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
