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USC / Biology / BIOL 250 / Are bacteriostasis and bacteriocide the same?

Are bacteriostasis and bacteriocide the same?

Are bacteriostasis and bacteriocide the same?


School: University of South Carolina
Department: Biology
Course: Microbiology
Term: Fall 2015
Cost: 50
Name: Exam 3 Study Guide
Description: Notes on all chapters that will be on exam 3 and some test questions.
Uploaded: 03/30/2018
16 Pages 103 Views 2 Unlocks

Chapter 11 – Eukaryotic Microbes & Parasites

Is bacteriostasis and bacteriocide, are the same?


Mainly a tropical issue.

Humans are hosts to ~300 species of parasitic worm (helminths) and ~70  species of protozoa. Mostly rare but about 90 are considered common Parasite – Animal that lives at expense of the host. Parasite obtains  nutrients in a way that is harmful to the host

Host – A living animal or plant from which a parasite obtains nutrition. ~15,000,000/yr people die of parasitic infections or their complications. Or complications of improper treatment

This is a problem in agriculture as well. Ex: wheat rust- fungal infection  that when left untreated can kill as much as 20% of crop

Parasitology Basics 

Parasite Types 

What is the filter paper method?

Ecto- parasitize the outside of organisms

Endo- parasitize the inside of their hosts

Obligate must parasitize hosts ex: plasmodium which causes  


Facultative may live without host but if host is present will  


Permanent/temporary permanent will be there forever even if it  is killed/ temporary carries the parasite ex: mosquito

Accidental parasites that typically have a certain range of hosts  but they may parasitize something outside of their host range

Hyper- parasites that parasitize other parasites

Vectors- something that transports a parasite

Biological parasite is attached to an organism and undergoes  

What is the difference between mechanisms and machinations?

some of its life cyle in that organism (ex: rabies is a virus → needs  biological medium) Don't forget about the age old question of What is the diffusion of innovation?

Mechanical transfer without growth or life cycle;  


Definitive hosts in which the parasitic organisms have sex If you want to learn more check out What are the crime rates by gender?

Intermediate hosts that harbor the parasite for a while and thin it  leaves or dies

Reservoir infected hosts that make parasites available to others Yellow fever in Brazil We also discuss several other topics like In accounting systems & financial statements, what are the examples of source documents?

Mechanisms & Machinations 

Most parasites have one or more special adaptation: 

Encystment formation of outer protective coating and make it  difficult for the host immune system to attack must be able to live  off host without killing them too quickly; cysts are less injurious to  the host and allows to invade immune system

Antigen switching organism reorganizes surface antigens at a  rate faster than the host immune system can adapt and target  


Antigen false flagging organism produces antigens that illicit and immune response that doesn’t actually target those antigens

Intracellular living live inside host cells so host immune system  does not attackDon't forget about the age old question of Why is political culture powerful?

Removal often does damage all its own. Ex: ticks embedded in skin Reproduction is key to success. Reproduce a lot and forgo adaptations  (usually intestinal bacteria) or do adaptations and reproduce less

Protists- form basis of food web; unicellular and sometimes colonial;  eukaryotes; mostly microscopic; 5 μ – 5 mm diameter

Plantlike: white cliffs of dover made of protist shells; limestone in the  great pyramids; marble

Prototheca – Protothecosis, enteritis or mastitis. One genus of  eukaryotic micro algae that can parasitize; no chloroplasts; asexual  reproduction; cause inflammation of bowels or breast tissue;  problem in cows


Oomycota – Water molds, common plant parasites. Downy mildew,  blight, white rust. Some look like fungi, some look like animals;  some other species that can cause diseases in fish


Cause many diseases. Heterotrophic; mostly unicellular; free living;  some commensal, some parasitic, some depending on the health of the host We also discuss several other topics like Where and when did clay pots become popular?

Mastigophorans – Sleeping sickness, giardia gastroenteritis, sandfly  skin lesions.

Amebozoa – “Brain-eating”

Apicomplexans – Cause malaria.

Ciliates – The largest group.

Fungi (fig 11.8) 

Fungi reproduction methods are diverse and unconventional

Zygomycota – Bread molds, generally don’t cause disease.

Ascomycota – Sac fungi, cause yeast infections, athlete’s foot, and  respitory infections.

Basidiomycota – Club fungi, some produce toxins.

Deuteromycota – Fungi Imperfecti, some produce antibiotics.

