MICRO EXAM #3

Antiherpes drugs:Know the general mode of action for antiherpes drugs (these drugs mimic structure of nucleotides and compete for sites on replicating DNA, so essentially they are analogs—what is the consequence of this? I said this in class a few times)

these drugs mimic structure of nucleotides and compete for sites on replicating DNA, so essentially they are analogs

Know when the human body is first colonized with normal flora and how newborns acquire normal flora

- Birth canal - Breast milk - Bottle-feeding - People - Air - Surfaces ** The only time that humans are sterile is when they are in the womb (in utero) **

Know the general properties of viruses

- Obligatory intracellular parasites - Virus= Latin for poison - Most viruses are tissue specific - Certain viruses can only infect certain cell types - Host range is determined by specific host attachment sites and cellular factors - Obligate intracellular parasites of bacteria, protozoa, fungi, algae, plants, and animals - Ultramicroscopic size - Not cellular in nature; structure is very compact and economical - Do not independently fulfill the characteristics of life - Inactive macromolecules outside the host cell and active only inside host cells - Basic structure consists of protein shell (capsid) surrounding nucleic acid core - Nucleic acid of the viral genome is either DNA or RNA but not both. - Nucleic acid can be double-stranded DNA, single-stranded DNA, single-stranded RNA, or double-stranded RNA - Molecules on virus surface impart high specificity for attachment to host cell. - Multiply by taking control of host cell's genetic material and regulating the synthesis and assembly of new viruses - Lack enzymes for most metabolic processes - Lack machinery for synthesizing proteins

Know which sites of the body typically harbor normal flora (i.e. skin; gastrointestinal tract, etc.)

- Skin and its contiguous mucous membranes - Upper respiratory track (oral cavity, pharynx, nasal mucosa) - Gastrointestinal tract (mouth, colon, rectum, anus) - Outer opening of Urethra - External genitalia - Vagina - External ear and canal - External eyes (lids, lash follicles)

Know how to describe the actions of antimicrobial agents (alteration in membrane permeability, damage to nucleic acid and protein)

1. Alteration of membrane permeability - Membrane damage causes leakage of cell contents - Naturally interferes with cell growth 2.Damage to nucleic acids and proteins - Prevention of replication, transcription, translation, peptide bond formation, protein synthesis - Damage DNA and RNA limits function and growth - Heat and chemicals can denature proteins by breaking bonds

Be able to describe the five mechanisms of drug resistance

1. Drug inactivation 2. Decreased permeability 3. Activation of drug pumps 4. Change in drug binding site 5. Use of alternate metabolic pathway

Know the four Genera that produce most antibiotics.

1. Streptomyces (bacteria) 2. Bacillus (bacteria) 3. Penicillium (mold) 4. Cephalosporium (mold)

Physical methods of microbial control

1.Heat - Moist heat/steam under pressure (sterilization) - pasteurization (disinfection) - dry heat (sterilization) - boiling water(disinfection) 2.Low Temperature - Cold Temperatures (microbiostatic) 3.Desiccation Lyophilization 4.Radiation - microwaves - ionizing (sterilization) - non-ionizing (disinfection)

Be able to describe the five actions of antimicrobial drugs.

1.Inhibition of Cell Wall Synthesis 2.Injury to Plasma/Cell Membrane 3.Inhibition of Nucleic Acid Replication and Transcription 4.Inhibition of Protein Synthesis 5.Inhibition of Essential Metabolites Synthesis/metabolic pathways

Know how to describe acute, persistent, latent viral infections

Acute viral infection: relatively short infection period A persistent viral infection occurs gradually over a long period; can be fatal; viral infection is not cleared by the immune system - Measles (Subacute sclerosingpanencephalitis) - Epstein Barr Virus (mononucleosis, Burkitt'sLymphoma) - HIV/AIDS - HPV (cervical cancer) Latent virus: remains in asymptomatic host cell for long periods causing a latent infection. - May reactivate due to changes in immunity - Herpes (cold sores), Varicella zoster virus (shingles)

Antibiotics that damage cell membranes:know what polymixins are, their mode of action, and what types of infections they are used to treat;

Antibiotics That Damage Bacterial Cell Membranes Polymixins, narrow-spectrum peptide antibiotics with a unique fatty acid component -Effective against gram-negatives -Interact with phospholipids and cause leakage -Treat drug resistant Pseudomonas aeruginosa and severe UTI -Combined with bacitracin and neomycin in nonprescription ointments (Neosporin)

Know the descriptions of the following chemicals used for microbial control: Phenol, Halogens, Alcohols, Surfactants, Peroxogens, and Organic Acids - Know the mode of action for each and general examples

