Exam 2 Flashcards
Factors to consider
Location, type & number of microbe, risk of infection
Why control microbial growth?
To prevent diseases,
protect the food supply,
create clean areas for research & development
Remember that not all microbes are pathogens and most are beneficial
By killing microbes
Cidal agents think “sui-“
By inhibiting microbial growth
Static agent
“inhibit” meaning that the bacteria stops growing BUT does not kill them. Static=electricity=shocks (things don’t move when they’re shocked)
Bactercidal
To kill bacteria
Sterilization
Removing all microbial life
Does not consider prions
Disinfection
Destroying harmful microbes on a surface or object
Some microbes will remain
Disinfectant
Chemicals used for disinfecting inanimate objects
Antiseptics
Destroy harmful microbes on living tissues/people
used on patients before invasive procedure
Asepsis
Free of microbial contamination
Aseptic techniques
Prevention of contamination through procedures
Decontamination
Reduces the number of pathogens to a safer level
Sanitation
Substantially reducing the microbial population to meet health standards
Pasteurization
Brief heating to reduce the number of spoilage microbes and destroy pathogens without changing the characteristics of the product
Preservation is a form of [?] method
bacteriostatic method inhibits the growth of bacteria but does not kill the bacteria
Preservation
A process of delaying spoilage
example would be refrigeration, which uses temperature to slow the growth of bacteria.
Chemical preservatives can be added to slow growth even further
Approaches to microbial growth
Depends on the situation: daily life, setting, laboratories, food production facilities, water treatment plants, and any other industries.
Daily life requirements for microbial control
Washing and soaping and scrubbing and detergent
most frequently misses spots when handwashing
under the nails, wrists, around, jewelry,
how does soap work to remove microbes during handwashing
nonpolar tails of micelle soap adhere to the dirt on the skin. Polar groups are soluble in water and help lift the dirt away from the skin
Soap is beneficial to skin microbiota because
the skin is not affected by regular use given that they reside deeper in underlying layers of skin
BSL4
lethal pathogen for which no vaccine or treatment is available
BSL-1
Microbes is not know to cause disease
Washing your hands
Soap aids in the mechanical removal of microbes
The most important step in stopping the spread of many infectious diseases
Health care associated infection HAIS
Patients are often more susceptible to infection due to their weakened condition
Patients may undergo invasive procedures cutting intact skin which exposes it to pathogens
Pathogens are more likely to be found in hospitals (feces, ventilation)
Operating rooms must be monitored
Surgical instruments must be sterilized
Prions are a relatively new concern and are very difficult to destroy
Microbial laboratory
Aseptic technique
Sterilization if materials cdc guideline
Bio safety levels range from BSL1-4 (1 microbes not know to cause disease)
(4 being lethal pathogens with no vaccine or treatment existing)
Food preparation
Perishables retain quality longer when contaminating microbes are destroyed removed or inhibited
Heat treatment (most common), irradiation (kill microbes) chemical additives (prevent growth)
Water filtration
Ensure that drinking water is free of pathogens
Uses filtration and chemical methods
Chlorine is traditionally used to disinfect water
Selection of an effective antimicrobial procedure depends on
The type and number of microbes
Environmental condition
Risk of infection
Composition of the item being treated
Length of exposure needed
Cost and availability
Toxicity
Microbes resistant to treatment
Bacterial endospore
Only extreme heat and chemical treatment destroy them
Protozoa cyst and oocytes
Resistant to disinfection but susceptible to boiling
Mycobacterium species
Pseudomonas species
Resistant to disinfectants and can even grow in some of them
Enveloped and non enveloped
Decimal reduction time
time required to kill 90% of populations under specific conditions
temperature and Ph can
influence effectiveness of disinfectants
