Microbiology Exam 3

Sterilization definition

The process that destroys all viable microorganisms, including spores

- heat and sterilants
EX: surgical instruments, syringes

Examples of sterilization

Heat (autoclave)

Sterilants (chemical agents that can rid endospores)

Disinfection definition

physical/chemical agent destroy vegetative pathogens NOT endospores

used on inanimate objects b/c the concentration of disinfectants required to be effective is harmful to human tissue

Disinfection examples

bleach, iodine, heat (boiling)

Decontamination/Sanitization definition

removes microorganisms & debris (PHYSICAL control)

*INATIMATE OBJECTS (non-living)

Decontamination/Sanitization examples

soaps, detergents, comercial dishwashers

cooking utensils, dishes, bottles, cans

Antisepsis/Degermation definition

Reduces # microbes on human skin, form of decontamination but on living tissues

• involves scrubbing the skin or immersing it in chemicals

• alcohol and sugical hand scrubs, iodine

Antisepsis/Degermation examples

alcohol wipe on skin before shot

surgical hand scrubs

Heat (physical agent): Moist

hot water, boiling water, steam...60C-135C

disinfection

30 min boiling = kill most non-endospore-forming-pathogens

can be easily re-contaminated once removed from water

lower temps & shorter exposure than dry heat (better)

Heat (physical agent): Dry

hot air or open flame...160C-1000C

dehydrates cell

denatures proteins

inc. stability of some proteins = need higher temp

- At very high temperatures, oxidizes cells and burning them to ash

Heat: Dry -> Inceration

flame

reduces microbes to ashes & gas

*downside = launch items into air

Heat: Dry -> Hot Air Oven

(same at house)

heated, circulated air transfers heat to materials in oven

*sterilization can occur after 2-4 hours @ 150C-180C (destruction of endospores)

Radiation Ionizing

uses high-energy rays (gamma, x-ray, electron beam) to kill microbes on med equipment/supplies/drug

breaks apart DNA, kills off cell

amount to kill not damage

dont use w/living tissue, electronics, some materials (plastics)

Radiation Non-ionizing

UV light

can damage after a while, not as penetrative

treats water and small volumes of liquid

Cold

slow growth

gradual cool = no affect

flash frozen = yes affect

Cold: Desiccation (dehydrate)

dry out by removing water

goal = preserve something, prevent growth, prepare for storage, can ruin form/function

(desiccation of tissue sample to preserve for biopsy)

Cold: Lyophilization

freeze dry something & keep structure/function

for long shelf life or stability

(drugs: vancomycin, acyclovir, pantoprazole, vaccines, etc.)

reconstitution

Autoclaving (pressure)

Method of sterilization using steam under pressure

high pressure & high heat & steam

denatures proteins & bursts cell walls

*must clean before

Filtration

keep microbes away without using harsh chemicals or energy like radiation or heat.

It’s all about physically blocking or removing the bad guys.

This makes it gentle, perfect for heat-sensitive liquids like some vaccines or proteins that can’t be boiled or irradiated.

It’s not about killing microbes on a surface but rather preventing them from getting where they don’t belong.

Chemical agents: High, intermediate, low germicides

high: kill endospores, used as sterilant...critical (surgical instruments, catheters, and implants, which enter sterile body areas.)

intermediate: kill fungal, BUT NOT bacterial spores, resistant pathogens, and viruses (endoscopes, laryngoscopes, and respiratory therapy equipment, which come into contact with mucous membranes but do not penetrate sterile tissues.)

low: eliminate only vegetative bacteria, vegetative fungal cells, and some viruses...non critical (blood pressure cuffs, stethoscopes, and bedrails, which come into contact with intact skin but not mucous membranes)

Factors affecting germicidal activity:

1. nature of microorganisms being treated

2. nature of material being treated

3. degree of contamination

4. time of exposure

5. strength/chemical action of germicide*

6. composition of material being treated

Strength/chemical action of germicide*: Dilution

small volume of the liquid chemical is diluted in a larger volume of solvent to achieve a certain ratio

-Describes how much you weaken something by adding solvent.

Strength/chemical action of germicide*: Percentage solution

solute added to water by weight or volume

-Describes how strong a solution is as a percentage.