Phenol and Phenolics: Disrupt cell walls and membranes and precipitate proteins - Bactericidal, fungicidal, virucidal, not sporicidal - Found in antimicrobial/antibacterial liquid soaps ex. Lysol Triclosan-antibacterial additive to soaps Bisphenols: Disrupt plasma membrane synthesis in Staphylococcus and Streptococcus species Ex. Hexachlorophene (used to treat skin infections) Halogens: Iodine - Impairs/alters protein synthesis by interfering with disulfide bonds of proteins - Milder medical and dental degermingagent; disinfectants, ointments Chlorine - Bleach: hypochlorousacid (HOCl) - Shut down cellular enzyme systems - Water, sewage, wastewater, inanimate objects Alcohols: Ethanol, isopropanol Acts as surfactants dissolving membrane lipids - Denature proteins - Requires water - Need to be an aqueous solution - This means 100% EtOH is INEFFECTIVE!! - No effect on endospores and non-enveloped viruses Surfactants (surface-active agents): Detergents and Soaps: Quaternary ammonia compounds (quats): Cations are bactericidal; act as surfactants that alter membrane permeability and denture proteins of some bacteria and fungi - Acid-anionic sanitizers - Anions react with plasma membrane Soaps - mechanically remove soil and grease containing microbes; emulsification; degerming Peroxygens (Hydrogen Peroxide): - Produce highly reactive hydroxyl-free radicals that damage protein and DNA while also decomposing to O2 gas -toxic to anaerobes - Antiseptic at low concentrations; strong solutions are sporicidal Organic Acids Inhibit metabolism - Organic acids prevent spore germination and bacterial and fungal growth Ex. - Acetic acid inhibits bacterial growth - Propionic acid retards molds - Lactic acid prevents anaerobic bacterial growth - Benzoic and sorbicacid inhibit yeast - Used to control molds and bacteria in foods and cosmetics

Know the drugs that are mentioned on the PowerPoint slide that highlights each of the five mechanisms(slides #16, 19, 22-23, 25-26). Some of the drugs that fall within this bullet point may come up in the "survey of major antimicrobial drugs" bullet point below. This means I don't want you to just list the five mechanisms, you need to understand what actually happens for each mode...in other words, how does it carry out its function. For example, for antimicrobial drugs that affect the cell wall, you should know that these drugs act on the peptidoglycan in the cell wall and inhibit peptide bridges in growing cells; penicillins and cephalosporins are examples of drugs that function in this way.

Antimicrobial Drugs That Affect the Bacterial Cell Wall: Most bacterial cell walls contain peptidoglycan Penicillins and cephalosporins block synthesis of peptidoglycan, causing the cell wall to lyse - Inhibits the peptide bridges - Active on young, growing cells - Many penicillins do not penetrate the outer membrane and are less effective against gram-negative bacteria Antimicrobial Drugs That Disrupt Cell Membrane Function: A cell with a damaged membrane dies from disruption in metabolism or lysis - These drugs have specificity for a particular microbial group, based on differences in types of lipids in their cell membranes - Polymyxins interact with phospholipids and cause leakage, particularly in gram-negative bacteria - Amphotericin B and nystatin form complexes with sterols on fungal membranes which causes leakage Drugs That Affect Nucleic Acid Synthesis: May block synthesis of nucleotides, inhibit replication, or stop transcription - Chloroquine binds and cross-links the double helix; quinolones inhibit DNA helicases - Antiviral drugs that are analogs of purines and pyrimidines insert in viral nucleic acid, preventing replication Drugs That Block Protein Synthesis: Ribosomes of eukaryotes differ in size and structure from prokaryotes; antimicrobics usually have a selective action against prokaryotes; can also damage the eukaryotic mitochondria - Aminoglycosides (streptomycin, gentamycin) insert on sites on the 30S subunit and cause misreading of mRNA - Tetracyclines block attachment of tRNA on the A acceptor site and stop further protein synthesis Drugs that Affect Metabolic Pathways (series of chemical reactions occurring in the cell) - Sulfonamides (or sulfa drugs) and trimethoprimblock enzymes required for tetrahydrofolate synthesis needed for DNA and RNA synthesis

Antiviral chemotherapeutic agents:Know WHY it is difficult to achieve complete selective toxicity when treating viral infections; Know the three mechanisms by which different antiviral agents work (i.e. some block penetration into the host cell, some prevent maturation of viral particles etc.)

