Infection Clinical Conditions

Question 1

What is Chronic granulomatous disease?

Answer 1

• Chronic granulomatous disease is an X-linked inherited primary immunodeficiency wherein the body cannot phagocytose pathogens due to difficulty forming the superoxide radical (no respiratory burst)
• This increases susceptibility to infections by bacteria and fungi

Question 2

What is Bruton’s disease?

Answer 2

Bruton’s disease is an inherited primary immunodeficiency caused by a severe block in B cell development and a reduced immunoglobulin production

Question 3

What is Streptococcal pharyngitis?

Answer 3

• Streptococcal pharyngitis is a form of pharyngitis caused by Strep pyogenes, spread through respiratory droplets and associated with over-crowding
• It presents with malaise, fever, headache, lymphoid hyperplasia, tonsillopharyngeal exudates and an abrupt onset sore throat

Question 4

What is the Human Immunodeficiency Virus?

Answer 4

• HIV is a retrovirus which infects cells with CD4+ surface receptor (T-helper cells, monocytes / macrophages)
• It replicates inside cells, destroys the cell, causes inflammation and spreads to / infects more cells

Question 5

What is Streptococcal toxic shock syndrome?

Answer 5

• Streptococcal toxic shock syndrome is a deep tissue infection with caused by Strep pyogenes
• It presents with bacteraemia vascular collapse and organ failure and patients go from health to death in hours

Question 6

What is Cellulitis?

Answer 6

• Cellulitis is a streptococcus pyogenes skin infection wherein the skin and subcutaneous tissue are infected
• Impaired lymphatic drainage and illicit injecting drug use are important risk factors

Question 7

What is Impetigo?

Answer 7

• Impetigo is a streptococcus pyogenes skin infection, often occurring in children of 2-5 years and commonly caused by glomerulonephritis
• It involves an initial skin colonisation, followed by intradermal inoculation

Question 8

What is malaria?

Answer 8

• Malaria is a mosquito-borne infectious disease, typically transmitted through an animal vector - an infected Anopheles mosquito
• It is the commonest imported disease in the UK

Question 9

What is an EBV infection?

Answer 9

EBV infection (aka infectious mononucleosis) is a viral latent infection which affects B lymphocytes and produces characteristic atypical lymphocytes that may be useful in the diagnosis of the disease

Question 10

What is Erysipelas?

Answer 10

• Erysipelas is a streptococcus pyogenes skin infection wherein the dermis of the face and/or lower limbs is infected with lymphatic involvement
• Facial lesions are preceded by pharyngitis and lower limb lesions are secondary to invasion of skin via trauma, skin disease or local fungal infection

Question 11

What is septic shock?

Answer 11

Septic shock is persisting hypotension requiring treatment to maintain blood pressure despite fluid resuscitation

Question 12

What is sepsis?

Answer 12

Sepsis is life-threatening organ dysfunction due to dysregulated host response to infection

Question 13

One complication of streptococcal pharyngitis is Acute Rheumatic Fever.

What is Acute Rheumatic Fever?

Answer 13

• Acute Rheumatic Fever is the inflammation of the heart, joints and CNS which follows on from pharyngitis
• It might arise due to auto-immunity, serum sickness or M proteins binding to collagen

Question 14

One complication of streptococcal pharyngitis is Acute post-streptococcal glomerulonephritis.

What is Acute glomerulonephritis?

Answer 14

Acute glomerulonephritis is the acute inflammation of renal glomerulus due to antigen-antibody complexes forming in the glomerulus

Question 15

One complication of streptococcal pharyngitis is Scarlet Fever.

What is Scarlet Fever?

Answer 15

• Scarlet fever is a condition arising due to an infection with streptococcal pyrogens (exotoxins strain of S.pyogenes)
• It is transmitted through local/haematogenous spread and presents with high fever, sepsis, arthritis, jaundice

Question 16

What is enteric fever?

Answer 16

• Enteric fever (typhoid & paratyphoid fever) is a potentially fatal mutisystemic ilness caused by the bacterium Salmonella typhi
• It is spread through the faecal-oral route (drinking/eating), due to poor sanitation

Question 17

What is Dengue fever?

Answer 17

• Dengue fever is a mosquito-borne tropical disease caused by the dengue virus
• It is commonest arbovirus and has 4 serotypes

Question 18

What is Ebola?

Answer 18

• Ebola is a viral haemorrhagic fever caused by a filovirus, spread by direct contact with body fluids
• It presents with flu-like symptoms (+ vomiting, diarrhoea, headaches, confusion, rash) as well as internal/external bleeding at 5-7 days

Question 19

What is Necrotising fasciitis?

Answer 19

• Necotising fasciitis is an Infection of deeper subcutaneous tissues and fascia, caused by streptococcus pyogenes
• It usually occurs secondary to skin break and involves rapid, extensive necrosis, presenting with severe pain initially and high fever (mortality 20-70%)

Question 20

What is Zika virus?

Answer 20

• Zika virus is an arbovirus (flavivirus) transmitted through the Aedes mosquito & through sexual contact
• It presents with mild dengue-like symptoms (only in 20%) and causes congenital microcephaly and/or foetal loss

Question 21

What is Severe Combined Immunodeficiency?

Answer 21

SCID is a primary immunodeficiency characterised by a severe defect in both the T- & B-lymphocytes

Question 22

What is Common Variable Immunodeficiency?

Answer 22

CVID is a primary immunodeficiency characterised by recurrent infections and low antibody levels (specifically IgG, IgM and IgA)

Question 23

What is meningococcal disease?

Answer 23

- Meningococcal disease is a bacterial form of meningitis, a serious infection of the meninges that affects the brain membrane

• It presents with a purpuric rash, light sensitivity, fever and neck stiffness

Question 24

What is hepatitis?

Answer 24

Hepatitis is the inflammation of the liver due to cell injury or viruses (hepatotropic) which can cause collateral liver damagee.g. EBV, CMV, VZV