Medical Microbiology exam #2

what are prions?

Rouge protein that may cause genetic mutation or cause other normal proteins to misfold

How do viruses contribute to some cancers?

They can destroy the function of certain genes that control the growth of cell (destroy repressor)

• ex: HPV

How can bacteriophage can be used for biological control?

used for Phage Therapy for bacterial infections and Prevent food Spoilage such on deli meat to prevent listeria

• injection its DNA into bacterium and bursts cell

why is Bacteriophage used for biological control?

• can’t infected human cells

• can infected specified bacterium

• disadvantage can ONLY kill only bacterium whereas antibiotic can multiple pathogens

What did Van Leewenhoek contribute to microbiology?

• First observe living microorganisms

• found animalcules in his mouth and sick people, and water

What did Homles contribute to microbiology?

Proposed the idea that doctors could be transmit disease on their hands

What did Semmelweis contribute to microbiology?

encouraged physicians to wash their hands before seeing and between patients as they would not when performing autopsies and delivering babies.

What did john Snow contribute to microbiology?

• outbreak of Cholera it was suspected that it called from not having proper sewers so install a sewer system which help the smell which did help but not overall

• - John made a spot map of cholera cases and discovered that cholera was transmitted in water but still didn’t know what about the water

What did Nightingale contribute to microbiology?

scrubbed the hosptial and washed the clothes and bandages of patients to improve sanitation

What did Lister contribute to microbiology?

used phenol (use as sterilization) during surgery resulting in fewer surgical deaths

What did Robert Koch contribute to microbiology?

• proposed the germ theory disease (certain germs can cause diseases)

• developed 4 postulates

• developed techquies for pure cultures

What is spontaneous generation?

if condition are right than it can be life

What did Louis Pasteur contribute to microbiology?

disproved Spanatneous generation by:

His design allowed air inside the flasks to be exchanged with air from the outside, but prevented the introduction of any airborne microorganisms, which would get caught in the twists and bends of the flasks’ necks. If a life force besides the airborne microorganisms were responsible for microbial growth within the sterilized flasks, it would have access to the broth, whereas the microorganisms would not. He correctly predicted that sterilized broth in his swan-neck flasks would remain sterile as long as the swan necks remained intact.

• developed a vaccine fro rabies

What did Hesses ontribute to microbiology?

Angelina proposed use Agar (comes from seaweed) to solidify his bacterial culture media

• one of the techniques use to grow pure cutlures

What are the four Koch’s Postulates?

1. The microorganism is found in every
case of the disease
2. The microorganism can be isolated
in pure culture (i.e. no other
contaminating organisms)
3. The same disease is produced when
the pure culture is inoculated into a
healthy but susceptible host
4. The same microorganism can be
recovered from the new hos

Why is it not always possible to prove Koch’s postulates?

some disease only have human host, ethic barriers, and some diseases are asymptomatic

What is meant by bacterial Growth?

Multiplying or dividing of bacteria ( the increase bacteria numbers)

What happens during binary fission regarding bacteria?

• happens often as e very 20 mins

• quicker than human cell cycle (takes 24hrs)

• doubling in every unit of time

What are the four stages of a bacteria growth curves?

1. Lag phase: ( Adaption to new environment making new enzymes

2. Log phase: bacteria growing dividing at a max rate ( best phase to function of bacteria)

3. Stationary phase: cell division = cell death due limited or oxygen or accumulation of toxic products/ acids ( quit increasing)

4. death/Decline: number of viable cells decrease ( cells undergo programmed cells death or genetically programmed to die release nutrients that can be used by other cells)

What are some conditions that can affect bacteria growth?

• Oxygen

• pH ( most bacteria grow at neutral pH)

• temp

• salt (most grow in non-salty environments)

What is a Halophile?

Bacteria can growth in extreme salty environments

What is a halotolerant?

Bacteria can tolerant growing in extreme salty environments

What is a psychrophile?

Bacteria can growth in extreme cold environments

What are psychrotolerant?

Bacteria can tolerant growing in extreme cold environments

What are mesophiles?

Bacteria can growth in neutral hot environments (human temp, and most bacteria that cause disease)

What are Thermophiles?

Bacteria can growth in extreme hot environments

What are Hyperthermophiles?

Bacteria can growth in extreme hot environments (hotter than Thermophiles)

What are obligate aerobes?

can ONLY grow with o2

What are obligate anaerobes?

can ONLY grow without o2

What are facultative anaerobes?

have the option to grow with or without o2 but prefer to grow with o2

what is a aerotolerant anaerobes?

can tolerant growing without or with o2 but doesnt have a preference of either

What is a biofilm?

a complex ecosystem containing a mix of bacterial types

What is the benefit of biofilm formation for microbes?

• higher resistance to antibiotics

• slow down of antibiotics or antiseptic the reaching to cells

• good site for horizontal gene transfer

What types of infections where biofilms are involved?

• periodontal disease

• cystic fibrosis

• infections medical devices in or on body

What are the steps of biofilm formation?

1. Attachement

2. Growth & friends

3. Quorum sensing (required #s of bacteria that all communicate to produce Ai’s. not enough bacteria Ai is low, alot of bacteria AI is high which triggers relesease of EPS) with Autoinducer

4. EPS ( makes biofilm): extracellar polymeric substance

5. biofilm community grows & thrives

What is central Dogma of biology?

1. DNA turns into RNA through transcription ( RNA polymerases reads DNA of make copy of RNA

2. Translation is when ribosomes read the RNA and builds protein

How is central Dogma biology applied to bacteria?

• Since there is no nucleus transcription & translation are coupled and can occur at the same time allowing rapid growth

• in eukaryotes RNA needs to processed and removed introns in order to create mRNA then go to the ribosomes while bacteria RNA doesn’t need to process they are read for translation

What are the difference between Bacteria genomes and eukaryotes genomes?

Bacteria are haploid ( one copy of each gene) whereas eukaryotes are diploid ( two copies)

• if a gene mutation can affect haploid immediately (if beneficial one can rapid evolution of the bacterial population)

What is vertical gene transfer?

Genetic inform is passed from generation to the next ( parent to child)

What is Horizontal gene transfer?

Genetic inform is passed between members of the same generation (peer to peer)

1. Transformation

2. Transduction

3. Conjugation

How was Horizontal Gene transfer discovered?

After injection of the smooth ( w/ capsule) of streptococcus into mouse that are heat-treated dead cells, the injection of rough of streptococcus into mouse which dies it is discovered that the rough streptococcus now has a capsule.

What are the consequences of Horizontal gene transfer?

• Enhances the rate at which bacteria can evolve

• being resistant to an antibiotic confers a selective advantage

How often does Horizontal Gene transfer occur?

• doesn’t happen frequently and extra genes can weight bacterium down)

What is transformation regarding HGT?

• involves a bacterium taking up DNA fragments that another bacterium ( probably died) has left in the environment

• occurs naturally in bacteria that cell need s to have those genes

• receiving bacterium must have gene similar to the gene being taken up so it can be integrated and maintained

What is transduction regarding HGT?

• involves bacteriophage

• during assembling the virus can accidentally pick pieces of the bacterium’s DNA and transfer the new bacterial cell it is trying to infect

in step 5: brings host DNA to new bacterial cell. only if its integrated to chromosomes it will be maintained

Limit to this is attachment has to happen, and host cell must have specific receptors

What is Conjugation regarding HGT?

• requires contact between donor and recipient bacteria

• mediated by an f pili encoded on an f plasmid that can get transferred to the recipient cell

• happens regularly

• 
  

Why must fragments must be integrate into chromosome?

They must be integrate the chromosome because they wont be replicated and cell eat it thinking its junk

What is transfer in a F+ cell?

In F+ cell one strand of F plasmid DNA is transferred to the F+ recipient cell

What is transfer in a Hfr ( high frequency recombination) cell?

• only if the f plasmid integrates into the host cell’s chromosome it becomes an Hfr cell

• DNA from the donor cell chromosome can be transferred to the recipient cell

How do we prevent microbial growth in order to preserve or extend the shelf life of food?

