MMBIO

500 nm
Ability of a microscope to differentiate two closely spaced objects as being distinct from one another

Resolving power increases as magnification of the objective lens increases

The distance from the end of the objective lens to the top of the slide when the specimen is in focus

shorter working distance

10 x 4 = 40x (Low Power)
10 x 10 = 100x (Low Power)
10 x 40 = 400x (High Power)
10 x 100 = 1000x (**Oil Immersion)

A specimen in focus under the low power objectives (4x or 10x) should be nearly in focus under the oil immersion objective as well

Non-living surfaces (fomites)
- Ex. drinking glasses, silverware, plates, tissues and towels, combs/brushes, doorknobs/buttons, countertops, clothing

Living Surfaces

Dust particles in the air

Transmitted by food handlers, contaminated utensils, improperly cooked foods, inadequate filtration or waste treatment, contamination of drinking water
Ex. Hepatitis A, Salmonella

NON-PATHOGENIC, AND DO NOT CAUSE DISEASE

OF LACK OF NUTRIENTS

Autoclave or steam sterilization (Sterilization of culture media, reagents, and laboratory tools)

Dry Heat (Sterilization of glassware and moisture sensitive preparations)

Filter sterilization (Sterilization of heat sensitive liquids)

Flame sterilization (Sterilization of tools like inoculating loops/needles)

Bacteria in the air
Contaminated lab equipment

Peptone
Beef extract
Distilled water
Agar

- Growth in broth is detected by cloudiness in the medium
- Growth on a slant is seen as a film of material on the agar surface (for S. aureus, it will be yellow)
- Growth in an agar deep is detected by some cloudiness in the agar at the stab line

A pure culture contains only a single type of organism
A pure colony arises from a single bacterium thru cell division
A pure culture can also exist in broth culture

Bile salts inhibit G+ bacteria and allow G- bacteria to grow
G- bacteria that ferment lactose to acids cause the indicator to change color to red, so that red or pink colonies appear.

B. megaterium has the ability to hydrolyze esculin, forming a black precipitate

Requires only a single stain to be applied
Shows cell morphology (shape) and arrangement
Does not distinguish between different types of bacteria (like G+ and G-)

Bacteria have an overall negative charge on the outside of the cell and an electrostatic attraction to basic dyes
A basic dye consists of a positive colored group and a negative ion (Dye+Cl-)
**Ex. Crystal violet (purple), safranin (pink or red), methylene blue (blue), and carbolfuchsin (pink)

An additional covering around the outside of the cell, usually composed of polysaccharide

Capsules enhance virulence (the ability to cause disease) in a variety of ways: Interfere with phagocytosis by macrophages Promote infection by adhering to host cells Resistant to the lethal action of complement (causes lysis of cells) and heavy metals Enhance resistance to dehydrating and attack of bacterial viruses

Laboratory test for the sero-identification of specific encapsulated bacteria
Capsular swelling in the presence of specific antibody

A small sample of a Klebsiella Pneumoniae (has capsules) is mixed with India ink and spread over the surface of a slide, then heat fixed
The bacterial film is stained with crystal violet for 1 minute, rinsed, and blotted dry
Cells stain violet and capsules appear as clear bright halos around the stained cells
The background is stained dark gray or black by the ink

Clinical identification of pathogens in spinal fluid, urethral exudate, urine, blood

Two membranes (outer of LPS)
Peptidoglycan layer is thinner

Cell membrane (contain teichoic and lipoteichoic acids)
Thick layer of peptidoglycan

An endospore is an oval, metabolically inactive structure that is formed within the bacterial vegetative cell
Spores are highly resistant to drying, freezing, UV light, high heat and many chemicals and disinfectants because of the dehydrating complex of calcium and dipicolinic acid

Endospores are not stained in the Gram stain procedure, but require steam to force the dye into the cell wall

Bacillus
Clostridium

*Mycobacterium frequently do not stain uniformly with the Gram-stain because they have a waxy lipid covering called mycolic acid
Mycolic acid resists the entry of crystal violet into the cell and produces a gram-variable result

(they are pink!)

