Assessment1: Part 1 – Flashcards

single flagellum at one pole of the cell

ex: Vibrio - all Vibrio have one polar flagella

In prokaryotes: rotates (propellar) and is powered by a proton motive force

found in gram postive and gram negative bacteria

*chemotaxis

filament extending from bacteriam is composed of the flagellin protien, which is a major antigentic target (high copy number) and is also called and H-Ag bc its a heat labile Ag

*recognized by TLR5

Structure: filament attaches to a hook, hook attaches to the basal body anchoring it to the cell membrane

In Euk: whip-like and is powered by ATP hydrolysis

flagella all over the cell

ex: Salmonella and Escherichia

characteristic of spirochetes

wound around the cell and are not exposed to the external env.

forms an axial filament, with the flagella in the periplasm

rotation of the flagella causes the bacterium to move like a corkscrew (ex: syphillis)

very efficient for moving thru tissues

cillia-like structures ONLY found in prok

(cillia are found in Euk)

Fimbriae: proteinaceus projections  (PILIN) used for adherence

pilli are also proteinaceus projections but are used for the transfere of genetic material(aka SEX)

found in both gram + and -

two major fxns:

1. adherence to other cells, tissues or surfaces - colonization and formation of biofilms (organized systems of bacteria)
2. motility, twitiching and gliding - the extension and retraction of the pili

Unique to bacteria (aka not in Euk, only in Prok)

The unique structure of the cell wall of bacteria makes is a target for antibiotic (penicillin)

Recognized by TLR

confers shape and protection from osmotic lysis

very porous - does not restrict diffusion of mols/prots

**some bacteria lack pep cell walls: Mycoplasma an Chlamydia

Composed of:

1. Glycan: N-acetylymuramic acid and Nacetylglucosamine - linked disaccharide chains that repeat many times
   
2. Peptido:pentapeptide-amino acids
   

Glycan (Disaccharide: N-acetylyamuramic acid (NAM) and N-acetylglucosamine(NAG)) linked to a pentapeptide and tetrapeptides (composed of amino acids) to form a cross linked mesh-like network

• In Gram (- ) 20% tetrapeptide cross link
• In Gram + 80% crosslinkage

*in some gram + there may be an additional pentaglycine intrapeptide bridge attached to the lysine in the third position

Gram + and Gram (-) are very simillar except for the third position

• Gram + have a L-lysine that may contain the interpeptide pentaglycine bridge
• there are 8 distinct forms of peptidoglycan found in gram +bacteria but they are NOT significant in terms of antimicrobial therapy 
• Gram (-) have DAP *which is only found in prok

Synthesis:constantly occuring, inhibition of synth or crosslinking leads to cell death

1. Single disaccharides (NAM-NAG) linked to a pentapeptide are synthesized in the cytoplasm and linked to a membrane bound bactoprenol carrier **this step is targeted by Bacitracin
2. Translocated accross cytoplasmic membrane
   
3. once outside the membrane, disaccharide chain is linked to a growing a glycan chain and crosslinking to other modules is completed 

Crosslinking: confers rigidity to the cell wall

1. catalyzed by transpeptidase activity of penicillin-binding protiens (PBPs) *** targeted by beta-lactams
2. In gram (-) always occurs b/w DAP and fourth D-ala on the adjacent pentapeptide strand
3. Gram + mainly occurs b/w terminal glycine of interpeptide bridge and 4th D-ala of adjacent pentapeptide
   
4. Results in the release of the 5th amino acid (D-ala)

sphere

streptococcus and staphylococcus

BUT wait -- bacterial arrangment can be more helpful than shape ...

strep are in long chain cocci

staph are grape like clusters

(I would remember this)

elongated sphere

francisella

Rod

ecoli. Pseudomonas

Comma shaped

V. cholera

all share a common characteristic?

