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All conditions - Year 3 > Infection & Immunology > Flashcards

Infection & Immunology Flashcards

1
Q

What is an Abscess

A

A painful collection of puss usually caused by bacterial infection

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2
Q

What are the 2 types of Abscess

A

Skin Abscess - Common - IV drug use is a major RF

Internal Abscess

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3
Q

What are signs and symptoms of Abscesses

A

Swollen pus-filled lump under the surface of the skin with associated fever and chills

Internal abscesses are not visible but are characterised by:

  • Pain in the affected area
  • Swinging fevers
  • Malaise
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4
Q

How are Abscess investigated

A

Ultrasound can be used in visualising and abscess

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5
Q

How are abscesses treated

A
  • Some small skin abscesses may disappear by themselves

Incision and Drainage

  • Before doing this, check to see whether a foreign object is causing the abscess (e.g. needle fragments in IV drug users)
  • The abscess is cut open and drained of pus (Do not do in non-lactational mastitis)

Antibiotics
- Can be used alongside incision and drainage

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6
Q

What is Anaphylaxis

A

Acute life-threatening multi system syndrome caused by sudden release of mast cell and basophil-derived mediators into the circulation

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7
Q

What are the causes of Anaphylaxis

A

Immunogenic: IgE-Mediated or immune complex/complement-mediated

Non-immunogenic - Mast cell or basophil degranulation without the involvement of antibodies (Vancomycin, codeine and ACEi)

Common Allergens:

  • Drugs (Penicillin)
  • Latex
  • Peanuts
  • Shellfish
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8
Q

What are the signs and symptoms Anaphylaxis

A 
Tachypnoea
Wheeze
Cyanosis
Swollen upper airways and eyes
Rhinitis
Conjunctival infection
Urticarial rash
Hypotension
Tachycardia
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9
Q

How is Anaphylaxis diagnosed

A

Clinical diagnosis

Serum tryptase level - Elevated

Serum Histamine levels
IgE immunoassays

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10
Q

How is Anaphylaxis treated

A

ABCDE

  • High flow oxygen
  • IM adrenaline
  • Chlorpheniramine (antihistamine)
  • Hydrocortisone
  • If continued respiratory deterioration, may require bronchodilator
  • Monitor pulse oximetry, ECG, BP
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11
Q

How is HIV transmitted

A

Sexual intercourse:

  • Heterosexual intercourse is the most common mode
  • Homosexual are the greater risk in the West

Blood (and other bodily fluids):

  • Mother of child (Interuterine, childbirth, breast-feeding)
  • Needles
  • Blood transfusions
  • Organ transplantation
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12
Q

What are the 3 phases and associated symptoms and signs of HIV

A
  1. Seroconversion phase:
    - Self-limiting
    - Fever
    - Night sweats
    - Generalised lymphadenopathy
    - Sore throat
    - Oral ulcers, rash, myalgia, headache, encephalitis, diarrhoea
  2. Early/Asymptomatic phase:
    - Apparently well
    - Some may have persistent lymphadenopathy
    - Progressive minor symptoms
  3. AIDS
    - Syndrome of secondary diseases resulting from immunodeficiency
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13
Q

What are the signs and symptoms of HIV in the AIDs phase

A

Direct effect:

  • Neurological: Polyneuropathy, dementia
  • Lung: Lymphocytic interstitial pneumonitis
  • Heart: Cardiomyopathy, myocarditis
  • Haematological: Anaemia, thrombocytopenia
  • GI: Anorexia, wasting
  • Eyes: Cotton wool spots

Secondary effects resulting from immunodeficiency:

  • Bacterial: TB, Skin infections, pneumococcal infections
  • Viral: CMV, HSV, VZV, HPV, EBV
  • Fungal: Pneumocystic jiovecii pneumonia, Crypotococcus, Candidiasis, Invasive aspergillosis
  • Protozoal: Toxoplasmosis, Cryptosporidia
  • Tumours: Kaposi sarcoma, SCC, Lymphoma
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14
Q

How is HIV diagnosed

A

HIV testing: HIV antigen/antibody (6 week window period - False negative)
PCR for viral RNA
CD4 count
Viral load

