Exam V

Question 1

Anton van Leeuwenhoek

Answer 1

Skilled at grinding special lenses
Drew the things he viewed: called them animalcules
Did not know where they came from; thought spontaneous generation

Question 2

Dr. Jenner

Answer 2

Small pox was a huge concern
He experimented with cow pox from milk maids and exposed boy to this and then exposed him to someone who had small pox – vaccination found!

Question 3

Semmelweis

Answer 3

Savor of the mothers – ran the maternity ward; strict rule of washing your hands but no one would listen to him at first
Those dissecting cadavers would deliver babies and expose the mothers to the diseases from these dead people

Question 4

Oliver Holmes

Answer 4

well rounded and was able to prove contagions passing from person to person

Question 5

Lister

Answer 5

people in battle were dying from medical treatments more than on the battle field; used phenol on instruments and air in surgery rooms to keep things clean; everyone didn’t believe him at first, but then they saw the changes in survival rates

Question 6

Pasteur

Answer 6

wine makers wanted wine to be consistent, so he made the association between the microbes growing on the grapes and figured out by heating the wine it would be always good; same with milk, apple cider, etc.; well known person who could solve things

Parasitic disease: silkworms that were not infected and kept them isolated and clean, and as long as silkworms infected didn’t come into contact with healthy ones they could do their work

Spontaneous generation: proved that things didn’t spontaneously come to be; used S shaped flasks and when that was cooked nothing would grow, but if you tipped the flask to let fluid out and sat it back up = growth because contamination with dust and bacteria within the peripheral part of the S

Vaccination for chicken cholera: attenuation = injecting the weakened microbe into the chicken so body can make Ab to fight the disease

developed the Rabies vaccine; took the spinal column of infected rabbits and grinded it down

Question 7

Koch

Answer 7

Proved one organism caused one disease; did this with anthrax and TB
Once he saw the pattern, he started checking the major diseases for which organism caused it; made so many connections = golden age of microbiology
Everything had a cause
Developed postulates that are still in use today
Won Nobel Prize
Present in every case of disease, absent in healthy organisms
Isolate and grow organism
Inoculate new host and get same disease
Re-isolate same organism from new host

Question 8

Molecular Postulates

Answer 8

Gene or product in virulent strains but not avirulent ones
Disruption of gene disrupts virulence
Introduction of gene into avirulent strain induces virulence
Gene is expressed while in host
Antibodies to gene product are protective

Question 9

Paul Ehrlich

Answer 9

Syphilis Treatment
Researcher in Koch’s lab
Tried 606 compounds
Arsenic derivative
Took to London, Fleming used

Question 10

Alexander Fleming

Answer 10

Plates he left out – nothing growing around it
Found the mold penicillin that went into the agar dish
In 1940s - mass production of antibiotics leading to the Antibiotics Era
Won the Nobel Prize for Medicine or Physiology

Question 11

Penicillin

Answer 11

1929 – published results
1932 – former student used filtrate on eyes of newborns with gonorrhea and/or staphylococcal infections – did not publish
1939 – Oxford group decided to study
No money in Britian
Rockefeller Foundation in America funded
during this time the war was going on and used the antibiotics for wounded soldiers (USA)
Resistance started in June 1941 - very rapid
Gram negative are more resistant than gram positive

Question 12

Chemotherapy

Answer 12

Sulfonamides discovered– 1932
End of Golden Age of Microbiology
Thought that they had found the medicine for everything…but they were wrong

Question 13

Emerging Infectious Disease Mechanisms

Answer 13

Environmental changes
Mutations to more virulent forms
New manifestations of known organisms
Antibiotic resistant strains

Question 14

Legionnaire’s Disease

Legionella pneumophilia

Answer 14

Can get it in water sources- legionella; legionnaires convention with elderly veterans that drink and smoke – so people in that demographic are prone to having pneumonia; several had the illness and died;
Environmental changes – air conditioning, vegetable water spray, hospitals outbreaks
Adding air conditioning made this a more prominent disease