Strength/chemical action of germicide*: Parts per million (ppm)

GAS measured

ex: chlorine gas kills off bacteria & people

Cold: Desiccation (dehydrate) vs Cold: Lyophilization

Desiccation is a general term for removing moisture from materials, often without freezing,

while lyophilization is a controlled freeze-drying process that preserves the material’s structure and is more commonly used for preserving sensitive biological substances.

pasteurization

heat...cool...repeat

technique in which heat is applied to liquids to kill potential agents of infection and spoilage

endospores go into vegetative state...can kill off then

osmotic pressure

pull out, bring in, isotonic

Antimicrobial Chemotherapy/ Antimicrobial Drug

Administer a drug to an infected person that destroys the infective agent without harming the host's cells

Antibiotics are metabolic products of

products of bacteria & fungi

1. streptomycin

2. bacillus

3. penicillin

4.Cephalosporins

What factors must be considered before beginning antimicrobial therapy

- identity of the microorganism causing the infection

- degree of microorganisms susceptibility to various drugs

- the overall medical condition of the patient

Kirby-Bauer Technique

determine how sensitive bacteria are to specific antibiotic

place antibiotic-soaked disk...incubate...see zone of inhibition

(chart, slide 8)

zone of inhibition

The zone where bacteria can't grow around a given antibiotic.

Therapeutic Index

toxicity vs. desired effect

high = safe

low = risky, > SE

Selective Toxicity

EX: excellent selective toxicity = block synthesis of peptidoglycan cell wall

decreases when infectious agent is closer in structure to host cell

5 categories of antimicrobial drugs

- inhibition of cell wall synthesis

- inhibition of nucleic acid structure and function

- inhibition of the ribosome in protein synthesis

- interference with cytoplasmic membrane structure or function
- inhibition of folic acid synthesis

Broad-spectrum

effective against more than one group of bacteria

EX: tetracycline

Narrow-spectrum

target specific group

Penicillin spectrum

OG penicillin was narrow & now, made into broad

Penicillin targets what?

Group of antibiotics that are often used to treat infections by gram-positive bacteria
- block the production of peptidoglycan cell wall

bacterial cell wall (peptidoglycan) -> high selective toxicity level

Why are fungal cells difficult to treat

euk cells = target own cells as well = low Ther. Index/ inc SE

only a few developled to tx

Anti-Helminthic drug therapy

euk in nature, organ system like ours = lower Ther. Index

targets "suckers" on worms, cannot latch onto body, get excreted

paralyze, break down, or stop worms from growing

Agents to treat viral infections

hard to kill...obligate parasitic organisms (use our cells for metabolism so disrupts ours)

have to target something in replication process that won't completely throw us out of homeostasis

-measles, mumps and hepatitis are prevented through the use of vaccines

-AIDS, influenza and the common cold attest to the need for more effective medications for the treatment of viral pathogens

Actions of antiviral drugs

1. inhibit entry

2. inhibit NA synthesis (repoducing)

3. inhibit assembly/release

What is drug resistance

begin to tolerate amount of drug thats usually inhibitory

can be both intrinsic & acquired

How does drug resistance develop

1. spontaneous mutations in critical chromosomal genes

2. acquisition of new genes or sets of genes via horizontal transfer another

3. slowing or stopping metabolism so that microbe cannot be targeted

2 ways of: acquisition of new genes or sets of genes via horizontal transfer another

Resistance factors: plasmids containing antibiotic resistance genes

OR

conjugation, transformation, transduction

Probiotics Vs. Prebiotics

pro: consume live microorganisms to boost what we have or replace

pre: consume foods that feed good bacteria in gut

Drug Toxicity (SE)

too much of the drug

EX: chemo contact w/foreign chem and can harm host

Allergy

An allergy is an immune system reaction to a substance, typically a drug, that is perceived as an antigen

This reaction can be triggered by either the intact molecule of the drug or by its metabolites, which are formed during the body’s metabolic processing of the drug.

