular enzymes

Skin

Wound infections, pus

endotoxic shock

a result of Endotoxins

Pathogenicity

ability of an infectious agent to cause disease

Immunity (Resistance)

ability to ward-off disease via defense mechanisms

Opa protein

allows attachment to host cells and internalization within the host cell Neisseria gonorrhoeae

what happens when bacterium is not destroyed by phagocyte

bacterium overcomes the host's defense by damaging the host cells

pathways of complement activation

classical pathway alternative pathway lectin pathway

Mucous membranes

conjunctiva, respiratory, gastrointestinal and genitourinary tracts

Dendritic cells

destroy microbes by phagocytosis initiate adaptive immunity responses.

Kinases

digests fibrin clots

Toxins produced by Bacteriophage

diphtheria toxin erythrogenic toxin Staphylococcal enterotoxin pyrogenic toxin botulinum neurotoxin Streptococcus pneumoniae capsule choleratoxin

membrane ruffling

disruption of the cytoskeleton of the host cell by bacterial invasins

lipid A

endotoxin in G- bacteria

Symptoms due to cytokines

fever, nausea, vomiting, diarrhea, sometimes shock or death

Skin

hair follicles and sweat ducts

Agranulocytes

have granules in their cytoplasm granules are not visible under the light microscope.

aspirin and acetaminophen reduce fever by

inhibiting the synthesis of prostaglandins

T Cells

initiate cell-mediated immunity

First Line of Defense

intact skin mucous membranes and their secretions normal microbiota

why is it important to determine the presence of endotoxins in drugs, medical devices and body fluids that have been sterilized?

it is possible that endotoxins are present but no bacteria can be cultured from the items

Granulocytes

large granules in the cytoplasm. differentiated based on the staining of the granules

Plasma

liquid remaining after the formed elements are removed from the unclotted blood

What infections increase WBC count

meningitis infectious mononucleosis appendicitis pneumococcal pneumonia gonorrhea

Line of Defense: Mucous membranes cont. Ciliary escalator mechanical factors

microbes trapped in mucus are transported away from the lungs toward the throat cilia Coughing and sneezing speeds up the process. Cigarette smoke impairs cilia function.

Lysogenic conversion

phage incorporates its DNA w/ bacterial DNA creating prophage and picking up new characheristics, produce toxins

endotoxins

part of the outer portion of the cell wall of gram negative bacteria -released when the bacterium die and the cell walls undergo lysis

Causing direct damage in the immediate vicinity of the invasion

pathogen enters the host cell and multiply or pass through the host cell causing rupture or disruption of the host cell

antigenic variation

pathogens alter their surface antigens

Monocytes

phagocytic as mature macrophages after entering tissues

what do capsules do

prevent phagocytosis by host cells; however -if host makes antibodies against capsule, it is destroyed by phagocytosis

How is innate system activated

protein receptors in the plasma membranes of macrophages bind to the invading microbes and activate an immune responses directed against the invading microbes. -After binding with defensive cells, TLRs induce the cells to release cytokines

antibodies

proteins that bind to antigens and inactivate or destroy them

Earwax

provides a physical barrier and a chemical protectant

cytolysis

punches whole in plasma membrane of bacterial cell

Portals of Entry

specific routes by which a particular pathogen gains access to the body

Basophils

release histamine that cause inflammation in allergic response

What infections decrease WBC count known as leukopenia

salmonellosis brucellosis some viral rickettsial infections

Third Line of Defense

specialized lymphocytes and antibody productions

what happens when Antibiotics used to treat diseases caused by G- bacteria lyse the bacterial cells

the reaction releases the endotoxin and the human body reacts to endotoxin which may lead to an immediate worsening of symptoms

protein receptors

toll-like receptors - TLR

hemolysins

toxins that destroy RBCs by forming protein channels

Susceptibility

vulnerability or a lack of resistance to a disease

Lacrimal apparatus

washes eye and drains tears

disseminated intravascular clotting (DIC).

when Endotoxins activate blood-clotting proteins resulting in small blood clots

Parenteral Route

wounds, bites, cuts, surgery, and injections of pathogens by deposition directly into tissues beneath the skin and mucous membranes.