Question 15

Lyme Disease

Answer 15

Borrelia burgdorferi
Found in Lyme, CN – build houses in deer’s domain; we moved into a territory that had this disease; same with probably ebola
Don’t infect deer, but infect mice and people
Hefty portion of ticks on peninsula carry lyme disease

Question 16

Necrotizing fasciitis

Answer 16

Streptococcus pyogenes
Strep infection; can cause scarlet fever with prickly rash; back in the day this was a dangerous disease; now our immune systems can better fight this
Same toxin that causes prickly outbreak, it also causes necrotizing fasciitis: very fast – 24 hours
The microbe changed over time – deadly; we don’t know what caused the switch

Question 17

Cat Scratch Disease

Answer 17

Bartonella henselae
cats scratch causing swelling in lymph nodes
Bacillary Angiomatosis – HIV patients get this; looks like blood vessel wart
The child must have a better immune system – can fight this; but HIV immune compromised patients cause the warts
Same organism with two different presentations

Question 18

Vancomycin Resistant Entercocci

Answer 18

Big problem in hospitals
Antibiotic testing to measure resistance
Different resistance patterns
Vancomycin is the last resort antibiotic – some strains have become resistant to it = extremely bad; must be extremely cautious of not passing it to other people in the hospital
Must treat the person with multiple antibiotics and this is not as effective but only resort
Must clean EVERYTHING to keep spread under control

Mechanism: will not allow the binding of the D ala residues on the termini so cross linking cannot occur in peptidoglycan and this destroys the cell wall; resistant stains put D lactate instead of D ala

Question 19

Acid Fast Stain

Answer 19

Mycobacterium sp.
Nocardia sp.
Waxes in cell wall
Does not gram stain because no cell wall and has wax like structure instead
Organism with heat fixation; use carbol fuchsin and phenol then rinsed with water, then acid, then rinsed; if redish color = positive
Not acid fast: takes blue counter stain

Question 20

Fluorescent Staining

Answer 20

Use Ab (primary and secondary)
Very helpful, can see organism when low concentration is present, quick to get results (especially when you don’t have the time aka patient is dying)

Question 21

Blood Agar

Answer 21

When an organism has hemolytic properties – key clue
Alpha – green color
Beta – yellow looking, but actually clear because killed all RBCs – extremely important if beta hemolysis
Gamma – no hemolysis and not used
Alpha and beta are what matters

Question 22

Chocolate Agar

Answer 22

Fastidious organisms- picky about where they grow
Haemophilus influenzae
Neisseria gonorrhoeae

Question 23

MacConkey Agar

Answer 23

Enterics grow in GI tract
ALL GRAM NEGATIVE grow, but the agar inhibits gram + organisms from growing
Lac + = E. coli – turns pink and is a lactose fermenter (easier to treat)
Lac - = P. aeruginosa – stays yellow/no color and is a non fermenter (hard to treat)

Question 24

Buffered Charcoal Yeast

Answer 24

Legionella

Question 25

Sabouraud Dextrose

Answer 25

Candida albicans (fungus)

Question 26

Lowenstein Jensen

Answer 26

Mycobacterium tuberculosis

Question 27

Klebsiella pneumoniae

Answer 27

mucoidal growth - encapsulated

Question 28

Mycobacterium

Answer 28

Pigmented Growth

Question 29

Proteus

Answer 29

swarming/wave-like

Question 30

Catalase Test

Answer 30

Differentiates Staphylococci (+) from Streptococci (-) Detects presence of catalase enzyme – breaks down peroxide + = bubbling/fizzing - = no reaction

Question 31

Coagulase Test

Answer 31

Conversion of fibrinogen to fibrin Differentiates Staphylococcus aureus (+) from other Staphylococci (-) + = forms a clot - = no reaction

Question 32

Indole Test

Answer 32

One test used to differentiate Escherichia coli (+) from other enterics + = magenta - = yellow

Question 33

Oxidase Test

Answer 33

Tests for presence of enzyme cytochrome oxidase c Pseudomonas aeruginosa (+) + = purple - = no change

Question 34

Drugs that Inhibit Prokaryotic Protein Synthesis

Answer 34

Chloramphenicol, Erythromycin, Tetracycline, and Streptomycin

Question 35

Quinolones (gram - vs. gram +)

