Other fun infections with a rash (Strep, Staph, VZV, Parvo, Roseola, Measles, Rubella, cellulitis) Flashcards
What two organisms cause Toxic Shock Syndrome? What is the primary clinical feature? Will blood cultures be pos or neg?
Staph aureus and Strep pyogenes - toxin-mediated so negative blood cultures. Presents with hypotension.
Name 5 manifestations of acute Strep pyogenes infection. Name 3 para/post-infectious consequences of Strep pyogenes infection, how they are caused and how they are associated with acute infection
Acute - Pharyngitis, skin infection, sepsis, pneumonia, necrotising fasciitis, endocarditis, Strep TSS
Delayed-onset:
Scarlet fever - delayed-type skin hypersensitivity to Strep pyogenes toxin (parainfectious) - have acute pharyngitis at the same time + sandpaper rash with perioral sparing
Rheumatic fever - post-infectious disease where Strep antigen induces autoimmune attack. Often 2-4 weeks after Strep pharyngitis
PSGN - autoimmune disease where antigen-antibody complexes accumulate in glomeruli causing GN. Often 2-4 weeks after Strep pharyngitis or skin infection
Name symptoms of VZV infection. Name 2 ways it’s spread. Give 3 indications to use acyclovir.
Prodrome of fever, malaise, anorexia
Pruritic, maculopapular rash with vesicles at all stages of development and crusting. Often most around scalp, face and trunk
Use acyclovir if a neonate, > 15 years, immunocompromised or signs of complications
Give 3 acute complications of severe VZV infection. 1 long-term complication?
Eye involvement Coagulopathy Pneumonia Encephalopathy Secondary bacterial infection Reye syndrome (acute liver and brain swelling)
Long term - shingles
What is the usual timeline of a parvovirus infection?
Prodrome of fever, headache, coryza
Rash appears 2-5 days later (slapped cheek, lacy diffuse macular rash) after viraemia has disappeared and child otherwise well. Rash usually lasts for a week, can last for several weeks. Non-pruritic.
What virus causes roseola? Go through the usual timeline of a roseola infection
HHV6
Get a high fever for 3-5 days, then blanching, maculopapular rash develops (neck and trunk that spreads to face and extremities) after fever resolves. Non pruritic. Rash lasts for 2 days
Name 2 viruses that cause hand, foot and mouth disease. Go through the timeline of the disease
Coxsackie A16 and enterovirus 71. Have mild fever/systemic symptoms, but ulcerations over mouth and oral cavity, and maculopapular/vesicular rash over hands, feet and buttocks. Lasts for 2-3 days
What is the difference between erysipelas and cellulitis? Name differences on examination
Erysipelas = infection of upper dermis, cellulitis = infection of deep dermis and subcutaneous fat.
Examination - may see skin changes and a clearer line of demarcation in erysipelas
Name 4 differentiating features between orbital and periorbital cellulitis. What is the other Ddx for an acutely swollen eye?
Orbital - proptosis, ophthalmoplegia, decreased acuity, headache
Periorbital - fever, local tenderness
Other Ddx - allergic reaction (chemical, insect bite)
Which is more dangerous, periorbital or orbital cellulitis and why? What Ix needs to be done urgently for the more dangerous one?
Orbital cellulitis - can be vision and life threatening (if becomes septic). Need CT orbit to see whether there’s an abscess and drainage of orbit is required
Go through the timeline of a measles infection.
Viral prodrome - high fever, cough, coryza, conjunctivitis, along with Koplik spots (white lesions on buccal mucosa). Then rash develops 2-4 days after prodrome - maculopapular rash spreading from head to toe. Nonpruritic. Clinical improvement generally 48 hrs after rash, rash often lasts 3-5 days.
Go through the timeline of a rubella infection.
Mild viral prodrome 1-5 days before rash begins. Rash spreads from face - hands - feet, usually lasts 3 days. Maculopapular, pruritic
When should you further investigate a fever without focal signs?
If under 3 months (much higher chance of bacterial infection), if they look toxic, or if fever is > 5 days.
Often do a UTI on any infant under 6 months (few focal features)
Name 3 agents that can cause orbital or periorbital cellulitis. What is the usual medical management of both?
Orbital - Strep pyogenes, Strep pneumoniae, Staph aureus. Treat with iv cephtriaxone + iv fluclox.
Periorbital - Strep pyogenes, Strep pneumoniae, Staph aureus. Treat with oral augmentin if mild, iv fluclox +/- ceftriaxone if severe.