Antiviral Chemotherapeutic Agents Selective toxicity is almost impossible due to obligate intracellular parasitic nature of viruses 1.Block penetration into host cell (entry and fusion inhibitors) -Block the receptors on the host cell that bind to the virus -Block fusion of the virus and cell 2.Block uncoating, genome integration, and nucleic acid synthesis -Prevent viral uncoating -Block replication, transcription, or translation of viral genetic material -Inhibit viral DNA integration into the host genome -Nucleoside analogs inhibit RNA or DNA synthesis -Acyclovir -herpesviruses -Ribavirin -a guanine analog -RSV, hemorrhagic fevers -AZT -thymine analog -HIV 3.Prevent maturation of viral particles (capsids, spikes, etc.) -Protease inhibitors -HIV*

Know the main purpose of the Centers for Disease Control and Prevention (CDC)

Centers for Disease Control and Prevention (CDC): principal government agency responsible for keeping track of infectious diseases nationwide - Publishes Morbidity and Mortality Weekly Report (MMWR) - Notifiable infectious diseases:diseases in which physicians are required to report occurrence

Know the steps of bacteriophage replication (i.e. lytic cycle); be able to describe what is happening in each step

Bacteriophages are viruses that parasitize bacteria. - Some undergo two cycles: LYTIC CYCLE: The lytic cycle is divided into five phases: 1. attachment (absorption) - to cell surface receptors (chance encounter - no active movement) 2. penetration - delivery of nucleic acid (only genome enters) 3. biosynthesis - viral protein and nucleic acid synthesis 4. maturation - assembly of the virions 5. release - rupture of cell to release virions as a result: Lytic or virulent phage Phage causes lysis and death of host cell LYSOGENIC CYCLE: The infected bacterium does not immediately produce viruses but may do so sometime in the future; the phage has a latent period and is called a prophage during this time. - Lysogenic or temperate phage - Phage DNA incorporated in host DNA (Prophage) - Viral DNA is passed to future host cell generations (binary fission) - Viruses can cycle out of the lysogenic cycle and into the lytic cycle

Be able to describe the different parts of a virus (capsid, nucleic acid, envelope, etc.) - Know which parts ALL viruses possess vs. parts only some viruses possess. - Know the function of each part

Capsid: - All viruses have these - protein coat that protects the nucleic acid = capsid made up of protein subunits called capsomeres - Some viruses have an external covering called an envelope - Protects the nucleic acid when the virus is outside of the host cell Nucleic acid: - Viral genome contains DNA or RNA, but never both - Carries genes necessary to invade host cells and redirect cell's activity to make new viruses - Number of genes varies for each type of virus Envelope: - Some are enclosed by an envelope made of lipids, proteins, and carbohydrates - Mostly animal viruses - Acquired when the virus leaves the host cell - No envelope=naked - Helps the virus bind to a cell surface and assists the penetration of the viral DNA or RNA into a suitable host cell Envelope Spikes: - Exposed proteins on the outside of the envelope - Essential for attachment of the virus to the host cell - Projections from envelope surface

Boiling Water

Boiling at 100oC for 30 minutes to destroy non-spore-forming pathogens - Denatures proteins Disinfection (a process to destroy vegetative pathogens, not endospores; used on inanimate objects)

Know the taxonomy of viruses

Classification based on type of nucleic acid, strategy for replication, and morphology. Family names end in - viridae Genus and species names end in - virus Viral species: A group of viruses sharing the same genetic information and ecological niche (host). Common names are used for species. Subspecies are designated by a number. ex. Herpesviridae - Herpesvirus Human herpes virus HHV-1, HHV-2, HHV-3 Family names end in - viridae Genus and species names end in - virus Subspecies are designated by a number

Know the difference between communicable and non-communicable diseases

Communicable disease -a disease that is spread from one host to another - Receiving host must become infected (ex. common cold, meningitis) - Highly communicable disease is contagious (ex. measles, influenza) - diseases that are easily and rapidly spread from one host to another Non-communicable - infectious disease is not spread from one host to another - Occurs primarily when a compromised person is invaded by his or her own normal microflora - Contact with organism in natural, non-living reservoir (ex. Soil -Clostridium tetani)

Know how competitive inhibition works as it relates to antimicrobial drugs, and an example of a drug that acts in this way (sulfa drugs)

Competitive inhibition - drug competes with normal substrate for enzyme's active site (ie. Sulfa drugs) - Affects Metabolic Pathways

Be able to describe/recognize the stages of an infectious disease (i.e. incubation period, prodromal period, etc.)

Disease Development and Stages Incubation period: - Time interval between initial infection and first appearance of signs and symptoms. Prodromal period: - Short period characterized by appearance of first mild signs and symptoms (nonspecific). Period of illness: - Disease is most severe: all disease signs and symptoms apparent (specific). Period of decline: - Signs and symptoms BEGIN to subside. Period of convalescence: - Body returns to pre-diseased state, health is restored.

Chemical Agents in Microbial Control

Disinfectants, antiseptics, sterilants, degermers, and preservatives Some desirable qualities of chemicals: - Rapid action in low concentration - Solubility in water or alcohol, stable - Broad spectrum, low toxicity - Penetrating - Noncorrosive and nonstaining - Affordable and readily available

Drugs that block metabolic pathways:know what sulfonamides(sulfa drugs)and trimethoprimare; know what they block the production of and the consequence of this blockage in bacteria.

