bio2 exam 4

human microbiome

the collection of microbes found in or on the human body

human virome

entire population of viruses present in and on human body

probiotic

live microbes applied to or ingested into the body, intended to exert a beneficial effect

prebiotic

a substance that passes undigested into the colon and stimulates the growth and/or activity of certain types of bacteria

Phage therapy

treatment of bacterial diseases using bacteriophages specific to a particular bacterium

resident microbiota

species of microbes that are always present on or in another organism in a specific area

transient microbiota

the microorganisms that are present temporarily in an area that do not permanently colonize

Sterile body parts examples

Blood, kidneys, liver, muscles, bone, brain, spinal cord, lower respiratory tract

Bacteriophages outnumber bacteria:

10:1

What role do bacteriophages play in microbial populations?

Regulate them by killing over growth, gene transfer

Advantage of Phage therapy

Alternative to using antibiotics to kill only specific bacteria without harming residents

Vaginal birth obtain initial microbes from

the vaginal canal

C-section birth obtain initial microbes from

gut/skin bacteria, environment

Advantage of vaginal birth

baby has more diverse microbiome

Disadvantage of c-section birth

baby tends to be overweight (fermentation)

Bifidobacterium

Found in GI tract of breast-fed infants; uses oligopolysaccharides for food

Benefit of bifidobacterium

Increased immunity, helps digest breast milk

In the twin mice study, what was transferred to germ-free mice?

Feces/gut microbiota of the lean and obese twins

What happened to the mice receiving microbes from obese twins?

increased number of firmicutes and methanogens made them grow obese as well

What happened to the mice receiving microbes from lean twins?

increased number of bacteriodetes, remained lean

Gut-brain axis

The affects of neurotransmitters, especially serotonin, based on gut microbiota health

Dietary fiber

nondigestible carbohydrates that feed gut microbiota

Short chain fatty acids

acetate, propionate, butyrate; result from gut bacteria

benefits of short chain fatty acids

reduces inflammation, helps colon, improves metabolism and immune health

infection

entry, attachment, and colonization of a specific body part by a specific bacteria

pathogen

nonresident microbe that if allowed to colonize causes disease

Opportunistic pathogen

takes advantage of a weakened host (eg immunocompromised patients)

exogenous infection

infection originating outside the body

endogenous infection

infection originating from inside the body (normal flora)

Focal infection

infection that began as a local infection but spreads to another part

Order of infection

Entry, Attachment, Colonization, Invasion/Immune evasion, Damage, Transmission

Examples of attachment

Fimbrae, Flagella, Adhesion Proteins, Capsules

Examples of entry

Oral, ocular, skin abrasion, pores, urogenital tact, respiratory

Examples of colonization

Forming biofilm

Quorum

Population threshold that when met signal rapid genetic change across the population

Quorum sensing

The ability of bacteria to sense the number of bacteria, share information, and adjust their gene expression

Examples of immune evasion

Viruses that envelop themselves in host cell membranes

Examples of damage

Release of toxins, enzymes that damage the host

virulence

Degree of damage or risk of life of an organism

virulence factor

any characteristic or structure of the microbe contributes to its ability to establish itself in the host and cause damage

Examples of virulence factors

Adhesion factors, exoenzymes, toxins, and immune evasion

The portal of entry of Streptococcus pneumoniae

upper/lower respiratory tract

Attachment mechanism of Streptococcus pneumoniae

Sticky capsule, fimbrae

Virulence factors of Streptococcus pneumoniae

- IgA Protease

- Penicillin Resistant

- Anti-phagocytic capsule

Portal of entry of salmonella typhi

fecal-oral route

Attachment mechanism of salmonella typhi

Fimbrae, flagella

Virulence factors of salmonella typhi

Capsule, Type 3 secretion

Infectious dose

minimum number of microbes required for infection to proceed

Lethal dose

minimum number of microbes required to kill host

Endotoxin

A toxic, heat stable component of the outer membrane of certain gram-negative bacteria that is released only when the bacteria die.

Exotoxin

a toxin released by a living, Gram-negative or positive, bacterial cell into its surroundings when it reachs quorum.

Botulinum toxin

Toxin produced by the bacterium Clostridium botulinum that produces tetanus.

tetanospasmin toxin

Toxin produced by the bacterium Clostridium tetani that produces tetanus.

Physiological effects of botulinum toxin

Flaccid paralysis, muscle weakness, drooping. Can reach vital organs like the lungs and disable them

Physiological effects of tetanospasmin

Spastic paralysis, lock jaw, high blood pressure

Mechanism of action of botulinum toxin

prevents acetylcholine release --> no muscle contraction --> paralysis

Mechanism of action of tetanospasmin

prevents GABA and glycine from signalling motor neurons to stop signalling -> acetylcholine continues to release -> muscle cannot relax

Acute infection

symptoms develop and resolve rapidly

Chronic infection

progress and persist over a long period of time

Subclinical infection

an infectious disease not detectable by the usual clinical signs

Latent infection

infection in which the infectious agent is present but not causing symptoms

opportunistic infection

Infections that occur when the body's defenses are weakened

systemic infection

infection spreads to several sites and tissue fluids usually in the bloodstream

local infection

pathogens are limited to a small area of the body

Plate count

Counts all living cells

Direct microscopic count

Counts all visible cells

Spectrophotometer

measures turbidity

Membrane filtration

used for counting in dilute samples

OD450

Optical density measurement at 450 nm wavelength.

Absorbance

The amount of light absorbed by a sample

Lag phase

intense activity preparing for population growth, but no increase in population

Log phase

The period of exponential growth of bacterial population.

Stationary phase

period of equilibrium; microbial deaths balance production of new cells

Death phase

population is decreasing at a logarithmic rate

Formula for bacterial growth

Nf = (Ni)2^n

Obligate aerobe

requires oxygen

Obligate anerobe

organism that cannot live in the presence of oxygen

Faculative anerobe

uses oxygen but can grow without it

Microaerophile

requires a small amount of oxygen but won't grow at normal atmospheric levels

aerotolerant anaerobes

do not utilize oxygen but can survive and grow in its presence

psychrophile

organism that grows at temperatures of -15 °C or lower

mesophile

bacteria that prefers moderate temperature and develops best at temperatures between 25 C and 40 C

thermophile

an organism that has adapted to living in very high temperatures (heat), such as bacteria or algae

hyperthermophile

organism that grows at temperatures between 80-122 °C

sterilization

kills all microbes including endospores

disinfection

kills vegetative cells but not endospores

sanitization

both physically removes or kills some microbes

antisepsis

kills some organisms on living things

degerming

physically remove germs from living things

microbistatic

inhibits the growth of microbes

microbicidal

kills microbes

Mechanism of action of alcohol

destroys cell walls of bacteria

Mechanism of action of soap

destroys cell wall, inhibits ability for bacteria to adhere to a surface

Mechanism of lysol

destroys cell walls but remains on a surface for a long time

Mechanism of boiling

coagulates, denatures proteins

Mechanism of UV light

Forms T=T dimers in nucleic acids

Mechanism of steam sterilization

denatures proteins, destroys membranes

Examples of extremely resilient microbes

Endospores, prions

Examples of moderately resilient microbes

Protozoan cysts, mycobacteria

Examples of weakly resilient microbes

Enveloped viruses, vegetative bacteria