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Charis & Ellie vs Dermatology > Infectious Diseases > Flashcards

Infectious Diseases Flashcards

1
Q

what patients need single room isolation and contact precautions?

A

Patient with group A strep infection

Patients with MRSA infection

Patients with scabies (also need long sleeved gowns)

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2
Q

Bacterial skin infections

A

necrotising fasciitis staph aureus strep pyogenes

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3
Q

what is necrotising fasciitis?

A

bacterial infection which spreads along the fascial planes below the surface of the skin causing rapid tissue destruction very painful

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4
Q

What are the 2 types of necrotising fasciitis?

A

Type 1: mixed bacteria, usually post-abdominal surgery Type 2: group A strep infection

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5
Q

what is a common example of necrotising fasciitis getting into the skin?

A

infected leg ulcers - treat the anaeorbes especially if diabetic

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6
Q

What is a virulence factor?

A

protein components which impact the pathology process of an infection - they can vary between species of bacteria they change quickly - similar to antibiotic resistance

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7
Q

examples of virulence factors

A
  • Adhesin: enables binding of the organism to host tissue, collagen-binding proteins and fibrinogen-binding proteins are types of adhesins
  • Impedin: enables the organism to avoid host defence mechanisms
  • Aggressin: causes direct damage to the host
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8
Q

staph aureus

A

a gram +ve, coagulase +ve superficial infections are self-limiting systemic infections are life-threatening

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9
Q

what does staph aureus do in terms of skin infection?

A

Toxinoses: toxic shock, scalded skin syndrome Toxinoses [TSS-1] is a superantigen which is especially associated with toxic shock (e.g. from menstrual tampons), there is a massive release of cytokines and an inappropriate immune response Panton-valentine leukocidin [PVL] is a cytotoxin released by some strains of staph aureus which is associated with severe skin infections, can cause necrotising pneumonia

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10
Q

Strep pyogenes

A

Gram +ve
Beta-haemolysis
Lance field surface antigen and superantigens

GAS - group A streptococci

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11
Q

what skin infections are caused by strep pyogenes?

A

Impetigo [honey coloured crust, can also be caused by staph aureus, can be treated with flucloxacillin/fusidic acid]
Cellulitis [erysipelas]
Necrotising fasciitis

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12
Q

pathogenesis of strep pyogenes

A

streptolysin S - destroys immune cells virulence factors of strep pyogenes - damage the immune system Virulence varies through horizontal gene transfer e.g. throat infection [bacterial], Scarlett fever [Scarlett fever has symptoms like strawberry tongue, treated with penicillin]

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13
Q

why do anti-inflammatory drugs sometimes work?

A

some pathogens can use the immune response to get nutrients

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14
Q

causes of fungal skin infections?

A

ring worm candida

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15
Q

what is ring worm?

A

dermarophyte fungal infection

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16
Q

where in the body do you get ring worm?

A

Tinea: capitis (scalp, usually in children), barbae (beard), corporis (body), manuum (hand), unguium (nails), cruris (groin), pedis (foot - ‘athlete’s foot’, very common in those who have cellulitis)

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17
Q

who gets ring worm?

A

males more common - especially tinea cruris and tinea pedis

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18
Q

Where do you catch ring worm?

A

other infected humans (anthropophilic fungi), animals (zoophilic) and soil (geophilic fungi, this is less common in the UK)

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19
Q

Pathogenesis of ring worm?

A

fungus enters abraded/saggy skin, hyphae (part of the fungus) spreads in the keratin layer - it only infects keratinised tissues (hair, skin, laters), this causes increased epidermal turnover leading to scaling which provokes the inflammatory response in the dermis

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20
Q

how does ring worm present?

A

a ring appearance due to the lesion growing outward with healing in the centre

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21
Q

How is ring worm diagnosed?

A

clinical appearance woods light appearance skin scrapings - from the scaly edge of the lesion nail clippings, hair - send these in a dermapak

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22
Q

How is ring worm treated?

A

small areas of infected skin/ nails = clotrimazole (canestan) cream or topical nail paint (amorolfine) extensive skin/ nail infections, scalp infections = oral terbinafine, oral itraconazole

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23
Q

what is candida?

A

a fungal infection

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24
Q

what is candida intertrigo

A

infection in skin folds - under breasts, groin, abdominal skin folds, nappy rash in babies) patients commonly obese

