Infection and Immunology Flashcards

1
Q

Define abscess.

A
  • a painful collection of pus, usually caused by bacterial infection
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2
Q

What are the presenting signs and symptoms of skin abscesses?

A
  • Swollen, pus-filled lump under the surface of the skin with associated fever and chills
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3
Q

What are the presenting signs and symptoms of internal abscesses?

A
  • Pain in the affected area (or referred pain)
  • Swinging fevers
  • Malaise
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4
Q

What are the appropriate investigations for abscesses?

A

o Ultrasound - can be useful in visualising an abscess

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5
Q

What is the appropriate treatment for abscesses?

A

o Some small skin abscesses may disappear by themselves

o Incision and Drainage

o Antibiotics

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6
Q

What is the most common cause of candidiasis?

A
  • candida albicans
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7
Q

What are the risk factors for candidiasis?

A

Broad-spectrum antibiotics

Immunocompromise (e.g. HIV, corticosteroids)

Central venous lines

Cushing’s disease

Diabetes mellitus

GI tract surgery

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8
Q

What are the presenting signs and symptoms of oral candidiasis?

A

o curd-like white patches in the mouth, which can be removed easily revealing an underlying red base

  • aka as oral thrush
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9
Q

What are the presenting signs and symptoms of oesophageal candidiasis?

A

Dysphagia

Pain on swallowing food or fluids

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10
Q

Name some AIDS-defining illnesses?

A

Candidiasis of the esophagus, bronchi, trachea, or lungs (but NOT the mouth)

Cervical cancer, invasive

Coccidioidomycosis, disseminated or extrapulmonary

Cryptococcosis, extrapulmonary

Cryptosporidiosis, chronic intestinal (greater than one month’s duration)

Cytomegalovirus disease or CMV (other than liver, spleen, or nodes)

Cytomegalovirus retinitis (with loss of vision)

Encephalopathy, HIV related

Herpes simplex: chronic ulcer(s) (more than 1 month in duration); or bronchitis, pneumonitis, or esophagitis

Histoplasmosis, disseminated or extrapulmonary

Isosporiasis, chronic intestinal (more than 1 month in duration)

Kaposi sarcoma

Lymphoma, Burkitt’s (or equivalent term)

Lymphoma, immunoblastic (or equivalent term)

Lymphoma, primary, of brain

Mycobacterium avium complex or M kansasii, disseminated or extrapulmonary

Mycobacterium tuberculosis, any site (pulmonary or extrapulmonary)

Mycobacterium, other species or unidentified species, disseminated or extrapulmonary

Pneumocystis pneumonia (PCP)

Pneumonia, recurrent

Progressive multifocal leukoencephalopathy

Salmonella septicemia, recurrent

Toxoplasmosis of brain

Wasting syndrome due to HIV

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11
Q

What are the presenting signs and symptoms of candidal skin infections?

A

Soreness and itching

Skin appearance can be variable

Red, moist skin area with ragged, peeling edge and possibly papules and pustules

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12
Q

What are the appropriate investigations for candidiasis?

A

o depends on the site

  • oral candidiasis = swabs and cultures are not particularly useful because a lot of normal people have candida in their mouth
  • oesophageal candidiasis = definitive diagnosis is by endoscopy
  • invasive candidiasis = blood cultures required if candidaemia is possible

o therapeutic trials of antifungal (e.g. fluconazole) can help with diagnosis

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13
Q

Define cellulitis?

A

Acute non-purulent spreading infection of the subcutaneous tissue, causing overlying skin inflammation

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14
Q

What are the presenting symptoms of cellulitis?

A

o History of cut, scratch or injury

o Symptoms dependent on the location of the cellulitis

  • periorbital cellulitis - painful swollen red skin around the eye
  • orbital cellulitis - painful or limited eye movements, visual impairment
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15
Q

What are the signs of cellulitis on examination?

A

o Lesion - erythema, oedema, warm tender indistinct margins, pyrexia - may suggest systemic spread

o Periorbital - swollen eye lids, conjunctival infection

o Orbital Cellulitis - proptosis, impaired visual acuity and eye movements, test for RAPD, visual acuity and colour vision

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16
Q

What is the treatement for cellulitis?

A

o Medical = oral penicillins (e.g. flucloxacillin) or tetracyclines are effective

o Surgical = orbital decompression may be needed in orbital cellulitis (EMERGENCY)

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17
Q

What are the possible complications of cellulitis?

