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2019/2020 Alcohol CLASP and Derm > Microbiology > Flashcards

Microbiology Flashcards

Microbiology of dermatological diseases

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Dermatology Board Prep flashcards
1
Q

Are staphs generally coagulase negative or positive and which is the exception?

A

Generally coagulase negative however S. aureus is coagulase positive

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2
Q

Which bacteria may be commensals of the skin?

A

Staph. aureus
Staphylococcus epidermidis
Corynebacterium sp. (diphtheroids)
Propionibacterium

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3
Q

What is the antibiotic of choice for Staph aureus?

A

Flucloxacilin

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4
Q

What drugs ill work against MRSA strains?

A 
Doxycycline
Co-trimoxazole
Clindamycin
Vancomycin
Linezolid (toxic reserve antibiotic)
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5
Q

Which kinds of toxins can different strains of S. aureus produce?

A

Enterotoxin = food poisoning
SSSST
PVL = panton valentine leukocidin

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6
Q

Describe Staphylococcus sp.

A

Gram positive cocci in clusters
Aerobic and facultatively anaerobic
2 imp. types are Staph aureus and coagulase negative Staph

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7
Q

Describe coagulase negative staphs

A

Skin commensals that are not usually pathogenic.

Example is Staph. epidermidis

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8
Q

When may coagulase negative staphs cause infectoin

A

In association with implanted artificial material

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9
Q

Describe Streptococcus sp.

A

Gram positive cocci in chains
Aerobic and facultatively anaerobic
Classified initially by haemolysis in blood

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10
Q

Which toxin is produced by beta haemolytic streptococci?

A

Haemolysin

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11
Q

Which serological group that beta haemolytic are further broken down into is important in skin?

A

Group A

Expample: Strep pyogenes

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12
Q

What are the 2 important categories of alpha haemolytic streptococci?

A

Strep. pneumoniae

Strep. viridans group

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13
Q

Non-haemolytic streptococci are commensals of where?

A

The bowel

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14
Q

What bacterial skin infections can strep pyogenes cause?

A 
Infected eczema
Impetigo
Cellulitis
Erysipelas
Necrotising fasciitis
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15
Q

What will Strep. pyogenes be treated with?

A

Penicillin

Flucloxacillin will often be used as it also covers Staph. aureus

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16
Q

What is necrotising fasciitis?

A

A bacterial infection spreading long fascial planes below the skin causing rapid tissue destruction

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17
Q

What are the 2 types of necrotising fasciitis?

A

Type 1 - mixed anaerobes and coliforms

Type 2 - Group A Strep

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18
Q

When should swabs of leg ulcers be taken?

A

Only if sign of cellulitis or infection are present

Skin has many commensals so treat the ulcer not the lab result

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19
Q

What tissues do dermatophytes infect?

A

Keratinised tissues only

Skin, hair, nails

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20
Q

Describe Dermatophyte pathogenesis

A

Fungus enters abraded soggy skin
Increases epidermal turnover and provokes inflammatory response in the dermis
grows outward and heals in centre giving ring-like appearance

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21
Q

What are the sources of dermatophyte infection?

A

Other infected humans (most likely)
Animals
Soil (less common in UK)

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22
Q

What are the man dermatophyte causal organisms?

A 
Trichophyton rubrum (~70%)
Trichophyton mentagraphytes (~20%)
Microsporum canis
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23
Q

How is diagnosis of dermatophyte infections made?

A

Clinical appearance
Woods light
Skin scraping for microscopy and culture

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24
Q

How is dermatophyte infection treated?

A

Topical cream such as clotrimazole
Nail paint like amorolfine
Terbinafine or itraconazole orally for more extensive cases

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25
Q

Where does candida cause infection?

A

In skin folds were it is warm and moist

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26
Q

How is candida diagosed?

A

Swab for culture

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27
Q

What is scabies caused by?

A

Sarcoptes scabiei

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28
Q

How does scabies present?

A

Intensely itch rash affecting finger webs, wrist and genital area

29
Q

What is the incubation period of scabies?

A

Up to 6 weeks

30
Q

How is scabies treated?