microorganisms in [?} are more resistant to any anti-microbial treatment
biofilm
Bleach is more effective at [?] ph
low
Dirt grease and body fluids
Can interfere with heat penetration action of chemicals
Risk for infection categories for medical instruments
Critical= must be sterile (direct body tissues)
Semi critical= must be free of viruses and vegetative bacteria (contact mucous membrane but not body tissues)
Non critical= pose a low risk of transmission (contact unbroken skin only)
Actions of antimicrobial agents
alteration of membrane permeability
damage proteins
damage nucleic acids
how does heat kill microbes
the cytoplasmic membrane is disrupted/ damaged
proteins and enzymes are denatured
Heat treatment is the best
and most useful methods for microbial control
can only be used to disinfect or sterilize
Types of heat
Moist heat=destroys microbes by irreversibly denaturing their proteins
Dry heat= less efficient than moist heat at killing microbes; requires longer times and higher temperatures
Moist heat
Boiling (100C) after 5 minutes bacteria is killed
Pasteurization; heating to a high temperature for a short time// does not sterilize
Dry heat
less effective because it takes longer times and higher temperatures
Incineration= components to ashes
Hot air oven= destroy cell components and irreversibly denature proteins
Autoclave
used to sterilize surgical instruments- increase pressure raises the stream temperature
kills endospores
can destroy prions
Commercial canning
uses an industrial size autoclave called retort//designed to destroy clostridium botulinum endospores
Low temperature
inhibits growth-bacteriostatic
Desiccation
removes water, prevent metabolism,
microbes may remain visible but are dormant for years
Osmotic pressure
high sugar/salt causes plasmolysis and inhibits metabolism
Surface tension depressants
soaps, detergents (loosens contamination from surfaces
Filtration
uses a membrane filter to remove microbes
membrane filters have microscopic pores that allow liquid to pass through
in air, High-efficiency particle air (HEPA) is used to remove airborne particeles
Radiation
can be used to destroy microbes
ultraviolet, ionizing, and microwaves are types of radiation
limitations to ultraviolet radiation
bacterial endospores are resistant to UV lights
poor penetrating power- only kills microbes on the surface
must be used carefully since it can cause skin cancer and damage retina
ultraviolet radiation
destroy microbes by damaging their DNA
UV light is absorbed by microbial DNA causing thymine dimers to form in DNA
used to destroy microbes in air, water and hard surfaces
UV light is most effective in close range against exposed microorganisms
Ionizing radiation
x rays, gamma rays
damage skin cells
used to sterilize heat-sensitive materials such as foods
Microwave
low energy wave that does not have a direct effect on microbes
microwaves kill by generating heat via water molecules
cook food unevenly
High pressure processing
Types of physical antimicrobial methods
Heat treatments
Moist heat, dry heat
Filtrations
Radiation
Soap aids in
Mechanical removal of microbes thorough handwashing
Transient
Pathogens not related to our microbe
Temperatures to kill microbe
Cytoplasmic
Denatured
Autoclave
121°C at, 15 min
131°C for 1 hr for endospores
Ultra violet radiation
Alters DNA
Germicide
Chemicals used to disinfect & in some cases sterilize (kills microorganisms & inactivates viruses
Sterilants
destroy all microbes including endospores and viruses; used to treat heat-sensitive critical instruments
Disinfection
elimination of microbes from inanimate objects
Disinfectants
agent used to eliminate microbes from inanimate objects
Antiseptic
an agent that kills or inhibits growth of microbes and is non-toxic enough to use be used on human tissue
Sanitation
an agent that reduces microbial numbers to safer levels
Considerations when selecting the appropriate germicide
Toxicity )
Length of contact required (contact time)
Concentration
Types & number of microbes present
Activity in presence of organic material
Comparability with materials being treated
Residues
Cost & availability
=~
Actions of antimicrobial agents can be achieved
through physical control methods and chemical
why 100% alcohol does not work