Answer 35

Action - gram negative bacteria inhibition of DNA gyrase, unable to pack DNA into cell Specific for bacterial DNA gyrase Action – gram positive bacteria Inhibition of topoisomerase IV

Question 36

Beta Lactams

Answer 36

family that includes penicillin | attacks the cell wall

Question 37

Sterols in Membrane

Answer 37

Only in mycoplasm

Question 38

Mesosome

Answer 38

Invagination in cytoplasmic membrane where DNA binds to replicate Segregation of chromosomal DNA into daughter cells

Question 39

Peptidoglycan

Answer 39

composed of alternating NAG NAM NAG NAM In gram +: peptidoglycan is thick, hydrophilic Gly cross bridges that hold the cell together by trans or carboxypeptidases kicking off the terminal D-Ala amino acid to form the Lys - Gly bridge In gram -: doesn't need the Gly bridge because only one layer think peptidoglycan, and so close that the molecules can directly link Lysozyme: breaks the NAG NAM bonds = bactericidal; use when you want to kill the bacteria completely ex. in cases of necrotizing fasciitis or meningitis; gram positive are sensitive to it, but gram negative are resistant because the outer membrane provides protection

Question 40

Penicillin Binding Proteins (PBPs)

Answer 40

Enzymes that cross-link amino acids Transpeptidases Carboxypeptidases Known as Penicillin Binding Proteins (PBP’s) because they are targets for action of penicillins and other beta-lactams (bactericidal because won't allow the cross bridge linkages within peptidoglycans)

Question 41

Peptidoglycan Synthesis

Answer 41

1. Cytosol- UDP- NAG and UDP-NAM polymers formed 2. Membrane- UDP-NAM is transferred to a lipid carrier via bactoprenol, UDP is displaced, and NAG added to NAM (bactoprenol transports to a cell wall growth point) 3. Periplasm/Exterior- autolytic enzymes cut NAM-NAG loose from bactoprenol so it can be added to the cell wall so cross linking can occur; cycle then continues

Question 42

Gram Negative vs. Gram Positive

Answer 42

Gram Positive: thick peptidoglycan, contains teichoic/lipoteichoic acids in cell walls (not sure purpose but our immune system can detect them), some strains produce endotoxin Gram Negative: LPS (endotoxin in some strains), outer and inner membrane, periplasmic space, lipoproteins

Question 43

LPS

Answer 43

On gram negative - endotoxin O antigen: Linear polysaccharide with 50-100 repeating units w/4-7 sugars /unit; Used in serotyping Core: No associated activities, contains unusual sugars, spacer between O antigen and Lipid A Lipid A: toxic portion that can cause sepsis; stirs up our immune system and contained in gram negative rods

Question 44

Septic Shock

Answer 44

Patient with sepsis and blood infection: start them on antibiotic which causes lysis of bacteria releasing more endotoxin = bad All we can do is keep the person alive long enough to survive the reaction of the immune system against the bacteria Research: they are looking at shutting down some components of the immune system to defeat it… must have immune system to correlate with meds, but need to shut it down just a little bit to get over the endotoxins

Question 45

Porins

Answer 45

Within the outer membrane of gram negative bacteria Restrict entry by size Important in antimicrobial choice Vancomycin is too large to enter Permits entry of hydrophilic molecules May restrict some antiseptics or disinfectants that act on cell membrane attachment site for bacteriophage

Question 46

Periplasmic Space

Answer 46

part of gram negative bacteria Contains degradative enzymes- “binding proteins” like trans and carboxypeptidases Enzymes that inactivate antibiotics like beta lactams= Beta-lactamase If you have a mixed infection and you pick penicillin, if you have an organism (gram positive) breaking down beta lactam into the environment, it is helping the gram negative bacteria; need to pick something that doesn’t allow it to go into the environment

Question 47

Beta Lactasmases

Answer 47

produced by gram negative and positive Numerous enzymes that cleaves beta lactam ring Penicillinases Cephalosporinases ESBLs (extended spectrum beta-lactamases) More than 200 different beta lactamases