Drugs That Block Metabolic Pathways - Sulfa Drugs and Trimethoprimare - most important are sulfonamides, or sulfa drugs -first anti-microbic drugs ("wonder drug") - Narrow-spectrum; block the synthesis of folic acid by bacteria Sulfonamides (or sulfa drugs) and trimethoprim block enzymes required for tetrahydrofolate synthesis needed for DNA and RNA synthesis

Drugs that interfere with protein synthesis:know the mode of action of aminoglycosides; tetracyclines; oxazolidinones; chloramphenicol; erythromycin. For example, aminoglycosides bind to the 30S ribosome, which leads to the misreading of the mRNA; this causes the incorrect protein to be produced.

Drugs That Interfere with Protein Synthesis: (Targets on the 70S Ribosome) Aminoglycosides - mRNA is misread,protein is in correct Tetracyclines - tRNA is blocked,no protein is synthesized Oxazolidinones - Prevent initiation and block ribosome assembly Chloramphenicol - Formation of peptide bonds is blocked Erythromycin - Ribosome is prevented from translocating

Drugs for treating influenza: know the mechanisms for Amantadine, Rimantidine, Relenza (oseltamivir) and Tamiflu (zanamivir); use the diagram on this slide for a better understanding

Drugs for Treating Influenza: Amantadine, rimantidine -restricted almost exclusively to influenza A viral infections; interfere with influenza virus uncoating and release of RNA —no viral synthesis Relenza (zanamivir) and Tamiflu (oseltamivir) -slightly broader spectrum; blocks neuraminidase in influenza A and B - Stop the actions of influenza neuraminidase required for budding and release from cell

Know the difference between endotoxins and exotoxins

Endotoxin -toxin that is not secreted,but is released after the cell is damaged - composed of lipopolysaccharide (LPS), part of the outer membrane of gram-negative cell walls - has a variety of systemic effects on tissues and organs-causes fever, inflammation, hemorrhage,diarrhea, decreased blood pressure, and shock Exotoxin -toxin molecule secretedby a living bacterial cell into the infected tissue - proteins that targets a specific cell type - affect cells by damaging the cell membrane and initiating lysis ex. Hemolysins (lyses red blood cells) Toxins are named according to their target -neurotoxins act on the nervous system -enterotoxins act on the intestines -hemotoxinslyse red blood cells -nephrotoxinsdamage the kidneys

Know examples of exotoxins and their effects

Examples of EXOTOXINS: Hemolysins - Lyse red cells Leukocidins - Enzymes that attack white blood cells Necrotizing Factor: "Flesh Eating bacteria" Necrotizing fasciitis: - causes death (necrosis) to tissue cells Botulinum toxin: - acts at neuromuscular junction; results in muscle paralysis Tetanus (toxin aka tetanospasmin): - blocks relaxation pathway; causes complete muscle contraction; causes spasms or lock jaw

Know what exoenzymes are and their effect on the host; be able to give an example of an exoenzyme and its specific effect on the host

Exoenzymes - enzymes secreted by microbes that break down and inflict damage on tissues - often dissolve the host's defense barriers to promote the spread of disease to other tissues Examples of exoenzymes: - hyaluronidase:digests the ground substance that cements animal cells together - coagulase:causes clotting of blood or plasma around the pathogen

Mechanical Methods of Microbial Control

Filtration HEPA (high efficiency particulate air filters) removes microbes >0.3 μm - Liquid Membrane filtration removes microbes from liquids - Liquids are drawn through a filter using a vacuum - Typically, microbes are removed using a 0.2μm pore filter - 0.01μm pore filters will retain virus

Agents to treat fungal infections: know that fungal cells are eukaryotic and a drug that is toxic to fungal cells is also toxic to human cells; know how amphotericin B and nystatin are used to treat fungal infections (what is their mode of action?)

Fungal cells are eukaryotic (like human cells) therefore a drug that is toxic to fungal cells is also toxic to human cells Amphotericin B and nystatin form complexes with sterols on fungal membranes which causes leakage Amphotericin B -mimic lipids, most versatile and effective, topical and systemic treatments Nystatin -topical treatment

Know the relative resistance of microbes. For example, know that bacterial endospores and prions are highly resistant to deactivation; know what microbes are the least resistant

Highest resistance - Prions, bacterial endospores Moderate resistance - Pseudomonas sp. - Mycobacterium tuberculosis - Staphylococcus aureus - Protozoan cysts Least resistance - Most bacterial vegetative cells - Fungal spores and hyphae, yeast - Enveloped viruses - Protozoan trophozoites

