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Flashcards in Microbiology Deck (97)
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1

Prion Proteins

Smallest infective agents
No DNA/RNA
Mad cow disease
Can't be sterilised - surgical instruments must be destroyed

2

Viruses

Contain DNA/RNA
Protein coat +/- lipid envelope

3

Bacteria

DNA+RNA
Cell membrane, cell wall
Coccus, bacillus, spirochates

4

Eukaryote

No cell wall

5

Gram +ve (cell wall)

Purple
Many layers of peptidoglycan which holds on to the purple gram stain colour

6

Gram -ve (cell wall)

Pink
Thin layer of peptidoglycan which doesn't hold on to the gram stain as much so shows up as a pink stain

7

Lipopolysaccharide

Gram -ve
Potent endotoxin

8

How do bacteria replicate?

Binary fission

9

Bacterial growth curve

Lag
Log
Stationary
Decline

10

"facultative"

Can grow with or without oxygen

11

"obligate"

Aerobe - requires O2
Anaerobe - Killed by O2

12

Exotoxin

Mainly gram +ve
Produced inside the cell then EXported from the cell

13

Endotoxin

Mainly gram -ve
Part of the gram -ve cell wall

14

Spores

Inactive forms of bacteria that can survive adverse conditions for many years but can't replicate
(eg - C. diff)

15

How do yeasts replicate?

Budding
eg: candida

16

Diagnostic investigations for bacteria

Microscopy
Culture
PCR
Antigen detection
Antibody detection IgM (serology)

17

Cocci

Mainly gram +ve (purple)
Round
Can be in clusters or chains

18

Cocci chains

eg: streptococcus, enterococcus
gram +ve cocci in chains
Differentiate by: Haemolysis test

19

Cocci clusters

eg: staphylococcus
gram +ve cocci in clusters
Bunch of grapes
Differentiate by: Coagulase test

20

Bacilli

Rod shaped
Can be large or small

21

Spirochates

Spiral shaped
Does not stain with gram stain

22

a-haemolysis

Partial haemolysis
Denatured haemoglobin causes green discolouration
eg: strep pneumonia, strep viridans

23

b-haemolysis

Complete haemolysis
Produce exotoxins that lyse red cells in the agar plate
Around the colony there will be a clear zone
eg: group A strep, group B strep

24

y-haemolysis

No haemolysis
Colony has not changed the agar plate at all
eg: enterococci

25

Group A strep "strep pyogenes"

Most pathogenic strep
Commonly causes tonsilitis

26

Coagulase +ve

Staph aureus

27

Coagulase -ve

All staph (apart from staph aureus)
Common cause of prosthetic joint and prosthetic heart valve infections
Don't produce toxins

28

Staph aureus

Can produce exotoxins - damage cells
Can produce endotoxins - food poisoning
Treatment of choice: flucloxacillin

29

Fever (mechanism)

Antigenic material interacts with macrophages
Macrophages release cytokines into bloodstream
Cytokines travel to hypothalamus
PGE is released which increases body thermal set point
Body perceives it's cold and shivers to conserve heat
Results in fever

30

Sepsis

Small blood cells become 'leaky' and loose fluid
Lower blood vol requires heart to work harder to maintain tissue oxygenation (tachycardia)
Poor tissue oxygen perfusion shuts of blood supply to organs to make sure there is enough blood supply for brain
Blood clotting system activated
Increased risk of haemorrhage

31

Sepsis

Small blood cells become 'leaky' and loose fluid
Lower blood vol requires heart to work harder to maintain tissue oxygenation (tachycardia)
Poor tissue oxygen perfusion shuts of blood supply to organs to make sure there is enough blood supply for brain
Blood clotting system activated
Increased risk of haemorrhage

32

Antibiotics

Active against bacteria
Not active against viruses

33

Antivirals

Active against viruses
end in -ivir

34

Virus detection investigation

PCR (detects viral nucleic acid)

35

Spread of infection (5 I's)

Inhalation - droplet, airborne
Ingestion - contact
Intercourse - contact
Inoculation - contact
Mother to Infant - vertical

36

Most commonly missed area of hand hygiene

Thumb
Fingertips

37

When to wash hands (5)

1. Before patient contact
2. Before aseptic task
3. After body fluid exposure risk
4. After patient contact
5. After contact with patient surroundings

38

PPE order

Apron
Gloves
Gloves
Apron

39

Black bag

Domestic waste

40

Orange bag

Clinical waste

41

Orange bag

Clinical waste

42

Bacteriostatic

Inhibits the growth of bacteria

43

Bacteriocidal

Kills bacteria

44

Oral administration

Peak serum levels 1 hour after administration

45

IV administration

Peak serum levels 15 mins after administration

46

Cell wall synthesis

Targeted by b-lactam ring (penecillins, cephlasporins) and glycopeptide antibiotics

47

Beta-lactam antibiotics
(and examples)

Broad spectrum
Consists of all antibiotic agents that contain a beta-lactam ring in their structures
Inhibit cell wall synthesis
eg: penecillins, carbapenems, cephlasporins
Advantages: safe, variety
Disadvantages: resistance, allergies, rapidly excreted

48

Penecillins - overview

Act on bacterial cell wall
Beta-lactam antibiotic
Safe in pregnancy
Excreted rapidly via kidney
Bacteriocidal

49

Penecillins - Flucloxacillin

Narrow spectrum
Treatment of choice for staph aureus

50

Penecillins - amoxicillin

Broad spectrum
Challenged by b-lactamases which destroy the beta lactic ring and eventually destroy amoxicillin

51

Penecillins - co-amoxiclav

Broad spectrum
b-lactamase inhibitor, thus it is better than amoxicillin
Combination of amoxicillin + clavulanic acid