proteins are more soluble and denature easily in alcohol mixed with water
limitations to alcohols
does not reliably destroy endospores and some non-eveloped virus
evaporates quickly, limiting contact time
can damage rubber, some plastics
Alcohol
Quickly kills vegetative bacteria & fungi
70% is used in hospitals & laboratories
Proteins are more soluable & denature more easily
Soap & water vs hand sanitizer
water reduces the amounts of all types of germs
60% hand sanitizer is recommended
Halogens
Chlorine & iodine
Common disinfectants that damage proteins & cellular components
limitations include being too irritating to the skin and mucous membrane to be used as an antiseptic
Chlorine
disinfectant
very low levels are used to disinfect drinking water
Iodine
antiseptic; kills vegetative cells, unreliable or endospores
What is added to water to disinfect
chlorine
Peroxygens
Hydrogen peroxide
Powerful oxidizer used as sterilants
Germicide on living tissue
Leaves no residue
limitations; less effective/potentially irritating gon living tissues due to catalase activity
Phonolics
Phenol one of the earliest disinfectants. kills most vegetative bacteria by destroying cytoplasmic membranes and denaturing proteins; not reliable on all viruses and endospores
positive charge of quat attracts
negative charges on cell surface of microbes
limitations to quats
can grow within the solutions
Quats
Quaternary Ammonium Compounds// destroys vegetative bacteria and enveloped viruses but is not effective on endospores
disrupts the cells membrane and negatively charged proteins
Ethylene oxide
destroys all microbes including endospores and viruses by chemically modifying proteins and nucleic acids
used to sterilize sensitive items (pacemakers, artificial hips. fabrics)
IS TOXIC
Aldehydes
capable of destroying all microbes; inactivates proteins and nucleic acids
toxicity;carcinogens
perishable products can be preserved by
chemical preservatives
low temperature storage
reducing the available water
chemicals preservatives
weak organic acids (alter membrane function lower Ph) and nitrate and nitrite (inhibit endospore germination)
Blacklights
Thawing food
some microbial cells are killed by ice crystal formation but many survive and can grow once thawed
reducing available water
adding sugar or salt which creates a hypertonic solution drawing water out of cell (plasmolysis)
drying food
stops microbial growth, but does not kill it
Discovery of antibodies
Alexander flaming identified mold
Antimicrobial medication
Drug that inhibits the growth of or kills infectious microorganisms
Antibiotics
Antiviral
Drug that
Characteristics to antimicrobial drugs
Selective toxicity to microbes
Antimicrobial action
Spectrum of antimicrobial activity
Tissue distribution, metabolism and excretion of
therapeutic index
lowest dose that is toxic divided by the therapeutic dose (high TI is less toxic)
Antimicrobial action
bactericidal: drug kills bacteria directly
bacteriostatic : inhibits bacterial growth
Selective toxicity
drugs cause greater harm to microbes than to human hosts
the spectrum of antimicrobial medication
broad-spectrum: gram-positive and gram-negative bacteria (disrupt normal microbiota. important for acute diseases
narrow spectrum: requires identification of pathogen and testing it for sensitivity
Tissue distribution, metabolism, & excretion of drugs
antimicrobial behaviors differ in the body
Route of administration
IV, IM, oral, tropical ect
Drug combinations
Antagostnic: medications interfere with each other
Synergistic: one medication enhances another
Additive: combinations that are neither are additive
Adverse effects
Allergies
Toxic side effect
Suppression of normal microbiote may lead to dysbiosis
Target of antimicrobial drugs
cell wall synthesis
cell membrane
protein synthesis
nucleic acid synthesis
metabolic pathways
Glycopeptide
vancomycin (last resort against MRSA)
bacitracin
topical, triple antibiotic ointment
Amoxicillin
Inhibits cell growth
Beta lactam antibiotics
all have a Beta lactam ring
medications that inhibit beta lactam
penicillin, cephalosporins, carbapenems, monobactam
resistance methods used by bacteria against Beta lactams
beta-lactamases: some bacteria synthesize Beta-lactamase, which break down the beta-lactam ring
types of beta lactamase