A

Sloughing of overlying skin

Orbital cellulitis - may cause permanent loss of vision, spread to the brain, abscess formation, meningitis, cavernous sinus thrombosis

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18
Q

Was viruses cause herpes?

A
  • HSV1 = oral herpes
  • HSV2 = genital herpes
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19
Q

What are the presenting symptoms of HSV1 infection?

A

o Pharyngitis, Gingivostomatitis (eating might be painful), Herpetic whitlow (abscess at the end of the finger caused by infection with HSV - it is very painful)

o THEN WHEN ON REACTIVATION = Prodrome of perioral tingling and burning, Vesicles/cold sores appear, Complete healing within 8-10 days

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20
Q

What are the presenting symptoms of HVS2?

A

Painful blisters and rash in the genital, perigenital and anal area

Dysuria

Fever

Malaise

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21
Q

What are the presenting symptoms of HSV2 encephalitis?

A

Usually caused by HSV1 so causes HSV1 type symptoms

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22
Q

What are the presenting symptoms of HSV2 keratoconjunctivitis?

A

Watering eyes

Photophobia

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23
Q

What are the signs of HVS1 infection on examination?

A

Tender cervical lymphadenopathy

Erythematous, oedematous pharynx

Oral ulcers filled with yellow slough (gingivostomatitis)

Herpetic whitlow

o Herpes Labialis (reactivation affecting the mouth) - Perioral vesicles/ulcers/crusting

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24
Q

What are the signs of HVS2 infection on examination?