Monotrichous

rigid corkscrew

helicobacter pylori

flexible, corkscrew

treponema pallidium

1. Can contain a capsule - does not mean it always will - regulated by growth phase and env.
2. Outer Membrane: (gram + do NOT have this!) contains LPS  in outer leaflet and protiens that allow it to be a permeable barrier, and act as adhesions , enzymes and transporters *contains porins
3. Peptidoglycan layer - thin, 1-2 layers, and not highly cross linked
4. *periplasmic space -- its contains to the peptidoglycan layer and many enzymes involved in cell wall biosynth.
5. cytoplasmic membrane: similar in both gram (-) and gram +

1. Can contain a capsule - does not mean it always will
2. Can have a surface protien layer (Fibrillar layer)***Gram (-) do NOT have this layer
3. Peptidoglycan layer - highly crosslinked, 40 layers think
4. cytoplasmic membrane

Extracellular, carb rich coating on some bacteria

made in the cell

Contains poly - saccharide/peptides and maybe lipids

two types:

1. Capsule:repeating carb units, prevents cell from drying out, or can act as an alternate energy source; acts as a virulence factor by hiding the Ag component of bacterium from host, antiphagocytic---> target for vaccines **hard to stain due to carbs - usually stained with negative stain (india ink) capsule appears as a halo
2. Slime Layer: (exopolysaccharide) loosely attached to cell surface, contributes to disease, ex: gooey alginate in lungs of CF patients from pseudomonas aeriginosa

invaginations of plasma membranes, form vessicles in gram (-) and gram + 

significance is not known

(cell wall, cell membrane and outer membrane if present)

And again... 40 layers of peptidoglycan

Contains teichoic acid and Lipoteichoic acid:

• Teichoic acid is NOT found in gram (-)
• polymers of ribitol and glycerol phosphates
• highly Ag!!
• Teichoic acids are covalently linked to peptidoglycan
• lipoteichoic acids are anchored by a lipid tail to the cytoplasmic membrane
• aid in identification

also contain protiens and carbs

may or may not have fibrillar layer or capsule

can form spores (gram (-) can NOT form spores)

secreted protiens that are anchored to the outer surface of the cytoplasmic membrane (in both gram + and gram-)

divided in to two categories:

High molecular weight: ESSENTIAL for growth, encode tanspeptidaes(*crosslinking) and transglycosylase activites

**Beta lactams inhibit transpeptidases and carboxypeptidase activites

Low moleculare weight PBPs: not essential for growth, encode only carboxypeptidase

glycosidase, hydrolyses the bond btw NAM and NAG in the peptidoglycan layer

important for antibacterial defense

particularly against gram +, less important for gram (-) because they have the outer membrane which resist lysozyme activity

present in tears, saliva, and in the lysomes of phagocytic cells

Main fxn: permeability barrier - protect the cell from antibiotics, lysozymes, toxins. Diffusion limit is 600 Da

Houses protien transporters:

Porins - diffusion channels, that are essential open to allow passive diffusion of small molecules, can also fxn as adhesion mol. or in antibiotic resistance

Or many other protiens- adhesins, flagella/pilli, phage recognition, autoagregation

outer membrane

responsible for the permeabiltiy barrier properties, and is ESSENTIAL for viability

Composed of :

O-Ag: composed of almost repeating units of oligosaccaharides, highly variable, not essential, can express a variation of Ag in many bacteria, O-ag positive bacteria have a smooth looking colony morphology 

Core polysacchride: ESSENTIAL, 7 conserved carbs, also have some unique carbs (KDO and heptose)

Lipid A: ESSENTIAL,negative charge to LPS and the outer membrane

  responsible for barrier properties,referred to as endotoxin, recognized by TLR4

(more details on another card)

Lipid A: ESSENTIAL, Gram (-)

• acylated glucosamine disaccharide
• often phosphorylated imparting the negative charge to LPS and the outer membrane
• adaptive responses by some organisms that can cap the phosphorylation/enzymatically remove it --reduction in (-) charge and affects interaction with innate immune system (less negative =RESISTANCE)
• responsible for barrier properties
• referred to as endotoxin
• recognized by TLR4
• core protien binds O-Ag to Lipid A

Inside of Outer membrane: phospholipids

outerleaflet: LPS w/ negative charge - reduction of this negative charge leads to resistance to antimicrobial peptides and may affect TLR recognition (TLR4) and stimulation of PAMPs