penicillinase (inactivates members of the penicillin family)
extended spectrum Beta-lactamases (inactivates a wide variety of beta lactam)
carbapenemases- inactivate the greatest number of beta lactams lead to carbapenem drug resistance
How antibiotic resistance happens
Lots of germs
Little resistance
Antibiotics kills bacteria causing the illness as well as good bacteria protecting the body of the infection
The drug resistance bacteria are allowed to grow and take over
Some bacteria give their drug resistance to other bacteria causing bacteria
Five general groups of penicillins
natural
penicillin resistant (methicillin)
broad spectrum (amoxicillin)
extended spectrum (ticaricillin)
pencillin + beta-lactamase (augmentin- amoxicillin+clavulanic acid)
Mechanism of drug resistance
Blocking entry of drug
Inactivate the drug enzyme and interfere with drug
Alteration or drugs target molecule
Inhibits protein synthesis by attaching to various subunits of the [?] 70s Ribosome
prokaryotic
Pleuromutlins
prevents peptide bonds from being formed
streptogramins
each interferes with a distinct step of protein synthesis
Lincosamides
prevents the continuations of protein synthesis by binding 50s subunit
resists many antibiotics
macrolides
prevent the continuation of protein synthesis by reversibly binding 50s subunit to prevent the translation from continuing
chloramphenicol
prevents peptide bonds from being formed by binding to 50s ribosomal subunit and prevents peptide bonds between amino acids
oxazolidinones
interfere with the initiation of protein synthesis
tetracyclines and glycylines
block the attachment of tRNA to the ribosome
Aminoglycosides
block the initiation of translation and cause the misreading of mRNA
irreversibly bind 30s ribosomal subunit
Fluoroquinolones
inhibits topoisomerase 2 or gyrase
Rifamycins
inhibits RNA synthesis by blocking prokaryotic RNA polymerase
Metronidazole
binds DNA in anaerobic organisms only
anaerobic metabolism required to convert to active form
Interfere with cytoplasmic membrane integrity
interfere with bacterial cytoplasmic membrane permeability or synthesis–> cell leakage and death
Target Metabolic pathways
broad spectrum, bacteriostatic
some antibiotics are folate inhibitors
acts as PABA substrate analogs to inhibit different folate pathways which produce nucleotides
sulfonamides, trimethoprim
inhibit different steps in synthesis of folic acid and coenzyme required for nucleotide synthesis
Sulfonamides and related are called
sulfa drugs
amoxicillin
treats bacterial infection by inhibiting bacterial cell wall growth
amoxicillin binds to the transpeptidase active site
amoxicillin blocks transpeptidase activity
amoxicillin interrupts bacterial cross linking and cell wall synthesis
Kirby baer disc diffusion test is routinely used to
determine susceptibility of a bacterial strain to antibiotics
Blocking entry of drug
Decreased uptake of the meditation
Changes in porin protein of the outer membrane in gram negative bacteria
Inactivation of drug by bacterial enzyme
Bacteria produces
Alteration of drugs target molecules
Minor structural changes that affect binding
Gram positive
Thick peptidoglycan layer absorbs
Surrounding layer absorbs surrounding
Gram negative
Harder to kill
Acquisition to resistance
Occur during DNA replication at a low rate but can have effect
In a population of 109 cells at least one will likely mutate
A single base pair change in a bacterial gene encoding a ribosomal proteins yields resistance to strepto
Horizontal gene transfer
Genes encoding resistance Can spread to different strains
R plasmids Can contain
Genes encoding for resistance to antimicrobial medications
Genes required for pilus synthesis
Mechanism
Conjugation
Transduction
Superbugs
Bacteria that is resistant to large numbers of antibiotics
Multiple and extensive drug resistant mycobacterium tuberculosis
Viruses
Obligate intracellular parasites
Not alive, acellular particles or agents
Not an organism
Not made up of cells
No metabolism, replication or motility
Hijack the host cells replications system to divide
Can viruses divide outside is a living cell
No
Viruses are ((n)) outside cells
Inert
Smallest to largest
10 to 800nm
All viruses have
Nucleic acid (Either DNA or RNA)
