Lecture Module 7: Control of Microbial Growth

Sterilization refers to the process of _____, including _____.

Destroying all microbial life on an object; endospores

Disinfection refers to the process of _____.

Reducing or inhibiting microbes on non-living surfaces

Antisepsis refers to the process of _____.

Reducing or inhibiting microbes on living tissue

Degermation refers to the process of _____.

Removing microbes from a limited area

Sanitization refers to the process of _____.

Lowering microbial counts on eating surfaces and utensils

Bacteriocidal drugs are drugs that _____.

Kill bacteria

Bacteriostatic drugs are drugs that _____.

Inhibit bacteria

Sepsis refers to _____.

Microbial contamination

Asepsis refers to the _____.

Absence of significant contamination

Washing your hands would be an example of what type of microbial control?

Degermation

What pattern does the rate of microbial death show?

Constant

The kill chemical of a chemical is dependent on/proportional to the _____, meaning that _____.

Number of microbes; the larger a population, the longer it will take to kill that population, even with the same death rate

Moist heat sterilization works by _____.

Denaturing proteins

An autoclave is a machine that utilizes _____ to sterilize culture media, instruments, and other heat-stable item (e.g. metal, glass, and cloth), making it a type of _____. The minimum operating conditions are _____ (temperature) for _____ (time) at _____ (pressure).

Steam under pressure; moist heat sterilization; 121ºC; 15 minutes; 15 PSI

If you tightly wrapped forceps in foil (and the steam from an autoclave could not contact the forceps), would the forceps be sterilized?

No, steam must come into contact with item

If you wanted to reduce spoilage organisms and pathogens in milk, juice, and wine, what physical control method should you use? This method (does/does not) sterilize the liquid because _____.

Pasteurization; does not; thermoduric organisms survive

Does dry heat or moist heat sterilize things more quickly?

Moist heat

Low temperature is a type of (bacteriocidal vs. bacteriostatic) control. Refrigeration works by _____, preventing bacteria from _____ and _____. Flash-freezing causes bacteria to become _____.

Bacteriostatic; lowering metabolism; replicating; producing toxins; dormant

High pressure is a type of (bacteriocidal vs. bacteriostatic) control. High pressure works by _____.

Bacteriocidal; denaturing proteins

Desiccation is a type of (bacteriocidal vs. bacteriostatic) control. Desiccation works by _____, preventing _____.

Bacteriostatic; removing water; metabolism

Osmotic pressure is a type of (bacteriocidal vs. bacteriostatic) control. Osmotic pressure works via _____, causing _____.

Bacteriostatic; high sugar/salt; plasmolysis

_____ and _____ are more resistant to osmotic pressure.

Molds; yeasts

Surface tension depressants refer to _____ and _____ that work by _____.

Soaps; detergents; loosening contamination from surfaces

What is the best method to sterilize liquid solutions that may be damaged by heat (for example, medications)?

Filtration

Filtration is the only practical way to eliminate microbes when working with _____, such as some culture media, enzymes, vaccines, and medications.

Heat-sensitive liquids

How does filtration work?

Liquid or gas passes through a screen-like material

High-energy/ionizing radiation refers to _____ and _____. This type of radiation works by _____, creating that _____ that damage _____. This is a type of (bacteriocidal vs. bacteriostatic) control used to sterilize _____ and disposable _____ such as gloves, plastic syringes, suturing material, and catheters.

X-rays; gamma rays; ionizing water; free radicals; DNA; bacteriocidal; pharmaceuticals; medical supplies

Non-ionizing radiation refers to _____. Non-ionizing works by _____, creating _____. This is a _____ (bacteriocidal vs. bacteriostatic) form of control. Although it is a _____ technique, it is not very _____ and only works on _____.

UV light; damaging DNA; thymine-thymine dimers; bacteriocidal; sterilizing; penetrating; surfaces

Factors influencing the effectiveness of control agents include the _____ of microbes present; the _____, _____, _____, and _____ of the agent; the _____ and _____ of the environment; the presence of _____ (which normally inhibits chemical agents); the _____ of exposure; and the _____ and _____ of the cells.

