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MB1: Principles > Microbiology > Flashcards

Microbiology Flashcards

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1
Q

describe layers of peptidoglycan relative to gram staining

A

Gram positive bacteria have a thicker peptidoglycan layer than gram negative bacteria and so stain a darker purple

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2
Q

what is the endotoxin and where is it found

A

lipopolysaccharide, contains toxins and antigens and is the outer cell membrane of gram negative bacteria

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3
Q

what are targets for antimicrobials

A 
Cell membrane 
Cell wall
Protein synthesis
DNA
Ribosomes
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4
Q

what appendages do bacteria have to aid movement

A

Gram positive have fimbriae, non flagella protein appendages

Gram negative have pili, which is absent of a motor

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5
Q

What are the requirements for prokaryotic growth

A 
Food
Temperature 
pH
Osmotic protection
Oxygen, or lack thereof
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6
Q

Growth phases of bacteria

A

Lag
Exponential phase
Stationary phase
Decline/Death phase

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7
Q

What is a mesophile

A

Bacteria which are optimum at body temperature

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8
Q

How is an abscess formed

A

bacteria secrete toxins to break down tissues for nutrients

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9
Q

Bacilli

A

Rod shaped

Exist in isolation or chains

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10
Q

Cocci

A

Can form chains called streptococci

Can form clusters called staphylococci

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11
Q

Spiral corkscrew

A

Rigid - spirillum
flexible - spirochaete
operate best in viscous environment

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12
Q

Fusiform

A

Stillbirth

Long and slender

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13
Q

Curved rods

A

Gram negative

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14
Q

Why are bacteria with capsules more virulent

A

Complement system cannot bind to these bacteria as effectively

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15
Q

Classes of oxygen tolerance

A 
Capnophilic 
Aerobic
Obligate aerobe
Obligate anaerobe 
Facultative anaerobes
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16
Q

What is selective media

A

identifies bacteria by presence of specific substances permitting its growth

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17
Q

What is differential media

A

incorporation of chemicals to provide visible changes in colonies for identifying

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18
Q

What are the different types of heamolysis and what does it mean

A

Alpha - colony greening, identifies Viridans group and lancefield D
Beta - discolouration of blood agar, pyrogens and lancefield A, B, C, F, G
Gamma - no heamolysis

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19
Q

qPCR does what?

A

amplifies DNA on bacteria to indicate presence of a specific microbe

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20
Q

What does MALDI-TOF do?

A

puts analyte into gas phase to separate ions by mass to charge ratio for identifying microbes