Capsid (protein coat)
Some virus have
Spikes
Envelope (more vulnerable)
Capsid
Protein coat that all virus’s have
Determines the shape of the virus
Protects the Nucleic acid
Capsid are protected
Virus shape
Helical Ebola
Polyhedral adenovirus
Complex bacteriophages
Virus envelope
No envelope= naked virus or non enveloped virus
Phospholipid bilayer membrane outside of the virus
Taken from host cell
Provide protection and attachments so it can hide from the immune system
Naked vs enveloped
N
E
Spikes
Glycoproteins
Outer surface protection
Important for attachment to the host cell
Adenovirus
Polyhedral
Double stranded DNA
Non enveloped
SARS CO V 2
Single stranded RNA
Helical
enveloped
Spikes glycoproteins
For a virus to replicate multiply
It must invade the host cell
It must take over that hose metabolism machinery
Host are anything alive
Virion
Modes of transmission
Direct transmission
Direct contact
Direct Spray
Indirect transmission
Airborne
Vehicle borne (fomite)
Vector borne carry the agent
Entry for virus
Epithelial surface
Viral taxonomy
-viridae
-virus
Enteric virus
Oral fecal
Zoonotic
Animals
Arbovirus
Animal virus
DNA or RNA
Animal virus cycle
Attachment
Bacteriophage
Virus that infects bacteria
Most numerous viruses on earth
important for ecology and evolution
Removes bacteria from ocean
Used as models for learning about animal virus
Lytic
Phage causes lysis and death of the host bacteria cell
Attachment
Genome
synthesis phage genome is transcribed
Assembly
Release bacterial cell lyses
Lysogenic
Phage DNA is incorporated into the host DNA
Attachment
Genome entry
Phage DNA is integrated into the hosts cells called prophage
Prophage replication
Temprate phage
Lambda
Can alter
Toxins are encoded by
Phage genes
Exotoxins
Released from bacterial cell
Potent
Clostridium tétani
Tetanus neurotoxin block nerve impulses
Clostridium botulinum
Botulinum toxin causes food poisoning
Botox prevents nerve impulses
Escherichia coli
Staphylococcus
Opportunistic infection
Disease that is caused by microbes that is not known to be harmful
Primary pathogens
Skin and mucus membranes are barriers
Mutualism
Commercialism
Acure
Short lived infection
Chronic
Infection that develops slowly and last long
Latent
Infection that is present but not causing symptoms
Exotoxin
Toxic protein produced by a microorganism
Normal microbiota
Group of microorganism found growing in healthy individuals
Resident microbiota
Inhabit sites for extended periods permanently colonize
Transient microbiota
Inhabit temporary
Human micro biome
Colonization at birth changes when c section and with vaginal delivery
Breastfeeding
Environment
Changes with lifestyle
Normal microbiota benefits
Protects against pathogens cancer
Antibiotic exposure kills normal bacteria leads to dysbiosis
Simulation of adaptive immune system
Promotes immune system tolerance
Aids in Digestion
Produces substances important to human health
Pathogenicity
The ability of an agent to cause disease
Virulence
The degree of pathogenicity of an organism
Virulence factors
Traits of a microbes that allow it cause disease genes can be transferred via horizontal gene transfer
Communicable
Infectious disease that spread from one host to another
Etiology
Cause of disease
Incubation period
Time between introduction of microbes to host and onset of signs
Convalescence
Recuperation
Carriers
Individuals who have recovered from the illness but still are capable of spreading disease
Sign vs symptoms
Sign what you see
Symptom what you’re told
Overview of the immune system
Collection of organs, tissues, and cells
Job is to guard the body against pathogen, abnormal malfunctioning cells,foreign cells or particles
Adaptive immunity
activated by exposure to specific pathogens; continually develops over your lifetime as its exposed to specific pathogens
immunological memory
Innate immunity
routine protection present at birth non specific, quick response
Thymus
T cells mature here
Spleen
Filtering out blood
Appendix
Lymphoid tissues
collectively, the main roles of the innate immune systems
prevent the entry of foreign material using physical and chemical barriers
prevent further spread of infection
adaptive immunity
we are not born with , but is acquired throughout our lifetime T cells and B cells when exposed to specific antigens