A 
Malthion lotion applied over night to whole body, washed off next day
Benzyl benzoate (avoid in children)
31
Q

What causes chicken pox and shingles?

A

Varicella zoster virus

32
Q

Explain the progression of chickenpox

A

Macules -> papules -> vesicles -> scabs -> recovery

33
Q

What can cause chicken pox to be denser?

A

Already inflamed skin

34
Q

What can pre-dispose to serious chickenpox?

A

Extremes of age

Immunosuppression

35
Q

What causes neonatal VZV

A

Maternal chickenpox late in pregnancy

36
Q

How does shingles present?

A

The reactivation of VZV in a dermatomal distribution

Stars with tingling pain

37
Q

What is the nature of zoster related pain?

A

Neuralgic

38
Q

Which dermatomes is shingles typical in in adults?

A

T or L dermatomes

39
Q

Which dermatomes is shingles typical in in children?

A

Face of S dermatome

40
Q

What is Ramsay Hunt syndrome?

A

Shingles infection affecting the facial nerve, can result in facial palsy

41
Q

How can shingles be prevented?

A

Higher titre of chickenpox vaccine can reduce the impact

Routinely given to 70 year olds

42
Q

What does HSV type 1 cause?

A

Recurrent cold sores typically at the vermilion border

43
Q

What is herpetic whitlow?

A

Cold sore where nail meets finger

44
Q

What is used as VZV and HSV therapy?

A

Aciclovir

45
Q

Does aciclovir eliminate latent virus?

A

It does not eliminate latent virus

46
Q

How does erythema multiforme present?

A

As target lesions with erythema shown

47
Q

How does molluscum contagiosum present?

A

Fleshy, firm, umbilicated, pearlescent nodules

48
Q

Erythema infectiosum is also known as what?

A

Slapped cheek disease

49
Q

What causes Erythema infectiosum?

A

Parovirus B19

50
Q

What are the complications of Erythema infectiosum?

A

Spontaneous abortion
Aplastic crisis
Chronic anaemia in immunosuppressed patients

51
Q

How is erythema infectiosum confirmed?

A

Antibody testing

Parovirus B19 IgM

52
Q

What is Orf?

A

Virus of sheep
Firm fleshy nodules in hands
Self-limiting

53
Q

Is lab confimation necessary for Orf?

A

No, clinical diagnosis is made

54
Q

How does primary infection of syphilis manifest?

A

Chancre

Painless ulcer at site of entry

55
Q

How does secondary infection of syphilis manifest?

A

Red rash over body, prominent on soles of feet and palms

“Snail track” ulcers on mucous membranes

56
Q

What is the vector for Lyme disease?

A

Ticks

57
Q

What pathogen causes Lyme disease?

A

Borrellia burgdorfi

Bacterial

58
Q

What is the early presentation of Lyme disease?

A

Erythema migrans

59
Q

What is the late presentation of Lyme disease?

A

Heart block
Nerve palsies
Arthritis

60
Q

What is the therapy for Lyme disease?

A

Doxycycline or Amoxicillin

61
Q

How many people infected with Zika virus become ill

A

~ 1 in 5

62
Q

What are the symptoms of Zika virus?

A 
Fever
Mild rash
Headaches
Arthralgia
Conjunctivitis
Presentation similar to dengue
63
Q

What are complications of Zika virus?

A

Microcephaly

Guillain Barre Syndrome

64
Q

What causes Toxic Shock Syndrome?

A

TSS toxin producing Staph aureus

65
Q

How does toxic shock syndrome present?

A

Fever
Hypotension
Diffuse macular erythematous rash followed by desquamation of the skin

66
Q

What is a super-antigen of S. aureus?

A

TSST-1

67
Q

What are important virulence factors of group A streptococci?

A

M surface proteins

68
Q

Why are M surface proteins important virulence factors in group A streptococci?

A

They inhibit opsonisation

69
Q

What is a super antigen of Strep. pyogenes?

A

Pyrogenic exotoxins

Produced by lysogenic strains

2019/2020 Alcohol CLASP and Derm (4 decks)

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