Mycosis – Fungal disease

Superficial top part of skin

Subcutaneous below the skin; slow progressing

Systemic will kill the victim


Parasite members fall into one of two types.

Platyhelminthes – Flatworms, some are animal parasites and may lack  circulatory and digestive systems.

Planarians = Free living, non-parasites.

Trematodes = Flukes; ecto/endo.

Cestodes = Tapeworms; endo.

Nematodes – Roundworms, parasitize plants and animals.

Look into the basic lifecycles of each. Note how many hosts they need (fig 11.18) If you want to learn more check out What curve is produced by the logistic growth model of population?


Generally not parasites, a few are.

Arachnids – Ticks and mites.

Insects – Biting flies, fleas

Crustaceans – Typically not parasites themselves.

Chapter 12 – Sterilization & Disinfection  

Basic Principles 

Sterilization – Killing or removal of all [micro]organisms and viruses in a material  or on an object; Not always attainable or practical; Sometimes it is essential. Disinfection – Reducing the number of pathogenic organisms in a material or on an object such that there is no threat of disease.

Disinfectants – For inanimate objects.

Antiseptics – For living tissue.

“Natural” unassisted Death rate is exponential and still is when treated with such  agents.

Microbes differ in their susceptibility. Endospores in particular are resistant Bacteriocide kills bacteria vs. Bacteriostasis slows or stops bacterial growth Potency 

Time more time for chemical reactions to occur

Temp speeds the rate of chemical reaction

pH impact how chemical agent enters the cell or how it affects the cell  directly

Concentration few exceptions include ethanol and isopropyl alcohol are less  effective if they do not have a little water in them


Phenol Coefficient 

A unit going back to 1867 when Joseph Lister introduced phenol as a disinfectant. Testing against Salmonella typhi and Staphylococcus aureus.

<1.0 = Less effective than phenol

1.0 = Equal to phenol

>1.0 = More effective than phenol

Has limitations.

D-value- time it takes to deactivate 90% of the population at a given concentration Filter Paper Method 

Simpler than the phenol coefficient.

Soak a filter paper in a disinfectant and place it on an inoculated plate. Molecules move differently in agar.

Presence of other materials (like blood) may have differential effects. Use-Dilution Test 

Almost as simple as the filter paper method.

Somewhat more current.

Not as susceptible to medium bias.

Uses a stainless steel cylinder.

Still doesn’t account for different surface types or chemical interference. Can use different concentrations of bacteria or disinfectant

Mechanism of Action – The way in which a specific antimicrobial agent does its  antimicrobial work.

General categories are those that affect: Proteins, Membranes, Other cell  components ex: nucleic acids, Viruses

Affecting Proteins

Denaturation – Permanent Change in conformation of the protein (fig. 12.2) Permanently denature the proteins (including enzymes) and you kill the organism.

Hydrolysis breaking of peptide bond by adding water to it; strong acids and  alkalides;  

Oxidation (KMnO4)

Attachment of elements or chemical groups. Halogens and heavy metals;  alkylating agents

Membrane Damage

Membranes can be impacted by the same things that denature proteins. They also contain lipids and so can be disrupted by surfactants, alcohols and  soaps (in engineering they are considered wetting agents, change surface  tension) and detergents. commonly used in laboratory settings to lyse cells in a  controlled fashion and keep cell parts in solution

Things that reduce the surface tension of water.

∙ Quaternary Ammonium Compounds.

∙ Anionic detergents are effective at disrupting all types of  

covalent bonds

Impacting Other Cell Components

DNA/RNA can be affected by alkylating agents.

Crystal violet inhibits cell wall formation.

Lactic or propionic acid can shut down fermentation pathways.

Impacting Viruses

∙ Viruses have to be inactivated.

∙ Enveloped viruses are more susceptible.

∙ Denaturing proteins is sometimes not sufficient; Requires  

damaging/destroying the nucleic acid.