LPS is stabilized in outer membrane by salt bridges formed by Mg 2+ bound to phosphates on adjecent LPS molecules

these salt bridges stabilize the outer membrane

inflammatory mediatory:

endotoxic shock - IL1 (fever), macrophages, PMN activation and oxidative burst, vascular permeabilty(hypotension), clotting activation, complement and tissue necrosis

ubiquitous, found in prok and Euks

transports drugs, carbs, peptides and protiens

not present in all bacteria-- pathogenic strains

important for pathogenesis - directly inject effector protiens into the host cells cytoplasm

related to porins

export protiens to the cell suface where they are released by the proteolytic cleavage into the extracellular space

1. extension of the cell wall
2. replication of the genome
3. segregation of chromosomes by membrane
4. septum formation
5. results in exponential growth : cell number = 2ⁿwhere N is the number of divisions

Also called doubling time

time required for one cell to grow and divide into two cells

can range from mins to mo

depends on conditions - pH, temp, salt content, nutrient

adaptation to a new enviroment

Can last an hr or days

cells may need to synth new enzymes to utilize nutrients in medium or adapt to pH, osmo, or temp

max growth rate- max DNA and protien synth

growth rate is CONSTANT!

***Time when bacteria are most susceptible to drugs

preferred time for staining

growth=death in culture pop

nutrient dep or accumulation of toxic waste

cells become metabolically inactive

induction of sporulation(*only in gram +)

***elevated resistance to antibiotics

complex aggregation of miccrogranisms encased in a protective and adhesive carb matrix

characterized by surface attachements, sturtural heterogeneity, genetic diversity, and complex community interactions

most bacteria grow in biofilms-Dental plaques, formations on catheters, CF, contact lens, ear infections

Source of recurrent infections: biofilm associated bacteria are resistant to antibiotics, and are protected from the immune system - antiphagocytic

Toxic byproduct produced during oxygen-mediated metabolism

broken down by catalase

oxygen tolerant organism have the enzymes to breakdown this product

aerobes contain both superoxide dismuates and catalase so that they can break down this toxic by product

obligate anaerobes cannot

toxic by product of O-mediated metabolism

oxygen tolerant bacteria contain superoxide dismutase and are able to "detox"

use O for respiration

obligates: require O

microaerophilles: require O level at 2-10%

do not require O

obligate: cannot tolerate O -- they do not contain enzymes to detoxify superoxide or hyrdogen peroxide (superoxide dismutase , and catalase )

Aerotolerant - do not use aerobic metabolism but have enzymes that detox

facultative anaerobes : can undergo aerobic respiration or fermentation in the absense of O

* some lack catalase (to break down hyrdogen peroxide but all have superoxide dismutase)

Too low: affect membrane fluidity and enzyme kinetics -->reduced growth rate

too high: protien denaturation, thermal lysis, and membrane collapse -->reduced growth rte (or death)

optimal temp: rxt occur at max rates = max growth rate

• Psychrophile - not a human health concern
• mesophiles - most human pathogens
• thermophiles - not human health concern
• hyperthermophiles - ""

normal acidity of certian region sof the body inhibit microbial growth -- but if this is altered ...

EX: vaginal secretions: remain at low pH due to residential flora, restricts growth of pathogenic microbes - but when altered (like antibiotics killing normal flora) the pathogenic microbes can move in = yeast infection

an organism capable of synthesizing all of its own metabolic needs

(ecoli, salmonella, pseudomonas)

lost the ability to synthesize certain substances required for growth - results from mutational changes

Ex: Chlamydia, lactobacillia, haemophilus, Neisseriae, Francisella

Iron is essential for growth

host defense: host have limited availabilty of iron by use of iron binding protiens (lactoferrin and transferrin) so not a lot of iron in cirrculation for bacteria

