derm - infections and infestations Flashcards
1
Q
what conditions can staph aureus infection cause
A
ecthyma impetigo cellulitis folliculitis: furunculosis, carbuncles staph scalded skin syndrome superinfects other dermatoses
2
Q
how does staphylococcus cause infections
A
expresses virulence factors e.g toxins, haemolysin, leukocidin, peptidoglycan layers etcc that confer pathogenic properties
3
Q
what virulence does strept possess that leads to infections
A
strept pyogenes - attaches to epithelial surface via lipoteichoic acid portion of fimbriae
- has m proteins (antiphagocytic) and hylauronic acide capsule
- produces erthrogenic exotoxins
- produces streptolysins S and O
4
Q
what conditions can strept cause
A
ecthyma cellulitis impetigo erysipelas scarlet fever necrotising fascitis superinfects other dermatoses
5
Q
what is folliculitis
A
follicular erythema - sometimes pustular
can be infectious/non infectious
recurrent cases may arise from nasal carriage of ataph aureus particularly strains expressing pvl
eosinophilic(non infectious) is associated with hiv
6
Q
what are the treatments for follicultis
A
antibiotics - usually flucloxacillin or erythromycin
incision and drainage is required for furunculosis
7
Q
what is difference between furuncle and carbuncle
A
furuncle = deep follicular abcess carbuncle = composes or furuncles and involves adjacent hair follicles
8
Q
why do some patients develop recurrent staph impetigo or recurrent furunculosis
A
have established themselves as part of resident microbial flora (in particular nasal flora) immunodeficiencies : -hypogammaglobulinaemia - chronic granulomatous disease - AIDS - diabetes mellitus
9
Q
what is panton valnetine leukocidin staph aureus
pvlsa
A
beta pore forming exotoxin
causes leukocyte destruction and tissue necrosis
= higher morbididity,mortality and transmissibility
in skin: recurrent and painful abcesses, follliculitis and cellulitis
*often painful, more than one site, recurrent, present in contacts
extracutaneous: necrotising pneumonia, necrotising fascitis and purpura fulminans
10
Q
what are the 5c’s risk of acquiring pvla
A
close contact e.g hugging, contact sports contaminated items crowding cleanliness cuts and grazes
11
Q
what is the treatment for pvla
A
antibiotics - tetracycline
decolonisation e.g chlorhexidine body wash for 7 days
nasal application of mupirocin ointment for 5 days
treatment of close contacts
12
Q
what is psedomonal follicultis
A
associated with hot tub use, swimming pools and wet suits
appears 1-3 days after exposure, as diffuse truncal eruption
causes follicular erythematous papule
rarely - abcesses, lyphangitis and fever
most cases self limited - no treatment req
severe/recurrent cases can be treated with oral ciprofloxacin
13
Q
what is cellulitis
A
infection of lower dermis and subcut tissue
tender swelling with ill defined,blanching erythema or oedema
most causes = strept pyogenes and staph aureus
oedema = predisposing factor
14
Q
what is the treatment for cellulitis
A
systemic antibiotics
15
Q
what is impetigo
A
superficial bacterial infection, stuck on honey coloured crusts overlyig an erosion
caused by strepttococci (non bullous) or staph (bullous)
caused by exfoliative toxins a and b, split epidermis by targeting desmoglein 1.
