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2MB Dermatology > Microbiology > Flashcards

Microbiology Flashcards

1
Q

Define ‘virulence’

A

The ability of an organism to cause disease within a host

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2
Q

Name 5 virulence factors

A 
Adhesin
Impedin
Invasin
Aggressin
Modulin
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3
Q

What are adhesins?

A

Bacterial cell surface components that help the organism stick/adhere to host tissue

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4
Q

What are invasins?

A

Enable organisms to invade host tissue

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5
Q

What are impedins?

A

Help the organism avoid the defence/immune response in host tissue

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6
Q

What are aggressins?

A

Cause direct damage to host tissue + immune cells, affecting the host’s ability to cope with disease in the future

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7
Q

What are modulins?

A

Cause indirect damage to the host by turning the immune system in on itself (host’s immune system causes damage to host tissue)

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8
Q

The nasal strain of Staph. aureus can protect the mucosa. True/False?

A

True

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9
Q

Staph. epidermidis can occupy up to 100% of our skin. True/False?

A

True

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10
Q

Where is the most common entry of Staph. aureus into the body?

A

Nasal entry

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11
Q

Name the 3 particularly important virulence factors of Staph. aureus disease

A

Fibrinogen-binding protein (adhesin)
Leukocidin (kills leukocytes)
TSST-1 (toxin)

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12
Q

Every strain of Staph. aureus carries every virulence factor. True/False?

A

False

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13
Q

Which 2 severe skin diseases is leukocidin associated with?

A

Necrotising fasciitis

Recurrent furunculosis

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14
Q

Leukocidin is more virulent in hospital-acquired MRSA than community-acquired. True/False?

A

False

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15
Q

Give an example of a superantigen released by MRSA

A

TSST-1 (toxic shock)

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16
Q

How exactly do superantigens avoid specific T-cell activation?

A

Bind to MHC II complex on the outside, i.e. not the conventional binding groove

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17
Q

Name 3 skin infections caused by Strep. pyogenes

A

Impetigo
Cellulitis
Necrotising fasciitis

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18
Q

How does the Lancefield system classify different subtypes of Step. pyogenes?

A

M-protein

M1 and M3 are predominant; M3 and M18 cause severe, invasive disease

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19
Q

Which 2 virulence factors are particularly important as adhesins for Strep. pyogenes disease?

A 
Hyaluronic acid (sticky capsule)
CD44 +ve keratinocytes
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20
Q

The bigger the capsule, the less virulent an organism is. True/False?

A

False

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21
Q

Where does impetigo usually affect?

A

Face

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22
Q

Where in the body is Strep. pyogenes normally found?

A

Throat (pharynx)

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23
Q

Which strain of Staph aureus commonly produces abscesses and boils, usually affecting numerous family members at once?

A

PVL (panton valentine leukocidin)

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24
Q

Which group of Strep causes throat and severe skin infections?

A

Group A

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25
Which bacteria cause impetigo?
Staph aureus | Group A Strep (step pyrogenes)
26
Which bacteria tends to cause nectrotising fasciitis?
Group A Strep (pyogenes)
27
What is the treatment of choice for Staph aureus?
Flucloxacillin | MRSA- doxycycline, vancomycin
28
What is the treatment of choice for Strep pyogenes?
Penicillin or flucloxacillin
29
What is necrotising fasciitis?
Bacterial infection spreading under the skin into fascia
30
What is the nickname of necrotising fasciitis?
Flesh-eating bacterial disease
31
Type I necrotising fasciitis is caused by Group A Strep. True/False?
False Type I = mixed anaerobes and coliforms Type II = group A Strep
32
What is the most common skin fungal infection caused by?
Ringworm (Tinea)
33
Tinea pedis is another name for what?
Athlete's foot
34
How is dermatophyte (Fungal) infection caused?
Fungus enters abraded skin and infects keratinised tissue, provoking inflammation and outward lesioning Increased epidermal turnover (scaling) and inflammatory response
35
Which organism is the most common cause of dermatophyte infection?
Trichophyton rubrum
36
How are small areas of dermatophyte infection treated?
Clotrimazole cream | Nail paint
37
How are dermatophyte scalp infections treated?
Terbinafine oral | Itraconzole oral
38
Which parasite causes scabies?
Sarcoptes scabiei
39
Incubation of the scabies parasites takes up to how long?
6 weeks
40
How is scabies treated?
``` Malathion lotion overnight Benzyl benzoate (not in children) ```
41
Chickenpox and shingles are due to which virus?
Varicella zoster
42
Where does varicella zoster become dormant following chickenpox?
Dorsal root ganglia of spine
43
Chickenpox can cause pneumonitis and encephalitis. True/False?
True
44
What is Ramsay-Hunt syndrome?
Reactivation of VZV in CN VII | Causes vesicles and pain in auditory canal and throat
45
What does herpes simplex virus cause around the mouth?
Primary gingivostomatitis | Extensive ulceration
46
What is the treatment of choice for varicella zoster and herpes simplex virus?
Aciclovir
47
Which virus tends to cause warts?
Human papilloma virus
48
Which treatment is effective for warts?
Salicylic acid
49
Which bacterium causes syphilis?
Treponema pallidum
50
How is syphilis treated?
Penicillin injections
51
Is staph aureus coagulase positive or negative?
Positive
52
What is the mode of action of capsule virulence factor?
Antiphygocytic
53
What is the mode of action of fibrogen binding protein virulence factor?
Adhesin
54
What is the mode of action of hawmolysins virulence factor?
Cytolytic (erythrocytes)
55
What is the mode of action of coagulase virulence factor?
Clots plasma
56
What is the mode of action of fibrinolysin virulence factor?
Digests fibrin
57
What is the mode of action of leukocidin (PVL) virulence factor?
Kills leukocytes
58
What is the mode of action of hyaluronidase virulence factor?
Hyaluronic acid (ECM)
59
What is the mode of action of protein A virulence factor?
Antiphagocitic
60
What is the mode of action of epidermolytic toxins A&B virulence factor?
Epidermal splitting/exfoliation
61
What is the mode of action of enterotoxin virulence factor?
Vomiting and diarrhoea
62
What is the mode of action of TSST-1 virulence factor?
Shock rash and dequamation
63
Where does tinea capits effect?
Scalp | Mainly in children
64
What is candida skin infection?
Seen in skin fold areas | ‘Warm and moist’ areas
65
What is the treatment for candida skin infection?
Clotrimazole cream | Oral fluconazole
66
What is scabies and where does it occur?
Itchy rash | Affecting finger webs, wrists and genital areas
67
How does chicken pox present?
Fever and itch Macules> papules > vesicles > scabs > recovery Dangerous in elderly/immunocompromised
68
How does shingles present?
Reaction of virus down one dermatome Erythema> vesicles > crusts More likely in elderly or immunocompromised Tingling and pain
69
What happens when shingles last more than 4 weeks?
Post herpetic neuralgia
70
What is type 1 HSV?
Main cause oral, half genital
71
What is type 2 HSV?
Rare cause oral, half genital
72
What is HPV?
Causes viral warts, genital warts, cervical cancer
73
What is the treatment for warts in HPV?
Salicylic acid | Cryotherapy
74
What is the most common causative organism for tinea?
Trichophyton rubrum
75
What does tinea have a ring appearance?
Heals from the inside out
76
What is the management for tinea?
Small areas- clotrimazole cream | Scalp- oral tebinafine, itraconzole
77
What is the treatment for scabies?
Permethrin- 1st line treatment | Malathion lotion- 2nd line treatment
78
How does Lyme disease appear?
The rash has a characteristic ‘bull’s-eye’ appearance and usually presents 1-2 weeks after the tick bite
79
What is treatment for Lyme disease?
Oral Doxycycline

2MB Dermatology (13 decks)

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