microbio session 2

Commensalism: 1 benefits and the other is unaffected

Symbiosis: stable relationship

Ammensalism: 1 injured, other one is unaffected (2 types of bugs in mouth: 1 bacteria produce Antibiotic and 1 is harm)

infection that is dormant within the host (TB lives inside macrophage laying dormant, HIV has latent phase) You can still infect others when you are in latent phase.

Parasite: host is damage in symbiosis gone bad.

Opportunistic pathogen: One that will cause disease in the right time and place. Any bacteria can cause disease if its in the right place at the right time.

• Strict pathogen: not flora EVER.
• (ex. M. tuberculosis)

Endogenous disease: disease is produced by organisms in the person's own microbial flora that spread to inappropriate body sites

Exogenous disease: diseases that arise when a person is exposed to organisms from external sources

colonization: long term symbiotic disease

Blood, brain, organs, bladder, urine

Skin: keratin - slightly acidic

Eye: tears that wash and flush with enzymes (lysozymes, staph from skin of eye)

Respiratory tract: mucous prevent adherence, cilia that beats the things up, enzymes, IgA, macrophages that lining the area, the deeper you go the lesser the flora, many health care have drug resistant bacteria in their

GI tract: 1 gram of feces = 10¹¹ bacteria, acids in stomach that protect, secretory IgA, BUGS. GI tract can seriously disrupt by antibiotics.

Women are more likely to get urinary tract infections because urethra is shorter.

None! Meningitis if bacteria or virus get in there.

How infective or harmful the organism is

Measure of virulence.

Of a bug, how many bacteria cells are needed to kill ½ animal in a study/ test group.

Low LD50 (more virulent the bacteria) or high LD50

• make an organism less virulent. We attenuate organisms to make vaccines. Live organism but less dangerous.
• Ex. BCG: M. tuberculosis

• Bacteria become more virulent if they:
• 1. Stick: Fimbria, pili, glycocalyx (capsule),
• 2. Invade: Make enzymes to break down your
• 3. Colonize and create biofilm (stuck and work together)

secreted toxins that damage your

• 1. Bacteria secrete enzyme to break down stuff so they can take in the stuff as food
• 2. Hemolysins break down red blood cells
• RBC. Allow break down of clot
• 3. A-B toxins: “A” subunit goes into your
• cell and alters translationa. Potent in GI tract
• 4. Superantigens: activates about 20% T
• cell at the same
• time nonspecifically.

• not secreted, part of bacterial cell, often part of cell
• 1. Ex. LPS. Gram – cell wall, fever

• associated with food poisoning
• stable to heating at 100 C for 30 minutes resistant to hydrolysis by gastric and jejunal enzymesproduced
• 30-50% of all S. aureus strains

Virulence factors: genes can be grouped pathogenicity island: plasmid or main chromosomegenes for some virulence mechanisms are grouped into thisthey are in control of a single promoter to allow their expression under appropriate conditions

a. Depends on the strain of bacteria

b. Capsules

c. Enzymes inactivate phagocytes

d. Salmonella: change protein on their coat routinely. Waves of nausea.

e. Superantigen: you get really sick but it’s not very useful cuz it’s non specific.

f. Some learn to live inside of phagocytes. Doesn’t get broken down in phagocytes and live in there

• Colony of bacteria that often has coating with the
• bacteria at the bottom is very protected.

i. Endocarditis: biofilm on the heart

• In water line and instrument: filters and
• flushing. More than just in body but the environment too.

a. Bacteriostatic: it stops division.

b. Bacteriocidal: kills bacteria

c. Bacteriolytic: lyses/ breaks down bacteria

a. work against infection. Often used outside of body (skin and mouth). Ex. Soap, triclosan, etOH, iodine, mouthwash, peroxide mouthwash (H2O2)

Not use internally

killing most but not all microbesnot given to pt except alcohol on skin does not kill spores (spores for survival/not production) or all viruses not for instrumentsuse for countertop

kill all microbes even sporesuse autoclave, gas, radiation, filtered (virus can get through this)

• 1. soap: antiseptic [ it's detergent/oi]
• 2. alcohol: antisept (you)/disinfect (surface)
• drying lipid
• denature proteins not sporicide
• not effective on TB
• alcohol on open wound is not recommended because creates a crust with bacteria underneath

