Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Foundations of Medicine > MicroBiology > Flashcards

MicroBiology Flashcards

1
Q

What is a Human pathogen?

A

organism capable of causing disease through infection (or other means)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Describe the 5 Classes of human pathogens

Bacteria, Virus, Fungi, Proin, Protazoa

A

Bacteria - single celled prokaryote
Virus - obligate parasite (ie non-living)
Fungi - plant like eukaryote organism, eg thrush
Prion - protein based infective agent (CJD)
Protazoa - single celled animals/eukaryotes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Cell wall + staining colours

A

Gram positive - stains Purple
Gram negative - stains Pink

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Why does Gram- positive stan purple?

A

-thick cell wall with many peptidoglycan layers
-absorbs more of the stain
-hence you get a darker

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Key differences between GRAM + AND GRAM -?

A
  • Gram + wall composed of many ropes of peptidoglycan layered on top of each other.
  • Gram - has wall composed of single layer of peptidoglycan, however contains an outer membrane
  • Gram - wall contains large periplasmic space
  • Gram - wall contains LPS chains which project from outer membrane, known as endotoxins
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Cocci/ Coccus

A

Spheres
Largely exist in 3 different ways → Diplococcus, Streptococcus or Staphlycoccus:

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Diplococci

examples

A

division occurs in 1 plane, isolated pairs
Key examples → Strep pneumoniae (gram +), Neisseria species (gram -)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Staphylococcus

examples

A

division occurs in 3 planes to produce a ‘clump’ (staff meeting)
Staph Aureus (gram +), staph epidermidis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Streptococci

examples

A

division occurs in 1 plane, forms continues long chains (strep form strips)
Strep pneumoniae, Strep Pyogenes (GAS)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Baccilus

examples

A

Rod shaped bacteria
Contain flagella to help with motility/ movement
e.g. Escherichia (ie E.coli), Klebsiella , Shigella, Salmonella

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

most bacteria causing diarrhoea tend to be?

A

gram NEGATIVE

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Coccobacillus

A

somewhere between a cocci (sphere) and bacillus (rod), rod w blunted edges
e.g. H. influenza

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Curved Rod/ Vibrios

examples

A

curved rod shape
e.g. Vibrio Cholera (causes cholera lol)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Spirillum and spirochaete

A

Syphilis and Lyme disease are both caused by spirochaetes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Virulence

A

the ability of a microbe to cause damage to the host

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Commensals

A

an organism that is part of the normal flora, often mutualistic relationship, found in gut and on skin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Opportunistic pathogen

A

an organism that is not normally pathogenic, however when circumstances arise (such as when you are ill, recovering from infection etc) jump at the chance to proliferate and cause infection (C.diff).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Properties of Bacteria

A

Aerobic - grow in oxygen/air.
Obligate aerobes - require oxygen.
Obligate anaerobes - killed by oxygen.
Capnophilic - prefer high CO2 levels.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

How to distinguish between organisms?

A

Gram stain → Gram positive or Negative
Shape form? → Cocci in strips? Cocci in clusters? Rod shaped/ bacillus?
Catalase enzyme present? → Staph are catalase +ve, strep are catalase negative

20
Q

Staph Test

A

Coagulase test, Oxidase test, Catalase test (+)

21
Q

Strep test

A

Blood agar/ haemolysis

22
Q

What is Haemolysis?

A

essentially the amount of blood cells the bacteria can chew through

23
Q

3 types of Haemolysis

A

Beta haemolytic → complete haemolysis, appears clear on blood agar plate (Strep pyogenes, other GAS)
Alpha haemolytic → partial haemolysis or green haemolysis (Strep viridans, strep pneumo)
Gamma haemolytic→ no haemolysis occurs (Enterococcus sp)

24
Q

Golden haemolysis

A

Very specific, buzzword for Staph Aureus

eve tho haemolysis is for strep not staph

25
Q

How do we distinguish between different Staphylococcus types?

