Bacteria

Question 1

What are the biggest pathogenic species?

Answer 1

Bacteria: 538/1400

Question 2

How are bacteria useful?

Answer 2

Ecosystems
Food production
Useful materials

Question 3

What are the harmful effects of bacteria?

Answer 3

Disease
Food spoilage
Biofouling and corrosion

Question 4

What are Koch’s postulates?

Answer 4

Present in every diseased organism
Can be isolated and purely grown
Reintroduction causes disease
An identical species can be re-isolated

Question 5

Which postulate has been re-evaluated?

Answer 5

Pathogens can be found assymptomatic/aquire virulence/non-pathogenic in healthy organisms too

Question 6

When are opportunistic pathogens active?

Answer 6

In deep tissues or immunocompromised people

Question 7

How many pathogens can cause each disease?

Answer 7

Multiple

Question 8

Where is normal flora rich?

Answer 8

GI,
urogenital tract
nose
skin

Question 9

What is the function of the human microbiome?

Answer 9

Provides colonisation resistance

Question 10

What type of infections do the normal flora cause?

Answer 10

endogenous

Question 11

What are the major disease causing normal flora?

Answer 11

Endogenous opportunistic

Question 12

What are exogenous infections?

Answer 12

Pathogens aquired from other organisms

Question 13

What percentage of human disease causing pathogens are zoonoses?

Answer 13

60%

Question 14

What type of pathogen is Mycobacterium tuberculosis?

Answer 14

an exogenous infection

Question 15

What symptoms does TB have?

Answer 15

Non-specific lung damage including granulomas, necrosis and fibrosis

Question 16

What form is TB commonly found?

Answer 16

Latent infection in a third of the worlds population

Question 17

What type of infection is Pneumonia?

Answer 17

exogenous

Question 18

What does pneumonia cause?

Answer 18

Build up of bacteria and WBCs in lungs reduces O2 uptake

Systematic infection has poor mortality

Question 19

Which pathogen has synergy with influenza?

Answer 19

Pneumonia

Question 20

What increase does HIV cause in TB activation?

Answer 20

800 fold

Question 21

What are the 2 types of food poisoning?

Answer 21

exotoxin produced by pathogen after ingestion or on food

endotoxin are part of pathogen

Question 22

What type of food poisoning causes cholera?

Answer 22

Exotoxin produced in intestine by Vibrio cholerae

Question 23

How do endotoxins cause disease?

Answer 23

lipopolysaccharide in gram negative capsule
Lipid A portion binds to membrane
LPS binds to LBP, activating macrophages
Septic shock

Question 24

What are the symptoms of septic shock?

Answer 24

Fever, 
coagulation
hypotension
inflammation
organ failure

Question 25

How do endotoxins spread?

Answer 25

Lysis of envelope spreads fragments through bloodstream

Question 26

Which kingdoms do not have cell walls?

Answer 26

protozoa | animals

Question 27

What is the function of cell walls?

Answer 27

Protect cell from hypertonic environments/osmotic stress | Provide anchorage from proteins to interact with extracellular environment

Question 28

What is the bacterial cell wall made out of?

Answer 28

Peptidoglycan/murein mesh with 2nm pores

Question 29

What is the structure of peptidoglycan?

Answer 29

NAG-NAM glycan strands | Cross links between NAM

Question 30

How are cross links formed from NAM stem peptides?

