Skin, rashes and infections Flashcards
What is chickenpox also known as?
herpes zoster
What causes chickenpox?
varicella zoster
What is the incubation period of chickenpox?
1-3 weeks
What is the prodrome for chickenpox?
nausea myalgia anorexia headache malaise
Explain the nature of the rash in chickenpox
Starts on head and trunk Progresses to peripheries 1. Macule to papules 2. Vesicles (itchy) 3. Pustules 4. Crusts w/in 5 days1
How is chickenpox spread?
personal contact and droplets
What is the treatment for chickenpox?
its self-limiting
topical calamine for itch
Chlorphenamine if >1yr
If immunocompromised: IV aciclovir
What are the complications of chickenpox?
- Secondary bacterial infection(staph, group A strep) -> TSS, NF
- Encephalitis -> VZV associated cerebellitis
- Purpura fulminans
- Primary VZV in immnocomp -> severe disseminated disease
What is the cause of rubella?
Rubella virus
What is the incubation period of rubella?
2-3 weeks
When is someone with rubella infectious?
5 days before and after start of rash
What are the signs of rubella other than rash?
Prodrome of mild fever
Lymphadenopathy
What is the nature of the rash in rubella?
Maculopapular rash on face which spreads to whole body Not itchy (unlike adults)
How long does a rubella rash take to fad?E
3-5days
What are the ix for rubella
can be confirmed serologically
What is the rx of rubella
self-limiting
prevention in immunisation
inform HPT
What are the complications of rubella
arthritis
encephalitis
thrombocytopenia
myocarditis
What is the cause of mumps?
RNA paramyxovirus
What is the incubation period of mumps?
2-3 weeks
wHEN IS mumps contagious?
7 days before and 9 days after parotid swelling
What are the features of mumps?
prodrome malaise and increased temp
painful parotid swelling unilateral -> bilateral
mild rash
What is rx of mumps
rest
prevention in immunisation
notifiable
What is the cause of measles?
RNA paramyxovirus
How is measles spread?
droplets
What is the incubation period of measles?
10-14days
wHEN is measles contagious?
prodrome until 4 days of rash
What are the features of measles?
prodrome: fever, cough, coryza, conjunctivitis
Koplik spots
Describe the nature of measles rash
Spread downwards from behind ears to whole body
discrete maculopapular rash becoming blotchy and confluent
What is the treatment of measles?
self-limiting
painkillers
notifiable
what is rx of measles in immunocompromised?
ribavirin
What is the cause of HSP?
IgA mediated small vessel vasculitis
What are the features of HSP?
SMALL artery biopsy showing IgA deposition
increased ESR
proteinuria
What are the features of HSP
- Abdo pain
- Polyarthritis
- IgA nephropathy: haematuria, proteinuria, rbc casts
describe the nature of HSP rash
palpable purpura on extensor surfaces of feet, legs, arms and buttocks w localised oedema
What is the cause of slapped cheek syndrome?
parvovirus B19
How is SCS spread?
resp route
direct contact w nose/throat discharges
Describe the rash in SCS
Slapped cheek facial rash week after viraemic phase
progressing to maculopapular ‘lace’ like rash on trunk and limbs
What isn’t usually involved in a rash in SCS?
palms and soles
What is the rx of SCS?
SELF-limiting
what are the complications of SCS?
aplastic crisis
fetal disease
When is SCS no longer infectious?
when rash appears
What is the cause of scarlet fever?
reaction to erythrogenic toxics produced by Group A haemolytic streptococci - usually S. Pyogenes
What is the incubation period of scarlet fever?
2-4 days
What are the features of scarlet fever?
fever 1-2days sore throat malaise, headache, N&V flushed face + circumoral pallor strawberry tongue
How is scarlet fever diagnosed?
throat swab
Describe the nature of the rash in scarlet fever
red-pinprick blanching rash on the chest, axillae or behind ears
When does a rash appear in scarlet fever?
12-48hrs after fever
what is the treatment of scarlet fever?
penicillin 10 days (start before results of throat swab)
clarithromycin if pen allergic
notifiable
What are the complications of scarlet fever?
otitis media
rheumatic fever
acute glomerulonephritis
sydenhams chorea
What is the cause of eczema?
Multifactorial:
genetic - atopy, FHx
infection
What is needed for a diagnosis of eczema?
Diagnosis: itchy skin + ≥3: 1. Onset <2yrs 2. Past flexural involvement 3. Hx of dry skin 4. PHx of other atopy Visible flexural dermatitis
What ix are done for eczema?
increased plasma IgE
RAST
skin prick
What are the features of eczema?
pruritus (main sx)
excoriations that become red, weeping and crusted
dry skin
lichenifications due to XS scratching + rubbing
What is the treatment of eczema?