- The primary dye Carbolfuchsin is forced into the cell with steam and turns the bacteria pink
- Waxy lipids (mycolic acid) in the bacterial cell wall hold the stain tightly and prevent the entry of the acid-alcohol decolorizer into the cell
- Bacteria that retain the primary dye after decolorization are referred to as acid-fast
- Non-acid-fast cells (like Staphylococcus) are decolorized when the acid alcohol is applied
- The counterstain Methylene blue stains non-acid fast cells blue

Directed motion of bacteria (energy is expended by the cell)

Back-and-forth jiggling motion due to collisions of water molecules with the cells (cells don't go anywhere)

Long, whip-like structures that extend beyond the surface of the cell and glycocalyx and propel the cell through its environment
*Composed of a protein called flagellin

Flagella stain
Hanging drop preparation
Stab inoculation

shows bacterial morphology and cell arrangement

divides bacterial genera into two groups (G+ and G-)
*First step in the ID of an unknown microorganism
Identifies bacteria as Gram-positive or Gram-negative
Shows shapes and arrangements of cells

some genera of bacteria producing capsules are Streptococcus and Klebsiella

bacteria in the genera Mycobacterium and Nocardia are acid-fast

endospores are found in the genera Clostridium and Bacillus

Grow at a range of -5℃ to 20℃
Optimum is 15℃

Grow at a range of 20℃ to 45℃
Optimum is 37℃ (**human body temperature)
Psychrotrophs represent a special category of mesophiles that can also grow at 0℃ (can cause food spoilage at refrigerator temps)

Grow at a range of 45℃ to 60℃
Facultative thermophiles will grow at 37℃, but grow best at higher temperatures
Obligate thermophiles will only grow at elevated temperatures

Lowest temperature at which growth occurs

Enzyme reactions occur efficiently, and reproduction proceeds at a *maximal rate

Upper limit at which reproduction is possible
Above this temperature protein denaturation, loss of enzyme activity and cell death occur

AN INCREASE IN TURBIDITY IN TUBES OF NUTRIENT BROTH
*Cloudy broth

An environment external to the cell with lower solute concentration and higher water concentration

An environment external to the cell with higher solute concentration and lower water concentration
*Plasmolysis results when the cell membrane shrinks from the cell wall and the cell protoplast becomes dehydrated

Survive NaCl conc. of 7.5% - 10%
Ex. **Staphylococcus aureus: synthesize proline when grown in a high salt concentration. Proline, a solute, makes the internal cytoplasm hypertonic to the outer environment, and water flows into the cell

Require high salt concentrations for survival

NEUTROPHILES
Grow well in a pH range of 6 to 9
OBLIGATE ACIDOPHILES
Only grow at the low pH of 2 to 3
ALKALOPHILES
Grow at a pH range of 10 to 12

Very low and high pH interfere with enzyme activity, denature proteins and can block transport of substances into cells

Depends on the production of acid by streptococci and lactobacilli which demineralizes tooth enamel and promotes caries formation

Protected by food particles as they pass thru the stomach and aren't destroyed by stomach acid
Can produce intestinal infections in the small and large intestine

REDUCES THE TRANSMISSION OF DISEASE-CAUSING ORGANISMS (NOSOCOMIAL INFECTIONS)

Bacteria (and other microbes) that are commonly found on the skin and readily eliminated by handwashing or killed by bodily secretions such as lysozyme from sweat glands, fatty acids from sebaceous glands and the low pH of the skin

**Ex: S. aureus, gram-negative coliforms, clostridia and aerobic spore-forming bacilli that are commonly found in air, water and soil

Bacteria (and other microbes) that are more permanent and *not easily removed by washing
**Ex: Corynebacterium, Propionibacterium, S. epidermidis

In the mid-1800s he established the importance of handwashing by medical staff in reducing the incidence of puerperal sepsis, or "childbed fever," in patients after birth

The breakdown (oxidation) of sugar that produces ATP, NADH, and pyruvic acid

Lactose is broken down by lactase to galactose and glucose

Produce primarily lactic acid from pyruvic acid

Produce lactic acid, ethanol, and carbon dioxide

Include aerobic, non-spore-forming bacilli that are non-saccharolytic and do not use or metabolize carbohydrates (sugars)

