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Dermatology > Microbiology > Flashcards

Microbiology Flashcards

1
Q

Gram positive cocci in clusters = ?
What are the two types?
Give an example of each

A

Staphylococcus sp

  1. Staph. aureus (coagulase positive-golden)
  2. Coagulase negative Staph (Staph. epidermidis, Staph. saprophyticus etc.)
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2
Q

What distinguishes staph aureus from all other staph species?

A

Produces enzymes, including coagulase, an enzyme that clots plasma; this distinguishes it from all other Staph. species

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3
Q

Staph epidermis = what type of staph?

A

Coagulase negative

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4
Q

UTI in women of childbearing age = which pathogen?

A

Staph. saprophyticus

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5
Q

Gram positive cocci in chains = ?

A

Streptococcus species

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6
Q

How are streptococcus species classified?

A

Classified initially by haemolysis on blood agar
• β(beta)-haemolytic (complete haemolysis) - clear
- Group A
- Group B
• α(alpha)-haemolytic (partial haemolyis) - green
• γ(gamma) or non-haemolytic (no haemolysis)

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7
Q

Alpha haemolytic strep

  • What sort of infections?
  • Which twp important species to remember?
A

Throat, severe skin

  • Strep. pneumoniae - pathogen, commonest cause of pneumonia
  • Strep. “viridans” - commensals of mouth, throat, vagina - rarely cause infection
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8
Q

Which infection does group B beta haemolytic strep cause?

A

Meningitis in neonates

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9
Q

Which bug tends to cause necrotizing fasciitis?

A

Strep pyogenes

GABHS

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10
Q

What are the two types of necrotizing fasciitis?

A

Type I – mixed anaerobes & coliforms, usually post-abdominal surgery
Type II – group A Strep infection – should be worried about this one

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11
Q

What is the most common cause of dermatophyte (fungal) infection?

A

Trichophyton rubrum

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12
Q

How can you diagnose dermatophyte infections?

A
  1. Woods light (fluorescence)

2. Skin scrapings, nail clippings, hair - send to laboratory in a “Dermapak” for microscopy and culture

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13
Q

Treatment for dermatophyte infection

  • Small areas of infected skin, nails?
  • Scalp infections?
A 
Small areas of infected skin, nails
- Clotrimazole (Canestan) cream or similar
- Topical nail paint (amorolfine)
Scalp infections
- Terbinafine orally
- Itraconazole orally
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14
Q

Where does candida cause skin infection?

Treatment?

A

Candida causes infection in skin folds where area is warm and moist “candida intertrigo”
Seen under the breasts in females, groin areas, abdominal skin folds etc, nappy area in babies
Treatment – clotrimazole cream, oral fluconazole

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15
Q

Organism in scabies?
Incubation period?
Treatment?

A

Sarcoptes scabei
6 weeks
Malathion lotion, applied overnight to whole body and washed off next day
Benzyl benzoate (avoid in children)

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16
Q 
What is Pediculosis?
- Captis?
- Corporis?
- Pubis?
Treatment?
A 
Lice (Pediculosis)
- Pediculus capitis (head louse)
- Pediculus corporis (body louse) - Vagabond’s disease
- Phthirus pubis (pubic louse)
Associated with intense itch
Treatment - malathion
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17
Q

Which patients need single room isolation and contact precautions?

A
  • Patients with Group A Strep infection
  • Patients with meticillin(flucloxacillin)-resistant Staph aureus (MRSA) infection
  • Patients with Scabies (N.B. long sleeved gowns also required for Norwegian scabies)
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18
Q

Varicella zoster virus

  • Causes which two infections?
  • Which is which?
A 
Chickenpox + shingles 
Chickenpox is Varicella
- Primary infection
- Typically in childhood
- Generalised rash and fever
- Virus establishes latency
- Sensory nerve roots
Shingles is Zoster
- Reactivation, typically in old age
- Dermatomal
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19
Q

Clinical features of chickenpox?

A 
Macules to papules to vesicles to scabs to recovery
- centripetal
- density varies
- inflamed skin
Fever
Itch
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20
Q

Give some complications of chickenpox.