• (e.g., penicillin can be converted into benzylpenicilloyl, which subsequently initiates the allergic response)

second time exposed = s/s

closer to our (euk) cells =

lower therapeutic range & lower selective toxicity (vise-versa for opposite)

Microbiome

sum of all microbes (bacteria) found on and in a human

*new breast/breast milk, amniotic fluid & fetus

Pathogen/ Pathogenicity

pathogen: microbe that causes infection and disease in its host

pathogenicity: potential to cause disease.

-True pathogens can cause disease in healthy individuals with normal immune defenses

-Opportunistic pathogens cause disease when the host’s defenses are compromised or when the pathogen is established in an unusual body location.

Virulence

microbes ability to establish itself in the host and cause damage

Microbiome inoculation

occurs during birth and external consumption

ex: lactobacillus gives digestive enzymes to digest milk

Five steps of bacterial entry and pathogenicity

1. finding a portal of entry

2. attaching firmly & negotiating the microbiome

3. surviving host defenses

4. causing damage (disease)

5. exiting host

Steps 1: Find portal of entry (Infectious dose (ID))

exogenous (outside body) OR endogenous (inside body)

Infectious dose: min # microbes needed to cause infection to proceed

Step 2- Becoming established

fimbria/pilus to attach to walls

- host molecule or receptor specific

- pathogen is limited to only cells to which it can firmly bind and not be removed by bodily defenses

Step three -Surviving host defenses

- pathogen needs to survive against phagocytes

-leukocidins: kill pathogens

-extracellular slime makes it difficult for the phagocyte to engulf the pathogen

Step 4: Microbes doing damage and causing damage (3 ways)

1. directly: bacterial toxins (endo & exo)

2. indirectly: induce host defense to response excessively

3. Epigenetic changes: made to host cells by microbes

Steps 5: Portals of Exit

-how pathogens exit

-shed through secretion, excretion, discharge, sloughed tissue

Bacterial Toxins - Endotoxin/Exotoxin

intracellular toxin produced and retained by bacterial cells and released only by destruction or death to the cells

- produced by lipopolysaccharide layer

- blood infections are dangerous and can lead to fatal shock

Exo: toxic substances that bacteria secrete into their environment

(hemolysins)

Hemolysis (type of exotoxin)

bacteria break apart RBCs to use for nutrients to grow

*alpha: not efficient

*beta: very efficient

Signs/Symptoms/Syndromes

Signs: objective (inflammation/infection,edema,vitals)

Symptoms: subjective (fever, pain, soreness)

Syndrome: disease identified by a complex s/s combo

stages in course of infection

1. Incubation period
2. Prodromal stage
3. Acute stage
4. Convalescent period
5. Continuation phase

Incubation

First stage

- time from initial contact with the infectious agent to the appearance of symptoms

- ranges from several hours to years

Prodromal stage

1-2 day period when earliest notable symptoms appear

Acute phase

infectious agent multiplies @ high lvls., and exhibits its greatest virulence

-fever and other prominent syndromic characteristics

- extremely variable in length of this period

Convalescent period

patient symptoms improve. and may want to stop taking abx/meds

Continuation phase

only some infections have this phase

- either the organism lingers for months, years, or indefinitely

Living Reservoirs

human -> human

-asymptomatic

-incubating (harbor)

-convalescent (no s/s)

-chronic (recovered, still have)

-passive carriers (nurse gets from one pt and goes to other pt and gives)

Zoonotic Reservoir

infections that are transmitted from

animals → human routinely (female mosquito)

Nonliving Reservoir

anything in biosphere that is NOT colonized by living things

-doorhandles, glasses

-most are not infectious

-opportunistic sometimes

Vertical Transmission

mother -> fetus (IN UTERO)

3 types of Horizontal transmission

Direct/physical: kissing/touching

Indirect: sneeze and touch door knob

Vector: zoonotic/species to move

Healthcare-associate infections

occur during acquired/developed during hospital/health care stay

ex: reusable instruments, indwelling devices, antimicrobial therapy

communicable disease / noncommunicable disease

diseases are transmitted from an infected host to another.

diseases arise from self infection or accidental exposure to microbes

Epidemiology

 Study of frequency and distribution of disease and other health-related factors in defined populations

• Involves many disciplines: microbiology, anatomy, physiology, immunology, medicine, psychology, sociology, ecology, and statistics

• Considers all forms of disease: heart disease, cancer, drug addiction, and mental illness

What is epidemics? Common source epidemics?