Number; concentration; age; evaporation; diffusibility; temperature; pH; organic mater; time; age; species

Do most chemical agents achieve sterility?

No

_____ are the most resistant to antimicrobial chemicals. These are infectious, _____-resistant _____ that are not _____. _____ are slightly less resistant, but they have a tough _____ shell. _____ are slightly less resistant, but they have a waxy _____ with _____. _____ are slightly less resistant, but they have a thick _____ made out of _____. _____ are slightly less resistant, but they have a _____, which is like a _____. _____ are slightly less resistant, but they have an _____ with _____. _____ are slightly less resistant, but they have a _____ made of _____. _____ are slightly less resistant because they have no _____ to be dissolved by _____-soluble antimicrobials. _____ and _____ are generally not resistant to anti-microbial chemicals.

Prions; heat; proteins; alive; bacterial endospores; keratin; mycobacteria; cell wall; 60% mycolic acid; protozoal cysts; cell wall; chitin; protozoal trophs; pellicle; cell wall; Gram-negative bacteria; outer membrane; porins; fungi; cell wall; chitin; naked viruses; envelope; lipid; Gram-positive bacteria; viruses with lipid envelopes

Chemotherapy refers to the _____.

Treatment of disease with chemical substances

An antibiotic is an antimicrobial agent, usually produced by a _____ or _____ in order to _____ (a type of _____). These are _____ metabolic products.

Bacterium; fungus; inhibit the growth of competing microbes in the same habitat; antagonism; natural

Selective toxicity refers to a property of some microbial agents to be _____ and _____.

Toxic to a microorganism; less/non-toxic to a host

Organism that produce the majority of antimicrobial drugs include _____ in the genera _____ and _____ and _____ in the genera _____ and _____.

Bacteria; Streptomyces; Bacillus; molds; Penicillium; Cephalosporium

Desirable characteristics of antimicrobial drugs include _____, which means that the drug targets the microbe without harming the host; the appropriate _____ (broad vs. narrow); the _____-effectiveness; limited _____; the _____ of the drug (meaning that the drug is able to get to where the infection is); whether the drug is _____ (killing) or _____ (inhibiting); an unlikelihood that bacteria will develop _____; _____ of administration and production; and if the drug is _____ (meaning most people will not be allergic to the drug).

Selective toxicity; spectrum; cost; side effects; solubility; bacteriocidal; bacteriostatic; resistance; ease; hypoallergenic

A broad spectrum drug is an antibiotic that is _____. A narrow spectrum drug is an antibiotic that is _____.

Effective against a wide variety of organisms; effective against only specific types of organisms

A superinfection refers to an _____, usually by _____.

Infection following a previous infection; microorganisms that have become resistant to the antibiotics used earlier

It is difficult to target a pathogenic virus without damaging the host cells because viruses are found _____ and are _____, making it difficult to find an appropriate drug.

Inside host cells; non-living

It is difficult to target a pathogenic protozoan, fungi, and helminths without damaging the host’s cells because they are _____ and _____-like, making them _____.

Eukaryotic; animal; similar to host cells

Antibiotics with a very broad spectrum of activity are not as useful as one might first think because they can _____.

Kill normal microbiota

If you have an infection with a Gram-negative organism, you should use a drug that is _____ because Gram-negative bacteria have an _____ with _____; if the initial structure ruptures, the latter compound acts as an _____ that can cause the patient to go into _____.

Bacteriostatic; outer membrane; Lipid A; endotoxin; shock

The five modes of antimicrobial inhibition are inhibition of _____, _____, _____, _____, and _____.

Protein synthesis; cell wall; cytoplasmic membrane; nucleic acids; metabolism

Drugs that inhibit protein synthesis target _____. These drugs (are/are not) selectively toxic because _____. These drugs are (bacteriocidal vs. bacteriostatic). Examples of such drugs include _____, _____, and _____.

Ribosomes; are; bacteria have 70S ribosomes, which humans do not have; bacteriostatic; azithromycin; streptomycin; tetracyclines

Drugs that inhibit cell wall synthesis and repair target the _____. These drugs (are/are not) selectively toxic because _____. These drugs are (bacteriocidal vs. bacteriostatic). Examples of such drugs include _____, _____, and _____.