Question 48

Mechanisms of resistance to beta lactam antibiotics

Answer 48

1. Block the drug from entering via the cell membrane 2. Change PBP 3. Secrete the beta lactamase to hydrolyze the drug used Gram negative- 1-3 Gram positive- 2 and 3

Question 49

Examples of Capsulated Organisms

Answer 49

Streptococcus pneumoniae Klebsiella pneumoniae Haemophilius influenzae type b Neisseria meningitidis Escherichia coli K1 prevents dehydration, provides protection from phagocytosis and environment, and adherence capsule does not provide growth, but virulence

Question 50

Pili/Fimbrae

Answer 50

Mostly gram negatives adherence and sexual conjugation virulence factor antigenic variation making it hard for the immune system ex. Escherichia coli and Neisseria gonorrhoeae

Question 51

Sporulation

Answer 51

GRAM POSITIVE ONLY Bacillus sp.: Aerobic and Gram-positive rod Clostridium sp.: Anaerobic and Gram-positive rod Harsh environmental conditions induce Change from vegetative state to spore Location of spore may be used in identification dehydrated like hibernation metabolically contains dipicolinic acid extremely hardy concern in disinfection, sterilization, etc.

Question 52

Transposons

Answer 52

can pick up and move to a different site on a DNA molecule Actual movement: transposition via transposase IS- insertion sequences; cut themselves out and insert into another area; two ways of transposition 1. Replicative: make a copy of itself and move somewhere and end up with 10 copies of capsule gene for example because it there is a mutation in one it doesn’t lose its virulence 2. Non-replicative: cuts itself out and moves to another location – no multiple copes; happens a lot from plasmid to chromosome A transposon can be located on a plasmid move to chromosome so it becomes permanent and part of chromosomal material We use plasmids in research and rely on these methods so the genes can be introduced into the bacteria and we can study it

Question 53

Competent Cells

Answer 53

use specialized buffers that help the cells pick up the DNA; when competent the cells are ready to pick up the DNA during transformation

Question 54

Bacillus thuringiensis

Answer 54

Bacillus thuringiensis is a gram positive soil dwelling bacteria, aerobic, capable of producing endospores. Commonly used as a pesiticide

Question 55

Bacterial Growth: Temperature & pH

Answer 55

Psychrophile – very cold Mesophile – middle temps Thermophile – slight higher temps Hyperthermophile – in hot springs – very hot temperatures Acidophil: acidic conditions Neutrophile: neutral conditions Alkaliphile: basic conditions

Question 56

Bacterial Growth: Oxygen Content

Answer 56

Obligate aerobes – need O2 to survive Obligate anaerobe – O2 will kill it and needs to be as far away from O2 as possible Micro-aerophil – likes lower O2 content but want some Facultative anaerobe – can grow with or without O2; most successful in the human body because the more flexible

Question 57

Bacterial Growth Curve

Answer 57

Take advantage of this to figure out when to harvest the bacterial All bacteria grow through four phase growth phase Lag phase – figuring out where it is and what genes do I need to turn on and off; growth is small Log – starts to replicate via binary fission with rapid growth Stationary phase: growth = death; plateau because the nutrients are being depleted and wastes are building up and it becomes toxic so then the death phase occurs from the toxic wastes During each stage of growth genes are constantly changing with which ones are being transcribed and translated or stopped Prime time to harvest: the stationary/plateau phase

Question 58

Nosocomial

Answer 58

hospital acquired/healthcare associated Endogenous source- from the patient Exogenous source- anything except the patient (equipment, flowers, etc.) Cut off: after 48 hours

Question 59

Opportunities Infections

Answer 59

an infection caused by a microorganism that does not usually cause a disease in a healthy individual example: foley catheter

Question 60

Vertical vs. Horizontal Transmission

Answer 60

Vertical: parent to child (mother to child, fetus, etc.) Horizontal: human to human; direct contact (STI's), human to fomite, and human to respiratory, fecal/oral, and blood (all intermediates to infect another human)

Question 61

Ingestion, Inhalation, Trauma, Needle Stick, Arthropod Bite, and Sexual Transmission