acquire immunity
slower but very effective
“creates memory” through memory cells
Immune tolerance
ability for the immune system to ignore normal self cells
what is an antigen
foreign particle that the body recognizes as non self
adaptive is antigen-specific
antigen presentation
requires the recognition of specific non self antigens during this process
antigens react specifically with antibody
B-cell and T cell receptors
antigenic determinants (epitope)
binds to receptors
immunological memory
the ability of the immune system to respond more rapidly to any pathogen or antigens that has been encountered previously
thanks to this, we can vaccinate against infectious disease and avoid through natural infection
neutrophils
common leukocytes found in the blood
when injury and or microbial occurs they are alerted via chemotaxis, they are the first to leave blood stream
phagocytes, they kill via phagocytosis and live hours to a few days then undego apoptosis
natural killer cells
innate immune system
derived from lymphoid stem cells so they are lymphocytes
recognizes the abnormality
monocytes macrophages and dendritic cells function
as phagocytes and form an important first line of defense against harmful
dendritic cells
phagocytes that live in blood or tissue
phagocytic and antigen-presenting cells
only connection between adaptive and innate
lymphocytes
type of white blood cell (leukocyte)
derived from lymphoid stem cells
t cells
cell-mediated immunity
direct the immune response by helping to stimulate b cells
B cells
humoral cells
humoral immunity
b cells mature in bone marrow, make antibodies, memory cells
cell mediated immmunity
t cells mature in the thymus helpert T cells activate B cells
cytoxic t cells are directly involved in killing infected cells
anatomy of the lymphatic system
secondary lymphoid organs contatn dense populations of lymphocytes and other immune cells
secondary lymphoid organs
lymph nodes, spleen, tonsils/adenoids/, apendix
peyers patches
lymphoid tissue in intestinal wall
cytotoxic t cells
directly involved in killing infected cells
helper t cells
stimulate b cells towards antibody production; releases cytokines to stimulate other immune cells
regulatory t cells
regulate and suppress immune cells as needed; peripheral tolerance
memory t cells
can respond quickly upon re-exposure to the same antigen
naive lymphocyte
has never encountered an antigen
activated lymphocyte
received specific signals, proliferates produces proteins
effector lymphocytes
memory lymphocytes
lymphocytes receptors
b cells and t cells have membrane bound receptors
function is to recognize and bind specific antigens
b cell receptor
membrane version of the specific version of the specific antibody; binds free antigens
t cell receptor
antigen presenting cells
have receptors that bind antigens
major histocompatibility complex proteins
what cells are responsible for t cell activation
dendritic cells
Fluoroquinolones
inhibits topoisomerase 2 or gyrase
Rifamycins
inhibits RNA synthesis by blocking prokaryotic RNA polymerase
Humoral activity
antibody response
three antigen presenting cells
dendritic
macrophages
b cells
plasma cells
affector cells
cytochines
chemical signal from helper T-cells to plasma cell
B cell mature in
bone marrow
BCR genes
V ariable, D iverity J oining regions
Diversity is created through
gene diversity of VDJ genes on the light and heavy chains of b cell receptors
Central tolerance
process during development where B cells that bind to self-antigens are destroyed
peripheral tolerance
most mature b cells require signaling and confirmation from Helper t cells to begin making B cells
Naive B cells
mature B cell with functional BC that has not yet encountered an antigen
A naive b cell encounters an antigen
in secondary lymphoid organs
antigen binds to the
variable region of the b cells receptor
B cells internalizes processes and
presents antigen epitope on MHCII
B cells presents antigen on MHCII to
Helper T cells (CD4)
Activated B cells proliferation and differentiate to form
effector B cells or plasma cells and memory B cells
Plasma Cells secrete
large quantities of antibodies that bind to the antigen
memory B cells are long lived descendants of activated B cells
