Physical and Chemical Control of Microbes

I. Joseph ______ started _________ techniques with medical applications. By using carbolic acid (_______) -soaked rags and instruments during and after surgery, gangrene and other infections following surgery greatly diminished.

II. Terminology and Methods of ControlA. __________ means COMPLETE destruction of viruses and

microbes (including endospores) so that even if they are placed

in a new growth medium, they will not revive or reproduce.

B. __________means to reduce the number of pathogens (including viruses) until they are not a hazard, usually involving the use of antimicrobial chemicals.

C. _____________ refers to removing toxins. D. __________ refers to a substantially

reduced microbial population that meets accepted health standards. A clean appearance is expected!

Lister aseptic pheno

l

Sterilization

Disinfection

Sanitization

Decontamination

E. Different situations warrant different levels of microbial control.1. daily life Simple ___________with plain soap and water is considered to be the single most important step in preventing the spread of many infectious diseases!

handwashing

Sanitized items (not sterilized!!)

2. hospitals

Danger of __________(hospital acquired) infections because of:

a. _________ condition of hospitalized patients

b. higher concentration of sick people with _________ microbes (*and many resistant forms!!)

c. _______ procedures (such as)

d. many health care workers are ______

e. lack of _______ care (handwashing

between patients, using gloves, etc.)

nosocomial

pathogenic

weakened

invasive

carriersasept

ic

3. microbiology/research/hospital laboratories must use ________ techniques a. Work surfaces should be ______. b. All media and instruments must be ______. c. Used ________ must be properly disposed of.

aseptic clea

n sterilecultures

surgery

III. Selection of an antimicrobial procedure depends on many factors such as the type of _______, the extent of ____________, ____________ conditions, and potential risk of _________.

A. types of resistant microbes

1. Bacillus and Clostridium can make ___________.

2. Mycobacterium has ______ cell walls.

3. ____________ is capable of metabolizing unusual

substances for food. (Like disinfectants!)

endosporeswax

y

microbe

contaminationenvironmen

talinfection

Pseudomonas

B. the extent of contamination (size of the microbial population) 1. ‘Industry standard’ requires that ____% of the population is

killed with every __ minutes of exposure to the treatmenta. 100 microbes 10 microbes 1 microbe in __ minutesb. 1010 microbes would take ___ minutes

SO, ________/_________ first helps reduce the population before disinfection or sterilization. C. environmental conditions 1. _____________ ( heat chemical action) 2. _____ 3. ____, _______, _______, ______ can all block chemical action

902

420

washing

scrubbing

temperaturepHdirt saliv

ablood

feces

D. Potential risk of infection

1. _______ items come into direct contact with body tissues.Critical

2. ____________ items come into contact with mucous membranes, but do not penetrate body tissues.

Semicritical

Surgical instruments

needles

Biopsy forceps

Respiratory equipment

Vaginal speculum

Anal proctoscope

3. ____________ items only touch keratinized skin surfaces.Noncritical

IV. Methods of Physical Control A. ______ works by_________ cell proteins /enzymes. It is the most common control method because it is fast, reliable, inexpensive & nontoxic. 1. ______ heat a. _______ 100°C/10 minutes (kills most microbes

& inactivates most viruses, but does not destroy __________).

Heat

denaturing

Moist Boilin

gendospores

stethoscope

Sphygmomanometer (blood pressure cuff)

Pasteurization

b. ____________: a brief heat treatment followed by rapid cooling. (Kills pathogens and reduces the number of spoilage organisms in milk, juices, wine, beer: Does not sterilize!) (1). LTLT (Low Temperature Long Term) 63°C/30 minutes *(2). HTST (High Temperature Short Term) 72°C/15 seconds

c. _________ (steam under pressure) (1). 15-20 psi/15-20 minutes/121°C (2). ________ equipment, media, etc. (3). used in canning procedures to destroy

Clostridium botulinum __________!

Autoclave

Sterilizes

endospores

2. ___ heat sterilizes.

a. Hot air ovens (160-170°C/2-3 hours) used when ________ is undesirable.

b. ____________ (burning)

(1). _________/___________used to destroy disposable items,

soiled dressings, tissue specimens etc. @ 800°C to 6500°C

c. The hottest part of a Bunsen burner flame reaches 1,870°C for ______ during lab.

Dry

Incineration

flaming

Microbiology is Fun!

moisture

furnaces

incinerators

B. Radiation (waves having energy but no mass) causes lethal changes in DNA, denatures proteins, but doesn’t reliably destroy endospores)!1. Nonionizing rays = _____________

radiation a. can be used to reduce the number

of organisms in air and on clean surfaces

b. of limited use, cannot penetrate materials like cloth, glass, paper

2. Ionizing rays = ________ or _____________ a. can be used to __________ items that are

heat or chemical sensitive, such as plastics b. more effective, penetrates liquids and most

solids (used to treat Washington DC mail) c. In the US, radiation is approved to treat

pork to prevent ___________, to treat beeffor ________ contamination and used totreat chicken for _________ contamination.