Give two predictors of severity?

A 
Complications
- secondary bacterial
- pneumonitis
- haemorrhagic
- scarring, absent or minor
- encephalitis
Predictors of severity
- extremes of age
- depressed cell mediated immunity
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21
Q

Neonatal varicella zoster virus

  • Secondary to what?
  • Complication?
  • Prevention?
A

Secondary to chickenpox in mother in late pregnancy
Higher mortality
Prevention with Varicella Zoster Immune Globulin in susceptible women in contact

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22
Q

In who is there an increased incidence and severity of shingles?

A

Elderly

Immunocompromised

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23
Q

What is post herpetic neuralgia?

A

Neuralgic pain from shingles which lasts >4 weeks

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24
Q

Lower thoracic dermatomal rash in an infant = which virus?

A

Herpes zoster

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25
Q

Ramsay-Hunt syndrome
Clinical features?
Aka?

A
  • Vesicles and pain in auditory canal and throat
  • Facial palsy (7th nerve palsy)
    Poorer prognosis than Bell’s palsy (idiopathic 7th nerve palsy)
  • Irritation of the 8th cranial nerve
  • Deafness
  • Vertigo
  • Tinnitus
    Also known as geniculate or otic herpes zoster
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26
Q

What type of vaccine is chickenpox one?

Who gets it in the UK?

A

Live attenuated

70 year olds

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27
Q

Give some features of type 1 and type 2 herpes simplex viruses

A 
HSV Type 1
- main cause of oral lesions
- causes half of genital herpes
- causes encephalitis
HSV Type 2
- rare cause of oral lesions
- causes half of genital cases
- encephalitis / disseminated infection (particularly in neonates)
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28
Q

Treatment of VZV and HSV?

  • How does it work?
  • Latent virus?
A

Aciclovir
It is selectively incorporated into viral DNA inhibiting replication
Does not eliminate latent virus

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29
Q

Target lesions with erythema = ?

Triggers?

A

Erythema multiforme
Many triggers including drug reactions and some infections
- Herpes simplex virus
- Mycoplasma pneumoniae bacterium

30
Q 
Fleshy, firm, umbilicated, pearlescent nodules
1 to 2 mm diameter = ?
- Natural history?
- Who gets it?
- Transmission?
- Treatment?
A

Molluscum contagiosum

  • Self limiting but take months to disappear
  • Common in children
  • Can also be sexually transmitted
  • Can be treated with local application of liquid nitrogen
31
Q

Warts

  • Pathogen? Which types?
  • Treatment?
A 
Human papilloma virus
Types 1-4 most common in warts/verrucas
Commonest in children
Self limiting, uncomplicated
Topical salicylic acid
32
Q

Cervical cancer

- Which virus and which types?

A

HPV

Types 16 and 18

33
Q

Blistering rash of back of mouth = ?
Which virus?
- Treatment?

A 
Herpangia
Caused by enterovirus not herpes virus
- coxsackie virus
- echovirus
Self-limiting
Swab of lesion, sample of stool for enterovirus PCR
34
Q

Pathogen in hand, foot and mouth disease?

A

Enteroviruses - most commonly coxsackie virus

35
Q

Child with red rash on cheek followed by lacy macular rash on the body, followed by acute arthritis = ?
Pathogen?

A

Erythema infectiosum

Parivirus B19

36
Q

Give 3 complications of parovirus B19

A
  1. Spontaneous abortion
  2. Aplastic crises - sudden drop in haemoglobin
  3. Chronic anaemia
37
Q

Test for parovirus B19?

A

By antibody testing rather than skin swabs

parvovirus B19 IgM test

38
Q

Firm, fleshy nodule on hands of farmers = ?

Disease of which animal?

A

Orf

Virus of sheep “scabby mouth”

39
Q

Syphilis

- Describe the primary vs secondary vs tertiary infection

A 
Primary infection
- Chancre
- Painless ulcers at site of entry
Secondary phase of infection
- Red rash over body
- Prominent on soles of feet and palms of hands
- Mucous membrane “snail track” ulcers
Tertiary
- CNS, cardiovascular, gummatous etc
40
Q

What is the pathogen in syphilis?