52

Penecillins - temocillin

Narrow spectrum
Treatment of choice for coliforms

53

IV form of penicillin

Benzylpenicillin (aka penicillin G)

54

Antibiotics that act on the bacterial cell wall

Targeted by b-lactam ring
Penecillins
Cephlasporins
Glycopeptides

55

IM form of penicillin

Benzathine penicillin

56

Penecillins - overview

All end in "-cillin"
Inhibit cell wall synthesis by blocking peptidoglycan formation
Beta-lactam antibiotic
Safe in pregnancy
Excreted rapidly via kidney
Bacteriocidal

57

Glycopeptides - overview

Inhibit cell wall synthesis by inhibiting peptidoglycan synthesis
NOT a beta-lactam antibiotic
Bactericidal
Only works on gram +ve bacteria
Excreted via kidneys and urine

58

Glycopeptides - vancomycin

Administered IV
Used if MRSA is suspected

59

Antibiotics which inhibit protein synthesis - e.g.

Attach to bacterial ribosomes

Mainly bacteriostatic - Usually protein synthesis resumes when antibiotic is removed
eg:
macrolides
tetracyclines

Some can be bactericidal
eg:
aminoglycosides

60

Macrolides

Eg: clarithromycin, azithromycin, erythromycin
Inhibit protein synthesis
Bacteriostatic
Erythromycin - safe in pregnancy
Excreted via liver

61

Tetracyclines

Eg: Clindamycin, doxycycline
Inhibit protein synthesis
Bacteriostatic
Broad spectrum
Resistance is increasing

62

Aminoglycosides

Eg: Gentamicin
Inhibit protein synthesis
Bactericidal
Mainly active against gram -ve aerobic organisms (coliforms)
Excreted in urine

63

Antibiotics which inhibit nucleic acid synthesis - e.g.

Metronidazole
Quinolones
Fluoroquinolones
Trimethoprium

64

Cephlasporins

All start in "ceph" or "cef"
Act on bacterial cell wall to block peptidoglycan formation
Beta-lactam antibiotic
Bacteriocidal
Broad spectrum
Safe in pregnancy
Excreted via urine and kidneys

65

Quinolones

Eg: ciprafloxicin
Inhibit nucleic acid synthesis
Bacteriocidal

66

Fluoroquinolones

Inhibit nucleic acid synthesis
Bacteriocidal
Broad spectrum
Excreted via urine

67

Trimethoprium

Inhibit nucleic aid synthesis
Broad spectrum
Excreted via urine

68

4 C's

Ciprofloxacin - quinolone
Cephlasporins -
Co-amoxiclav - penecillin
Clindamycin - tetracycline

69

Tetracyclines

Eg: Clindamycin, doxycycline
Inhibit protein synthesis
Bacteriostatic
Broad spectrum
Resistance is increasing

70

Aminoglycosides

Eg: Gentamicin (IV)
Inhibit protein synthesis
Bactericidal
Mainly active against gram -ve aerobic organisms (coliforms)
Excreted in urine

71

Combination of antibiotics in TB

To prevent development of resistance

72

Metronidazole

Inhibit nucleic acid synthesis due to strand breaking of DNA
Administered oral/IV
Used for anaerobes (clostridium, bacteroides)
Avoid alcohol

73

Is it safe to combine bacteriocidal and bacteriostatic antibiotics?

NO

74

Fluoroquinolones

Inhibit nucleic acid synthesis
Bacteriocidal
Broad spectrum
Excreted via urine

75

B-lactamases

Act on and destroy antibiotics with a beta lactam ring

76

4 C's

Ciprofloxacin - quinolone
Cephlasporins -
Co-amoxiclav - penecillin
Clindamycin - tetracycline

77

Resistance to antibiotics

Giving unnecessary antibiotics
Giving sub-therapeutic doses
Genetic mutation - due to fast replication which can cause misreading of DNA

78

Name the most common antibiotic which is given for anaerobe infection?

Metronidazole

79

Name 4 antibiotics which work on anaerobes

Metronidazole
Clindamycin
Co-amoxiclav
Carbapenems

80

Pseudomonas is a strict aerobe/anaerobe?

Strict aerobe

81

Name an example of a spirochete?

Syphilis

82

Gram +ve diplococci

Strep pneumonia

83

Treatment of choice for strep infection?

Penicillin

84

Enterococcus is treated with penicillin. True or false?

False

85

Where is most gram -ve bacilli found

In the gut and urinary tract

86

E coli

Gram -ve
Rod shaped bacilli
Lactose fermenter

87

Gram -ve intracellular diplococci

Neisseria species

88

Which drug is used for gram -ve organisms if gentamicin is contra-indicated?

Astreolam

89

What does vancomycin treat?

MRSA
Clostridium (c diff)

90

What happens to the agar plate if a bug is resistant to an antibiotic?

There will be growth right up to the disc, the antibiotic doesn't stop the organism from growing

91

What happens to the agar plate if a bug is sensitive to an antibiotic?

There will be a clear area (the drug will stop the bug from getting into that zone)

92

What causes C. diff infection?

Use of broad spectrum antibiotics

93

What is more beneficial: high dose antibiotic therapy for shorter duration? OR low dose antibiotic therapy for longer duration?

High dose for shorter duration

94

Where are gram positive organisms usually found in the body?

Skin and mucous membranes
- pneumonia
- cellulitis
- osteomyelitis
- wound infection
- line infection

95

Where are gram negative organisms usually found in the body?

GI tract
- UTI
- peritonitis
- biliary infection
- pancreatitis

96

Where are anaerobes usually found in the body?

Mouth, teeth, throat, sinuses, lower bowel
- abscesses
- dental infections
- peritonitis
- appendicitis

97

Carbepenems

Active against ESBL producers
Eg meropenem
Reserve antibiotics