- Emollients - equal parts liquid paraffin and soft paraffin
- Topical CS
- Immunomodulators: tacrolixus, pimecrolimus
What can be used to help break the itch cycle in eczema?
sedating anti-histamines -hydroxyzine at night
What is a complication of eczema and how is it treated?
infection - abx w hydrocortisone
What is the cause of ITP
Immune mediated reduction in platelet count
What are the features of itp
Acute bruising
petechiae (looks like rash)
purpura
What are the ix of ITP?
Measure platelets (<20x10^9) Blood film to exclude other abnormalities
What is the management of ITP
Most managed at home
platelet transfusion if XS bleeding
Splenectomy if chronic and Rx falls
Rituximab and anti-D reduce need for splenectomy
What is a serious complication of ITP?
life-threatening bleeding
What is the name of the organism causing scabies?
sarcoptes scabiei
How is scabies spread?
prolonged skin contact
What parts of the body are especially affected by scabies in infants?
palms soles
face scalp
What are the effects scratching in scabies?
excoriation and infection
Describe the nature of scabies rash
v itchy papules, vesicles,, pustules and nodules affecting finger webs, wrist flexures, axillae, abdo, buttocks groin
What is an almost diagnostic feature of scabies?
itchy red penile or scrotal papules
What is rx of scabies?
permethrin for 24hr covering whole body
ivermectin if severe
What causes erythema multiforme?
hypersensitivity reaction, due to: mostly HSC CMV, orf drugs e.g. penicillin mycoplasma
What are the features of major erythema multiforme?
systemic upset
fever
mucosal involvement
What are the features of the rash in erythema multiforme?
target lesions
initially on backs of hands and feet then on torso
upper limbs> lower
pruritus sometimes
what is the rx of erythema multiforme?
none usually
rx cause: aciclovir for HSV
abx for mycoplasma
topical steroids for sx
What is the cause of impetigo?
bacterial skin infection:
staph. aureus
strep pyogenes
what is the incubation period of impetigo?
4-10 days
What are the features of impetigo?
golden crusted lesions typically round the mouth
usually starts around nose and face
What is rx for impetigo?
topical fusidic acid
oral flucloxacillin
erythromycin if pen allergci
What can impetigo be a complication of ?
existing skin condition e.g. eczema
or scabies
What is the cause of scalded skin syndrome?
exfoliative staph toxin
What are the clinical features of scalded skin syndrome?
fever
malaise
purulent crusting localised infection around eyes, nose and mouth
widespread erythema and tenderness
Nikolsky sign - epidermis separates on gentle pressure which dry and heal w no scarring
What is the management of scalded skin syndrome
IV anti-staph abx
analgesia
fluid balance
What is scalded skin syndrome also known as?
ritter’s disease
What is the cause of periorbital cellulitis
staph aureus
strep pyogenes
H. influenzae in those not vaccinated
How can someone get periorbital cellulitis infection
local skin trauma
paranasal sinus infection
dental abscess
What are the features of periorbital cellulitis?
fever
red, tender swollen eyelid
usually unilateral
What is the rx of periorbital cellulitis?
IV abx promptly
What are the complications of periorbital cellulitis?
Abscess formation
Meningitis
Cavernous sinus thrombosis (blood clot within the cavernous sinus)
What are the features of orbital cellulitis?
proptosis
painful limited ocular movement
reduced visual acuity
How is orbital cellulitis confirmed
CT
What are the causes of napkin rash?
- contact dermatitis
- infantile seborrhoeic dermatitis
- candida infection
- atopic eczema
What is a distinguishable feature of irritant dermatitis as a cause of napkin rash?
creases spared
What is a distinguishable feature of candida dermatitis as a cause of napkin rash
red rash involving flexures
characteristic satellite lesions
What is a distinguishable feature of seborrhoeic dermatitis as a cause of napkin rash?
red rash w flakes
may be coexistent scalp rash
What is a distinguishable feature of psoriasis or atopic eczema as a cause of napkin rash?
other areas of the skin will be affected
What is the general management of napkin rash?
disposable nappies > towel nappies
expose nappy area to air when possible
barrier cream - zinc and castor oil
mild steroid cream (hydrocortisone) in severe cases
What is the rx of candida dermatitis causing nappy rash?
topical imidazole (antifungal)
What are examples of pigmented birthmarks?
moles
cafe au lait spots
mongolian spots
What are 4 or more cafe au lait spots associated w?
neurofibromatosis
What are pigmented birth marks due to?