A widespread outbreak of an infectious disease.

•Common-source epidemic: overtime infected,Everyone gets sick because they were exposed to the same bad thing over time (school cafeteria serves food that has bacteria in it for a whole week, kids who eat it might keep getting sick)

•Point-source epidemic

same time infected, infectious agent came from a single source, and everyone is infected at once (birthday cake at a party has bacteria in it, everyone who eats it gets sick on the same day)

•Propagated epidemic:

series of peaks as it spreads, results from an infectious agent that is communicable from person to person and is sustained over time in a population

(If one kid has the flu and spreads it to their friends, then those friends spread it to more kids, and it keeps going, like what happened with COVID-19)

herd immunity

a significant portion of a population becomes immune to an infectious disease

index case

case that caught the attention of officials

endemic

disease that is native or confined to a particular region or people

epidemic

# of cases go up for expected population (compromised have more)

pandemics

span epidemic that is geographically widespread
- multiple continents

Immunopathology

study if disease associated w/overactivity/under-activity of immune response (hypersensitivity OR hyposensitivity)

hypersensitivity

allergy and autoimmunity
- tissues are innocent bystanders attacked by immune components that can't distinguish one's own tissue from foreign materials

Hyposensitivity

immunodeficiency
- immune system is incompletely developed, suppressed, or destroyed

4 HS types

1: "common" allergy /anaphylaxis (most fast)

2: IgG- and IgM-mediated (B cell secretes)

3: immune complexes (form soluble immune complex)

4: T-cell response (delayed)

type 1 hypersensitvity

Allergy and anaphylaxis
- IgE mediated; involves mast cells, basophils, and allergic mediators
- majority are relatively mild
- some allergies last a lifetime while others are outgrown

Type 1 hypersensitivity 2 examples

Hay fever: general term for allergic rhinitis. seasonal reaction to inhaled pollen/mold airborne (congestion, sneezing, itch)

Asthma: rapid constriction of airways induced by leukotrienes after allergen/antigen presented

-recruits other immune cells (NK cells) destroy others and lead scarring and damage

Allergy

exaggerated immune response that is manifested by inflammation

Allergen(s)

Anything that foreign in our body

-some can be "outgrown"

-most T1 mild/some death

*proteins most common, carbs, fats, NA also

Atopy

Chronic local allergy (sticks w/you entire life)

Hay fever & asthma

Anaphylaxis

Systemic, fatal reaction bcs over reaction rapid manner that obstructs airways & circulatory

Cytokines

*body releases chemical signals to say we have infection going on

*inc mucous, HR, sweating HA, bronchoconstriction

*happens exponentially

Histamine: stimulates eosinophils, Chemicals that can stimulate mucus and fluid production

Bradykinin: a powerful vasodilator that increases capillary permeability and constricts smooth muscle. pleiotropic effects

Serotonin: similar to histamine and bradykinin

Leukotriene: smooth muscle contraction (airways)

Prostaglandins: smooth muscle contraction

Dx T1 Hypersensitivity

BLOOD

1. RAST (radioallergosorbent): measures levels of IgE to specific antigens

2. Tryptase test: measures enzyme released by mast cells, that increases during an allergic response

3. Leukocyte histamine test: measures amount of histamines

SKIN TEST (patch test)

-in vivo metho to detect atopic or anaphylactic

Tx T1 Hypersensitivity

1. take drugs block action of response cells

2. avoid allergen

3. desensitization (controlled exposure to antigen)

Type 2 - Rh factor (surface)

SURFACE BOUND

lyse foreign cells -> natural barrier process

produce antibody to Rh factor (is foreign to the pt)

+ = dominant

- = recessive

mom (-) & child (+)

+ released into circ. of mom & develops antibodies & affects 2nd child

alloantigen (blood type)

Molecules that differ in the same species that are recognized by the lymphocytes of the recipient

• Not an immune dysfunction; the immune system is functioning normally by reacting to foreign cells in an organ or tissue transplant