Cell wall; are; bacteria have cell walls, while humans do not; bacteriocidal; penicillin; vancomycin; cephalosporins

Drugs that inhibit the cytoplasmic membrane target the _____, resulting in _____. These drugs (are/are not) selectively toxic because _____. These drugs are (bacteriocidal vs. bacteriostatic). Examples of such drugs include _____. 

Cell membrane; loss of selective permeability; are not; human and bacterial cell membranes both have a phospholipid bilayer; bacteriocidal; polymyxins

Drugs that inhibit nucleic acids target _____/_____. These drugs (are/are not) selectively toxic because _____. These drugs are (bacteriocidal vs. bacteriostatic). Examples of such drugs include _____ and _____.

DNA/RNA; are; bacteria have circular chromosomes, while humans do not; bacteriostatic; quinolones; rifampin

Drugs that inhibit metabolism target _____. These drugs (are/are not) selectively toxic because _____. These drugs are (bacteriocidal vs. bacteriostatic). Examples of such drugs include _____.

Folic acid synthesis; are; bacteria synthesize folic acid, while humans do not; bacteriostatic; sulfonamides

_____ antimicrobial drugs contain a B-lactam ring. These rings are needed to make _____, preventing the _____ and inhibiting _____ synthesis. These drugs target _____ bacteria more than _____ bacteria because the former has a _____.

Penicillin; peptidoglycan; cross-linking of peptidoglycan; cell wall; Gram-positive; Gram-negative; thicker layer of peptidoglycan

Natural penicillin refers to penicillin that is _____. These generally have a _____ spectrum of activity (for _____ bacteria). Natural penicillins are more susceptible to _____/_____, which turns penicillin into _____ and prevents it from _____.

Extracted from Penicillium (fungi) cultures; narrow; Gram-positive; penicillinases/B-lactamases; penicilloic acid; inhibiting peptidoglycan

Some bacteria produce the _____ enzyme, making them resistant to penicillin. These enzymes work by _____ present in penicillin, preventing activity. These enzymes are common in _____ species.

Penicillinase; cutting the B-lactam ring; Staphylococcus

Semi-synthetic penicillins have the advantage of chemically-added _____ that make them _____ or _____ (e.g. to some _____).

Side chains; resistant to penicillinases; extend their spectrum of activity; Gram-negative bacteria

What do penicillin, amoxicillin, cephalosporin, and ampicillin have in common in terms of their structure?

B-lactam ring

Bacitracin is a type of _____ antibiotic that is used to kill _____ bacteria on our _____ like _____ or _____ species by inhibiting _____ synthesis. This drug is typically applied _____ and has a (narrow vs. broad) spectrum.

Polypeptide; Gram-positive; skin; S. aureus; Streptococcus; cell wall; topically; narrow

Vancomycin is a type of _____ antibiotic that is used as a first-line drug against _____. This drug works by inhibiting _____ synthesis. This drug has a (narrow vs. broad) spectrum and can be very _____.

Polypeptide; methicillin-resistant S. aureus); cell wall; narrow; toxic

Isoniazid and ethambutol are used to treat _____.  These are both (narrow vs. broad) spectrum drugs against _____. Isoniazid is used inhibit the _____ of mycolic acid, while ethambutol is used to inhibit the _____ of mycolic acid. Both of these drugs are often _____.

Tuberculosis; narrow; Mycobacterium; synthesis; incorporation; used in combination with other drugs

Streptomycin, tetracycline, and chloramphenicol prevent microbial growth by inhibiting _____ and _____ targeting _____.

Protein synthesis; selectively; 70S ribosomes

Rifamycin targets _____ (specifically _____) synthesis and is used to treat _____ because it can _____. This drug is _____ spectrum because it cannot _____.

Nucleic acid; mRNA; tuberculosis; penetrate the tissues; narrow; pass through the cell envelope of Gram-negative bacteria

_____ is a drug that is used topically, is combined with bacitracin and neomycin in non-prescription ointments, and works by injury to the cell membrane. This drug targets _____ bacteria.