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25
why does candida intertigo infect skin folds?
because those areas are warm and moist
26
how is candida intertigo diagnosed?
swab for culture
27
how is candida intertigo treated?
clotrimazole cream oral fluconazole
28
What skin infections are caused by parasites?
scabies lice
29
What are scabies?
Caused by sarcoptes scabiei [Chronic crusted form = Norwegian scabies] Has an incubation period of up to 6 months
30
how does scabies present?
very itchy rash can cause burrows affect finger webs wrists genital area
31
how is scabies treated?
Permethrin cream (topical insecticide) Malathion lotion (overnight, whole body - washed off next day), Benzyl benzoate (avoid in children)
32
what are the types of lice?
• Pediculus: capitis (head), corporis (body - can cause vagabond’s disease), phthirus pubis (pubic)
33
how do lice present?
intense itch
34
how are lice treated?
malathion lotion
35
what skin diseases are caused virally?
chicken pox neonatal VZV shingles herpes simplex virus rasmay-hunt syndrome erythema multiforme molluscum contagiosum warts HPV
36
what is chickenpox?
caused by the varicella zoster virus (varicella) it is a primary infection normally during childhood
37
how does chicken pox present?
general rash fever affects sensory nerve roots - ich macules which become papules which then become vesicles - lead to scabs and then recover virus establishes latency
38
potential complications of chickenpox
secondary bacterial infection pneumonitis haemorrhagic rash scarring enecphalitis more severe if extremes of age - adult chickenpox can cause varicella pneumonia
39
how is chickenpox managed?
there is a vaccine but it is not routine in children in the UK used in susceptible healthcare workers
40
what is neonatal VZV?
secondary to chickenpox in mother in late pregnancy higher mortality
41
how is neonatal VZV prevented?
if mother has chickenpox late in pregnancy give her VZ immune globulin or aciclovir
42
What is shingles?
caused by varicella zoster virus (zoster/herpes zoster) reactivation of the VZV unusally in old age - incidence and severity increased in the immunocompromised and the elderly - greater age = greater pain
43
how does shingles present?
starts with tingling and pain erythema develops - then vesicles - then crusts dermatomal distribution scarring isn't common
44
what kind of pain does shingles have?
neuralgic pain if it goes beyond week 4 - this is called post herpetic neuralgia (usually in the elderly, has a trigeminal distribution)
45
potential complication of shingles?
• Can affect ophthalmic (this can happen in children esp. if chickenpox in utero or if they become immunocompromised), maxillary and mandibular divisions of the trigeminal nerve
46
how is shingles prevented?
• Vaccine which is routine in 70 yr olds
47
what is ramsay-hunt syndrome?
Caused by varicella zoster virus (herpes zoster) Reactivation of VZV Also known as geniculate/otic herpes zoster
48
how does ramsay-hunt present?
vesicles, pain in auditory canal and throat, facial (7th nerve) palsy, irritation of the 8th cranial nerve [vestibulocochlear] causes deafness, vertigo, tinnitus (hearing noises that are not caused by an outside source)
49
what is herpes simplex virus?
50% will have it before they're adults, can be asymptomatic - usually in pre-school children
50
how does herpes simplex virus present?
primary gingivostomatitis, extensive ulceration in and around the mouth, lasts around a week, can get recurrent, blistering rash at vermilion border (border between lips and skin) Herpetic whitlow = when is spreads to the fingers Eczema herpeticum = can be life-threatening
51
what are the 2 types of herpes simplex virus?
HSV type 1 - main cause of oral lesions - can cause genital herpes and encephalitis HSV type 2 - especially occurs in neonates, can cause genital herpes and encephalitis
52
How is HSV treated?
aciclovir
53
What is erythema multiforme?
caused by drug reactions and some infections (HSV, mycoplasma pneumoniae bacterium)
54
How does erythema multiforme present?
target lesions with erythema
55
what is molluscum contagiosum?
it is common in children can also be sexually transmitted (appears around the genitals)
56
how does molluscum contagiosum present?
fleshy firm umbilicated pearlescent nodules (1-2mm diameter)
57
How is mollusum contagiosum treated?
self-limiting (takes months to disappear) can be treated with local application of liquid nitrogen
58
what are warts?
caused by human papilloma virus (HPV) called verrucas if on feet a wart is an infection of keratinocytes - skin barrier is damaged in people with warts
59
who gets warts?
common in children can be sexually transmitted
60
how are warts treated?
self-limiting but can use topical salicyclic acid
61
types of HPV
80 different types of HPV HPV 6 and 11 = genital warts HPV 16 and 18 = cervical cancer (there is now a vaccine for this)
62
what is herpangina?
caused by enterovirus
63
how does herpangina present?
blistering rash of back of mouth
64
how is herpangina managed?
Self-limiting swab of lesion and sample of stool for enterovirus PCR
65
what is hand, foot and mouth disease?
Caused by enterovirus (esp. coxsackie) Typically children, usually have family outbreaks
66
What is erythema infectiosum?
aka slapped cheek caused by parovirus B19
67
what complications does erythema infectiosum cause?
Commonly causes acute arthritis (esp. in wrists) as the rash fades (esp. in adults)
68
what are the complications of parovirus B19?
Spontaneous abortion Aplastic crises (sudden drop in haemoglobin) Chronic anaemia
69
how is erythema infectiosum diagnosed?
antibody testing (parvovirus B19 IgM test)
70
what is orf?
scabby mouth which is caused by sheep virus it is on the hands of farmers
71
how does orf present?
firm fleshy nodules on the hands self-limiting condition with a clinical diagnosis
72
what is syphilis?
it is due to an STI - bacterial infection Treponema pallidum more common in male-male sex
73
how does syphilis present?
Primary infection: chancre (painless ulcers, genitals and mouth) Secondary phase of infection: red rash over body (prominent on soles of feet and palms of hand), mucous membrane ‘snail track’ ulcers) Tertiary: CNS and cardiovascular involvement, gummatous (non cancerous tumour specific to syphilis)
74
how is syphilis diagnosed?
blood test swab of chancre for PCR
75
how is syphilis treated?
injections of penicillin
76
what are the potential complications of syphilis?
pulsatile chest swelling
77
what is lyme disease?
Bacterial infection (Borrelia burgdorferi), the vector is ticks
78
how does lyme disease present?
Early = erythema migrans (look up pic) Late = heart block, nerve palsies, arthritis
79
how is lyme disease treated?
amoxicillin or doxycycline
80
what is the zika virus?
1 in 5 people infected with zika get ill Caused by Aedes aegypti (yellow fever mosquito) Usually tropical countries (endemic), can be sexually transmitted
81
how does the zika virus present?
similar to dengue and chikungunya infection (both of which are also caused by the yellow fever mosquito), mild fever, maculopapular rash (flat, red area covered with small confluent bumps), headaches, arthralgia, myalgia, non-purulent conjunctivitis
82
what are the potential complications of zika virus?
severe disease which requires hospitalisation or is fatal is rare microcephaly (head smaller than normal) Guillain Barre syndrome (autoimmune, attacks healthy nerve cells in the PNS)
83

Charis & Ellie vs Dermatology (26 decks)

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