∙ Alkylating agents, halogens, alcohols, detergents, some dyes. Specific Chemical Agents 

Soaps are hard and are a result of saponification & Detergents liquid Acids & Alkalis effective against bacteria

Heavy Metals microbes do not build resistance but they do not kill spores; mostly  surface treatments

Halogens height electronegativity, effective against viruses and bacteria, strongly  impaired by organic material

Alcohols denature proteins, effective against bacteria that are growing and viruses, precipitate proteins, need water to be most effective, antimicrobial properties go up  as molecular weight goes up

Phenols disrupt membranes, denature proteins, inactivate enzymes, not very  susceptible to inactivation by presence of other organic material, can maintain  activity for days, can add halogens to increase effectiveness, specifically effective  on enveloped viruses, bacteria, fungi, does not induce resistance  Oxidizing agents hydrogen peroxide, potassium permanganate, oxidize disulfide  bonds in proteins to change their shape, has activity against aerobic and anaerobic  organisms, can kill some of own tissue, effective against fungi, bacteria, and viruses if applied properly

Alkylating agents disrupt protein actions and nucleic acids, can be carcinogenic,  formaldehyde, ethylene oxide, effective against any living thing, often effective  against viruses, can be used to develop vaccines

Dyes often interfere with DNA structure and replicaqtion, interfere with cell wall  synthesis, effective against bacteria and fungi, and sometime effective against  viruses

Others sulfite, nitrite, essential oils

 Physical Antimicrobial Agents 

Heat figures 12.8 and 12.10; dry heat is typically not as effective as moist heat Thermal Death Point/Time & Decimal Reduction Time whatever the  temperature and time that will kill a 24 hour old broth culture within 10  minutes  

Moist- better not to crowd things in an autoclave, figure 12.11 autoclave  schematic

Pasteurization sanitizing, inactivates most infectious agents, temperatures  and times had to be adjusted for listeria in the mid 20th century,   Refrigeration doesn’t kill things but slows down growth

Freezing for several days is enough to kill most worm parasites, standard (-20 C), science (-80 C), cryopreservation with liquid nitrogen used for  preservation rather than killing

Drying stops enzymes from working,  

Lyophilization freeze drying, preservation, ex: astronaut ice cream Radiation UV sterilizer, Morcherinkov radiation, gamma radiation Visible light sunlight has infrared and ultraviolet light, UV light is effective  against viruses, bacteria, and fungi

Ultraviolet direct line of site, not effective against endospores, effective  against bacteria, fungi and viruses, need to have frequent maintenance  schedule

Ionizing knock out protons, neutrons, and electrons from body cells, can  create free radicals, can sterilize plastics and foods

Microwave not as useful without pressure vessel

Sound sonic/ultrasonic waves; of limited effectiveness, useful for dislodging dirt  particles, can break up cell walls

Filtration- diatomaceous earth, passing liquid through a strainer, usually  inexpensive, doesn’t require a lot of maintenance, but filters can get clogged,  usually let through viruses and mycoplasmas, use on media that can’t be heated Osmotic pressure draws water out to slow down organism; salt inhibits microbial  growth in this way

Pasteurization sanitizing, inactivates most infectious agents, temperatures and  times had to be adjusted for listeria in the mid 20th century,  

Refrigeration doesn’t kill things but slows down growth

Freezing for several days is enough to kill most worm parasites, standard (-20 C),  science (-80 C), cryopreservation with liquid nitrogen used for preservation rather  than killing

Drying stops enzymes from working,  

Lyophilization freeze drying, preservation, ex: astronaut ice cream

Chapter 13 – Antimicrobial Therapy

Antimicrobial Chemotherapy 

Chemotherapy- the administration of chemical substances for the purpose of  killing pathogenic organisms with out injuring the host

Chemotherapeutic agent (drug)- chemical that has some sort of efficacy for  some sort of disease

Antimicrobial agent- substances which possess systemic antimicrobial  action

Antibiotic- “against life”, 1942 by Selman Waksman**, a chemical  substance produced by microorganisms which has the capacity to  inhibit the growth or even destroy bacteria and other  

microorganisms in a dilute solution

Synthetic drug- made in the laboratory without the aid of microbes Semisynthetic drug- made with the aid of microbes


1619 A.D. – First recorded malaria cure using cinchona bark extract (quinine). ~1680 A.D. – Ipecacuanha used to treat “bloody flux”. (diarrhea), basis of syrup  of ipecac  

1909 A.D. – Salvarsan developed and marketed by Paul Erlich. 1929 A.D. – Alexander Fleming discovers penicillin but doesn’t publish until  1940.

1932 A.D. – Prontosil, the first sulfinlimide, is discovered.

Antimicrobial Agents – General Properties 

Selective toxicity – Killing of thee and not of me; All antimicrobial agents have  it.