Know what is meant by host range and specificity as it pertains to viruses

Host range - Spectrum of cells a virus can infect Virus / host cell interaction is usually very specific (narrow host range) - due to tissue tropism. Tissue tropism - cells or tissues of a particular host that support the growth of a particular virus Virus coincidentally collides with a susceptible host cell and adsorbs specifically to receptor sites on the membrane Host Range - Spectrum of cells a virus can infect ex. Hepatitis B - human liver cells Poliovirus - primate intestinal and nerve cells Rabies - various cells of many mammals

Know the following definitions: infection; virulence; endogenous infection; exogenous agents; endogenous agents; opportunistic infection; toxemia; bacteremia; viremia

Infection: growth and multiplication of a microbe in or on the body with or without the production of disease Virulence: is the degree of pathogenicityor a measure of disease severity endogenous infection: occur when normal flora is introduced to a site that was previously sterile exogenous agents: originate from source outside the body endogenous agents: already exist on or in the body (normal flora) opportunistic infection: is an infection caused by pathogens (bacteria, viruses, fungi, or protozoa) that take advantage of an opportunity not normally available, such as a host with a weakened immune system, an altered microbiota (such as a disrupted gut flora), or breached integumentary barriers. toxemia: Toxins in the blood bacteremia: small numbers of bacteria present in blood not necessarily multiplying viremia: small number of viruses present not necessarily multiplying

Low Temperatures (Cold Temperatures)

Inhibits microbial growth; Bacteriostatic/Microbiostaticeffect - Refrigeration: bacteriostatic (no growth and limited toxin production); psychrotrophsand psychrophilesmay grow; 0-15C - Deep-freezing: induces dormant state (0C) - Lyophilization: drying technique to preserve microbes (bacterial lyophilization); but this is also used in the food industry {freeze drying}

Radiation

Ionizing radiation (X rays, gamma rays, electron beams) - Ionizes water to release OH- - Damages DNA by causing lethal mutations - Nonionizing radiation(UV, 260 nm) - Damages DNA by creating thymine dimers - Microwaves kill by heat; not especially antimicrobial

Know the following terms regarding drug susceptibility testing: Kirby-Bauerdisk diffusion test; dilution tests, E-test; minimum inhibitory concentration; therapeutic index(effective dose vs. toxic dose)

Kirby-Bauer disk diffusion test: is an agar diffusion test - Essential for groups of bacteria commonly showing resistance Dilution tests: used to determine the minimum inhibitory concentration(MIC) -smallest concentration of drug that visibly inhibits growth - Essential for groups of bacteria commonly showing resistance E-test: a quantitative method for determining drug effectiveness (also provides the MIC; more precise) - Essential for groups of bacteria commonly showing resistance The MIC and Therapeutic Index: in vitro (outside the body) activity of a drug is not always correlated with in vivo (inside the body) effect-If therapy fails, a different drug, combination of drugs, or different administration must be considered•Best to chose a drug with highest level of selectivity, but lowest level toxicity -measured by therapeutic index therapeutic index: -the ratio of the dose of the drug that is toxic to humans as compared to its minimum effective dose - High index is desirable

Know what an oncogenic virus is

Mammalian viruses capable of initiating tumors are called oncoviruses Oncogenic viruses - genetic material become integrated into the host cell's DNA and induce tumors -Papillomavirus - cervical cancer - Epstein-Barr virus - Burkitt's lymphoma - Hepatitis B -liver cancer

Dry Heat Sterilization

Moderate to high temperatures; dehydration, alters protein structure (denaturation) - Used to sterilize some medical equipment or objects that cannot undergo moist heat sterilization - Takes longer than moist heat Three types: 1. Flame-open flame (oxidation or burning) 2. Incineration-oxidation ( this is what you do to the loop in lab) 3. Hot air oven-oxidation - Treatment of 170°C for 2 hours

Moist Heat Sterilization

Moist Heat sterilization is achieved using a chamber in a machine called an autoclave - Free-flowing steam - Moist heats: denature proteins - High pressure: denatures proteins Autoclave: Chamber of moist heat (steam) under pressure - Designed to kill all microbes including endospores when the temperature reaches 121°C - Steam must contact solid surfaces to sterilize them - Test strips are used to indicate sterility - Lower temperatures; Shorter exposure time (when compared to dry heat) - Sterilization requires temperatures above boiling

Know what normal (resident) flora is--also known as microflora or microbiota - Know the positive impacts of normal flora (slide #20) - Know the harmful effects of the absence of normal flora (slide #21)

Normal Flora (also called Microflora, Microbiota) - Resident Microflora(aka Normal Microbiota) > microbes always present in or on the body--they become well established; do not cause disease under normal conditions > most areas of the body in contact with the outside environment harbor resident microbes > each site has particular populations positive impacts of normal flora - Normal flora is essential to the health of humans - Flora create an environment that may prevent infections and can enhance host defenses 1.Exclude potential pathogens - microbial antagonism: Normal microbiota are unlikely to be displaced by incoming microbes - compete for nutrients - limited number of attachment sites - chemical or physiological environment created by resident microbiotais hostile to other microbes (affect pH and available oxygen) 2.Provide some nutrition to the host (i.e. vitamins) 3.Immune stimulation 4.Can also have potential negative impacts (i.e. opportunistic infections) - endogenous infections-occur when normal flora is introduced to a site that was previously sterile ** Normal flora is beneficial, or at worst, commensal to the host (in good health with a functioning immune system) ** The absence of normal flora can have harmful effects: - Vitamin deficiencies, especially vitamin K and vitamin B12 - Increased susceptibility to infectious disease - Poorly developed immune system, especially in the gastrointestinal tract - Lack of "natural antibody" or natural immunity to bacterial infection

Know what normal flora are and how they relate to a superinfection

Normal flora - Microorganisms that normally reside at a given site and under normal circumstances do not cause disease. super infection - an infection occurring during antimicrobial treatment for another infection. It is usually a result of change in the normal tissue flora favoring replication of some organisms by diminishing the vitality and then the number of competing organisms, as yeast microbes flourish during penicillin therapy prescribed to cure a bacterial infection. - super infections disrupt the balance of normal flora

Know what a nosocomial infection is and the most common type of nosocomial infection (UTI; you can find this info in the pie chart on slide #79)

Nosocomial (Hospital-Acquired) Infections - Acquired as a result of a hospital stay. - Affect 1 in 25 hospital patients - 2 million per year infected; 99,000 deaths - Aseptic techniques can prevent nosocomial infections. - Hospital infection control staff members are responsible for overseeing the proper cleaning, storage, and handling of equipment and supplies.

Know factors that influence the effectiveness of treatment (# of microbes, environment, time of exposure, etc.). Be able to recognize or briefly describe these factors.

Number of microbes - Larger populations take longer to kill - Small populations are killed more quickly - Population is called "load" Environment (organic matter, temperature, biofilms) - Can inhibit treatment effectiveness by limiting exposure to the treatment - Warm environments increase effectiveness - Cool environment decrease effectiveness - Fats and proteins create barriers Time of exposure - How long were the microbes exposed to the substance - Extended exposure to treatments increase effectiveness Microbial characteristics - Endospores, capsules, acid-fast cell walls, gram state all influence the effectiveness of treatment

Know the portals of entry and exit; know how a pathogen might gain entry into a host using the portals of entry and how a pathogen can potentially exit the body (i.e. microbes can be released from the respiratory tract by coughing or sneezing)

Pathogens use portals of entry best suited to their mechanisms of pathogenesis - Microorganisms have a preferred portal of entry - Usually if pathogens enter the "wrong" portal, they will not be infectious Streptococcus pneumoniae - if inhaled can cause pneumonia - if enters through the G.I. tract, no disease Salmonella typhi - if enters the G.I. tract can cause Typhoid Fever - if on skin, no disease Inoculation of the nasal mucosa with the Influenza virus will result in infection, but if the virus contacts the skin, no infection occurs

Antibacterial drugs that act on the cell wall:know the names of the two most prominent beta-lactam antibiotics; know the primary problems with the use of penicillins (i.e. allergies, etc.); know the descriptions of the three non-beta-lactam cell wall inhibitors (vancomycin, bacitracin, etc.)

Penicillins and cephalosporins are two antibacterial drugs that act on the cell wall. - block synthesis of peptidoglycan, causing the cell wall to lyse -Inhibits the peptide bridges Penicillins and cephalosporins are also the most prominent beta-lactams Primary problems with Penicillins -allergies and resistant strains of bacteria Non Beta-lactam Cell Wall Inhibitors: 1. Vancomycin -narrow-spectrum, most effective in treatment of Staphylococcal infections in cases of penicillin and methicillin resistance or if patient is allergic to penicillin; toxic and hard to administer; restricted use 2. Bacitracin -narrow-spectrum produced by a strain of Bacillus subtilis; used topically in ointment 3. Isoniazid (INH) -works by interfering with mycolic acid synthesis; used to treat infections with Mycobacterium tuberculosis

Desiccation

Prevents metabolism - Metabolism is prevented while water is absent - Gradual removal of water from cells, leads to metabolic inhibition - Not effective microbial control -many cells retain ability to grow when water is reintroduced - Lyophilization-freeze drying; preservation

Pasteurization

Reduces spoilage organisms and pathogens without destroying food flavor or value - Heat-resistant microbes survive, but are unlikely to cause disease Not sterilization -kills non-spore-forming pathogens and lowers overall microbe count; does not kill endospores or many nonpathogenic microbes

