Microbiology Exam Ch 1-5

Microbiome

Home of microorganisms

• Human microbiomes are good! They are beneficial to us and our environment.

• Prevent diseases

• Aid digestion

• Promote immune system function

• Affect brain chemistry

Microorganisms

Organisms that can only be seen with a microscope

• virus, bacteria, fungus, amoeba, Protozoa, prion (misfolded protein)

• referred to as “microbe”

Pathogens

a bacterium, virus, or other microorganism that can cause disease. Disease-causing microorganism

• RESPECT THE PATHOGEN

Morbidity

Disease

Mortality

Death

HAIs

Hospital Acquired Infection

Chronic

Able to treat and not cure

• some microorganisms cause autoimmune diseases, diabetes, and some cause cancer (HPV)

• oral bacteria cause cardiovascular disease

Prokaryotic cell microbes

Single-cell, no membrane-bound nucleus

• some do not have cell walls, in this case, they would then also have a capsule

• divide by binary fission

Eukaryotic cell microbes

Membrane bound nucleus, organelles

• divide using mitosis and meiosis

Three domains of Microbes

• Bacteria (Prokaryotic)

• Archaea (Prokaryotic)

• Eukarya (Eukaryotic)

Coccus (cocci) shaped bacteria

spherical

Bacillus (baccili) shaped bacteria

rod shaped

Vibrio (vibrios) shaped bacteria

short, curved rod

spirillum (spirillia) shaped bacteria

long curved rod forms spirals

spirochete (spirochete) shaped bacteria

long, spiral shaped

pleomorphic shaped bacteria

vary in shape

diplococci

pairs of cocci

Streptococcus

Long chains

• “strepto” =twisted chain

Staphylococcus

Clusters of cocci

• “staphylo” = bunch of grapes

Archaea

singled cell prokaryotes similar in size, shape, and properties to bacteria

• extremophile

• found in digestive systems and on skin

Eukarya

Singled cell or multicellular eukaryotes

• fungi

• algae

• protozoa

• helminths (worms)

virus

An acellular infectious agent consisting of nucleic acid surrounded by a protein coat

• can only be seen with an electron microscope

prions

An acellular infectious agent consisting only of protein

• misfolded protein

• CAN NOT be killed (resistant to sterilization)

Six primary elements of living organisms

“CHNOPS”

C - carbon

H- hydrogen

N- nitrogen

O- oxygen

P- phosphorus

S- sulfur

gram-positive bacteria (+)

• (+) Has a thick peptidoglycan layer

• stains purple

• bacillus, streptococcus, staphylococcus

• more susceptible to penicillin

• sensitive to lysozymes

gram- negative bacteria (-)

• (-) Has a thin peptidoglycan layer that often has a different placement

• stains pink

• escherichia, nessiria, psuedomonas

• less susceptible to penicillin

• not sensitive to lysozymes

lysozyme

breaks bonds linking glycan chains

• enzymes found in tears, sweat, saliva, and other bodily fluids

nucleoid

single circular double-stranded DNA molecule

plasmids

• similar to chromosomes but much smaller

• may be shared with other bacteria; antibiotic resistance can spread as a result of plasmids

endospore

type of dormant cell

• extremely resistant to destruction

• can live for 100s of years

• can only be killed through sterilization

• NOT in vegetative state

vegetative cells

cells are active endospores- able to infect

Light microscope

magnify 1000 x

electron microscope

magnify more than 100,000 x

scanning probe microscope

can produce images of individual atoms on a surface

bight-field microscope

evenly illuminates the field of view and generates a bright background

magnification

increases in size

objective

a lens type of a modern microscope

• relays the real image of the object to the eyepiece

• (4x, 10x, 40x, 100x)

ocular

used to further magnify the image alongside the objective lens

• 10x

resolution

ability to distinguish two objects that are very close together

contrast

determines how easily cells can be seen

• stains increase contrast but kill microbes

dark-field microscope

cells appear as bright objects against a dark background

phase contrast

makes cells and other dense materials appear darker

Differential Interference contrast (DIC) Microscope

three dimensional appearance of image

Fluorescent microscope

used to observe cells tagged with fluorescent dyes

scanning laser microscopes (SLM)

species stained with fluorescent dye and 3D images of thick structures form

wet mount

• drop of liquid specimen overlaid with coverslip

• allows observation of living organisms

smear

drying and fixing specimen before staining to visualize

correct order of steps in a basic stain

smear, fix, stain

• smear a thin film of the specimen over the slide, let air dry, heat with Bunsen burner, flood the smear with stain, rinse, dry

correct order of reagents used in gram stain

1. crystal violet (primary stain)