Some are too toxic to take internally. Ex: Neosporin is toxic to liver and kidneys  but can be applied topically

Chemotherapeutic index- Gap between Therapeutic <----> Toxic Min dose

Max tolerable dose/ kg

¿cure/ kg¿

Large chemotherapeutic index equals less toxic

The greater the similarity between host and parasite, the lower the index. Worms vs. Fungi vs. Bacteria

Spectrum of Activity – can be broad or narrow; what sort of organisms the  compound will work against

Broad Spectrum not enough time to examine and diagnose infection Narrow Spectrum exact source of infection can be determined; ex: strep  throat; less likely to induce resistance

Modes of Action – What, specifically, does it do?

Antimicrobials can kill or slow down invaders but the host’s immune system does the elimination.

5 Basic types:

Inhibition of cell wall synthesis

Disruption of membrane function ex: polymyxins

Inhibition of protein synthesis usually interfere with translation Inhibition of nucleic acid synthesis

Antimetabolic activity. Something that looks like a key metabolite and  takes up the enzymes that do that job

Side Effects – Both direct and indirect.



Allergy response of proteins that your body makes reacting with the drug  to make an allergen


Disruption of microflora diarrhea, thrush, yeast infections, UTIs Microbial resistance – Antimicrobial agents decrease in effectiveness over  time

Can be biochemical, locational, or based on phenotypic plasticity (ex:  heteroresistance).

Chromosomal usually to a single drug or extrachromosomal multiple  genes for multiple types of resistance. (Cassettes- smaller plasmids) Mechanisms of resistance 

Alteration of target- target of antibiotic is altered by changing  conformation of ribosome

Alteration of membrane permeability- changes to the proteins embedded  in the membrane

Development of enzymes- enzymes to damage antibiotic

Alteration of an enzyme- change binding affinities of current enzymes Alteration of metabolic pathway- eliminates steps affected by antibiotics Cross-resistance resistance to one antibiotic which induces resistance to closely  related antibiotics

Quorum Sensing certain bacterial infections do not start producing toxins until  there is a certain quorum in body; if you can block quorum sensing it allows your body to catch up to infection and fight it

Assessment Methods 

Disk Diffusion (Kirby-Bauer) nutrient Agar plate and sterile swab used to  inoculate plate as thoroughly as possible, introduce small amounts of different  antibiotics to the medium, lower molecular weight drugs diffuse faster, diameter  of clear zones used to determine whether organism is affected by antibiotic, just  because therr is a big clear zone does not mean that the antibiotic will clear the  infection

E Epsilometer plastic strips with a continuous concentration gradient of a given drug, must be careful to follow manufacturers instructions for incubation time,  temperature, and medium; tells you minimal inhibitory concentration (MIC) the  lowest concentration that will inhibit the growth of that organism Dilution usually take place in 96 well plate, can be used to determine MIC, fairly inexpensive, need a plate reader to read results of growth which gives optical  density factor

Serum Killing Power result of spontaneous clotting, what is left behind is  serum; take blood samples at different intervals and test the serum for antibiotic concentration or use it as a growth medium to see if antibiotic is effective Automated Methods vitek AST- cards that are preloaded with antimicrobial  drugs which are inoculated, incubated, and put into reader machine, results in 3- 6 hours, very expensive

Specific Antimicrobial Agents **need to know what are the modes of action,  how they are given, and any interesting contraindications and basic uses** Cell Wall

Penicillins (Gen 4) penicillin B and G come from Penicillin notatum,  susceptible to more than 1000 known beta-lactamase enzymes which  cleave beta-lactam ring, when dosed with clavulanic acid which is a beta lactamase inhibitor it is effective, will occupy enzymes, work by

preventing peptidoglycan cross linking making it much weaker, penicillin  fungi, mainly bacteriostatic

Cephalosporins (Gen 5) come from fungi genus Cephalosporium  “head/brain like spores”, natural forms have limited use, we use  semisynthetic derivatives of these, some cross resistance from penicillin’s similar activities and also has a beta-lactam ring, may set off allergies in  people allergic to penicillin, often given before major surgery


Polymyxins structure figure 13.15; come in forms A ,B , C, D, and E;  differ in absorption; must be either injected or inhaled; internally used as  a drug of last resort, haver neuro and nephron toxicity; mainly  bacteriocidal; fatty tail is responsible for lethal action; some E. coli have  been found to be resistant in China, Laos, and Malaysia