A

ALL staph are catalase POSITIVE
Next test for coagulase:
Coagulase +ve = Staph. Aureus
Coagulase -ve = staph epidermidis, other staph species

26
Q

Browns Classification

A
27
Q

Examples of Gram -ve cocci

A

N. meningitidis
N. gonorrhoeae

28
Q

Examples of Gram +ve cocci

A

Group A Strep (GAS) - Strep pyogenes.
Strep pneumoniae - alpha haemolytic cocci
Non-haemolytic strep eg enterococcus faecalis and enterococcus faecium
All staphylococcus species

29
Q

Staph Aureus Treatment

A

Flucloxacillin

30
Q

What is Staph Aureus

A

Staph aureus causes, skin commensal (eg ally) however causes wound infections, prosthetic infections + cardiac implant infections. PWID (people who inject drugs) is a buzzword for a staph aureus infection.

31
Q

Examples of Gram -ve rods

A
  • Salmonella
  • Gut commensals and Pathogens - E. coli, klebsiella, enterobacter, proteus.
  • Coliforms - term used to describe species of gram negative bacilli that look like E. coli on gram film and when cultured on agar. Many part of normal bowel flora.
32
Q

Example of Gram +ve rods

A

C.diff (spore forming anaerobe)

33
Q

3 Mechanisms of antibiotics

A
  • Target cell wall
  • Target Prokaryotic nucleic acid (target bacterial DNA)
  • Target Bacterial Protein synthesis
34
Q

3 examples of antibiotics that target cell wall?

A

Penicillins
Cephalosporins
Glycopeptides

35
Q

3 examples of antibiotics that target prokaryotic nucleic acid (target bacterial DNA)?

A

Fluoroquinolones (class of Abx)
Metronidazole (singular abx type)
Trimethoprim (singular abx)

36
Q

3 examples of antibiotics that target Bacterial Protein synthesis?

A

Macrolides
Tetracyclines
Aminoglycosides

37
Q

How do Penicillins + cephalosporins Target cell wall?

A
  • Contain structure called Beta-lactam ring
  • which binds to the ‘penicillin-binding-protein’ (PBP) found on cell wall of bacteria
  • Prevents addition of peptidoglycan layers formation, killing bacteria
38
Q

How do Glycopeptides Target cell wall?

A

bind to the LPS side chains on cell wall, preventing formation. Only work on Gram -ve bacteria since only gram -ve contain Lipopolysaccharides (LPS)

Vancomycin

39
Q

How do quinolones Target Prokaryotic Nucleic acid?

A

Quinolones → inhibit DNA synthesis by preventing DNA ‘supercoiling’
Eg. ciprofloxacin

40
Q

How do Trimethoprim Target Prokaryotic Nucleic acid?

A

Trimethoprim → inhibits folic acid synthesis
Causes tendonitis (achilles heel)

41
Q

How do Metronidazole Target Prokaryotic Nucleic Acid?

A

Metronidazole → causes DNA structure to unwind
NO ALCOHOL
Used against anaerobes + protazoa

42
Q

How do Tetracyclines Target Bacterial Protein synthesis?

A

Tetracyclines → bind to 30s and stops protein chain elongation
Eg doxycycline

43
Q

How do Macrolides Target Bacterial Protein synthesis?

A

Macrolides → binds to 50s subunit of ribosome, interferes with protein synthesis
Eg erythromycin (Note, this macrolide is safe in pregnancy)

44
Q

How do Aminoglycosides Target Bacterial Protein synthesis?

A

Aminoglycosides → Binds to aminoacyl site of 16s within 30s subunit to cause misread of genetic code
Gentamicin

45
Q

What are the 4 Naughty Cs?

A

Cephalosporins
Ciprofloxacin
Clindamycin
Co-amoxiclav

Don’t give to over 65s, higher risk of C.diff infection

46
Q

How to treat C.Diff?

A

oral vancomycin

Foundations of Medicine (15 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions