Objectives come from your Unit 3 sheet  and the content/examples come from the PowerPoints . ⸻ UNIT 3 COMPLETE STUDY GUIDE (Based strictly on your slides + objectives) ⸻ CHAPTER 11 — CONTROLLING MICROBIAL GROWTH Difference Between Antisepsis, Disinfection, Sanitization, Sterilization, Degerming, Decontamination Sterilization Complete destruction of all microbial life including viruses and endospores. Examples from slides: • Surgical instruments • Syringes • Packaged foods Endospores must be destroyed for something to be considered sterile.  ⸻ Disinfection Destroys most vegetative pathogens on nonliving surfaces. Examples: • Disinfecting medical equipment • Hospital surfaces ⸻ Antisepsis Use of antimicrobial chemicals on living tissue. Examples: • Skin prep before surgery • Cleaning wounds ⸻ Degerming Mechanical removal of microbes by scrubbing. Example: • Handwashing ⸻ Sanitization Reduces microbial numbers to public health safe levels. Examples: • Cleaning food preparation surfaces • Restaurant sanitation ⸻ Decontamination General removal of microbes from objects or surfaces. Example: • Cleaning contaminated hospital equipment ⸻ Difference Between Static and Cidal Cidal Kills microbes. Example Bactericidal antibiotics. ⸻ Static Stops growth but does not kill. Example Bacteriostatic antibiotics. ⸻ Variables That Influence Effectiveness of Antimicrobial Methods 1. Population size Large populations require more time to kill. 2. Nature of microbes Some microbes are more resistant. Example: Bacterial endospores. 3. Temperature Higher temperature increases killing. 4. Concentration of agent 5. Contact time 6. Organic matter present Example: Blood or mucus interfering with disinfectants. 7. Mode of action of agent 8. Biofilms Biofilms protect microbes from antimicrobials.  ⸻ Most Resistant vs Least Resistant Microbes Most resistant: Bacterial endospores Reason: Thick protective layers. ⸻ Less resistant: • Mycobacteria • Gram-negative bacteria • Gram-positive bacteria • Fungi • Viruses Endospores are the target of sterilization methods.  ⸻ Mechanisms of Antimicrobial Agents Agents work by damaging: Cell wall Example Detergents and alcohol disrupt cell wall. ⸻ Cell membrane Effects • Loss of permeability • Leakage of molecules ⸻ Proteins Agents denature proteins. Examples • Heat • Alcohol • Strong acids ⸻ DNA and RNA Example Radiation damaging DNA. ⸻ Practical Concerns When Choosing Control Method Consider: • Does item require sterilization or disinfection? • Can item tolerate heat, pressure, radiation, chemicals? • Cost effectiveness • Safety • Ability of agent to penetrate surfaces.  ⸻ PHYSICAL AND MECHANICAL METHODS ⸻ Pasteurization vs Sterilization Pasteurization: Reduces microbial numbers but does not sterilize. Used for: Milk and beverages. Sterilization: Destroys all microbes including endospores. ⸻ Boiling Kills many pathogens but may not destroy endospores. ⸻ Autoclaving Uses steam under pressure. Conditions from slides: 121°C 15 minutes 15 psi Mechanism: Denatures proteins and disrupts metabolism.  ⸻ Most Rigorous Heat Method Incineration (dry heat) Burns microbes completely. ⸻ Ionizing Radiation vs UV Radiation Ionizing radiation Examples: Gamma rays X-rays Effect: Destroys DNA and proteins. Highly penetrating. ⸻ UV radiation Example: Germicidal lamps. Mechanism: Forms pyrimidine dimers (thymine dimers). Effect: DNA replication blocked.  ⸻ Filtration Removes microbes from liquids or air. Examples: • Water purification • Milk filtration • Air filtration systems • HEPA filters • N95 masks HEPA filters remove 99.97% of particles.  ⸻ Osmotic Pressure High salt or sugar removes water from microbes. Examples: Salt: Cured meats Sugar: Jams and jellies Causes plasmolysis and prevents growth.  ⸻ Cold and Drying Cold: Slows microbial metabolism but rarely kills microbes. Drying (desiccation): Removes water necessary for microbial metabolism. Example: Freeze drying (lyophilization).  ⸻ CHEMICAL METHODS ⸻ Characteristics of Good Chemical Antimicrobials • Rapid action • Effective at low concentrations • Broad spectrum • Stable • Non-toxic to tissues • Affordable • Effective in presence of organic matter  ⸻ Major Chemical Agents ⸻ Halogens Examples: • Chlorine • Iodine Common example: Household bleach (sodium hypochlorite) Mechanism: Oxidizes cellular molecules and damages enzymes.  ⸻ Phenols Mechanism: Disrupt cell membranes and denature proteins. Examples: Phenolic disinfectants. ⸻ Alcohols Examples: • Ethanol • Isopropanol Mechanism: Denature proteins and disrupt membranes. Common use: Hand sanitizers. ⸻ Quats Quaternary ammonium compounds. Mechanism: Disrupt membranes. Example: Lysol wipes ⸻ Peroxides Example: Hydrogen peroxide. Mechanism: Forms reactive oxygen molecules that damage cells. ⸻ Detergents / Surfactants Mechanism: Break down lipid membranes. Examples: Soap and cleaning detergents.  ⸻ CHAPTER 12 — ANTIBIOTICS ⸻ Alexander Fleming Discovered penicillin in 1928 from the fungus Penicillium.  ⸻ Characteristics of a Good Antimicrobial Drug • Selective toxicity • High therapeutic index • Targets unique microbial structures • Effective against pathogen • Minimal harm to microbiota  ⸻ Selective Toxicity Ability of a drug to kill microbes without harming host cells. Example: Penicillin targets bacterial cell walls, which human cells lack. ⸻ Susceptibility Tests ⸻ Kirby-Bauer Disc diffusion test. Antibiotic discs placed on bacterial culture. Zone of inhibition measured. Results: Sensitive Resistant  ⸻ MIC Minimum inhibitory concentration. Smallest drug concentration preventing visible growth. ⸻ MBC Minimum bactericidal concentration. Smallest concentration that kills bacteria. ⸻ Therapeutic Index TI = toxic dose / therapeutic dose Example from slides: TI of 10 safer than TI of 1.1.  ⸻ Antibiotic Mechanisms ⸻ Cell Wall Inhibitors Example: Penicillin Mechanism: Prevents cross-linking of NAM-NAG peptidoglycan. Cell bursts due to osmotic pressure. Other examples: • Methicillin • Cephalosporins  ⸻ Cell Membrane Disruption Examples: • Polymyxin • Daptomycin • Colistin Mechanism: Creates pores causing leakage.  ⸻ Protein Synthesis Inhibitors Example: Tetracycline Mechanism: Blocks 30S ribosomal subunit. Other examples: • Erythromycin • Azithromycin • Chloramphenicol  ⸻ DNA / RNA Inhibitors Example: Fluoroquinolones Examples: • Ciprofloxacin • Levofloxacin Mechanism: Inhibit DNA gyrase. ⸻ Metabolic Pathway Inhibitors Example: Sulfa drugs Block folic acid synthesis. Example drug: Bactrim.  ⸻ Drugs for Eukaryotic Pathogens ⸻ Antifungals Examples: • Fluconazole • Amphotericin B • Azoles Target ergosterol in fungal membranes. ⸻ Antiprotozoal Drugs Examples: • Metronidazole • Chloroquine ⸻ Antihelminthic Drugs Examples: • Pyrantel • Mebendazole • Ivermectin  ⸻ Antiviral Drugs Targets: • Viral attachment • Viral transcription/translation • Viral assembly or release Examples: Acyclovir Blocks viral DNA replication. Tamiflu Prevents influenza virus release.  ⸻ HIV Drugs Target steps in HIV replication: 1 Reverse transcriptase 2 Integrase 3 Protease 4 Viral attachment Combination therapy prevents resistance. ⸻ Antibiotic Resistance ⸻ How Resistance Develops • Mutation • Natural selection • Overuse of antibiotics ⸻ Mechanisms of Resistance • Drug-destroying enzymes • Efflux pumps • Target modification • Reduced permeability  ⸻ CHAPTER 13 — MICROBIOTA ⸻ Normal Microbiota Microorganisms living on body surfaces without causing disease. Examples from slides: Skin: Staphylococcus epidermidis Gut: Escherichia coli Breast milk microbes: • Bifidobacterium • Lactobacillus • Streptococcus • Clostridium  ⸻ Benefits of Microbiota • Produce vitamins • Digest food • Stimulate immune system • Produce neurotransmitters • Prevent pathogen colonization  ⸻ Dysbiosis Imbalance in microbiota. Associated diseases: • Diabetes • Obesity • Cancer • Asthma • Allergies • Heart disease  ⸻ Microbiota Development Microbiota develop: 1 During birth 2 Through breast milk 3 Environmental exposure Stable microbiome forms by age 3. ⸻ Probiotics vs Prebiotics Probiotics: Live microbes that improve microbiota. Example: Yogurt. ⸻ Prebiotics: Food that feeds beneficial microbes. Examples: • Garlic • Onions • Asparagus • Agave • Artichokes  ⸻ Fecal Microbiota Transplant Transfer of microbiota from healthy donor. Used for: Clostridioides difficile infections Success rate: 70–90%.  ⸻ Virulence Factors Examples: Adhesion structures: Capsules, fimbriae Exoenzymes: Hyaluronidase Coagulase Biofilms increase resistance.  ⸻ Toxins ⸻ Exotoxins Secreted protein toxins. Examples: • Cytotoxins • Neurotoxins • Enterotoxins ⸻ Endotoxins Found in gram-negative bacteria. Example: LPS containing lipid A. Effects: • Fever • Inflammation • Shock  ⸻ CHAPTER 14 — EPIDEMIOLOGY ⸻ Epidemiology Study of disease frequency, distribution, and control in populations.  ⸻ Epidemiological Terms Index case: First identified patient. Incidence: Number of new cases. Prevalence: Total existing cases. Mortality rate: Deaths in a population. Case fatality rate: Deaths among infected individuals.  ⸻ Disease Occurrence Sporadic: Random cases. Endemic: Constant presence. Outbreak: Localized increase. Epidemic: Large regional increase. Pandemic: Worldwide epidemic.  ⸻ Healthcare-Associated Infections (HAIs) Common examples: • CAUTI Catheter-associated urinary tract infection • CLABSI Central line bloodstream infection • Surgical site infections • Ventilator associated infections  ⸻ Causes of HAIs • Low patient immunity • Antibiotic resistant organisms • Invasive procedures • Healthcare worker transmission Example: Healthcare workers moving between patients.  ⸻ Prevention of HAIs • Medical asepsis • Surgical asepsis • Universal precautions • Infection control officers Examples: • Needlestick precautions • Surface decontamination • Barrier protection  ⸻ If you want, I can also give you the 20–30 questions your professor is MOST likely to put on the exam from these slides. Micro professors tend to repeat the same exact conceptual questions every semester, and your slides have some really obvious ones.