Treatment?

A

Due to sexually transmitted infection with bacterium Treponema pallidum
Treated using injections of penicillin

41
Q

Pseudomembranous lesions and erosions of the tongue, the hard and soft palate, and tonsils = ?

A

Secondary syphilis

42
Q

Lyme disease

  • Vector?
  • Pathogen?
  • Presentation?
  • Treatment?
A
  • Vector = Ticks
  • Cause: bacterial - Borrelia burgdorferi
    Presentation
  • Early: erythema migrans
  • Late: heart block, nerve palsies, arthritis
    Therapy: doxycycline or amoxicillin
43
Q

Periorbital rash, joint pain, headache = ?

A

Lyme’s disease

44
Q

What is erysipelas?

A

Sharply defined superficial skin infection caused by strep pyogenes

45
Q

How is cellulitis treated?

A

Benzylpenicillin IV + flucloxacillin PO

46
Q

What causes celllulitis?

A

Beta haemolytic streps (and sometimes staphs)

47
Q

Which organism causes Lymes disease?

A

Borrelia burgdorgeri

48
Q

Which organisms causes most dermatophyte skin infections?

A

Trichophyton rubrum

49
Q

Treatment for general skin dermatophyte infection?

A

Clotrimazole

50
Q

Treatment for scalp dermatophyte infection?

A

Treat empirically with

  • Oral griseofulvin
  • Oral terbinafine
51
Q

Treatment for candida intertrigo?

A

Clotrimazole cream

Oral fluconazole

52
Q

How is candida albicans differentiated from candida albicans?

A

Oral candida albicans wipes off with a spatula

53
Q

Pityriasis versicolor

  • Causative organism?
  • How does it present?
  • Treatment?
A

Malassezia species
Multiple hypopigmented scaly macules on upper trunk and back
Imidazole BD

54
Q

Where does scabies present in babies?

A

Palms and soles

55
Q

How does Norwegian scabies differ from normal scabies?

A

Same mite, but in elderly/immunocompromised

-> harbour 2 million mites, highly contagious

56
Q

Treatment of headlice?

A

Malathion

57
Q

What is Phthiriasis pubis?

  • How do you get it?
  • Treatment?
A

Crab lice
Often sexually transmitted involving pubic hair
Can also involve eyebrows, lashes, axillae
Topical malathion

58
Q

Which organism causes warts?

A

Human papilloma virus 1-4

59
Q

Treatment of common warts and plantar warts?

A

Salicylic acid (keratolytic)
Cryotherapy
Duct tape

60
Q

What are plane warts?

A

Flat skin coloured or brown lesions which Kobernize in scratch marks and are often resistant to treatment

61
Q

What is the proper name for genital warts?
Pathogen?
Treatment?

A

Condylomata acuminate
Human papilloma virus 6 and 11
Topical imiquimoid, cryotherapy

62
Q

Which pathogen causes hand, foot and mouth disease?

A

Coxsackie virus

63
Q

What is the other name for slapped cheek disease?
Pathogen?
Other skin/body problems?

A

Erythema infectiosum
Parovirus B19
Followed by a lacy macular rash
Acute polyarthritis

64
Q

Pathogen in Zika virus?

A

Aedes aegypti

65
Q

What type of vaccine is the one for chicken pox?

A

Live attenuated

66
Q

Which vaccine is given to prevent shingles?

A

Same live attenuated VZV vaccine used in chicken pox just in a higher titre

67
Q

What happens when herpes simplex spreads to eczema?

A

Eczema herpeticum

68
Q

Treatment of herpes simplex virus?

A

Oral aciclovir

69
Q

Describe the differences between HSV 1 and 2

A 
HSV1 
- Main cause of oral lesions 
- Causes half of genital herpes
- Causes encephalitis 
HSV2
- Rare cause of oral lesions 
- Cause half of genital herpes
70
Q

Target lesions with erythema = ?

Triggers?

A

Erythema multiformae
Triggers:
- HSV
- Mycoplasma pneumoniae

Dermatology (17 decks)

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