affects face: perioral, ears and
16
Q
treatment of impetigo
A
treatment with topical and with or without systemic antibiotics
17
Q
what is impetiginisation
A
refers to superficial infections
occurs in atopic dermatitis
typically gold crust and caused by staph aureus
18
Q
what is ecthyma
A
severe form of strept impetigo
-thick crust overlying punch out ulceration surrounded by erythema
usually in lower extremities
19
Q
what is staph scalded skin syndrome
A
usually in neonates, infants and immunocompromised adults
due to exfoliative toxin
infection occurs at distant site i.e conjunctivitis/abcess
organism cannot be cultured from denuded skin
in neonates - kidneys cannot excrete exfoliative toxin quickly
diffuse tender erythema with rapid progression leads to flaccid bullae, wrinkle and exfoliate leaving oozing erythematous base
clinically resembles sjsten
20
Q
what is toxic shock syndrome
A
febrile illness caused by group a staph aureus strain that produces pyrogenic exotoxin tsst1
21
Q
signs and symptoms of toxic shock syndrome
A
fever >38.9
hypotension
diffuse erythema
involvement of: gi,muscular,cns,renal and hepatic systems
mucous membranes - erythema
haematological (plts <1000000)
desquamation of palms ans soles 1-2 wks after resolution of erythema
22
Q
what is erythrasma
A
infection of corynebacterium minutissiumum
well demarcated patches in interriginous areas
initially pink and becomes brown and scaly
23
Q
what is pitted keratolysis
A
pitted erosions of soles
caused by corynebacteria
24
Q
what is pitted keratolysis treated by
A
topical clindamycin
25
what is eryspipeloid
erythema and oedema of hand after handling of raw fish/meat
extends slowly over weeks
caused by erysipelothrix rhusiopathiae
26
what is anthrax
painless necrotic ulcer with surrounding oedema and regional lymphadenopathy (with pain in lymph nodes) at site of contact with hides, bone meal or wool infected with bacillus antracis
27
what is blistering distal dactylitis
rare infection caused by strept pyogenes or staph aureus
typically in young children
1/more tender superficial bullae on erythematous base on volar fat pad of a finger
toes may rarely be affected
28
what is erysipelas
infection of deep dermis and subcutis
casued by beta haemolytic strept or staph aureus
painful
prodrome of malaise,fever and headache
presents as erythematous indurated with sharply demarcated border and cliff drop edge +- blistering
face and limb +- red streak of lymphangitis and local lymphadenopathy
portal of entry must be sought e.g tinea pedis
29
how is erysipelas treated
with intravenous antibiotics
30
what is scarlet fever
disease of children
caused by upper rti with erythrogenic toxin producing strept pyogenes
preceded by sore throat,headache, malaise,chills, anorexia and fever
eruption begins 12-48 hrs later
- blanchable tiny pinkish red spots on chest,neck and axillae
- spread to whole body within 12 hrs
- sandpaper like texture
31
what are some complication of scarlet fever
```
otitis
mastoiditis
sinusisitis
pneumonia
myocarditis
hepatitis
meningitis
rheumatic fever
acute glomerulonephritis
```
32
what is necrotising fasciitis
initial dusky induration (usually of limb) followed by rapid painful necrosis of skin, connective tissue and muscle
- potentially fatal
usually synergistic: strept,,staph,enterobacteriacae and anaerobes
33
treatments/diagnosis for necrotising fasciitis
prompt diagnosis essential followed by broad spectrum parenteral antibiotics and surgical debridement
mri can aid diagnosis
blood and tissue cultures determine organisms and sensitivities
mortality is high
can affect scrotum - fourniers gangrene
34
what is atypical mycobacterial infection
important cause of infection in immunocompromised states
- mycobacterium marinum causes indolent granulomatous ulcers(fish- granuloma) in healthy people, sporotrichoid spread
- mycobacterium chelonae and abcesses - puncture wounds, tattoos, skin trauma or surgery
- mycobacterium ulcerans - important cause of limb ulceration in africa (buruli ulcer) or australia (searles ulcer)
35
what is borreliosis(lymes disease)
annular erythema develops at site of borrelia infected tick
bite form ixodes tick infected with borrelia burgdorferi
initial cutaneous manifestations - erythema migran - only 75%
- erythematous papule at bite site
- progression to annular erythema of >20cm
36
what can occur 1-30 days after infection, fever and headache in lyme disease