Ultraviolet (UV)

X-rays Gamma rayssteriliz

e

trichinosisE. coliSalmonella

3. microwaves a. do not affect microbes directly, but may kill by _____ they generate b. drawback is that microwave heating is ________

heat

uneven

C. Filtration (may be used for air, some heat sensitive materials such as serum, vaccines, drugs, IV fluidsbeer/wine) 1. _____ ________ ________ ____ (HEPA) filters remove airborne contaminants; used in operating rooms, for people with allergies, etc. 2. In fluid filtration, _______ are separated from ________ by passing through _______ with extremely fine pores a. Mechanical force or vacuum suction helps fluid through the filter b. does not sterilize unless pore size is small enough to trap

everything (smaller pores, cost)

High-Efficiency Particulate Air

solids

liquidsfilter

s

V. Methods of ________ Control (* for heat sensitive items, large surfaces)Destructive actions include injury to the cell _________,

denaturation of cell ________, inhibiting replication of _____.

A. Disinfectants Vs Antiseptics 1. _____________ are chemicals used on inanimate

objects.a. ___________ are chemicals that KILL/

DESTROY germs. (examples: fungicides, bactericides, viricides)

b. __________ refers to chemicals that do not kill, but prevent the growth of microbes.

(examples: bacteriostatic, fungistatic) 2. __________ are disinfectants nontoxic

enough to be used on skin.

Chemical

membraneprotein

sDNA

Disinfectants

Germicides

Germistatic

Antiseptics

B. Germicides are grouped according to their _______ (strength) 1. __________ destroy everything, including endospores (for sterilizing scalpels, respiratory therapy equipment, proctoscopes, plastic Petri dishes, endoscopes)

(ethylene oxide gas, hydrogen peroxide)

2. ____ level disinfectants (do not reliably destroy endospores) (used for GI endoscopes) (iodine, phenol, chlorhexidine, heavy

metals such as silver nitrate) 3. ___________ level disinfectants (will kill Mycobacterium, but do not destroy all viruses or endospores, even with prolonged exposure) (used for stethoscopes, electrodes, thermometers) (alcohols: ethyl alcohol, isopropyl)

4. ____ level disinfectants (will not kill Mycobacterium) (soaps, detergents)

High

Intermediate

Low

potency

Sterilants

C. ______ _________ (5% Phenol is the standard against which chemical agents are tested and compared)

1. Each chemical is compared for the same length of _____ on the same _________ under ________ conditions 2. IF the chemical being tested requires a greater

____________ or a longer ______ than phenol, its efficiency is _____ than phenol.

IF the chemical being tested requires a lower concentration or a shorter time than phenol, its efficiency is _______ than

phenol.

3. Ratio of: tested chemical activityphenol activity

< 1 means _____ efficient than phenol > 1 means _____ efficient than phenol

Phenol coefficient

concentrationtim

e

greater

lessmore

timeorganis

midentical

less

D. Selecting the Appropriate germicidal chemical 1. ________ (the benefit of disinfecting or sterilizing an item or

surface must be weighed against the risks associated with the use

of that chemical) (hospital Vs home/office) 2. compatibility with the ________ being treated

(metal, rubber, glass, plastic) 3. ________ may necessitate rinsing 4. _____ and availability (bleach) 5. ________ and stability (concentrates

require less space and store for long periods, but when diluted/mixed, often have limited shelf life)

6. _____________risk (safe disposal procedures needed)

Toxicity

material

ResidueCostStorage

Environmental

VI. Methods used for Preservation (delaying spoilage) of Perishable Products

A. ________ preservatives (both nonfood and food)1. organic ______ lower pH (inactivates enzymes, inhibits growth, but does not always destroy microbes)2. ________ and _______ inhibit germination of Clostridium

botulinum endospores! B. Low Temperatures

1. _____________ a. 0-10° C (___° C average) b. retards but does not

prevent growth2. ________ a. ___° C b. prevents growth but

does not kill all organisms

Chemical acid

snitrates

nitrites

refrigerator

freezer

4

-20

E. ____________ (freeze-drying)1. materials _______ frozen at temperatures well below 0°C2. vacuum while frozen to remove ________ (lightweight)3. biological cultures, medications, foods (expensive)

Lyophilization rapidl

y moisture

C. Increased _______ pressure by adding _____ or _____; causes water to leave the cell, killing it. D. ___________ (dehydration) of the material (natural [sun] or artificial)

osmotic

saltsuga

r

Desiccation

Elements of Chemotherapy

I. TerminologyA. ____________ = use of chemical agents to treat diseaseB. _______________ agent (CTA) = chemical agent used for treatment of disease (even cancer)C. ___________ agent (AMA) = chemical agent used to treat

diseases caused by microbesII. Antimicrobial Agents

A. Types of antimicrobial agents1. _______ agents = metabolic products produced by

certain groups of fungi and fungal-like bacteria that are antibacterial in action