Protein Synthesis  

Aminoglycosides come from bacteria ; disruption of peptide elongation by  binding to #0s ribosomal subunit ; may also interfere with codon reading ;  streptomycin ; bactreriostatic at lower doses and bacteriocidal at high doses,  resistance is not uncommon but work synergistcally with many other antibiotic  compounds; nephrotoxic

Tetracyclines come from same genus as aminoglycocides, bind to 30s subunit  and A site of ribosome, mainly bacteriostatic and will not corss blood brain  barrier, widest spectrum of known anitbiotics, cause gastrointestinal problems,  kidney damage, fetal skull abnormalities, and graying of teeth (when given to  children), can be affected by iron and calcium, can cause light sensitivity,  actively binds to 40s subunit of eukaryotes but more effective in bacteria  because they actively pump it in

Chloramphenicol used to come from stroptomyces but now almost fully  synthetics ; mode of action inhibits peptide chain elongation by intefering with  sticking amino acids together, binds to rRNA in50s subunit, can disrupt function  of bone marrow, usually a last resort drug, bacteriostatic

Macrolides – Erythromycin. Blocking addition of new amino acids to chain,  may interfer with mRNA translation, usually use in a multi drug treatment, only  common treatment that will treat pnemonia caused by legionares, one of the  least toxic, light snsitivity

Lincosamides 50s subunit, premature disassociation of tRNAs ; mainly  bacteriostatic, clindomycin, less toxic than the originals  

Nucleic Acid Synthesis

Rifampin semisynthetic from Streptomyces, binds to pocket of RNA  polymerase b subunit, by binding inhibits activity of RNA polymerase by  stopping mRNA elongation, bacteriocidal, high number of reactions to  other drugs, causes liver damage in high doses, may cause sweat pee or  cry orange red

Quinolones synthetic analogs of a former antibiotic, block DNA gyrases  and topoisomerases, currently in 4th generation, known also to inhibit DNA synthesis in mitochondria and chloroplasts


Sulfonamides sulfa drugs, not all antimicrobial, one antimicrobial one  diabetes drug or herbicide, entirely synthetic, block synthesis of folic acid  needed to make a range of critical metabolites, bacteriostatic, can cross

blood brain barrier, nausea and rashes are not uncommon, can function  against some fungi

Isoiazid analog of nyocin and b6; has to be activated by the bacterium  itself; block some cytochrome parts of electron transport chains in  mycobacterium, works well on rapidly dividing cells, multidrug cocktail Ethambutol inhibits cell wall synthesis by inhibiting certain enymes,  makes cell wall more permeable, fully synthesitc, effective against  tuberculosis, resistance rising, generally part of cocktail

Nitrofurans synthetic, amage bacterial DNA, ribosomal protein,  respiration components, acute or chronic UTIs, some activity against  eukaryotic cells, bacteria have specific enzyme to activate it in cells,  Antifungal  

Imidazoles & Triazoles higher risk of host toxicity, synthetic, most available  without prescription, Zoloft almost all creams or solutions applied topically,  inhibit synthesis of key membrane components

Polyenes injection only, binds to plasma membrane causing it to leak Griseofulvin come from penicillium, used often on hair skin and nails, mess  with mitotic spindle to slow cell division, some nail infections will stay for a year  through straight treatment


Base (purine) Analogs introduce disinformation into viral genome, fake  adenine thymine and guanine

Amantadine block key protein channel crucial to flu virus budding Interferons proteins that infected cells make telling cells nearby to begin  making antiviral machinery; attempting to make these synthetically  Immunoenhancers stimulate T cell activity

Resistance- viruses have no biochemistry of their own, can only be grown in  vivo, studying them is much slower

Quinine- isolated from the bark of the cinchona tree, used to treat malaria,  alkaloid compound, mechanism not entirely clear

Chloroquine & Primaquine- used to treat malaria; inhibit parasite from  attacking red blood cells

Metronidazole causes spontaneous abortions, flagellated, causes profuse  vomiting with alcohol consumption

Chapter 14 – Host-Microbe Relationships

Host-Microbe Relationships 

Host- any organism that harbors another organism

Symbiosis living together of living things, usually quite close associations  between two or more species

Mutualism both of the members in the relationship benefit

Parasitism one organism benefits and the other is harmed

Commensalism one organism benefits and the other receives neither  benefit nor harm

Contamination the presence of microorganisms that you would not like to have there

Infection the multiplication of any parasite in or on its host; refers to disease  caused by microbes