Pathogen response: iron stealing - specific transporter for lactoferrin and transferrin, along with the production of siderophores (iron binding compounds); cytotoxins to release intracellular stores of iron

subset of species that differ by some minor but identifiable difference

can be defined by serotype(serological means)

can be defined by biotype(biochemical, drug resistance, agglutination of blood cells ect)

stains cells of genera Myobacterium and Nocardia (TB and Leprosy)

these bacteria have waxy lipids in cell walls - no water base dyes can get thru

method:

1. fix bacteria on slide
2. add carblofuchsin and hear  - drive dye into slide
3. wash with HCl - dye is washed away in nonacid fast cells
4. counter stain with methylene blue
5. Acid fast = red, non acid fast = blue

derived from enviroment

finite time, removed with cleaning

can be pathogenic or non pathogenic

population of org regularly found at site (skin, mouth, GI **internal tissues should be free of microbes)

relatively stable

reestablishes itself following a disturbance

also called normal flora

mostly bacteria(10¹³) by some fungi and protozoa

GI tract: most populated region, primarily anerobic and faculatitive anerobic (esp colon)

many opportunistic pathogens - Salmonella, Pseudomonas, staph aureus, enterococus

Skin: also has some (staph epidermidis)

Internal:NONE!

bacteria occupy multiple niches (like staph) or just one nicne

there are multiple factors that can influence diveristy of flora at a site: Age and sex, Diet, sanitation

antagonize bacterial growth:fatty acids, peroxides, bateriocins kill or inhibit nonindigenous species

synthesize and excrete Vitamins: vitamin K, vitamin B12

stimulate develpoment of certain tissues:Caecum and lymph, and immune system

prevent colonization thru competition of attachment and nutrients

Normal bacteria infect new sites- where they become pathogenic

While Ecoli is normal in GI it can be pathogenic in other sites - like lung or UT

Oral surgery can result in the introduction of strep to the blood stream --> abscesses in the alveolar bone, lung brain - can colonize heart valve 

intraabdominal abscesses:anaerobes from GI can colonize

Oppprotunistic pathogens are present in our normal flora when immunocomprmised - surgery, trauma, antibiotics

result from a stay in the hosptial

2 million patients per year -90,000 deaths/yr

70% are antibiotic resistant : high prevalence, compromised host (25% are in ICU-immunocomp), efficient mechanism of transmission

***Hand washing is the single most important method to limit cross contamination

physical or chemical agents to inhibit or destroy microorganisms on inanimate objects

does not! guarantee all organisms are eliminated but does reduce the number of potential pathogens

Ex: alcohols, phenols, aldehydes, surfactants

use of chemical or physical agents called antiseptics to inhibts or destroy microorgansims on skin or other tissue

does not guarantee all organisms are eliminated - reduces the number of pathogens

ex: iodine, alcohol

indicates inhibition not complete destruction

• Temp, pH affect death rates: warmer temp, more acidic -->kill more pathogen
• Compostition/ quantity of infectious material:fat, feces, vomit, bld, and secretions of biofilm interfere with effectivness of heat, chemicals, and some forms of radiation
• Contact time: longer the better

used to disinfect (ie surface not skin), sanitize, sterilize and pasteurize

Method: denatures protiens and detroys cell membrane

**more effective than dry heat - h2o is a better conductor of heat than air

EX: boiling, autoclaving, pasteurization

dairy products and fruit

not sterilization

kills pathogens but heat resistant microbes still live

kills vegatative cells of bacteria, fungi, protazoans, and most viruses within 10 min at sea level

**boiling time is important (more time is needed at highter elevations)

not compelete sterilization -- endospores, protozoan cyst and some viruses can live on!

achieving true sterilization rq heat greater than 100 C

pressure is key to achieving such a temp

so basically you need - temp - 121C and 15 psi for 15 mins for true sterilization

*extra time for solid substancce and large vol.

material that cannot be sterilized with or are damaged by moist heat (powders, oil, metal)

method: denatures protiens and oxidizes metabolic and structural chemicals

requires higher temps and longer time than moist heat (171C for 1 hr or 160C for 2 hrs)