  • Pneumocystic pneumonia - CXR
  • Cryptococcal meningitis - brain CT or MRI, LP
  • CMV (colitis) - colonoscopy and biopsy
  • Toxoplasmosis - brain CT or MRI
  • Cryptosporidia - stool
    microscopy
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15
Q

What is Infectious mononucleosis

A

This is the clinical syndrome caused by primary EBV infection - Glandular fever

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16
Q

Describe the infection pattern seen in Infectious mononucleosis

A

It is transmitted by close contact (e.g. kissing, sharing eating utensils)

Atypical lymphocytes in the peripheral blood are a classic feature of Infectious mononucleosis.

EBV remains latent in lymphocytes. Reactivation may occur following stress or immunosuppression

17
Q

Who is commonly affected by Infectious mononucleosis

A

1-6yrs

14-20yrs

18
Q

What are the signs and symptoms of Infectious mononucleosis

A

Incubation period of 4-8 weeks

Abrupt onset of symptoms:

  • Sore throat
  • Fever
  • Fatigue
  • Headache
  • Malaise
  • Anorexia
  • Sweating
  • Abdominal pain
  • Oedema and erythema or the pharynx
  • White creamy exudate on the tonsils
  • Palatal petechiae
  • Cervical/generalised lymphadenopathy
  • Splenomegaly
  • Hepatomegaly
  • Jaundice
  • Widespred maculopapular rash
19
Q

How is Infectious mononucleosis diagnosed

A

EBV-specific antibodies
+
Heterophile antibodies - Non-specific for EBV infection
= Diagnostic

Real-time PCR - Expensive but good

20
Q

How is Infectious mononucleosis treated

A
  • Bed rest
  • Paracetamol and NSAIDs - Fever and malaise
  • Corticosteroids in severe cases
  • No not give ampicillin or amoxicillin if Infectious mononucleosis is suspected - nearly 100% of patients with glandular fever develop a maculopapular
  • Avoid contact sports for 2 weeks (because of risk of rupturing spleen)
21
Q

What are complication to Infectious mononucleosis

A
  • Lethargy for several months
  • Respiratory obstruction and secondary infection
  • Haemolytic or aplastic anaemia, thrombocytopenia
  • Splenic rupture, fulminant hepatitis, pancreatitis, mesenteric adenines, renal failure
  • CNS - GBS, Encephalitis, Viral meningitis
  • EBV-associate malignancy - Burkitt’s lymphoma, nasopharyngeal cancer, Hodgkin’s lymphoma
22
Q

What is Rheumatic fever

A

This is an autoimmune disease that may occur following group A streptococcal throat infection. It can affect multiple systems including, joints, heart, brain and skin.

23
Q

What are signs and symptoms of Rheumatic fever

A 
Fever
Joint pain
Recent sore throat
Chest pain
SOB
Palpitations
Heart murmur - MR
Pericardial rub
Signs of cardiac failure
Swollen joints
24
Q

How is Rheumatic fever diagnosed

A

It is diagnosed using the Jones criteria. There must be a recent strep infection plus 2 Major criteria, or 1 major and 1 minor.

Evidence of a group A strep infection:
- Positive throat culture (Usually negative by the time RF symptoms appear)
- Rapid streptococcal antigen test +ve.
- Elevated or rising streptococcal antibody titre (eg anti-streptolysin O (ASO) or
DNase B titre).
- Recent scarlet fever.

Major:

  1. Carditis: Tachycardia, Murmurs, Pericardial rub, CHF, Cardiomegaly, Conduction defects (45–70%)
  2. Arthritis: A migratory, ‘flitting’ polyarthritis; usually affects larger joints (75%)
  3. Subcutaneous nodules: Small, mobile, painless nodules on extensor surfaces of joints and spine (2–20%)
  4. Erythema marginatum: Geographical-type rash with red, raised edges and clear centre; occurs mainly on trunk, thighs and arms (2–10%)
  5. Sydenham’s chorea (St Vitus’ dance): Occurs late in 10%. Unilateral or bilateral involuntary semi-purposeful movements. May be preceded by emotional lability and uncharacteristic behaviour.