Answer 61

Ingestion: Salmonella, Shigella, E. coli Inhalation: Mycobacterium, Legionella Trauma: Clostridium tetani Needle Stick: Staphylococcus epidermidis, S. aureus Arthropod Bite: Borrelia, Ehrlichia, Rickettsia Sexual Transmission: Neisseria, Chlamydia

Question 62

Capsule

Answer 62

``` Structure surrounding the cell Usually composed of polysaccharides; exception: Bacillus anthracis Several functions: adherence prevents dehydration avoid phagocytosis nutrient sources Bacteria: Neisseria meningitidis Streptococcus pneumoniae Klebsiella pneumoniae Haemophilus influenzae type b Pseudomonas aeruginosa Bacillus anthracis ```

Question 63

Biofilm

Answer 63

A community of microorganisms encased within an exopolysaccharide matrix attached to a solid surface or to each other. attachment, growth, and detachment cause 65% of nosocomial infections

Question 64

Direct and Indirect Ways Pathogens cause Damage

Answer 64

Direct: Invade and disrupt cells, produce degradative enzymes (elastase via pseudomonas) and toxins, gain access to nutrients Indirect: Trigger an Immune response where the host can damage itself Superantigen: causes massive immune response resulting in shock and organ failure.

Question 65

Toxins

Answer 65

Exotoxins: proteins produced and secreted by the bacterium into the extracellular environment (Gram negative and positive); have varied mechanisms of action, attack different host cells, preformed toxins: food poisoning, ex. S. aureus; superantigen; toxic shock 1. Neurotoxins: interfere with neural transmission; Clostridium tetani tetanus toxin 2. Enterotoxins: Vibrio cholerae cholera toxin Endotoxin: only LPS on gram negative; septic shock

Question 66

AB toxin example: diphtheria toxin

Answer 66

A subunit is the active portion B subunit binds to the receptor and transports the toxin into the target cell Need both to work ``` Mode of Action: Same as P. aeruginosa Exotoxin A ADP-ribosyl transferase Inactivates elongation factor 2 Inhibits host protein synthesis ```

Question 67

Cholera

Answer 67

ADP ribosylates a protein that regulates adenylate cyclase in intestinal epithelial cells. irreversibly activates the regulatory protein activates adenylate cyclase causing cAMP concentration to rise triggering the cell to pump water from the bloodstream into the intestinal tract causing diarrhea

Question 68

Superantigen

Answer 68

Cross linking of T-cell receptors and MHC II molecules Stimulates massive cytokine production and inflammatory response Result can be toxic shock leading to death Gram positive cocci: TSST 1 Staphylococcus aureus

Question 69

Mechanism of LPS

Answer 69

LPS binds to CD14 and toll like receptor 4 (TLR4) on monocytes and macrophages Induces IL-1 and TNFα production IL-1 produces fever TNFα more cytokine production and fever Activates complement pathway: vasodilation Stimulates B cells: antibody production Overall can lead to hypotension and shock

Question 70

Evasion of Host Defenses

Answer 70

1. Prevent phagocytosis S. pneumoniae, H. influenzae, and K. pneumoniae, produce a capsule S. pyogenes produces M protein 2. Kill white blood cells Staphylococcus & Streptococcus produce leukocidins to destroy leukocytes and macrophages 3. Confuse the immune system Antigenic variation: change structure of surface antigens therefore antibodies do not recognize bacteria example: Neisseria gonorrhea Molecular mimicry: bacteria camouflage themselves with host proteins example: IgA 4. Grow intracellularly Prevent phagosome/lysosome fusion: Mycobacterium Escape the phagosome: Listeria and Rickettsia. Break down H2O2: Staphylococci produce catalase

Question 71

Location of Virulence Factor Genes

Answer 71

The chromosome: Pathogenicity islands Plasmids Bacteriophages Transposons

Question 72

Virulence Mechanisms

Answer 72

``` Adherence Invasion Byproducts of growth (gas, acid) Toxins Degradative enzymes Cytotoxic proteins Endotoxin Superantigen Inflammation Evasion of phagocytosis Capsule Resistance to antibiotics Intracellular growth ```