Microbiology Exam #3 Study Guide

Flashcards for Chapter 11, 12, 13, 14, 15, 17

Heat

Moist (autoclave) and dry (incineration) destroy microbes by denaturing proteins.

Cold and Desiccation

Microbiostatic; slows growth or preserves microbes, doesn't kill all.

Radiation

Damages DNA; used to sterilize food and medical supplies.

Filtration

Physically removes microbes from liquids or air without heat.

Ways bacteria can avoid phagocytosis

Producing capsules or biofilms.

Ways bacteria can avoid phagocytosis

Releasing leukocidins that kill phagocytes.

Ways bacteria can avoid phagocytosis

Remaining dormant or resisting digestive enzymes.

Ways bacteria can avoid phagocytosis

Mimicking host molecules to appear as "self."

Disinfectants/antiseptics

Include phenolics (triclosan), halogens (chlorine, iodine), alcohols, heavy metals (silver, mercury), and surfactants (soaps).

Ways drug resistance is developed in microbes

Enzyme production that inactivates drugs (e.g., penicillinase).

Ways drug resistance is developed in microbes

Decreased permeability or efflux pumps.

Ways drug resistance is developed in microbes

Altered drug targets or alternative metabolic pathways.

How viruses contribute to drug resistance in bacteria

Viruses transfer resistance genes between bacteria.

How plasmids influence drug resistance in a population of bacteria

Plasmids carry resistance genes and can spread them through conjugation.

Sterilization

Destroys all microbes, including spores.

Disinfection

Destroys vegetative pathogens.

Antiseptics

Used on body surfaces to inhibit pathogens.

Sanitation

Mechanical removal of microbes (e.g., soaps).

Pasteurization

Heat treatment that kills pathogens without affecting taste.

Cellular targets of control methods

Cell wall, cell membrane, DNA/RNA/protein synthesis, and proteins (enzymes).

Methods bacteria use to survive effects of an antibiotic

Inactivate drugs, pump them out, modify drug targets, form biofilms.

Selective toxicity

Drug targets microbes without harming host tissues.

Microbiostatic

Slows microbial growth.

Desiccation

Removes water to inhibit metabolism.

Filtration

Physically removes microbes.

Why someone can't be on an antibiotic drug indefinitely

Risk of side effects, killing normal flora, and developing resistance.

Probiotics

Live microbes used to restore or enhance normal flora (e.g., in yogurt).

How antibiotics lead to antibiotic resistance in a bacterial population

Antibiotics kill susceptible bacteria, allowing resistant strains to survive and multiply.

Normal flora

Microbes living on body surfaces in mutualistic/commensal relationships.

Benefits of normal flora

Compete with pathogens, aid immunity, synthesize vitamins.

Portals of entry

Skin, GI, respiratory, urogenital, placenta.

Portals of exit

Saliva, feces, skin, urogenital fluids, blood.

Infectious dose

Minimum number of microbes needed to cause infection. Smaller ID = more virulent.

How microbes attach to tissues

Using adhesins to bind to host receptors.

Virulence factor

Trait that enhances a microbe's ability to cause disease.

Exoenzymes

Digest tissues (e.g., collagenase).

Toxins

Endotoxins (LPS), exotoxins (secreted).

Antiphagocytic factors

Capsules, leukocidins.

Localized infection

Stays in one area.

Systemic infection

Spreads via blood.

Mixed infection

Multiple microbes.

Primary infection

Initial infection.

Secondary infection

Different microbe follows primary.

Fomites

Contaminated objects.

Direct contact

Physical touch, droplets.

Indirect contact

Food, water.

Mechanical (vector)

Passive transfer.

Biological (vector)

Pathogen replicates inside vector.

Nosocomial

Acquired in healthcare settings.

Epidemiology

Study of disease patterns.

Sporadic

Occasional (e.g., tetanus).

Endemic

Constant in area (e.g., malaria).

Epidemic

Sudden increase (e.g., flu outbreak).

Pandemic

Global (e.g., COVID-19).

Neutrophils

Phagocytosis.

Eosinophils

Parasites/inflammation.

Basophils

Histamine release.

Lymphocytes

Adaptive immunity.

Monocytes/Macrophages

Phagocytosis.

Physical barriers

Skin, mucus, cilia, flushing.

Chemical barriers

HCl, lysozyme, bile, acidic pH.

Genetic barriers

Natural immunity in some hosts.

The inflammatory response

Redness, heat, swelling, pain.

Margination

WBCs adhere to vessel walls.

Diapedesis

WBCs exit vessels to tissues.

Chemotaxis

Movement toward chemical signals.

The value of fever

Inhibits microbial growth, enhances immune function, reduces iron availability.

Phagocytosis

Engulf/destroy invaders.

Interferon

Blocks viral replication.

Complement

Lyses cells, enhances opsonization and inflammation.

B cells

Produce antibodies (humoral immunity).

T cells

Kill infected cells (cell-mediated immunity).

Active natural immunity

Infection.

Passive natural immunity

Breast milk.

Active artificial immunity

Vaccination.

Passive artificial immunity

Antibody injection.

Plasma cells

Produce antibodies.

Memory cells

Long-term immunity.

Helper T cells

Stimulate other immune cells.

Regulatory T cells

Suppress immune response.

Cytotoxic T cells

Kill infected cells.

Neutralization

Blocks pathogen interaction.

Agglutination

Clumping for removal.

Precipitation

Removes soluble antigens.

Opsonization

Enhances phagocytosis.

Types of Vaccines

Killed/inactivated, live attenuated, subunit, recombinant, mRNA.

Phenotypic test method

Culture/microscopy.

Genotypic test method

DNA analysis.

Immunologic test method

Antigen-antibody (e.g., ELISA).

ELISA

Detects antibodies/antigens.

Western Blot

Confirms proteins.

Gel electrophoresis

DNA analysis.

Salk vaccine

Inactivated, safe, less immunity.

Sabin vaccine

Live attenuated, stronger, risk of reversion.

Lactobacillus acidophilus

Part of normal flora, probiotic, ferments sugars to lactic acid, lowers pH, inhibits pathogens.