• drying

• Salt/sugar (osmotic pressure)

• pH

• Heat to kill & then seal

• Modified Atmospheric Packing (MASP): things package with inert gasses to inhibit microbial growth

What is disinfection?

Destruction of most microorganisms and viruses on nonliving tissue

• ex: alcohol or soap on equipment or surfaces

What is pasteurization?

Use of heat to destroy pathogens and reduce the number of spoilage microorganisms in foods and beverages

• Ex: milk and fruit juices

What is Sanitization?

removal of pathogens from objects to meet public health standards

• ex: washing tableware in scalding water in restaurants

What is sterilization?

Destruction of all microorganisms and viruses in or on an object

• ex: canned food

What is the range of susceptibility of bacteria, enveloped viruses, unenveloped viruses, endospores, and cysts? (most resistant to most susceptible)

Endospores, cysts, unenveloped viruses, bacteria, and enveloped viruses

How does Ultraviolet work as antimicrobial agent?

• preventing replication and transcription & replication (denaturing DNA)

• good for surfaces because it penetrates poorly

How does Ionizing work as antimicrobial agent?

• formation of free radicals which damage nucleic acids and proteins

• penetrates material well

• increases shelf-life

• makes food safer and reduces food-borne illness

How does temperature work as antimicrobial agent?

denaturing enzymes & proteins degrading nucleic acids and disrupting cell membranes

Why is moist heat better than dry heat?

• better heat transfer

• water avabile for hydrolysis

• can kill bacteria spores due to heat and pressure

How does filtration work as antimicrobial agent?

stops bacteria & viruses going through if they are large enough

How does salt work as antimicrobial agent? ( ask kelly about)

creates salty environments where bacteria can grow

Why can cholera be filter through multiple layers of cloth?

Cholera have these copepods which are tiny crustaceans that cling to the bacteria. Through filtering they copepods get hung on cloth & reduces the risk of cholera

What are Phenolics do and example of them?

• denature proteins and disrupt membranes

• ex: antibacterial soap, disinfectant in Lysol

What do metals do an example of them?

• binds to proteins and inhibit enzyme activity

• ex: Sliver & copper

• example uses: topical antiseptic, mouth wash, treatment of wounds and burns

What do Halogens do an example of them?

• Oxidation and destabilization of cellular macromolecules

• ex: iodine, chlorine

• example uses: water disinfectant, prevention of dental caries

What do Alcohol do an example of them?

• denature proteins and disrupt membranes

• ex: ethanol

• example uses: disinfectant or antiseptic

What do Surfactants do an example of them?

• Lowers surface tension of water to help with washing away of microbes and disruption of cell membranes

• ex: quaternary ammonium salts

• example uses: soaps and detergent, disinfectant, antiseptic mouthwash

What do Bisbiguanides do an example of them?

• disruption of cell membranes

• ex: Chlorhexidine

• example uses: oral rinse, hand scrub for medical personnel

What do Alkylating agents do an example of them?

• inactivation of enzymes and nucleic acids

• ex: formaldehyde

• example uses: tissue specimen storage, embalming, sterilization of medical equipment

What do peroxygens agents do an example of them?

• oxidation and destabilization of cellular macromolecules

• ex: hydrogen peroxide & benzoyl peroxide

• example uses: acne medication, toothpaste ingredient

How was antibiotics were found?

Paul Ehrlich coined the term chemotherapy (use chemical against disease)

• synthetic chemicals that were more toxic to microorganisms than to humans

Who found penicillin?

Alexander Fleming in 1928

• usesful but is limited to small quantites

• discovered it worked through experiment on a police man: started to get better when using it but later died after they had ran out

Who found the first drug to treat tuberculosis?

selamn Waksman discovered that antibiotics made by the soil bacterium streptomyces ( used to for TB)

What does bactericidal mean?

bacteria are killed

What does bacteriostatic

growth of bacteria is inhibited

What does spectrum of activity refer to?

• range of bacteria for which they are effective

• Broad spectrum: Kills/inhibits growth of bacteria a wide range of bacteria

• Narrow spectrum: Kills/inhibits growth of just a few types of bacteria

What is the pros & cons of Broad spectrum drugs?