Infestation usually for larger organisms, often eukaryotes

Disease a disturbance in the state of the body wherein normal functions are  interrupted

Pathogenicity usually in reference to an organism, its capability of causing  disease

Virulence the intensity of the disease

Animal Passage- virulence can sometimes be augmented as it passes  through other animals; acquire new abilities

Attenuation via Transposal- the taking of a virus that affects one animal and  infecting other animals with it to make it weaker, so it can be used to make a  vaccine

Normal Microflora 

There are ~10x more microbial cells in/on a typical human body than human  cells comprising that body. Found on skin surface, mucous membranes,  digestive tract, upper respiratory tract, reproductive tract

Second genome- The vast array of genes express by those microbes that vastly outnumber you; you can detect differences in different people, ex difference in  bacterial composition of babies born through natural birth and by C-section,  breastmilk vs. formula, can affect what genes you express- capable of making  mRNAs that will turn on certain genes in cells adjacent to them → some make  the attachment of helminths easier in the stomach walls;  


“Normal” live in and on us and don’t cause disease if immune system is  working properly  

Resident always present, different depending on what site you are  looking at

Transient ones that are present under certain conditions

Opportunist residents who under certain conditions will attack their host,  ex: if immune system lags or is impaired or microbes are introduced to a  site they are not normally found

Koch’s Postulates (bacterially caused diseases, used to determine causation of infections)

1) Specific causative agent must be observed in every case of disease. 2) Agent must be isolated from a diseased host and must be grown into a pure  culture.

3) When cultured agent is inoculated into healthy, susceptible hosts, the same  disease must result.

4) Agent must be isolated again from the diseased experimental hosts and be  identified as original agent.

Kinds of Disease 

Infections infectious biological factors vs. Noninfectious caused by other  agents or factors

Communicable transmittable from host to host vs. noncommunicable (anthrax is noncommunicable but still infectious)

More detailed:

Inherited genetic information errors

Congenital structural or functional disorders developed at birth Degenerative usually a function of age, usually focus on one body  system

Nutritional deficiency result of inferior diet or parasitic infection Endocrine excess or deficiency of hormones

Mental syphilis, mad cow disease

Immunological allergies, immunodeficiencies, autoimmune diseases Neoplastic abnormal cell growth, tumors

Iatrogenic doctor caused diseases, surgical errors, drug reactions Idiopathic no idea what causes it

Disease Process 

Direct bacterial action salmonella, virulence factors help microbe infection  (fig. 14.5)

Toxin production exotoxins secreted into the environment, endotoxin built into  the outer membrane, different depending on infection and intoxication, infection  when micorbes are living and reproducing and toxins are byproduct, intoxication  is when toxins are ingested and are already in what you are eating and drinking

Viral effects (fig. 14.7) cytopathy, viral infection causes a change in the  morphology of the cells,

Eukaryotes heartworms, fungi, can be direct or intoxicating, protozoans, can  create substances that cause allergic reactions

Stages of Disease 

Read Signs, Symptoms, and Syndromes as well as Types of Infectious Disease. Incubation (fig 14.9) asymptomatic, but may be contagious (ex: flu), length of  time affected by location of infection and how far it is from optimal site Prodromal Greek for forerunner; nonspecific symptoms, not all diseases have  it, definitely contagious

Invasive typical symptoms, peak of symptoms (ACME)

Decline symptoms start to subside, secondary infections may occur Convalescence symptoms are gone, tissues being repaired, strength is  gradually regained, still may be contagious if you have certain organisms  especially those that cause surface lesions

Treatment usually just lessens severity of symptoms. May reduce convalescent  time

Duration & Recovery

Why aren’t diseases eradicated? 2010 data from the book (fig. 14.11) ∙ Available options are not exercised. Not all people are vaccinated against  infectious diseases

∙ Antibiotic resistance; even if you eradicate all pathogenic organisms, more would arise

∙ New or rare diseases come to the fore.