Common genera: Bacillus, Streptococcus, Lactobacillus
Pathogens: Mycobacterium tuberculosis (TB), Brucella (brucellosis), Salmonella typhi (typhoid fever), Coliforms (E. coli), Coxiella burnetii (Q fever), Listeria monocytogenes (Listeriosis)

*Anything other then a B, S, L is a no

Thermoduric organisms survive pasteurization
*Ex. Streptococcus (S. lactis) and Lactobacillus, some Bacillus

should not exceed a count of 20,000 bacteria/mL and should not have more than 10 coliforms/mL

Ex. Contact with udder, incorrect handling, utensils, settling of dust particles, etc.

Stop the multiplication of bacteria, but do not necessarily kill them

Kill bacteria

Phenols: denature proteins, break down the cell membrane
Halogens: potent oxidizing agents
Alcohols: dissolve lipids in cell membranes, denature proteins
QUATS: break down the the cell membrane and denature the proteins

*Halogens are the odd men out

The area of no bacterial growth around the chemical disk.

Antimicrobial agent produced by living organisms

Effective against Gram + and Gram - bacteria
Kills wide range of disease-causing bacteria

Penicillins
Cephalosporins

Tetracyclines
Macrolides
Aminoglycosides

Quinolones - interfere with DNA replication
Polymyxins - damage cell membrane

UV radiation in the range of *260 nm is strongly absorbed by purine and pyrimidine bases in DNA

When two pyrimidine bases are next to each other on the same DNA strand, and absorb UV radiation, they can form pyrimidine dimers (most commonly *thymine dimers)

In the presence of longer wavelength light (e.g., 500 nm), the photolyase enzyme breaks cyclobutane bonds in the dimer and restores adjacent pyrimidines to their original shape

Formation of pyrimidine dimers and photoreactivation is prevented by placing a barrier like a piece of paper or aluminum foil between the UV light source and the culture

Boils, carbuncles, impetigo, toxic shock syndrome and staphylococcal scalded skin syndrome
Staphylococci carried by asymptomatic carriers or infected persons can be readily spread to others through any organ or tissue in the body or contaminated food

Trypticase Soy agar (TSA) Non-selective medium (will grow a wide variety of bacteria, yeasts and molds)

Mannitol Salt agar (MSA), Selective medium (7.5% NaCl) for halotolerant organisms like the staphylococci

Catalase pos.
Coagulase pos.
Mannitol pos. (fermentation)
Produces colonies with a yellow halo on MSA

*Staphylococcus aureus always positive

Moisten a sterile swab in PSS and swab the back of the throat - don't touch the teeth, tongue, or uvula (use a tongue depressor)

Streptococcus mitis/salivarius/pneumoniae
Staphylococcus aureus
Candida albicans
Haemophilus influenzae
Moraxella catarrhalis

Observed on blood agar

Alpha hemolysis (partial) Ex. Strep pneumoniae
- green ish

Beta hemolysis (complete) Ex. **Strep pyogenes
- yellow

Gamma hemolysis (none) Ex. Haemophilus influenzae

Used to estimate the relative number of *lactobacilli in saliva based on acid production

Streptococcus

- Glucose can be polymerized into the polysaccharide dextran
- Dextran surrounds the cells and forms a covering called a *glycocalyx that can become attached to teeth; Streptococci and lactobacilli become trapped in the dextran coating
- The collection of polysaccharide dextran and bacteria is called plaque

*glycocalyx = dextran

DENTAL EXTRACTIONS OR ORAL SURGERY

unicellular eukaryotes

multicellular eukaryotes

cross walls

no cross walls

Arthroconidia - rectangular, larger in size

Chlamydoconidia - round, thick-walled

Sporangiospores - formed within a sac-like structure (sporangium)

*groups mold together

diploid

Zygomycetes: aseptate hyphae, sporangiospores, and produce zygospores

Ascomycetes: septate hyphae, pulmonary infections

Basidiomycetes: presence of dikaryon

Deuteromycetes: do not undergo sexual reproduction, majority of human pathogens

*groups fungi together

Two different forms of growth depending on the conditions of growth (eg - temp): mold form at 25°C and yeast form at 37°C

undefined