Infections and Immunology Flashcards by Sreenithi Balaji

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

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What are the complications of varicella zoster?

Bacterial superinfection
Dehydration
Conjunctival lesions
Pneumonia
Encephalitis (presenting as ataxia)
Ramsay Hunt syndrome
Shingles

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How is chickenpox managed?

Usually does not require treatment
Aciclovir in immunocompromised patients
Calamine lotion

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what are the features of shingles?

unilateral vesicular rash that follows dermatomal distribution
painful rash that does not cross the midline

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how is shingles managed?

paracetamol and NSAIDs
oral aciclovir

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What is Ramsay Hunt syndrome?

Reactivation of the varicella zoster virus in the geniculate ganglion of the seventh cranial nerve

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What are the features of Ramsay Hunt syndrome?

Auricular pain
Facial nerve palsy
Vesicular rash around the ear
Vertigo and tinnitus

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How is Ramsay Hunt syndrome managed?

Oral aciclovir
Corticosteroids

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What causes infectious mononucleosis?

Epstein-Barr Virus

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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

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How is infectious mononucleosis investigated?

Heterophil antibody test (Monospot test) - 2nd week of illness, repeat if negative after 5-7 days
FBC (raised lymphocytes)

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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)

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What is the first and second most common cause of tonsillitis in children?

Streptococcus pyogenes is most common
Streptococcus pneumoniae is second most common

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What are the symptoms of tonsillitis?

Sore throat
Fever (above 38°C)
Pain on swallowing
Anterior cervical lymphadenopathy

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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)

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How is tonsillitis treated?

Phenoxymethylpenicillin for 10-day course
Clarithromycin if allergic
ONLY IF BACTERIAL TONSILLITIS

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What is anaphylaxis?

Type 1 IgE-mediated hypersensitivity reaction to certain triggers

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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