∙ People travel and carry infections with them  

Chapter 16 – Innate Defenses

Innate & Adaptive Host Defenses 

Innate = Nonspecific will attack foreign things of all sizes, does not have to be  programmed

Adaptive = Specific (Chapter 17) Antigen -> Antibody + lymphocyte activation Innate Immunity: Barriers 


∙ Skin first line of defense, hardened against abrasions, sunlight, and microbes ∙ Mucous membranes body opening, slows and physically traps  microorganisms, large number of bacteriophages present

∙ Hair creates pockets of low velocity air so that microbes and dust settle out ∙ Cough/sneeze/vomit/diarrhea/ urination remove epithelial cells and attached  pathogens

∙ Tears & saliva traps particles and causes them to be moved away from  possible infection site


∙ Sweat & sebum acidic and salty

∙ Stomach acid highly acidic

∙ Lysozyme enzyme capable of breaking bonds in peptidoglycan cell walls,  present in tears, saliva, and mucous  

∙ Transferrin present in saliva and mucous & Lactoferrin present in blood; bind  up free iron in body, iron is a key nutrient for pathogen proliferation ∙ Defensins small proteins with cationic charge that can assemble to create  pores in cell membranes, found in mucous

Cellular Defenses 

∙ Come into play once organisms make it past other barriers.

∙ Mediated in Blood

60% Plasma- water and dissolved solvents and electrolytes

40% Formed elements- elements that come from pluripotent stem cells in  bone marrow

Erythrocytes red blood cells

Platelets cell fragments of megakaryocytes

Leukocytes white blood cells

 Leukocytes – Defensive Cells (figure 16.1) 

Granulocyte cells that when you stain them have grainy cytoplasm and irregular  nuclei

Basophils release histamine, which initiates inflammatory responses Mast cells also release histamine, more common in connective tissues, also in high concentration near blood vessels

Eosinophils present in larger numbers during allergic reactions, release  histamine degrading enzymes

Neutrophils found in skin, blood, mucous membranes, phagocytic, congregate in areas of injury, do not divide, have programmed apoptosis within a few  days, fight bacteria and some viruses

Dendritic cells (figure 16.2) hae long membrane extensions used for  phagocytosis, also have a role in adaptive response

Agranulocyte (figure 16.1) usually have round nuclei

Monocytes phagocytic, released from bone marrow, can ultimately become  macrophages, can attack invaders and clean up dead neutrophils, congregate in areas of injury, not as fast as neutrophils but come in much greater  numbers

Lymphocytes (T & B) circulate in blood and lymph, found in lymph nodes,  spleen, thymus

 Phagocytosis & Extracellular Killing- Greek, phago and cyte “eating cell”;  Neutrophils, monocytes/macrophages, dendritic cells.

Chemotaxis being able to travel along a gradient of some chemical signal, cells  travel in response to a call put out by injured or dying cells (cytokines or  chemokines); messages received by toll-like receptors

Adherence & Ingestion attach and bring in organism as a vacuole

Digestion merge vacuole with a lysosome and then dump contents outside of cell Extracellular killing t-cells, used against things too big or too dangerous to be  eaten, eosinophils also function in this by attaching to parasite surfaces and dump  major basic protein (MBC) to digest  

Lymphatic System 

∙ Closely associated with the cardiovascular system (CVS).  

∙ Has its own tissues, vessels, and nodes.


∙ Collects excess lymph from intercellular spaces.

∙ Transports digested fats to CVS.

∙ Provides many innate and adaptive responses (largely phagocytic). ∙ Circulation

Organs (figure 16.6 lymph node) b cells, plasma cell and macrophages in medulla;  t cells and dendritic cells in cortex; thymus- where t-cells mature; spleen is largest Additional tissues peyer’s patches in intestinal epithelium- pockest that have high concentrations of active immune cells, tonsils  

 Inflammation blood vessels become leaky and open spaces for macrophages to  migrate to sites of infection;  

The body’s response to tissue damage: Mechanical, Heat, UV, Chemicals Acute Process response to an injury to start repair process

Damage -> histamine into capillaries/venules -> dilation -> edema -> macrophages arrive & call for more

Repair & Regeneration begins almost as soon as the injury occurs; inflammation  and repair are active at the same time; this process is generally better in younger  people with better circulation; vitamins A, C, and K are important to this process Damage -> inflammation -> clotting -> inflammation down -> capillary intrusion ->  fibroblasts form granulation (scar) tissue  

Chronic Cases (figure 16.8) can cause granuloma formation, edema can become a  problem

 Fever -systemic increase in temperature

Normal range = 36.1 – 37.5 oC; Fever = oral > 37.8 oC or rectal 38.4 oC; Danger =  40 oC; Death ≈ 43 oC

Cause – Pyrogens interact with body temperature regulators in brain (VLPO) to  raise it