XS skin pigment cells
What are examples of vascular birthmarks?
macular stains
haemangiomas (strawberry mark)
port wine stains
What is the difference between strawberry marks and port wine stains?
port wine stains don’t fade w age
strawberry marks resolve by age 10
What is the cause of toxoplasmosis ?
toxoplasma gondii
What is the usual animal reservoir of toxoplasmosis?
cat
How does toxoplasmosis present?
most asymptomatic
if symptomatic: fever, malaise, lymphadenopathy
when is treatment of toxoplasmosis required? what is rx
severe inf. or immunosuppressed
pyrimethamine plus sulphadiazine for at least 6 weeks
What are the effects of congenital toxoplasmosis?
microcephaly
hydrocephalus
cerebral calcification
choroidoretinitis
What are the causes of acne?
familial tendency
androgens
acne bacteria
immune activation w inflammatory mediators
distension and occlusion of hair follicles
what is an open comedones also known as?
blackhead
what is a closed comedones also known as?
whitehead
What are the types of scarring caused by acne?
hypertrophic or keloidal
What lesions are involved in severe acne?
nodules
pseudocysts
what is mild acne classed as?
lesion count <30
What is moderate acne classed as?
lesion count 30-125
What is severe acne classed as?
> 125
What is the 1st line therapy of acne
topical agents:
- keratolytics - benzoyl peroxide
- topical retinoids - tretinoin or isotretinoin
what is 2nd line therapy of acne
low dose oral abx
hormonal - cyproterone and ethinylestradiol
What is a major contraindication of retinoids?
pregnancy
What are the signs of encephalitis?
flu like prodrome reduced consciousness odd behaviour vomiting fits increased temp meningism
What are the infective causes of encephalitis?
HSV enteroviruses (coxsackie, echo) mumps varicella zoster rabies parvovirus immunocompromised influenza toxoplasmosis
What are non-infective differentials of encephalitis?
hypoglycaemia DKA kernicterus hepatic failure lead poisoning SAH malignancy
What are the IX for encephalitis?
CSF PCR blooods (enteroviruses) stools urine EEG/CT/MRI
What are the specific investigations that would aid a diagnosis of herpes simplex encephalitis?
EEG/ct/mri - temporal lobe changes
HSV abs in CSF
What is rx of herpes simplex encephalitis?
High dose IV aciclovir
What are the causes of viral meningitis?
enteroviruses
EBV
Adenovirus
How do the sx of viral meningitis compare to bacterial?
like bacterial but much less severe
How is a diagnosis of viral meningitis confirmed?
culture/ PCR of CSF
culture of stool, urine, nasopharyngeal etc
What is in a septic screen?
Blood cultures urine microscopy and culture CXR LP Throat swabs/skin swabs (FBC/CRP - won't identify source of infection)
what is sepsis
bodys overwhelming and life-threatening response to infection that can lead to tissue damage, organ failure and death
What are red flags of sepsis
temp <36 or >38.5
inappropriate tachycardia
altered mental status (lethargy, floppiness)
reduced peripheral perfusion, prolonged CRT
how does sepsis differ from bacteraemia?
bacteraemia is presence of bacteria in the blood screen
what are causes of bacteraemia in neonates?
GBS
E. coli
Listeria
What are causes of bacteraemia in infants?
staph aureus strep pneumoniae Group A streptococcus Neisseria Haemophilus influenzae
What are causes of bacteraemia in adolescents?
neisseria meningitids
staph aureus
group a strep
strep pneumonia
How does meningococcal disease present
has two presentations - either meningococcal sepsis or meningitis
what is a severe presentation of meningococcal sepsis?
purpura fulminans
how does UTI present in infants compared to older children
Infants - non specific (fever, lethargy, vomiting/diarrhoea, poor feeding, failure to thrive, prolonged jaundice)
Older - dysuria, frequency, fever, riggers, D&V, abdominal pain, incontinence)
what are you looking for in urine dip for uti
nitrites, proteins, white cells
What is criteria for urine culture to diagnose UTI
> 10^5
What are investigations following UTI?
Micturating cystourethrogram - reflux
DMSA - renal scarring (wait 3 months)
US - structural abnormalities e..g multicystic kidney
what causes bacterial tracheitis ?
staph aureus
what is common sx of pneumonia that can confuse It with other x?
abdo pain
what are signs of resp distress
rapid rr head bobbing tracheal tug intercostal/subcostal recession grunting agitated/ frightened look
typical hx of mycoplasma
headache vomitng temp cough occasional wheeze and creps give clarithromycin
what causative organisms re associated w empyema?
strep pneumoniae
group A strep
what is rx of empyema?
chest drain
urokinase
prolonged cause of empyema
consider underlying immune deficiency