Polymyxin B; Gram-negative

Most drugs that cause injury to the plasma membrane are applied _____ because _____.

Topically; most skin cells are dead

What is the term used to describe when the effect of two drugs together is greater than either alone?

Synergy

_____ and _____ are two drugs that are synergistic and target folic acid synthesis. _____ prevents _____ from turning into _____, while _____ prevents _____ from turning into _____.

Trimethoprim; sulfamethoxazole (TMP-SMZ); sulfamethoxazole; PABA; dihydrolic acid; trimethoprim; dihydrofolic acid; tetrahydrofolic acid

The three factors that must be known before antimicrobial therapy can be administered are the _____, the _____, and the _____.

Identity of the microorganism causing the infection; microorganism’s susceptibility/sensitivity to various drugs; overall medical condition of the patient

The Kirby-Bauer method is used to _____. If an organism is sensitive to an antibiotic, it will have a _____ zone of inhibition. If an organism is resistant to the antibiotic, it will have a _____ zone of inhibition. Zones of inhibition are measured in _____ and compared to a _____.

Determine the appropriate antibiotic for treatment; large; little to no; millimeters; standardized table

The advantages of using the Kirby-Bauer method are that it is relatively _____, _____, _____, and _____.

Common; easy; cheap; standardized

If there is clearing around an antibiotic disk, does it mean the bacteria is definitely dead in that area? Why or why not? How could you test if the bacteria in that area are dead?

No, bacteria may have stopped growing, but are not dead; take a swab of area and see if anything grows

The E test is a _____ method that determines the _____ (MIC), which is the _____.

Gradient diffusion; minimal inhibitory concentration; lowest concentration of antibiotic that can prevent bacterial growth

The therapeutic index (TI) of a drug is the _____. A drug with a _____ therapeutic index is generally considered safer. The _____ the ratio, the greater the potential for toxic drug reactions.

Ratio of the dose of the drug that is toxic to humans as compared to the minimum effective/therapeutic dose; larger; smaller

Failure of antimicrobial treatment can be due to the inability of the drug to _____, _____ microbes in the infection that did not make it into the sample for testing, an infection caused by _____, or patients that _____.

Diffuse into tissues; resistant; multiple pathogens; do not take antibiotics correctly

The four mechanisms of resistance to antibiotics include reducing _____, which means that drugs are _____; _____ of the antibiotic using _____ that remove the drug from cells; altering the antibiotic’s _____, which prevent the drug from _____ via mutation; and _____ antibiotics (e.g. penicillinase can inactivate penicillin).

Permeability; less likely to enter cells; restricting access; efflux pumps; target site; binding to its target; mutation; inactivating

T/F: Antibiotics cannot create a resistance allele.

True; variation in resistance was already present in population, presence of antibiotics just favored resistant organisms

Reduced permeability as a mechanism of resistance to antibiotics are common in _____ bacteria, which have _____ in their _____ that can reduce permeability by _____ or _____. Changes in _____ structure can also prevent antibiotics from entering cells (e.g. _____).

Gram-negative; porins; outer membrane; decreasing expression; physically changing; cell wall; capsules

The three ways that bacteria can acquire the genes needed for antibiotic resistance are _____, _____, and _____.

Transduction; transformation; conjugation

Transduction refers to when _____.

A virus (bacteriophage) acts as a genetic vector, passing DNA from donor to recipient

Transformation refers to when _____.

Naked DNA is transferred from a dead donor into a competent recipient

Conjugation refers to the _____.

Transfer of genetic material from one cell to another via cell-to-cell contact

Genetic recombination can occur through _____ (during reproduction, between different generations of cells), _____ (changes in the DNA sequence), and _____ (transfer of genes within the same generation of cells).

Vertical gene transfer; mutation; horizontal gene transfer

Ways to prevent antibiotic resistance include only _____ as necessary, _____ infection through vaccination, hand-washing, etc, stop using antibiotics in _____, improve _____ to detect infection, and developing _____ antibiotics.

Prescribing; preventing; livestock; testing; new