Exogenous – From infectious agents. Ex: lipopolysaccharide

Endogenous – From macrophages. Ex: interleukin 1

By raising body temperature you move out of optimal temperature for microbial  growth and allows your body to overwhelm them, at slightly higher temperatures  microbial toxins can be deactivated, raising temperature allows defense reactions to proceed faster; triggers an increase in interferon production

 Interferon small soluble proteins that cause nearby cells to raise defenses and act  as cytokines to call in backup; can prevent co infection with other organisms * lymphocytes and NK cells also produce these proteins

 Type I – α and β (figure 16.9) stimulate synthesis of antiviral proteins; often  interfere with RNAs

 Type II – γ does not need infected cells; is produced in cells turned on by A  and B

Therapeutic use almost all therapeutic interferon A is recombinant, can be  used to treat genital warts, hepatitis, some cancers, some viruses have  resistance mechanisms for this

Compliment System 

∙ A cascade. Stimulus leads to a vastly amplified response, system of 20  defense regulatory proteins that start working as soon as an infection is  detected

∙ Enhance phagocytosis.

∙ Lyse invading cells & enveloped viruses.

∙ Generate inflammation peptides.

Three paths to the same destination(s): (fig. 16.1)

Classical antibody-antigen stimulation

Lectin begins as phagocytosis begins to be completed

Alternative can be active earlier than the classical, complement proteins  interact directly with pathogen polysaccharides

Opsonization opsonins bind to and coat the surface of an invader, allow C proteins  to bind which allows phagocytosis to be completed more quickly Inflammation complement enhances acute response by stimulating chemotaxis Membrane Attack Complexes (fig. 16.11) form lesions in the membranes of  pathogens;  

impairment is congenital and C3 is most essential to complement system Acute Phase Response; Evident in some acutely ill persons.

Non-specific defense. Stimulated by phagocytosis, stimulates interleukin-6 Acute phase proteins. Produced in liver in response to interleukin 6 Works in an opsonin-like manner.

CRP – C-reactive protein cell surface

MBP – Mannose binding protein. Recognize carbohydrate patterns on surface of  pathogenic bacteria, binds to organism, serves as activator to lectin pathway, also  binds to your own cells going through apoptosis

∙ Activates complement system.

∙ Facilitates phagocytosis.

Summary figure (figure 16.12)

Exam Questions:

Which of the following chemical antimicrobial agents (activities) likely would be  ineffective against enveloped viruses?

A.) Halogens (denature proteins)

B.) Phenols (dissolve membranes and denature proteins)

C.) Alkylating agents like formaldehyde (disrupts nucleic acids and proteins) D.)Crystal violet (disrupts cell wall synthesis) 

E.) All of these

An object to be sterilized should be cleaned prior to treatment. This statement is in  direct support of which of the principles of controlling microbial growth? A.) Sterility is not always practically achievable

B.) The fewer organisms present, the shorter the time needed to achieve  sterilization

C.) Microorganisms differ in the susceptibility to antimicrobial agents D.) Two of these

E.) None of these

You have discovered a new pathogen that has a low capacity to cause disease, but  once it does, the disease is very intense. This pathogen would best be described in  the following way:

A.) High pathogenicity, high virulence

B.) High pathogenicity, low virulence

C.) Low pathogenicity, high virulence 

D.) Low pathogenicity, low virulence

E.) None of these

Which of the following is true about fungi?

A.) Most are saprophytic

B.) Most are composed of a mycelium that consists of threadlike hyphae C.) Fungi are most important as decomposers in the ecosystem D.)All of these 

E.) Two of these


A.) Oxidize disulfide bonds

B.) Dissolve lipids and denature proteins 

C.) Alter nucleic acids

D.)Alter the pH

E.) None of these

This pro inflammatory cytokine causes vasodilation:

A.) Histamine 

B.) Bradykinin

C.) Prostaglandin


E.) None of these

Which of the following antibiotics is an inhibitor of DNA gyrase? A.) Ethambutol

B.) Ciprofloxacin 

C.) Tobramycin

D.) Neomycin

E.) None of these

Sequential steps taken by a phagocytic cell destroying an invading microorganism  include:

A.) Chemotaxis -> adherence -> ingestion -> digestion

B.) Finding -> filtering -> secreting ->enzymes -> streptolysin C.) Chemotaxis -> granuloma ->adherence -> histamine D.) Finding -> invading -> clotting -> regulating -> temperature E.) None of these

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