multiple secondary lesions develop - similar but smaller to initial lesions
- neuroborreliosis: facial palsy/other cn palsies, asesptic meningitis, polyradiculitis
- arthritis - painful and swollen large joints
- carditis
37
how to diagnose lyme disease
serology not sensitive and histology is non specific therefore high index of suspicion is used to make diagnosis and based of clinical features
38
what is tularaemia
caused by francesella tularensis
acquired through: handling infected animals,tick bites and deerfly bites
- ulceroglandular form
- primary skin lesions is small papules at innoculation site that rapidly necrosis leading to painful ulceration
+- local cellulitis
painful regional lymphadenopathy
39
what are the systemic features of tularaemia
fever, chills, headache and malaise
40
what is ecthyma gangrenosum
pseudomonas aeruginosa
usually occurs in neutropaenic patients
red macules - oedematous - haemorrhagic bullae
- may ulcerate in late stages/form eschar surrounded by erythema
41
what is syphilis
caused by treponema pallidum
primary infection chancre - painless ulcer with firm indurated border
painless regional lymphadenopathy one week after primary chancre
chancre appears within 10-90 days
42
what is secondary syphilis
```
begins 50 days after chancre
skin manifestations:
pityriasis rosea like rash
allopecia
mucous patches
lymphademopathy
residual primary chancre
condylomata lata
hepatosplenomegaly
```
43
symptoms of secondary syphilis
| systemic symptoms
```
malaise
fever
headache
pruritus
loss of appetite
iritis
```
44
what is lues maligna
rare manifestation of secondary syphilis
pleomorphic skin lesions with pustules,nodules and ulcers with necrotising vasculitis
more frequent in hiv maifestations
45
what is tertiary syphilis
glumma skin lesions - nodules and plaques
extend peripherally while central areas heal with scarring and atrophy
mucosal lesions extend to and destroy nasal cartilage
can also develop cvd and neurosyphilis
46
how to diagnose syphilis
clinical findings
serology
strong index of suspicion required in secondary syphilis
47
what is the treatment for syphilis
im benzylpenicillin or oral tetracycline
48
what is leprosy
caused by mycobacterium leprae
| obligate intracellular bacteria - predominantly affects skin and nerves but can affect any organ
49
what is the difference between lepromatous leprosy and tuberculoid leprosy
lepromatous :
- multiple lesions: macules,papules and nodules
sensation and sweating normal early on
tuberculoid: solitary or few lesions with elavated borders, atrophic center sometimes annular
hairless,anhidrotic,numb
50
what is tuberculosis
can affect any organ incl skin
only 5-10% lead to clinical disease
caused by mycobacterium tuberculosis
51
how can cutaneous tuberculosis be acquired
exogenously - primary innoculation tb and tuberculosis verrucosa cutis
contigous endogenous spread - scrofulderma or autoinnoculation can develop into periorificial tuberculosis
haematogenous/lymphatic endogenous spread - dissemination( lupus vulgaris, miliary tb, gummas)
52
what are the investigations for tuberculosis
interferon gamma release assay
histology - zn stain
culture/pcr
53
what is tuberculous chancre
- painless, firm, reddish brown papulonodule that forms ulcer
54
what is tuberculosis verrucosa cutis
wart like papule that evolves to form redbrown plaque
55
what is scrofulderma
subcutaneous nodule with necrotic material - becomes fluctuant and drains, with ulceration and sinus tract formation
56
what is orificial tb
non healing ulcer of nasal mucosa that is painful
57
what is lupus vulgaris
red brown plaque +- central scarring and ulceration
58
what is miliary tb
pinhead sized, bluish red papules capped by minute vesicles
59
what is tuberculous gumma
firm subcutaneous nodules, later ulcerates
60
what is molluscum cantagiosum
poxvirus infection
common in children and immunocompromised
usually resolves spontaneously
61
what is the differential diagnosis for molluscum contagiosum
verrucae
condyloma acuminata
basal cell carcinoma
pyogenic granuloma
62
what are the treatment options for molluscum contagiosum
curettage
imiquimod
cidofovir
63
what is herpes simplex virus
primary and recurrent vesicular eruptions
favour orolabial and genital regions
transmission can occur even during asymptomatic periods of viral shedding
64
how does hsv 1 spread
direct contact with contaminated saliva/ other oral secretions
virus replicates at mucocutaneous site of infection
travels by retrograde axonal flow to dorsal root ganglia
65
how does hs2 spread
sexual contact
66
what are the symptoms of hsv
symptoms occur within 3-7 days of exposure
preceded by tender lymphadenopathy, malaise, anorexia +- burning and tingling
painful rouped vesicles on erythematous base -> ulceration/pustules/erosions with scalloped border
crusting and resolution within 2-6 weeks
orolabial lesions - often asymptomatic
genital involvement - often excruciatingly painful -> urinary infection
systemic manifestations - aseptic meningitis in upto 10% of women
reactivation - spontaneous, uv, fever, local tissue damage, stress
67
what is eczema herpeticum
emergency
| monomorphic punched out erosions - excoriated vesicles
68
how is eczema herpeticum treated
intravenous acyclovir accompanies by antibiotics for superinfections with staph aureus or strept
69
whatis hepatic whitlow
hsv 1>2 infection of digits - pain swelling and vesicles
misdiagnosed as paronychia or dactylitis
often in children
70
what is hepres gladiatorum
hsv1 involvment of cutaneous site reflecting sites of contact with another athletes lesion
contact sports e.g wrestling
71
what is neonatal hsv infection
exposure to hsv during vaginal delivery - risk higher when hsv acquired near time of delivery
hsv1/2
onset from birth to 2 wks
locally usually - on scalp/trunk
vesicles - bullae erosions
encephalitis - mortality >50% without treatment, 15% with treatment, can lead to neurological deficits
72
how to treat neonatal hsv
requires iv antivirals
73
what is severe/chronic hsv
immunocompromised patients e.g hiv/transplant recipients
most common presentation - chronic enlarging ulceration
often atypical e.g verrucous, exophytic or pustular lesions
involvement of resp/gi tract can occur
74
how to diagnose for hsv
swab for polymerase chain reaction
75
what is treatment for hsv
dont delay!
oral valacyclovir/acyclovir 200mg 5 times daily in immunocimpetent localised infections
intravenous 10mg/kg tds
76
what is varicella zoster virus
is dermatomal disease
| can affect singledermatomes or multidermatomal
77
what is hand foot and mouth disease
caused by coxackie a16, echo71
an acute self limiting coxsackievirus infection
prodrome of fever, malaise and sore throat
spread by direct contact via oral oral route and oral faecal route
78
how does hand foot and mouth disease present
red macules, vesicles and ulcers develop on buccal mucosa, tongue,palate and pharynx - may also develop on hand and feet
79
what viruses cause morbilliform( measle like) eruptions
```
measles
rubella
ebv
cmv
hhv6
hhv7
leptospirosis
rickettsia
```
80
what causes petechial/purpura infestations
coagulation abnormalities
vasculitis
infections
viruses - hep b, cmv, rubella, yellow fever, dengue fever, west nile virus
bacterial - borrelia, rickettsia, neisseria,endocarditis
other: plasmodium falciparum, trichnella,ten,ergot poisoning raynauds
81
what is giannoti crosti syndrome
papular acrodermatitis of childhood
viral eruption that causes acute symmetrical erythematous papular eruption on face,extremities and buttocks - usually age 1-3 yrs
82
what are the causes of gianotti crosti syndrome
```
ebv - most common
cmv
hhv6
coxsackie virus a16,b4,b5
hep b
```
83
what is erythema infectiosum
parovirus b19
initially mild fever and headache
few days later = slapped cheeks for 2-4 days
ten reticulated rash of chest and thighs in 2nd stage
84
what is roseola infantum
```
aka exanthem subitum aka 6th disease
common in children
2-5 days high fever
followed by appearance of small pale pink papules on trunk and head
last hrs to 2 days
caused by hhv6 and hhv7
```
85
what is orf
Caused by parapoxvirus
direct exposure to sheep or goats
dome shaped, firm bullae that develop umbilicated crust
usually develop on hands and forearms
generally resolve without therapy in 4-6 wks
86
what are warts
caused by 200 subtypes of hpv
87
what are superficial fungal infections caused by
| pity:
hypopigmented, hyperpigmented or erythematous macular eruption +- fine scale
caused by malassezia spp
begins during adolescence when sabaceous glands become active
flares when temperatures and humidity are high - immunosuppression
88
what are superficial fungal infections treated with
topical azole
89
what are dermatophytes
fungi that live on keratin
90
what causes the most fungal infections
trichophytan tonsurans
91
what is kerion
an inflammatory fungal infection that may mimic a bacterial folliculitis or an abscess of scalp.