Know the description of an infectious dose (ID); know that microbes with smaller IDs have greater virulence

Requirement for an Infectious Dose (ID) - Minimum number of microbes required for infection to proceed - Microbes with small IDs have greater virulence - Lack of ID will not result in infection

Know the difference between resident and transient flora

Resident Microflora (aka Normal Microbiota) - microbes always present in or on the body--they become well established; do not cause disease under normal conditions Transient Flora microbes present for shorter periods of time (minutes to months)....just passing through! - most are harmless, some are pathogens

Drugs for treating HIV infections and AIDS: know why blocking reverse transcriptase is a useful treatment for HIV infections; know the mechanism of integrase inhibitors and protease inhibitors in the treatment of HIV

Retrovirus offers 2 targets for chemotherapy: -Interference with viral DNA synthesis from viral RNA using nucleoside reverse transcriptase inhibitors (nucleotide analogs) -Interference with synthesis of DNA using nonnucleoside reverse transcriptase inhibitors Azidothymidine(AZT) -first drug aimed at treating AIDS, thymine analog Integrase inhibitors - interacts with integrase and blocks its action; HIV DNA is not spliced into host chromosome Protease inhibitors - these insert onto HIV protease, an enzyme that clips viral proteins into functional pieces. Viruses are defective and unable to infect other cells

Know the following key terms related to microbial control: sterilization, bactericidal(biocide/germicide), microbiostatic/bacteriostatic/bacteriostasis, disinfection, decontamination, sanitization, degermation

Sepsis - refers to bacterial contamination Asepsisis - the absence of significant contamination > aseptic surgery techniques prevent the microbial contamination of wounds Sterilization - a process that destroys all viable microbes, including viruses and endospores Disinfection - a process to destroy vegetative pathogens, not endospores; inanimate objects Antiseptic - disinfectants applied directly to exposed body surfaces Antisepsis - destroying harmful microorganisms from living tissue Degerming - the mechanical removal of microbes from a limited area Sanitization - lowering microbial counts to safe levels Degermation - reduces the number of microbes through mechanical means Biocide/germicide(bactericidal/microbicidal): killing microbes Bacteriostasis(microbiostatic): inhibiting, not killing, microbes

Know the difference between signs and symptoms of disease (if you understand the difference between these two terms, you will be able to identify the examples of each).

Signs: Symptoms: - Fever - Chills - Septicemia - Pain, Irritation - Microbes in tissue fluids - Nausea - Abnormal chest sounds - Malaise, Fatigue - Skin eruptions - Chest tightness - Leukocytosis - Itching - Leukopenia - Headache - Swollen Lymph Nodes - Weakness - Abscesses - Abnormal cramps - Tachycardia - Anorexia (increased heart rate) (loss of appetite) - Antibodies in serum - Sore throat

Know what prions are and the type of disease they can cause (type of disease meaning spongiform encephalopathies)

Small proteinaceous infectious particles (very resistant to inactivation) - misfolded proteins, contain no nucleic acid - Extremely resistant to usual sterilization techniques Caused by altered protein: - Mutation in normal PrPcgene (sporadic CJD), or contact with the abnormal PrPScprotein - Inherited and transmissible by ingestion, transplant, and surgical instruments - Causes spongiform encephalopathies: Cavity producing proteins in the brain that damage neural tissue 100% fatal

Know the steps of animal virus replication; be able to describe what is happening in each step

Some undergo two cycles: LYTIC CYCLE: The lytic cycle is divided into six phases: 1. attachment/absorption - Virus attaches to proteins/glycoproteins of the plasma membrane. 2. penetration/entry - Entire animal virus penetrates host cell by endocytosis. Receptor-mediated endocytosis or fusion 3. uncoating - Once inside, the virus is uncoated to remove the envelope and capsid. 4. biosynthesis - The viral genome, either DNA or RNA, is now free and biosynthesis proceeds. - Transcription of mRNA and translation of proteins to produce viral particles - Steps at this point are different, depends on if it's an RNA or DNA virus 5. maturation/assembly - Nucleic acid and capsid proteins spontaneously assemble. 6. release - The assembled viruses bud from the cell and acquire envelopes or exits through cell lysis. Budding occurs with the release of enveloped viruses. - The envelope is partially derived from the host plasma membrane or nuclear membrane.(Does not necessarily kill the cell) - Nonenveloped viruses are released via the rupture of the host's plasma membrane. (This kills the host cell) LYSOGENIC CYCLE: Can animal viruses undergo both the lytic and lysogenic phases/cycles? YES! Viruses such as Varicella zoster virus (causes shingles) or Human herpes virus have a lysogenic cycle, where the virus can remain dormant until triggered by stress, UV radiation, aging, immune depression, etc. - In Lysogenic phase/cycle when dormant or latent - "provirus"

Know the following terms that describe antimicrobic drugs: broad/narrow spectrum; selective toxicity; antibiotics; prophylaxis

Spectrum - range of activity of a drug Narrow-spectrum - effective on a small range of microbes - Target a specific cell component that is found only in certain microbes Broad-spectrum - greatest range of activity - Target cell components common to most pathogens (ribosomes) selectively toxic - drugs should kill or inhibit microbial cells without simultaneously damaging host tissues Antibiotics - are common metabolic products of aerobic bacteria and fungi prophylaxis - action taken to prevent disease, especially by specified means or against a specified disease.