Minor criteria:

  1. Fever.
  2. Raised ESR or CRP.
  3. Arthralgia (but not if arthritis is one of the major criteria).
  4. Prolonged PR interval (but not if carditis is major criterion).
  5. Previous rheumatic fever.
25
Q

What is Neutropenic sepsis

A

The development of sepsis in s patient with neutropenia

Diagnostic criteria:

  • Temperature > 38 degrees
  • Neutrophil count < 0.5

Neutropenic shock is possible without a fever as patients may be on antipyretic drugs or steroids

26
Q

What are cause of neutropenic shock

A

Incidental Neutropenia:
Congenital
- Ethnic variation
- Cyclical neutropenia in children

Acquired

  • Decreased/ineffective neutrophil production: Bone marrow infiltration, Aplastic anaemia, B12/folate deficiency, chemotherapy, radiotherapy
  • Felty’s syndrome
  • Hypersplenism
  • Malaria

Others

  • Toxoplasmosis
  • Dengue fever

Febrile neutropenia: Temperature over 38.5 or over 38 for 2 hours and an absolute neutrophil count < 0.5

27
Q

What are the signs and symptoms of Neutropenic sepsis

A

Check history for:

  • High risk features: Active cancer, recent chemo, use of immunosuppressants or immunosuppressive illness
  • CKD
  • Recent blood products
  • Intravascular devices

Examination findings:

  • Signs of infection
  • Fever
  • Features of IE
  • Lymphadenopathy
  • Skin rashes
28
Q

How is Neutropenic sepsis diagnosed

A

FBC: Neutrophils <0.5
Blood cultures: Positive for causative organism

Others - Blood film, D-dimer (for DIC), U&Es, creatinine, LFTs

29
Q

What is Necrotising fasciitis

A

A life-threatening infection of subcutaneous soft-tissue that may extend to the deep fascia but not into the underlying muscle

30
Q

What are causes of Necrotising fasciitis

A

Type I: Polymicrobial due to mixed anaerobic/facultative anaerobic organisms. Bacteroides or peptostreptococcus + E Coli, Enterobacter, Klebsiella, Proteus or non-Group A Strep

Type II: Due to a single organism, most commonly Streptococcus pyogenes, also called group A streptococcus.

31
Q

What are the signs and symptoms of Necrotising fasciitis

A
  • Anaesthesia or severe pain over site of cellulitis that may be disproportionate to the skin lesion
  • Fever
  • Palpitations, tachycardia, tachypnoea, hypotension
  • N+V
  • Redness and oedema
  • Haemorrhagic blisters may be present
32
Q

How is Necrotising fasciitis investigated

A 
Low Na
High Urea and creatinine
CRP elevated
CK elevated
Lactate elevated

Diagnostic - Blood and tissue cultures

Surgical exploration

33
Q

What is Malaria

A

Infection with protozoan plasmodium

34
Q

What are the 5 types of plasmodium that can cause Malaria

A

Plasmodium:

  1. Falciparum - Most serious
  2. Vivax
  3. Ovale
  4. Malariae
  5. Knowlesi
35
Q

How is Malaria transmitted

A

Bite of the female Anopheles mosquito

The protozoa grow in red blood cells

36
Q

Which population of people have innate immunity to malaria

A

Sickle cell trait
G6PD deficiency
Pyruvate kinase deficiency
Thalassemia

37
Q

What are signs and symptoms of Malaria

A 
Feverish traveller (Incubation up to 1 year)
Cyclical symptoms:
- High fever
- Flu-like symptoms
- Severe sweating
- Shivering cold/rigors
  • Anaemia
  • Hepatosplenomegaly

The cycles of symptoms are slightly different in different types of malaria

Cerebral Malaria:

  • Headache
  • Disorientation
  • Coma
38
Q

How is Malaria diagnosed

A

Thick and thin blood smears stained with Giemsa stain remain the ‘gold standard’ - Detection of the parasite
Thick - Quantify
Thin - Identify

FBC - Haemolytic picture

Urinalysis - Protein, UBG + CB

All conditions - Year 3 (16 decks)

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