scalp is tender and patient usually has posterior cervical lymphadenopathy
- frequently secondarily infected with staph aureus
92
what is tinea pedis
```
trichophyton rubrum - scaling and hyperkeratosis of plantar surface of food
trichophyton mentagrophytes( interdigitale) - sometimes vesiculobullous reaction on arch/side of foot
```
93
what is an id infection
aka dermatophytid reaction
inflammatory reactions at sites distant from associated dermatophyte infection
may include urticaria, hand dermatitis or erythema nodosum
likely secondary to host immunologic response against fungal antigens
94
what us majocchi granuloma
follicular abscess produced when dermatophyte infection penetrates follicular wall into surrounding dermis: tender
trichophyton rubrum/ mentagrophytes are usually culprit
95
what is candidiasis
caused by candida albicans
predisposed by occlusion, moisture, warm temp, diabetes m
most sites show erythema oedema, thin purulent discharge
usually an intertriginous infection (affecting axillae, submammary folds, cururae and digital clefts) or of oral mucosa
common cause of vulvovaginitis
may affect mucosae
can be systemic - immunocompromise
96
what are deep fungal infections
```
capacity for deep invasion of skin or production of skin lesions secondary to systemic visceral infection
subcutaneous fungal infections - infections of implantations (inoculation)
- sporotrichosis
- phaeohypomycosis
- chromomycosis
- mycetoma
- lobomycosis
- rhinospordiosis
```
97
what do systemic resp endemic fungal infections include
```
blastomycosis
histoplasmosis
coccidiomycosis
paracoccidoiomycosis
penicillinosis
disease in both immunocompetent and immunosupressed
```
98
what is a risk factor for aspergillosis
neutropaenia and corticosteroid therapy
99
what is aspergillosis
primarily resp pathogen
cutaneous lesions being well circumscribed papule with necrotic base and surrounding erythematous halo
propensity to invade blood vessels causing thrombosis and infarction
lesions destructive - may extend into cartilage, bone and fascial planes
should be considered in differential of necrotising lesions
fusarium causes similar illness and cutaneous lesions both clinically and histologically
100
what is presentation of mucormycosis
fever, headache, facial oedema, proptosis, facial pain, orbital cellulitis +- cranial nerve dysfunction
101
what can mucormycosis be caused by
apophysomyces, mucor, rhizopus, absidia, rhizomucor
102
what are the associations with mucormycosis
```
diabetes mellitus
malnutrition
neutropenia
meds: steroids/antibiotics/desferoxamine
burns
hiv
```
103
what is the treatment for mucormycosis
aggressive debridement and antifungal therapy
| - culture positive in only 30% of cases
104
what are scabies
contagious infestations caused by sarcoptes species
female mates, burrows into upper epidermis, lays eggs and dies after one month
affects interdigital areas of digits, volar wrists, axillary areas, genitalia
105
what is hyperkeratosis
crusted/norwegian scabies
| often asymptomatic - found in immunocompromised individuals
106
what is the treatment for scabies
permethrin
oral ivermectin
- 2 cycles of treatment are required
107
what are head louse
pediculus humanus capitis
entire life cycle spent in haor
secondary infection common
108
what is the treatment for head louse
malathion
permethrin
oral ivermectin
109
what is body louse
pediculus humanus corporis
lives and reproduces in clothing - lives to feed, rarely found on skin
- pruritic papules and hyperpigmentation
- found in overcrowding, poverty and poor hygiene
- eliminated by thorough cleaning/discarding clothes
110
what is pubic louse
phithrus pubis aka crabs - 3 pairs of legs
| eggs found on hair shaft, also found in occipital scalp, body hair, eyebrow and eyelash, axillary hair
111
what is the treatment for pubic louse
malathion/permethrin
| oral ivermectin
112
what are bedbugs
climex lectularis - reddish browb, wingless insect
| itch weals around central punctum