Incineration is a very effective form of sterilization -- think inoculating loop

halts growth (but NOT for yersinia or Listeria)

slow freezing works better - ice/water crystals puncture membranes

exclude particles based on size  - only if cant tolerate other methods of destruction (ex:protien solutions, drugs, antibiotics, serum )

fitlers are made of polymers with holes formed by a laser (0.2 micron hole)

High Efficiency particulate air filter

filters microbes out of air and gas

OR and ICU

shorter wavelenth (less than 1nm) so it has more energy, penetration and microbial control

creates ions by ejecting electrons from atoms

Electron beam results: rapid cell death but poor tissue penetration; used for sterilization of plastic, medical and dentals supplies

Gamma ray results: slow death but good tissue penetration, sterilizes food

wavelength is greater than 1 nm

excites e-, making new covalent bonds

affects protien and nucleic acid structure

UV radiation: Thymidine dimmers, poor tissue penetration, disinfects air, transparent fluids, and surfaces

methods: denatures protiens and disrupts cell membranes

uses: organic matter (bld, vommit, feces) remains active for a long time

used in health care settings, labs and homes(lysol)

bad odor and can cause rashes and irritation

Bacteriocidal, fungicidal, virucidal, against enveloped viruses ***but not fungal spores or endospores

method: denatures protiens and disrupts cell membrane, dessicates

evaporates rapidly - this can be good (no residue to be spread) but short exposure time

uses: tinctures, swabbing skin (antisepsis) with 70% and can be a disinfectant

Iodine, Bromide, Flourine, Chloride

effective against: vegatative bacterial and fungal cells, fungal spores, some bacterial spores, protazoan cysts and viruses

method: damages enzymes via oxidation or by denaturing

ex: iodine tablets, tincture, Cl treatment of h2o

peroxide, ozone, and peracetic acid

method: kill be oxidation of the microbial enzyme

ex: hydrogen peroxide - disinfectant and sterilize surface objects(can be neutralized by catalase)

Ozone - treatment of h20

peracetic acid - sporocid, sterilizes equipment

reduce surface tension of solvents to make them more effective at dissolving solutes

1. detergents: charged organic surfactants that are more soluble in water and soaps, good at cleaning but not good disinfectant?
2. Quats : antimicrobial, used in many medical and industrial applications, disrupt cell membranes

Salts of mercury, Cu and silver

Silver Nitrate- prevents blindness due to N. gonorrhoeae

Thimerosal-- mercury, preserves vaccines

crosslink with amino, hydroxyl, sulfhydryl, and carboxyl grps to denature protiens and inactivate nucleic acids

Glutaraldehyde (2%) disinfects and sterilizes (after long exposure)

Formalin (37%)embalming and disinfects

ethylene oxide, propylene oxide, beta-proplactone

very toxic and hazardous

used in closed chamber to sterilize medical equipment

denatures protiens and crosslinks of dna

Proks:

• smaller (0.2-2.0 in diameter), no nucleus, no membrane bound organelles 
• No cillia
• No cholesterol in their membrane
• they DO have a gycocalyx, flagella that rotates (proton motive force), and fimbriae and pilli
• cell wall: peptidogylcan
• ribosomes: 70s
• chromosomes: usually single, circular no histones no introns

EUK:

• larger, with a nucleus and membrane bound organelles
• they can have a glcocalyx, flagella (undulates, whips - ATP), and cillia
• they do NOT have fimbriae or pilli
• Many have a cell wall: cellulous, algin, agar, carrageenan, silicate, glucosmannan, chitin
• ribosomes: 80s
• chromosomes: usually more than one, linear with histones and introns (most of the time)

1. Shape - this can be misleading depending on phase of growth and nutrition 
2. arrangement: this is somewhat better - strep (chains) v. staph (clusters)
3. requirements for O
4. optimal growth temp
5. abiltiy to adapt to acidic enviroments
6. GRAM STAIN and various other lab test
7. nutrient requirements -- and the abilty to obtain this requirements (prototrophic, auxotrophs)
8. End product of fermentation: The EMB plate is used to differentiate btw lactose fermentation

same genus, different species, different diseases

one causes typhoid fever the other a gastroenteritis