Sterilization

The complete destruction or removal of all microorganisms, including viruses and endospores.

Disinfection

Destroys most microbial life (vegetative pathogens) on nonliving surfaces.

Antisepsis

Application of chemicals to living tissues to destroy microbes.

Degerming

Mechanical removal of microbes, usually by scrubbing.

Sanitization

Reduces microbial numbers to safe public health levels.

Decontamination

Broad removal of contaminants and microbes from surfaces.

–cidal

Kills microbes.

–static

Stops microbial growth but does not kill them.

Population size

Larger populations require more time to kill.

Nature of the microbe

Some microbes are inherently more resistant.

Temperature

Higher temperature increases killing rate.

Concentration of antimicrobial agent

Higher bleach concentration kills microbes faster.

Presence of organic matter

Blood, mucus, or dirt can reduce effectiveness of disinfectants.

Contact time

Short exposure to disinfectant may not kill microbes.

Biofilms

Biofilms protect microbes from antimicrobial agents.

Bacterial endospores

Considered the most resistant microorganism to sterilization methods.

Cell wall

Antimicrobials work by damaging the cell wall of microbes.

Cell membrane

Disruption of the cell membrane results in loss of selective permeability.

Proteins

Agents that denature proteins can lead to cell death.

DNA and RNA

Damage to nucleic acids can stop microbial replication.

Moist Heat

Kills microbes by coagulating and denaturing proteins.

Dry Heat

Kills microbes by oxidation.

Cold

Cold slows microbial activity but does not usually kill microbes.

Desiccation

Removal of water inhibits microbial metabolism.

Osmotic Pressure

High salt or sugar concentrations remove water from cells.

Ionizing radiation

Destroys DNA and proteins; examples include gamma rays and X-rays.

Non-ionizing radiation

Examples include UV light, which forms pyrimidine dimers in DNA.

Filtration

Removes microbes by passing liquids through filters with very small pores.

Halogens

Substances like chlorine and iodine that oxidize cellular components.

Phenols

Substances that damage membranes and denature proteins.

Alcohols

Denature proteins and disrupt membranes, e.g., ethanol and isopropanol.

Quats

Quaternary Ammonium Compounds that disrupt membranes and proteins.

Peroxides

Produce reactive oxygen molecules that damage cells, e.g., hydrogen peroxide.

Selectively Toxicity

Ability of antimicrobial drugs to kill microbes without harming host cells.

Kirby-Bauer Test

Method to determine antibiotic effectiveness by observing the zone of inhibition.

Minimum Inhibitory Concentration (MIC)

Smallest concentration of drug that prevents visible bacterial growth.

Minimum Bactericidal Concentration (MBC)

Smallest concentration that kills bacteria.

Therapeutic Index (TI)

TI = toxic dose ÷ therapeutic dose; higher TI indicates a safer drug.

Cell Wall Inhibitors

Antibiotics like penicillin that prevent cross-linking of peptidoglycan.

Membrane Disruption

Antibiotics that create pores in bacterial membranes.

Protein Synthesis Inhibitors

Drugs like tetracycline that block ribosomal functions.

DNA/RNA Inhibitors

Drugs like fluoroquinolones that inhibit DNA gyrase and topoisomerase.

Metabolic Pathway Inhibitors

Drugs like sulfa drugs that block folic acid synthesis.

Antifungal drugs

Drugs that target ergosterol in fungal membranes.

Antiprotozoal drugs

Drugs like metronidazole for treating protozoan infections.

Dysbiosis

Imbalance in microbiota associated with various diseases.

Virulence Factors

Microbial features that enhance infection and disease severity.

Exotoxins

Secreted proteins that are extremely potent and can cause potent effects on host.

Endotoxins

Found in gram-negative bacteria, can cause fever and shock due to Lipopolysaccharide.

Epidemiology

Study of disease frequency, distribution, and control in populations.

Incidence

Number of new cases of a disease.

Prevalence

Total number of existing cases of a disease.

Mortality rate

Number of deaths in a population due to a disease.

Sporadic

Occurrences of a disease that happen randomly.

Endemic

Constant presence of a disease within a geographic area.

Outbreak

Localized increase in disease cases.

Pandemic

An epidemic that spreads worldwide.

Healthcare-Associated Infections (HAIs)

Infections that occur in patients during the process of care in a healthcare facility.

Prevention of HAIs

Strategies employed to reduce the risk of infections in healthcare settings.