A

Maculopapular rash

Vesicles

Ulcers

All of these are found on the external genitalia, anal margin and upper thighs

Inguinal lymphadenopathy

Pyrexia

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25
What investigations should be carried out for herpes?
Diagnosis is usually CLINICAL Vesicle fluid can be sampled and sent for electron microscopy, PCR
26
What are the 3 stages of HIV?
o Seroconversion - self-limiting, fever, night sweats, generalised lymphadenopathy, sore throat, oral ulcers, rash, myalgia, headache, encephalitis, diarrhoea o Early/Asymptomatic - apparently well, persistent lymphadenopathy, progressive minor symptoms (e.g. rash, oral thrush, weight loss) o AIDS - syndrome of secondary diseases resulting from immunodeficiency
27
What are the direct effects of HIV infection on the neurological system?
polyneuropathy dementia
28
What are the direct effects of HIV infection on the lungs?
lymphocytic interstitial pneumonitis
29
What are the direct effects of HIV infection on the heart?
cardiomyopathy myuocarditis
30
What are the direct effects of HIV infection on the haematological system?
anaemia thrombocytopenia
31
What are the direct effects of HIV infection on the GIT?
anorexia wasting
32
What are the direct effects of HIV infection on the eyes?
cotton wool spots
33
What are the appropriate investigations for HIV?
o HIV testing - HIV antibodies, PCR for viral RNA, CD4 count, viral load o Pneumocystic pneumonia - CXR o Cryptococcal meningitis - brain CT or MRI, LP o CMV (colitis) - colonoscopy and biopsy o Toxoplasmosis - brain CT or MRI o Cryptosporidia - stool microscopy
34
Define infectious mononucleosis.
Clinical syndrome caused by primary EBV infection AKA glandular fever
35
What are the presenting symtpms of infectious mononucleosis?
o Incubation period: 4-8 weeks o Abrupt onset of symptoms = Sore throat, Fever, Fatigue, Headache, Malaise, Anorexia, Sweating, Abdominal pain
36
What are the signs of infectious mononucleosis on examination?
PYREXIA Oedema and erythema of the pharynx White/creamy exudate on the tonsils Palatal petechiae Cervical/generalised lymphadenopathy Splenomegaly Hepatomegaly Jaundice (5-10%) Widespread maculopapular rash (in patients who have received ampicillin)
37
What are the appropriate investigatiosn for infectious mononucleosis?
o Bloods - FBC = leucocytosis, LFTs = high AST/ALT o Blood Film - lymphocytosis with atypical lymphocytes o Heterophil Antibody Test - mixing blood of an EBV-positive human with animal blood will make the animal's red cells aggregate and precipitate out of solution o Throat swabs - exclude streptococcal tonsillitis o IgM or IgG to EBV viral capsid antigen o IgG against Epstein-Barr nuclear antigen (EBNA)
38
What is the treatment for infectious mononucleosis?
Bed rest Paracetamol and NSAIDs - helps with fever, malaise Corticosteroids in SEVERE cases Advice - avoid contact sports for 2 weeks (because of risk of rupturing your spleen)
39
What are the possible complications of infectious mononucleosis?
Lethargy for several months Respiratory - airway obstruction from oedematous pharynx, secondary bacterial throat infection, pneumonitis Haematological - haemolytic or aplastic anaemia, thrombocytopenia GI/Renal - splenic rupture, fulminant hepatitis, pancreatitis, mesenteric adenitis, renal failure CNS - Guillain-Barre syndrome, encephalitis, viral meningitis EBV-associated malignancy - Burkitt's lymphoma (in sub-Saharan Africa), nasopharyngeal cancer, Hodgkin's lymphoma
40
Define malaria.
Infection with protozoan Plasmodium - Plasmodium falciparum = most serious
41
What populations have innate immunity to malaria?
Sickle cell trait G6PD deficiency Pyruvate kinase deficiency Thalassemia
42
What are the presenting symptoms of malaria?
Feverish traveller (incubation period can be up to 1 year) Symptoms are CYCLICAL/PAROXYSM: High fever Flu-like symptoms Severe sweating Shivering cold/rigors
43
What are the presenting symptoms of cerebral malaria?
Headache Disorientation Coma
44
What are the signs of malaria on examination?
Pyrexia Anaemia (haemolytic) Hepatosplenomegaly
45
What are the appropriate investigations for malaria?
o Thick/Thin Blood Films - thick for quantifying, thin for identifying type of malaria o Bloods - FBC, U&Es, LFTs, ABG o Urinalysis -check for blood or protein
46
Define varicella zoster.
Primary infection is called varicella (chickenpox). Reactivation of the dormant virus (found in dorsal root ganglia), causes zoster (shingles).
47
What are the presenting symptoms of chicken pox?
Prodromal malaise Mild pyrexia Sudden appearance of intensely itchy spreading rash mainly affecting face and trunk Vesicles weep and crust over New vesicles appear Contagious from 48 hrs before the rash until after the vesicles have all crusted over (7-10 days)
48
What are the presenting symptoms of shingles?
May occur after a period of stress Tingling/hyperaesthesia in a dermatomal distribution - dermatomal because the rash remains dormant in the dorsal root ganglia and reactivation makes the virus travel down the sensory axon to produce a dermatomal shingles rash Painful skin lesions Recovery: 10-14 days
49
What are the signs of chicken pox on examination?
Maculopapular rash Areas of weeping and crusting Skin excoriation (from scratching) Mild pyrexia
50
What are the signs of shingles on examinations?
Vesicular maculopapular rash Dermatomal distribution Skin excoriation
51
What are the appropriate investigations of varicella zoster?
Usually CLINICAL diagnoses Vesicle fluid may be sent for electron microscopy viral PCR (RARELY necessary) Chicken pox in an adult with previous history of varicella infection may require HIV testing
52
What is the treatment plan for chicken pox?
Children - treat symptoms Adults - consider acyclovir
53
What is the treatment of shingles?
Acyclovir, valaciclovir, famciclovir
54
What are the complications of chicken pox?
Secondary infection Scarring Pneumonia Encephalitis Congenital varicella syndrome
55
What are the complications of shingles?
Postherpetic neuralgia Zoster ophthalmicus (rash in the ophthalmic division of the trigeminal nerve) Ramsay-Hunt syndrome Sacral zoster Motor zoster
56
What is Ramsay-Hunt syndrome?
Reactivation of VZV in the geniculate ganglion causing zoster of the ear and facial nerve palsy. Vesicles may be seen behind the pinna of the ear or in the ear canal.
57
Define TB.
Infectious bacterial disease characterized by the growth of nodules (tubercles) in the tissues, especially the lungs.
58
What are the presenting symptoms of TB?
o Persistent cough. o Haemoptysis o Constant fatigue o Weight loss o Loss of appetite o Fever o Night sweats o Tb outside the lungs = persistently swollen glands, abdominal pain, pain and loss of movement in an affected bone or joint, confusion, a persistent headache, fits (seizures)
59
What are the clinical signs of TB on examination?
o Dullness on percussion - Rales o Vocal fremitus over affected area
60
What are the appropriate investigations for TB?
o Pulmonary TB = CXR and sputum cultures o Extra-pulmonary TB = CT/MRI/USS, endoscopy, Bloods, Urine, aspiration/CSF samples for culture o Latent TB = Mantoux test