2. iodine (mordant)

3. alcohol (decolorizer)

4. safranin (counterstain)

simple staining

single dye used to stain specimen

• crystal violet

• methylene blue

cell wall

• rigid structure

• peptidoglycan layer

• distinguishes between different types of bacteria

cell membrane

• phospholipid bilayer embedded with proteins (hydrophobic tails, hydrophilic heads)

• regulates movement of molecules going in and out of cells

exponential growth

population doubles in size each division

generation time

time it takes for population to double

pure culture

population of cells derived from a single cell

culture medium

• liquid broth or solid gel

• contains nutrients dissolved in water

• ex: agar plates

Agar

used to solidify medium

• few microbes can degrade

• not destroyed by high temperatures and can be sterilized

• solid over-temperature range for most microbial growth

Petri dish

• two-part covered container of glass or plastic

• allows air to enter but stops contaminants

lag phase

no increase in number of living bacterial cells

log phase

exponential increase in number of living bacterial cells

stationary phase

plateau in number of living bacterial cells; rate of cell division and death are roughly equal

death or decline phase

exponential decrease in the number of living bacterial cells

aerobic respiration

uses oxygen

anaerobic

do not use oxygen

obligate aerobe

grows ONLY when O2 is available

facultative anaerobe

grows BEST when O2 is available, but can grow without it

obligate anaerobe

CAN NOT grow when O2 is available

microareophile

grows only if SMALL amounts of O2 are available

areotolerant anaerobe

grows EQUALLY with or without O2

acidophiles

grow optimally at a pH below 5.5

akaliphiles

grow optimally at a pH above 8.5

turbidity

cloudiness of microbial suspension is proportional to concentration of cells

• measured with spectrophotometer

Most to Least resistant microbes

Prions

mycobacteria

cysts of protozoa

vegetative protozoa

gram-negative bacteria

fungi, including spores

viruses without envelopes

gram-positive bacteria

viruses with lipid envelopes

sterilization

removal or destruction of all microorganisms and viruses

• free of microbes including endospores, but not prions

disinfection

elimination of most if not all pathogens

• some viable microbes may remain

disinfectants

chemicals used on objects

• often called germicides

antiseptics

chemicals used on living tissue

• ex: alcohol

decontamination

reduces number of pathogens to a safe level

• washing, heating, or chemicals

sanitization

reduces microbial population to meet accepted health standards that minimize the spread of disease

preservation

the process of delaying spoilage of perishable products

pasteurization

brief heating to reduce and destroy pathogens in food

standard precautions

used in patient care to prevent infection in both patient and personnel

• gloves

• masks and gowns

• handwashing

transmission-based precautions

used when a patient is infected with a highly transmissible disease

aseptic technique

procedures to prevent the spread of organisms

• handwashing

• gloves

• cleaning skin with alcohol

• sterile technique

• not contaminating equipment

BSL-1

microbes not known to cause disease in healthy people

• gloves

• lab coat

• glasses

BSL-2

moderate-risk microbes that cause disease but have limited potential for transmission

• gloves

• face-shield

• gown

BSL-3

pathogens that cause serious or potentially fatal disease through inhalation

• gloves

• gown

• respirator

BSL-4

easily transmitted deadly pathogens

• full body suit

Autoclave

increased pressure raises steam temperature; kills endospores

Moist heat

denatures proteins, boiling kills most microbes and viruses

• does not sterilize

dry heat

requires higher temperatures and longer time than moist heat to kill endospores

filtration of air

HEPA filters remove nearly all microbes over 0.3 micro meters including endospores

Ionizing radiation

(gamma rays, x-rays), directly destroys DNA and damages cytoplasmic membranes, destroys endospores

UV radiation

destroys microbes directly but does not destroy endospores, damages DNA

microwave irradiation

do not effect microorganisms but the heat they generate can be lethal

alcohol

destroys vegetative bacteria and fungi

• not endospores, non-enveloped fungi

• commonly used as antiseptic

• evaporates quickly

chlorhexidine

most effective germicidal chemical

• antiseptic

• low toxicity

• destroys vegetative bacteria, fungi, non-enveloped viruses, (not endospores)

• prescription mouthwashes

Ethylene oxide

gas used for heat - or moisture sensitive- items

• destroys bacteria, endospores, and viruses

• penetrates fabrics, equipment, and implantable devices

Chlorine

a halogen that destroys all microorganisms, endospores, and viruses.

• organic material decreases effectiveness

• disinfects surfaces, objects, and water

iodine

kills vegetative cells, unreliable on endospores

• used as tincture (in alcohol)