Answer 30

``` muramic acid L ala D Glu Mesodiaminopimelate ------ D ala D ala ```

Question 31

Which organisms have indirect cross links between NAM?

Answer 31

penicillin resistant strains

Question 32

Which stem peptide residue is highly conserved?

Answer 32

D-ala

Question 33

How is peptidoglycan synthesised?

Answer 33

D-ala-D-ala synthesised by racemase and ligase D-glu synthesised by racemase UDP NAM pentapeptide dervived from F6P by MurA-F MraY attaches NAM to undecaprenyl phosphate on membrane MurG attaches NAG to NAM Transfer across bilayer Penicillin Binding Proteins cause transglycosylation onto existing glycan and transpeptidisation using energy provided by cleavage of pentapeptide

Question 34

What is the structure of the cell wall in Gram negative bacteria?

Answer 34

Thin layer of PG tethered to capsule by Braun's lipoprotein

Question 35

What is the structure of the gram positive bacterial cell wall?

Answer 35

Thick cell wall with techoic acids binding proteins and lipotechoic acids anchoring to cell membrane

Question 36

What cell wall do chlamydiae have?

Answer 36

Cysteine rich P layer

Question 37

What cell wall do archaebacteria have?

Answer 37

S layer or pseudo-peptidoglycoprotein

Question 38

What organisms have a chitin cell wall?

Answer 38

Fungi

Question 39

Why are chlamydiae susceptible to antibiotics targetting Peptidoglycan?

Answer 39

Peptidoglycan scaffold/cytoskeleton

Question 40

What are the 3 ways PG is recognised by the immune system?

Answer 40

intracellular, soluble extracellular

Question 41

What are the extracellular recognition mechanisms for PG?

Answer 41

CD14 and TLR2 receptors trigger cytokine cascade

Question 42

What are the intracellular recognition mechanisms for PG?

Answer 42

NOD1 detects Mesodiaminopimelate from gram negative bacteria | NOD2 inimmune cells detects NAM-ala-glu

Question 43

What are the soluble receptors of PG?

Answer 43

CD14 and C-type lectins | Activate complement cascade

Question 44

How do some bacteria reduce competition?

Answer 44

Produce lysostaphin metalloendopeptidase to cleave serine residues in other organisms

Question 45

What are antibacterial drugs?

Answer 45

Drugs produced that are selectively toxic to bacterial cells

Question 46

How are antibiotics produced?

Answer 46

Secondary metabolites of fungi and bacteria

Question 47

What are the 2 main classes of antibacterial agents?

Answer 47

Bacteriostatic | Bacteriocical

Question 48

How do antibacterials selectively target cells?

Answer 48

Differences in metabolism to convert prodrugs Cannot enter mammalian cells Target absent/modified processes in bacteria

Question 49

What are the main mechanisms of antibacterial action?

Answer 49

Steric hindrance Substrate analogs Enzyme inactivation Disruption/subversion

Question 50

What are most antibacterials?

Answer 50

Antibiotics

Question 51

What are the main targets of antibacterials?

Answer 51

``` DNA Cell wall Cell membrane Nucleotides Transcription Translation ```

Question 52

Which antibacterial agents target the Cell wall synthesis?

Answer 52

``` β lactams fosfomycin vancomycin bacitracin D-cycloserine Isoniazid & ethionamide ```

Question 53

Which drugs target the cell membrane?

Answer 53

polymgoxin B&E | Daptomycin

Question 54

Which antibacterials target nucleotides?

Answer 54

Sulphonamides | Trimethoprim

Question 55

What do Fluoroquinones and quinolones target?

Answer 55

DNA intercalation

Question 56

What does rifamicin target?

Answer 56

transcription

Question 57

What drugs target translation?

Answer 57

``` Linezoid Fusidic Acid Mupirocin Tetracyclines Chloramphenicol Streptomycin Erthyromicin ```

Question 58

What is antibacterial agent resistance?

Answer 58

The ability of bacteria to survive and grow in the presence of an antibiotic concentration that can be safely achieved at the site of infection in humans

Question 59

What social effects does antibiotic resistance have?

Answer 59

Increased mortality Increased morbidity Increased cost

Question 60

How can bacteria develop resistance?

Answer 60

Intrinsic resistance caused naturally | aquired resistance through horizontal transfer or spontaneous mutation

Question 61

What are the mechanisms of drug resistance?

Answer 61

``` Alteration to target structure Change in quantity of target Decreased permeability Increased efflux Enzymatic inactivation Acquisition of an alternative target for bypass ```

Question 62

How many resistance mechanisms can a bacterium show?

Answer 62

Multiple

Question 63

What are examples of resistance by target acquisition?

Answer 63

PBP2a variant in MRSA

Question 64

What are examples of target structural alteration causing resistance?

Answer 64

RNA polymerase point mutation blocking Rifamicin CFR methylase aquired to act on ribosome Mutated PG terminal blocking vancomycin

Question 65

What resistance does VISA have?

Answer 65

Thickened cell wall so vancomycin can't reach new PG

Question 66

How can efflux-induced drug resistance be caused?

Answer 66

Upregulation of existing transporter or acquisition of new target

Question 67

Which type of resistance is produced by β lactamases?

Answer 67

enzymatic inactivation of antibiotic

Question 68

How are aminoglycosides modified in drug resistance?

Answer 68

adenylation, hydroxylation or phosphorylation

Question 69

How can antibacterial resistance be prevented?

Answer 69

develop new antibiotics recycling improved control of infections restriction of use