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21
Q

What is agglutination

A

Clumping together of cells due to antibodies binding to their antigens

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22
Q

What is metabolic profiling

A

uses carbon sources and exo enzyme production to identify microbes

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23
Q

what are exo enzymes

A

what is metabolised by microbe

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24
Q

What does a positive coagulase indicate

A

Staph Aureus

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25
What are serological tests
detection of IgM antibody to microbe in vitro by agglutination
26
What is the difference between polyclonal and monoclonal antibodies
Polyclonal - specific to microbe | Monoclonal - specific to single component
27
Describe the structure of viruses
Protein coat Envelope Genetic information as RNA or DNA
28
Structure of a virus in terms of shape
Helical | Icosahedral
29
Describe the virus life cycle
``` Attachment Entry Uncoating Nucleic acid and protein synthesis Assembly Release ```
30
Why are viruses harder to develop drugs against
they have less structures to target
31
Where is antiviral resistance most common
Immunocomproised patients
32
Types of immunity to viruses
Innate Humoural T-cell recognises non self antigens and invokes apoptosis
33
How are viruses identified
PCR, antigen detection NGS, mass spectroscopy Electron microscopy and culture - falling out of use
34
What are endogenous bacteria
Bacteria from inside the body in gut flora, can occasionally be pathogenic in some circumstances
35
What are exogenous bacteria
Bacteria from outside the body, they can be pathogenic
36
What are oppertunistic pathogens
an organism that causes infection given an opportunity
37
what is virulence
capacity of a microbe to cause disease
38
What is a pathogen
disease causing microorganism
39
Yeast infection? What can it form?
Candida spp. | Hyphae, spike growing down epithelial cells
40
Types of protozoan disease?
Malaria and toxoplasma
41
2 main types of gram negative cocci
Neisseria meningitidis (most common meningitis) and gonnorhoeae
42
Endogenous coliforms
E coli Proteus spp Klebsiella spp Enterobacter spp
43
Exogenous pathogenic coliforms
Salmonella spp Shigella spp Ecoli 0157, 0104 - producing verotoxin
44
Treatment for coliform infections?
Gentamycin
45
True/false - any coliform can cause an infection
True- even endogenous coliforms can cause infection in sterile sites such as the urinary tract
46
What causes acute antibiotic associated diarrhoea?
Clostridium difficile | Most common in vulnerable patients in absence of normal gut flora due to removal by broad spectrum antibiotics
47
What class is C. diff and what can it produce
Can produce spores | Gram positive anerobic bacilli
48
2 types of staphylococci and how they appear
Clusters Staph Aureus - wound and skin infection. coagulase positive and can become MRSA Staph epidermis
49
How does streptococci appear, what types are there and how are they identifed
``` Chains of streptococci identified by heamolysis Alpha - strep pneumoniae Beta - pygrogenes, group A Gamma - Enterococcus spp - can either be very sensitive to amoxicillin or very resistant ```
50
Why do patients with coliform sepsis get so ill so fast
Release of endotoxin from bacteria when they die
51
What dies the endotoxin cause the immune system to release
Acute phase cytokines
52
What do acute phase cytokines do
Can cause release of prostaglandin E at hypothalamus to cause fever or can lead to sepsis
53
What do beta lactams target
Bacterial cell wall, penicillin binding protein by mimicking D-alanine D-alanine dipeptide to compromise cell wall
54
Types of beta lactams
Penicillins | Cephalosporins
55
What penicillin is the first line broad spectrum
Amoxicillin
56
What is given when bacteria are beta lactamase and resistant to amoxicillin
Co-amoxiclav, containing clavulanic acid to inhibit beta lactamase
57
What is given for staph or strep
Flucloxacillin, MRSA is resistant to it
58
what penicillin is active against ESBL
Temocillin, but only really coliforms as gram negative
59
Where are penicillins excreted?
Kidneys and urine
60
True/false - cephalosporins are bacteriostatic
False- they are bacteriocidal
61
why are cephalosporins not used as much anymore?
they can cause C. diff due to them being so broad spectrum
62
What antibiotic would be given for MRSA
vancomycin - part of bacteriocidal glycopeptides but are not beta lactams
63
First line antibiotic gentamycin and issues
only gram negative and IV, bacteirocidal | toxic to kidneys as well as VIII cranial nerve
64
What antibiotics can be used to treat intracellular pathogens
Macrolides
65
How do tetracyclines work
reversibly bind to 30S ribosomes, but can damage intestinal flora. teteacycline and doxycycline
66
What is trimethoprim often used to treat
UTI - excreted via urine. can be given on its own or in combination with a sulphonamide
67
What type of antibiotics increase risk of c. diff in vulnerable patients
broad spectrum
68
Never combine ...
bacteriostatic and bacteriocidal
69
What antibiotics are avoided?
``` 4 Cs Cephalosporins Co-amoxiclav Clindamycin Ciprofloxacin ```
70
What is natural resistance?
Absence of target required for antibiotic or presence of persistor cells or biofilms - antibiotics cannot reach inside of these
71
how is antibiotic resistance passed onto other bacteria?
Horizontal gene transfer
72
What is the difference between cross resistance and multiple resistance
cross resistance is the resistance to related antibiotics where multiple resistance is resistance to unrelated antibiotics
73
3 types of resistance to beta lactams
Penicillinase - penicillin resistant ESBL (extended spectrum beta lactamase) - penicillin and cephalosporin resistant as well as monobactams Carbapenemase - resistance to penicillins, cephalosporins and carbapenems (last resort antibiotics such as colistin)
74
How is resistance increased
unnecessary antibiotics or ones in sub therapeutic doses
75
5Is
``` inhalation ingestion intercourse mother to infant inoculation ```
76
5 hand hygiene moments
``` before patient contact before aseptic task after body fluid exposure after patient contact after patient environment contact ```

MB1: Principles (10 decks)

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