microbiology

Question 1

What are common side effects of all antibiotics

Answer 1

Nausea, vomiting, diarrhoea - all disrupt guts natural flora

Question 2

side effects of gentamycin

Answer 2

Renal and vestibulocochlear

Question 3

S.E of metronidazole?

Answer 3

reacts with alcohol

Question 4

S.e of ciprofloxacin?

Answer 4

tendonitis

Question 5

What antibiotics increase risk of C diff

Answer 5

avoid the 4 C’s

ciprofloxacin, cephalosporins, co-amoxiclav and clindamycin

Question 6

What antibiotics are to be avoided in pregnancy

Answer 6

Trimethoprim and metronidazole are to be avoided in the first three months of pregnancy

Gentamycin, tetracycline and fluoroquinolones are to be avoided all together !!

Question 7

Pathogen?

Answer 7

harmful organism

Question 8

commensal?

Answer 8

organism that is part of the normal flora

Question 9

opportunistic pathogen

Answer 9

Only cause infection in the immunocompromised

Question 10

Contaminant

Answer 10

organism that has gotten into a culture by accident

Question 11

pathogenecity

Answer 11

ability of the microorganism to produce disease

Question 12

virulence

Answer 12

the degree in which a pathogen can do harm

Question 13

How does bacteria replicate?

Answer 13

binary fission - start off as one and then divide

Question 14

What are the three types of atmosphere bacteria can grow in?

Answer 14

aerobic - in presence of oxygen
microaerophillic - reduced O2 increased CO2
anaerobic - without O2

Question 15

What are the two different types of toxins?

Answer 15

Exotoxin - released from gram positive cell from within and exocytosed out

endotoxin - released from gram negative cell and is part of the cell wall

Question 16

What do fungi like moulds and yeasts release? (what conditions can arise out of these)

Answer 16

moulds - spores and hyphae (aspergillus)

yeasts - single cells that reproduce by budding - candida

Question 17

What is the antibiotic of choice for staph aureus

Answer 17

flucloxacillin

Question 18

Describe the way in which a fever forms

Answer 18

antigen attacks macrophage
releases cytokines
travel up to the anterior hypothalamus of the brain
release prostaglandin E
increases body temp to above normal
body thinks its cold so starts to shiver
pathogens grow more slowly in increased heat

Question 19

What is the first line antibiotic of coliforms?

Answer 19

gentamicin

Question 20

What is the first line treatment for infections caused by anaerobes?

Answer 20

Mentronidazole

Question 21

What are some properties of mycobacteria?

Answer 21

thixy waxy outer coat, involved in TB and ziehl neelson stain is used - acid fast bacilli

Question 22

What are the three different ways of gene transfer in bacteria?

Answer 22

Transformation - DNA from dead bacteria taken up by living bacteria and incorporated in the genetic part of cell

conjugation - sex plius produced by one bacteria through which a plasmid can be transferred

Transduction - viruses infecting bacteria can transfer bits of DNA from one bacteria to another

Question 23

What are the five I’s of infection?

Answer 23

mother to infant, inoculation, ingestion, inhalation and intercourse

Question 24

Describe the chain of infection

Answer 24

starts with infectious microbe, reservoir, portal of exit, mode of transfer, portal of entry, susceptible host

Question 25

Define bactericidal and bacteriostatic

Answer 25

kill bacteria and inhibit bacteria growth

Question 26

What are the antibiotics that work on the cell wall?

Answer 26

Penecillin, cephalosporins (ceftriexone) and glycopeptides (vancomycin)

Question 27

Describe the cell wall of gram positive and negative organisms

Answer 27

positive - Cell wall has thick layer of peptidoglycan and a single phospholipid bilayer negative - Cell wall has two phospholipid bilayers and a thin layer of peptidoglycan

Question 28

What does penicillin inhibit? Is it bactericidal? Is it a beta-lactam antibiotic

Answer 28

Inhibits cell wall synthesis by preventing cross linking of peptodiglycan subunits bactericidal beta- lactam antibiotic

Question 29

When is flucloxacillin used?

Answer 29

Skin and wound infections, cellulitis

Question 30

What are some properties of cephalosporins? inhibit what?

Answer 30

inhibit cell wall synthesis bactericidal beta lacatam may induce C. diff

Question 31

Glycopeptides? (vancomycin) - cell wall what? | what are they only effective against?

Answer 31

cell wall active antibiotic binds to end growing chain - prevents cross linking and weakens bacterial cell wall bactericidal only effective against gram +ve

Question 32

What are the antibiotics that inhibit protein synthesis?

Answer 32

macrolides (clarithromycin) - bacteriostatic tetracyclines (doxycycline) - bacteriostatic aminoglycodsides (gentamycin) - bactericidal

Question 33

When are macrolides particulary useful?

Answer 33

they are lipophyllic and especially useful for infections that hide from the hosts immune system

Question 34

What are some side effects of tetracyclines - doxy (broad spectrum)

Answer 34

Broad spectrum - destruct intestinal flora leading to an increased risk of secondary infection can permanently stain the teeth of kids

Question 35

What are aminoglycosides mainly used for ?

Answer 35

gram negaives aerobes - coliforms and pseudomonas aeruginosa

Question 36

What are some antibiotics that work on bacterial DNA

Answer 36

metronidazole, trimethoprim and fluroquinolones

Question 37

When is metronidazole used?

Answer 37

true anaerobic infections - strand breakage of bacterial DNA

Question 38

How does trimethoprim work?

Answer 38

inhibits bacterial folic acid synthesis

Question 39

How does a fluoroquinolone work?

Answer 39

Prevent supercoiling of bacterial DNA - restricted use due to C diff

Question 40

What are the 6 stages of viral replication?

Answer 40

attachment - interact with specific receptors in target cell entry - endocytosis uncoating - viral nucleic acid released from capsid nucleic acid and protein synthesis - host ribosomes used + host polymerases assembly - nucleic acid and proteins packed together release - budding ( doesnt kill, virus released with envelope) lysis - virus accumulates until cell burst - kills cell

Question 41

Why are cytotoxic T lymphocytes useful?

Answer 41

recognise proteins on cell surface as being foreign and will signal infect cell to commit suicide so virus doesn't spread

Question 42

What is selective media?

Answer 42

specific substance that permits growth of one organism over anotehr

Question 43

Differential media

Answer 43

incorportation of chemicals that facillitate identification

Question 44

What is the process of becoming septic?

Answer 44

small blood vessles become leaky and loose fluid into surrounding tissue lower blood volume requires heart to work harder to maintain oxygenation of tissues less blood supply to vital organs clotting system is activated which uses up clotting factors and increasing the risk of bleeding

Question 45

What is the structure of a virus

Answer 45

nucleic acid genome protein capsid lipid envelope associated with virus proteins

Question 46

How do you detect a viral infection

Answer 46

PCR - antigen swab test | host response - IgG or IgM