infectious diseases Flashcards
what are the essentials of a septic screen?
- blood culture
- FBC including differential WCC
- CRP and ESR (acute phase reactants)
- urine sample
which investigations can be done where appropriate as part of the septic screen?
- CXR
- LP
- rapid antigen screen on blood/CSF/urine
- meningococcal and pneumococcal PCR on blood/CSF
- PCR for viruses in CSF (esp in herpes simplex and enteroviruses)
changes to CSF in bacterial meningitis?
- cloudy, turbid
- increased WBC (esp neutrophils)
- increased protein
- low glucose
typical features of meningitis?
- headache
- fever
- neck stiffness
- photophobia
a) describe the rash seen in meningococcal septicaemia
b) which organism causes this?
a) non-blanching petechial, purpuric rash with a necrotic centre
b) Neisseria meningitides
changes to CSF in viral meningitis?
- clear
- increased WBC (esp lymphocytes)
- increased protein
- normal glucose
which organism most commonly causes bacterial meningitis in:
a) newborns?
b) <6 year olds?
c) >6 year olds?
a) L. monocytogenes
b) N. meningitides
c) N. meningitides
causative organisms in viral meningitis? give 4
- HSV 2
- VZV
- mumps
- HIV
differentials for seizures in a febrile child?
- febrile convulsions
- meningitis
- encephalitis
which extra investigations are done in tuberculous meningitis?
- CXR
- Mantoux test
- sputum culture
- early morning urine
signs of toxic shock syndrome?
- fever >39C
- hypotension
- diffuse red macular rash
- inflamed eye/mouth/genital mucosa
- D+V
- thrombocytopenia
- altered consciousness
management of toxic shock syndrome?
- immediate management of shock
- surgically debride infected areas
- ceftriaxone w/ clindamycin
what is impetigo?
- localised, highly contagious skin infection
- more common where there’s a pre-existing skin condition like eczema
where do lesions normally present in impetigo?
- face
- neck
- hands
describe the lesion in impetigo
- red macules
- become vesicular
- then bullous (blisters)
- when they burst they become honey-coloured and crusty
presentation of periorbital cellulitis?
- fever
- red, tender oedematous eyelid
- unilateral
causative organism of periorbital cellulitis in unimmunised children?
H. influenzae B
treatment of periorbital cellulitis?
IV antibiotics
cause of scalded skin syndrome?
staphylococcal toxin that separates layers of epidermal skin
demographic of scalded skin syndrome?
- infants
- young children
presentation of scalded skin syndrome?
- fever
- malaise
- purulent, crusting local rash
- starts around eyes, nose and mouth
- spreads to rest of body
viral differentials of a maculopapular rash?
- in <2 year olds, roseola infantum by HHV7
- parvovirus (slapped cheek, 5-7yrs old)
- enteroviral rash
- measles, rubella (think unimmunised)
bacterial differentials of a maculopapular rash?
- group A streptococcus (scarlet fever)
- salmonella typhi (typhoid fever)
non-infectious causes of a maculopapular rash?
- Kawasaki disease
- JIA
viral differentials of vesicular rash?
- VZV (chickenpox, shingles)
- HSV
- Coxsackie (hand, foot + mouth)
bacterial differentials of a vesicular rash?
- impetigo (staph or strep)
- scalded skin syndrome (staph toxin)
bacterial differentials of a petechial, purpuric rash?
- meningococcal septicaemia
- infective endocarditis
non-infectious differentials of a petechial, purpuric rash?
- post-URTI / post-chickenpox
- Henoch-Schonlein purpura
- thrombocytopenia
- vasculitis
- malaria (travel Hx)
where is HSV-1 more likely to present?
cold sores on lips and mouth
where is HSV-2 more likely to present?
genital sores
investigation for herpetic lesion near the eye?
- urgent ophthalmic assessment
- slit lamp examination of cornea
a) what are herpetic whitlows?
b) where can they be found?
a) painful, red, oedematous pustules
b) fingers
features of primary varicella infection?
- initial fever
- vesicular rash
- starts on head and trunk
- spreads to peripheries
- itchy
- clears up within 10 days
complications of chickenpox? give 3
- secondary bacterial infection
- encephalitis
- purpura fulminans
- pneumonia
what is purpura fulminans?
- a purpuric skin rash due to vasculitis of the skin vessels
- rare complication in chickenpox
management of primary varicella infection?
- conservative
- paracetamol for pain relief
- emollient to reduce itchiness
where does shingles present?
- dermatomal distribution of sensory nerves
- usually in thoracic region
what does recurrent / multidermal shingles suggest?
a T-cell defect (e.g. HIV)
causative agent in infectious mononucleosis?
Epstein-Barr virus
presentation of glandular fever?
- fever
- malaise
- tonsillitis / pharyngitis (severe!!! limits food intake)
- lymphadenopathy
less common:
- petechiae on soft palate
- hepatosplenomegaly
- maculopapular rash
- jaundice
how long do the symptoms of glandular fever persist?
1-3 months
treatment of glandular fever?
- corticosteroids if there is compromised breathing
- penicillin if group A strep. found on tonsils
- otherwise conservative
how is CMV transmitted?
- saliva
- genital secretions
- breastmilk
which condition is the presentation of CMV infection very similar to?
- infectious mononucleosis (glandular fever)
- the lymphadenopathy is less severe here
- most people get it subclinically
presentation of CMV infection in an immunocompromised host?
- retinitis
- pneumonitis
- bone marrow failure
- encephalitis
- hepatitis
- oesophagitis
- enterocolitis
treatment for severe CMV infection?
IV ganciclovir
how can HHV-6 and HHV-7 present?
roseola infantum:
- high fever
- malaise
- then generalised macular rash
how does parvovirus B19 present in an infant?
- erythema infectiosum
- “slapped cheek syndrome”
- prodrome of fever, malaise, headache, myalgia
- red rash on face later
- maculopapular rash on trunk later
what is the most serious complication of a parvovirus B19 infection?
- aplastic anaemia
- affects kids with SCD, thalassaemia or malignancy
how does maternally transmitted parvovirus B19 infection present in a fetus?
- majority survive
- fetal hydrops
- death from severe anaemia
commonest causative organism in toxic shock syndrome?
S. aureus
how long is measles infectious for?
from prodrome (2 weeks) up to 4 days after start of rash
features of measles?
- irritable
- conjunctivitis
- fever
- Koplik spots (white spots in mouth, come on before the rash does)
- rash begins behind ears then spreads
investigations for measles?
IgM antibodies detectable within days of onset of rash
complications of measles?
- commonest is otitis media
- deadliest is pneumonia
- encephalitis (weeks later)
- febrile convulsions