• 1. chlorhexidine
• 2. fluoride
• 3. peroxide
• 4. mouthwash

• a. disrupts cell membranes
• Absorbs onto the gum and teeth for residual activity (+)

a. inhibits enolase (enzyme in glycolysis)

i. Good for application NOT ingestion (ingested fluoride might be good for something else but not for teeth)

a. oxidizing agent

i. Damaging to tissue at high concentration

• ii. Bacteria
• can’t handle the oxidative stress but acts same way on your tissue

Listerine: phenolics denature enzymes and proteins. Remain active in the presence of other organic molecules. Problem: high concentration can be toxic

Scope: quat Ammonium act as a surfactant. Target lipid membrane. Can be irritating to tissue and can be inactivate by organic.

use of physical procedures or chemical agents to destroy all microbial forms, including bacterial spores

sterilant: agent used to kill all microbes; ex. ethylene oxide

gasdisinfection: process of eliminating nearly all pathogens, but not all, from surface or inanimate object

disinfectant: antimicrobial agent used primarily on inaminate objects, too toxic for patient

M. tuberculosis: more resistant to low level disinfectants than other bacteriaHIV (virus) is relatively easy to kill compared to M. tuberculosis

• high germicidal efficacy
• germicidal activity in presence of dried
• blood, other organic matter
• wide antimicrobial spectrum
• rapid lethal action
• penetrate well
• chemical stability
• low cost, easily available
• noncorrosive
• must kill M. tuberculosis, P. aeruginosa, polio virus

• Low: used for noncritical instruments/devices, or general cleaning of floors, countertops.
• Inter: used for semi-critical instruments and when contamination by resilient microbes or endospores is unlikely.
• high level: necessary for invasive devices that cannot withstand sterilization

• are detergents - amphipathic molecules kill bacteria by disrupting cell membrane through interactions with lipids in lipid bilayer
• grap + bacteria most susceptible to destruction many viruses and all bacterial spores are resistant
• some bacteria resistant; mycobacterium and pseudonas
• low level

• an oxidizing agent use as a disinfectant - kills most bacteria at a concentration from 3-6%
• sterilant: kills all organisms, including spores, at [10-25%]
• free hydroxyl radicals formed from H₂O₂ decomposition. these are the sterilizing agents, oxidize microbes
• high level

rarely used disinfectant, too caustic original disinfectant used in hospitals, denatures proteins intermediate-level

• alkylating agentformalin - 37% formaldehyde solution in H₂O
• high/intermediate

• active component of hypochlorite (bleach)
• high-level disinfectant
• corrode stainless steel
• need to get stuff off of the instrument before putting them in autoclave

• heat: for hospitals and are indicated for most materials (except heat sensitive, consist of toxic, or volatile chemicals)
• radiation: limitation - direct exposure is required
• filtration: removing bacteria and fungi from air or from solns. limit - viruses and some small bacteria

• ethylene oxide: most common. efficient but limit - flammable, explosive, carcinogenic
• formaldehyde gas: carcinogenic
• plasma gas: H₂O₂ is vaporized, reactive free radicals are produced w/ no toxic byproducts. this might replace ethylene oxidehydrogen peroxide: oxidizing nature

• antiseptics, disinfectants, sterilant
• speracetic acid: oxidizing agent, excellent activity, end product is non-toxic
• glutaraldehyde: safety concern

• baking
• using for things that might corrode in autoclave
• way longer than autoclave

• most common. efficient but limit-flammable, explosive, irreversibly inactivates DNA and proteins by alkylation
• inactivates DNA more than other chemical sterilants
• Adv: use at low temp, does not melt, damage, or corrode things, can sterilize in packages
• Disad: long time, toxic, flammable

• alkylates molecules and inhibits function
• highly lethal to all microbes (including bacterial endospores)
• used as liquid immersion sterilant
• adv: most potent category of chemical germicide (liquid), capable of killing spores, use on heat sensitive materials
• dis: long period , toxic to human

knock down some pathogens but not sterileother microbes reduced in number

• a. 121 C, 15-20 minutes, 15 psi
• b. test through the use of strips of spores, indicator organisms

• a. UV light: makes thymine dimers Not generally
• use in real life

• Damaging to eye and skin. It doesn’t penetrate glass
• See this mostly in food prep area or research lab
• b. filtration: useful for heat-sensitive liquids/gases does not remove viruses and bacterial endospores