2. _________ agents = produced in the laboratory 3. _____________ agents = derivatives of natural agents

altered in the laboratory by adding chemical groups to

improve effectiveness

ChemotherapyChemotherapeuticAntimicrobial

Natural

SyntheticSemi-synthetic

B. Modes of action 1. interfere with microbe’s chemosynthesis by inhibiting ________ 2. Disruption/interference with

a. of an essential metabolite by _________ inhibition (Sulfa drugs mimic PABA, blocking folic acid synthesis)

(p. 77)

enzymes

competitive

PABA

Folic acid

Competitive Inhibition

B. Modes of action 1. interfere with microbe’s chemosynthesis by inhibiting ________ 2. Disruption/interference with

b. by weakening/disrupting the bacterial cell ______ (Penicillin inhibits the enzyme that builds the amino

acid cross- linkages of peptidoglycan) (p. 78)

enzymes

wall

Glycan “backbone”

B. Modes of action 1. interfere with microbe’s chemosynthesis by inhibiting ________ 2. Disruption/interference with

c. by damaging the cell ___________ (Polymixin cleaves the layers of the membrane like a knife) (p. 78)

membrane

hydrophilicAmphipath

ic

enzymes

hydrophobic

B. Modes of action 1. interfere with microbe’s chemosynthesis by inhibiting

________ 2. Disruption/interference with

d. by inhibiting ________________ at 70s ribosomes (p. 79) (Erythromycin inhibits translocase, freezing the

ribosome on the mRNA.)

(Tetracycline blocks tRNA attachment to mRNA) (Chloramphenicol inhibits transferase,

preventing peptide bond formation between amino acids.)

(Streptomycin causes a misreading of mRNA.)

protein synthesis

enzymes

e. by inhibiting nucleic acid (______ and/or ____) synthesis (Antiviral: AZT inhibits reverse transcriptase.)

(Antibacterial: Rifampin inhibits RNA polymerase.)(Antifungal: Griseofulvin inhibits RNA polymerase.)

DNA RNA

2. ________ of activity = range of microbes inhibited or killed a. ______spectrum usually effective against Gram+ and Gram-

bacteria(1). useful when no time to figure out exactly which

microbe is causing disease

(2). disadvantage is that it disrupts normal flora too (resulting in

_________ infections caused by opportunists). b. _______spectrum requires identification of the pathogen

3. Tissue distribution, metabolism & excretion a. ______ in body fluids (to be distributed in the blood) b. _______ in body fluids (so it is not broken down easily)

assuring constant and effective levels in the body (pH of stomach may limit ____ administration unless coated)

c. must be _________ by body tissues affected d. _________ refers to the elimination rate of a drug

(this dictates the ___________ of dosage needed)

Spectrum Broa

d

secondaryNarro

wSoluble

absorbed

Stable

Half-life

oral

frequency

C. Criteria that determine the effectiveness of antimicrobial agents 1. ________ toxicity = destroys or inhibits microbe without

affecting host cells

Selective

4. should be non __________ and not cause adverse reactions5. should be non __________ to reduce development of resistant

strainsD. Disadvantages of antimicrobial therapy

1. ______ effects on normal tissues (especially liver &/or kidneys)2. disturb ____________3. ________ reactions4. development of __________ strains of bacteria, usually by

producing _________ that destroy AMA (such as penicillinase)a. _________ occur naturallyb. resistance genes on _________ that can be spread from

bacterial cells to other bacterial cells by ____________, ______________, or ____________.

allergenicmutagenic

toxic normal

floraAllergic resistan

tenzymesmutatio

ns plasmids Conjugati

onTransformation

Transduction

E. Avoid disadvantages by1. __________ (careful) use of AMA a. Dr: proper ____________ of disease

microbe & proper __________ of AMA b. patient: maintain proper levels by

(1). taking medication at prescribed _________

(2). taking medication for prescribed length of _____

2. _________ effect of combination of 2-more AMA when resistance is likely to develop

Synergistic

Discriminate identificatio

n prescription

intervals

time

F. AMA testing = _________________ method (p. 66)1. procedure a. Inoculate a solid ______ of bacteria on agar b. Place paper disks saturated with various _________ on the

surface c. ________ 24 hours and then observe2. The principle behind this is that during incubation, the antibiotic

diffuses into the agar and, if effective, ________ growth of the bacteria in its presence.3. observations a. _________________ (no growth around the disk means the

AMA is effective) b. _________ colonies are isolated colonies in the zone of

inhibition (They represent ________ cells from the original

population!)

inhibits

Zone of inhibitionSatellite

Location of satellite colonies if present

resistant

Overlapping antibiotics (with synergistic effects) may be needed if satellite colonies appear.

disk-plate diffusion

lawn antibioti

csIncubate