Know the structures that are used by microbes in establishing an infection (see slide#38 entitled "attaching to the host"); be sure to also look at structures depicted in the diagrams on that slide (i.e. spikes, capsule, etc.)

Structures used for attachment: - Fimbrae - Capsules - Flagella - Glycocalyx - Cilia - Suckers - Hooks - Barbs - Spikes (viruses)

Know the parts of the body that typically do not harbor resident flora (sterile sites of the body)

There are some areas of the body such as the brain, the circulatory system and the lungs are intended to remain sterile (microbe free).

Know what determines which cells a virus can infect (i.e. think about the receptors here)

Viruses are specific to a particular host cell because they bind to a particular plasma membrane receptor.

Know the following definitions: epidemiology; epidemic; pandemic; endemic; sporadic

epidemiology - The study of the frequency and distribution of disease and health-related factors in human populations epidemic - a disease acquired by many hosts in a short period of time; disease spreads rapidly - when prevalence of a disease is increasing beyond what is expected pandemic - epidemic across continents endemic - disease that exhibits a relatively steady frequency over a long period of time in a particular geographic locale; disease constantly present in a population sporadic - when occasional cases are reported at irregular intervals; disease that occurs only occasionally

Know the following definitions as it pertains to an infection: local; systemic; focal; primary;secondary;subclinical

local infection - limited to small area of body (ex. pimple) systemic infection - spread throughout body via blood (ex. bacteremia, viremia) focal infection - spread from local infection to specific areas (ex. infection in tooth or tonsils spreads to nearby organ) - systemic infection that began as a local infection primary infection - acute infection causing initial illness secondary infection - occurs after host is weakened from primary infection subclinical infection - (inapparent): no noticeable signs and symptoms—these are the infections that go unnoticed so person doesn't seek medical attention

Know the difference between opportunistic pathogens and strict pathogens

opportunistic pathogens: are typically members of normal flora and cause diseases when they are introduced into unprotected sites or when host defenses are compromised, usually occur in people with underlying conditions. Pseudomonas sp& Candida albicans Strict pathogens: are more virulent and can cause diseases in a normal person. Treponemapallidum (syphilis); HIV (AIDS); Plasmodium vivax(malaria)

Know what side effects are

side effect - a serious adverse reaction to the drug Major side effects: -Direct damage to tissue due to toxicity of drug -Allergic reactions -Disruption in the balance of normal flora-superinfections

Know the difference between a vector (biological and mechanical), carrier, reservoir, zoonotic, and a fomite when discussing disease transmission.

vector A live animal (other than human) that transmits an infectious agent from one host to another is called a Majority of vectors are arthropods -fleas, mosquitoes, flies, and ticks Some larger animals can also spread infection -mammals, birds, lower vertebrates Vectors can transmit disease by two general methods: 1. Biological vectors-actively participate in a pathogen's life cycle; they are infected 2. Mechanical vector-not necessary to the life cycle of an infectious agent and merely transports it without being infected; they are NOT infected Reservoir: - The natural host or habitat (living or nonliving) of a pathogen - Continual source of infectious agents - Nonliving: > soil (Clostridium tetani, Bacillus anthracis) > water (Cholera, Giardia) > food (E. coli, Salmonella, Listeria) Zoonotic: - infections caused by vectors and animal reservoirs spreading their own infections to humans fomites (contaminated materials) - Vehicles > Food, water, biological products (blood, serum, tissue), fomite (door knobs, toilet seats, etc.) > Fecal-oral (aka oral-fecal)

Know all the cytopathic effects viruses can have on host cells

virus-induced damage to cells Refers to structural changes in host cells that are caused by viral invasion. The infecting virus causes lysis of the host cell or when the cell dies without lysis due to an inability to reproduce. 1.Changes in size and shape 2.Cytoplasmic inclusion bodies 3.Cells fuse to form giant multinucleated cells (enlarged cells are called syncytia) 4.Cell lysis 5.Alter DNA (chromosomal changes in host cell) 6.Transform cells into cancerous cells - Damage to host cells during virus invasion. - Thus identification of a viral infection can be made by examining The characteristic cytopathic effect produced on different cell sheets