Infections and Immunology Flashcards
How does varicella zoster present?
Fever
Itch
General fatigue and malaise
Widespread, erythematous, raised, vesicular (fluid filled), blistering lesions - stop being contagious when they scab over
What are the complications of varicella zoster?
Bacterial superinfection
Dehydration
Conjunctival lesions
Pneumonia
Encephalitis (presenting as ataxia)
Ramsay Hunt syndrome
Shingles
How is chickenpox managed?
Usually does not require treatment
Aciclovir in immunocompromised patients
Calamine lotion
what are the features of shingles?
unilateral vesicular rash that follows dermatomal distribution
painful rash that does not cross the midline
how is shingles managed?
paracetamol and NSAIDs
oral aciclovir
What is Ramsay Hunt syndrome?
Reactivation of the varicella zoster virus in the geniculate ganglion of the seventh cranial nerve
What are the features of Ramsay Hunt syndrome?
Auricular pain
Facial nerve palsy
Vesicular rash around the ear
Vertigo and tinnitus
How is Ramsay Hunt syndrome managed?
Oral aciclovir
Corticosteroids
What causes infectious mononucleosis?
Epstein-Barr Virus
What are the symptoms of infectious mononucleosis?
Symptoms usually resolve after 2-4 weeks
Sore throat
Lymphadenopathy
Fever and malaise
Transient macular rash
Mild hepatosplenomegaly
How is infectious mononucleosis investigated?
Heterophil antibody test (Monospot test) - 2nd week of illness, repeat if negative after 5-7 days
FBC (raised lymphocytes)
How is infectious mononucleosis managed
Conservative management
Analgesia
Avoid ampicillin and amoxicillin - can cause an itchy maculopapular rash
Avoid contact sports for at least 3 weeks (due to risk of splenic trauma)
What is the first and second most common cause of tonsillitis in children?
Streptococcus pyogenes is most common
Streptococcus pneumoniae is second most common
What are the symptoms of tonsillitis?
Sore throat
Fever (above 38°C)
Pain on swallowing
Anterior cervical lymphadenopathy
How is the cause of tonsillitis determined?
Centaur score will determine bacterial vs viral - give antibiotics if score 3 or more
Fever over 38ºC
Tonsillar exudates
Absence of cough
Tender anterior cervical lymph nodes (lymphadenopathy)
How is tonsillitis treated?
Phenoxymethylpenicillin for 10-day course
Clarithromycin if allergic
ONLY IF BACTERIAL TONSILLITIS
What is anaphylaxis?
Type 1 IgE-mediated hypersensitivity reaction to certain triggers
What are the symptoms of anaphylaxis?
Widespread urticaria, itching and flushing
Angio-oedema
Sneezing
Wheeze
Abdominal pain, nausea, vomiting, diarrhoea
Tachycardia and hypotension
How is anaphylaxis managed?
IM adrenaline (500 mcg in adults, in thigh)
Antihistamines, e.g. oral chlorphenamine or cetirizine
Steroids, e.g. IV hydrocortisone
Lie patient flat and raise legs
IV fluids if hypotensive
What are the symptoms of HIV?
Initial flu-like illness 3-12 weeks after infection
Fevers, night sweats, weight loss
Maculopapular rash
Lymphadenopathy
Sore throat
Mouth ulcers
Diarrhoea
TB
Genital STIs
How is HIV investigated?
HIV p24 antigen and HIV antibody test (IgG, IgM)
ELISA
CD4 count
How is HIV managed?
2 nucleoside reverse transcriptase inhibitors (NRTIs) and one protease inhibitor (PI) or non-nucleoside reverse transcriptase inhibitor (NNRTI)
If CD4 <200, give co-trimoxazole as prophylaxis against Pneumocystis jiroveci pneumonia
How is HSV transmitted?
Via direct contact with mucosal tissue or secretions of another infected person
HSV-1: usually in childhood via saliva
HSV-2: through genital contact
How does genital herpes present?
Painful genital ulcers
Neuropathic pain
Dysuria and pruritis
Fever
Inguinal lymphadenopathy
Constipation, rectal pain, tenesmus, proctitis
How does herpes labialis present?
Painful oral ulcers
High fever
Sore throat
Pharyngeal oedema
Myalgia
Cervical lymphadenopathy
What are the risk factors for recurrence of HSV?
Menstruation
Stress
Minor trauma
Sun exposure
How is genital herpes treated?
Oral aciclovir for 5 days
Topical lidocaine for symptomatic relief
What are the types of necrotising fasciiitis?
Type 1: polymicrobial infection caused by mix of aerobes and anaerobes - more common, occurs post-surgery in diabetics
Type 2: streptococcus pyogenes
What are the risk factors for necrotising fasciiitis?
Diabetes mellitus (particularly if treated with SGLT-2 inhibitors)
CKD
Alcohol excess
Increasing age or frailty
Malnutrition
Metastatic cancer
Immunocompromised
What are the features of necrotising fasciitis?
acute onset
pain, swelling, erythema at the affected site
pain out of keeping with clinical signs
fever and tachycardia
How is necrotising fasciiitis treated?
urgent surgical referral debridement
intravenous antibiotics
what are the features of peritonsillar abscess?
severe throat pain, which lateralises to one side
deviation of uvula to unaffected side
trismus (difficulty opening mouth)
reduced neck mobility
fever, chills, malaise
how is peritonsillar abscess treated?
needle aspiration or incision and drainage and IV antibiotics
consider tonsillectomy
what are the features of measles?
prodromal phase: fever, irritable, conjunctivitis
Koplik spots: white spots on the buccal mucosa (pathognomic)
discrete maculopapular rash - begins behind ears and spreads to rest of body
how is measles investigated?
IgM antibodies can be detected a few days from disease onset
what are the complications of measles?
otitis media (most common complication)
pneumonia (most common cause of death)
encephalitis
subacute sclerosing panencephalitis
keratoconjunctivitis
febrile convulsions
diarrhoea
myocarditis
how is measles managed?
self-resolving after 7-10 days of symptoms
isolate until 4 days after onset of symptoms
notifiable disease
what organism causes scarlet fever?
scarlet fever is a reaction to erythrogenic toxins produced by Group A haemolytic streptococci - usually Streptococcus pyogenes
what are the features of scarlet fever?
red-pink, blotchy macular rash with rough ‘sandpaper’ skin - starts on the trunk and spreads outwards
red, flushed cheeks
fever
lethargy, headache, nausea, vomiting
sore throat
‘strawberry’ tongue
cervical lymphadenopathy
how is scarlet fever investigated?
throat swab - commence antibiotics immediately
how is scarlet fever managed?
oral penicillin V for 10 days - azithromycin if allergic
children can return to school 24 hours after starting antibiotics
notifiable disease
what are the features of rubella?
caused by togavirus
prodrome, e.g. low-grade fever
maculopapular rash - initially on face, spreads to rest of the body (lasts 3 days)
lymphadenopathy
what are the complications of rubella?
arthritis
thrombocytopaenia
encephalitis
myocarditis