• pros: not sure what is ( might it without knowing what it is)

• Cons: Kill healthy microbes ( might kill the ones we need)

What is the pros & cons of narrow spectrum drugs?

• pros: Knowing or have time to find out (protects health microbes)

• cons: if wrong or missed target patient be in a terrible prolong state

What does selective or differential toxicity mean?

very toxic for bacteria but minimally toxic for mammals

What does Therapeutic index mean?

refers to ratio of toxic dose/ Therapeutic does

• High is good bc their is a big zone between safe & toxic

• low must be careful to dose bc small zone between safe & toxic

What are some sources of antibiotics?

• Natural: made from species of bacteria or fungi

• semi-synthetic: modifications are made to naturally occurring compounds to enhance their activity

• synthetic

How are antibiotics different between chemical antimicrobial agents in terms of safety and mechanism of action?

chemical antimicrobial agents can use on non living tissue while antibiotics can be use inside the body

What are the five mechanism of antibiotic kill/inhibit bacteria?

1. Inhibition of cell wall synthesis

2. Inhibition of protein synthesis

3. Disruption of cell membranes

4. inhibition of metabolic pathways

5. inhibitors of Nucleic Acid synthesis

Why do antibiotics use Inhibition of cell wall synthesis is effective against microorganisms?

• inhibits the formation of NAM-NAM crosslinks ( inhibits the linking enzymes so NAM & NAG are just neighbors- tretapeptide side chains) the cell bursts from osmotic pressure bc wall isnt maintained

• safe for human cells bc they dont have a cell wall

• very therapetuic index bc no animal cell walls

• ex: penicillin

How do beta-lactam antibiotics works?

There B-lactam ring interacts with enzymes from tetrapeptide side chains to stop wall

Why do antibiotics use Inhibition of protein synthesis is effective against microorganisms?

• affect the translation through by targeting 70s ribosomes

• not safe for pregnant women or young children due to effects on developing teeth

• high therapeutic index bc eukaryotes have 80s ribosomes

• ex: Doxycycline

Why do antibiotics use Disruption of cell membranes is effective against microorganisms?

• targets different type of sterols of cell membranes ( animal= cholesterol, bacteria= something similar to cholesterol- ergosterol)

• can have some toxicity to humans

• ex: Polymixin

Why do antibiotics use inhibitors of Nucleic Acid synthesis is effective against microorganisms?

• inhibits the enzymes for unwinding circular bacterial DNA to proceed to replication & transcription

• less selectively toxic than other antibiotics than other antibiotics

• ex: Metronidazole

What is the mechanism of amoxicillin & side effects?

• inhibition of cell well synthesis

• rash

What is the mechanism of doxycycline & side effects?

• inhibit protein synthesis

• darkened skin color

What is the mechanism of cephalexin & side effects?

• inhibit cell wall synthesis

• purple skin rash with peeling

What is the mechanism of ciprofloxacin & side effects?

• inhibit nucleic acid synthesis

• Tendon problems or nerve damage

What is the mechanism of clindamycin & side effects?

• side effects: vaginal itching

• inhibit of protein synthesis

What is the mechanism of metronidazole & side effects?

• inhibit of nucleic acid synthesis

• side effects: Nerve damage of limbs or optic nerve

What is the mechanism of azithromycin & side effects?

• inhibit protein synthesis

• side effects: yellowing of skin or eyes

What is the mechanism of Sulfamethoxazole and trimethoprim & side effects?

• side effects: anorexia

• inhibit metabolic pathway work

What is the mechanism of Augmentin (amoxicillin and clavulanate) & side effects?

• inhibit cell wall synthesis

• side effects: diaper rash or bloody diarrhea

What is the mechanism of levofloxacin & side effects?

• Inhibit Nucleic acids synthesis

• side effects: tendon rupture

Why do antibiotics use inhibitors of metabolic pathways is effective against microorganisms?

• Bind critical enzymes act as Competitive inhibitors to shut down critical metabolic pathway

• ex: Sulfanilamide resembles PABA so it prevents folic acid synthesis( made from bacteria in our body) which ultimately inhibits synthesis of nucleotides