Theme 3 Lecture 16: Investigations of specific infections Flashcards

1
Q

What is meant by the specificity of a test?

A

the proportion of people without the disease who have a negative test

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2
Q

What is meant by the sensitivity of a test?

A

the proportion of people with the disease who have a positive test

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3
Q

How do you work out the sensitivity of a test?

A

true positive / (true positive + false negative)

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4
Q

How do you work out the specificity of a test?

A

true negative / (true negative + false positive)

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5
Q

What is M,C & S?

A
  1. Microscopy - cell count, gram stain, direct visualisation of organisms
  2. Culture - difficult culture media, slopes
  3. Sensitivity - EUCAST dict testing, strips
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6
Q

In a blood test for detection of immunity, what does the presence of IgG show?

A

previous infection

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7
Q

In a blood test for detection of immunity, what does the presence of IgM show?

A

current infection (or reactivation)

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8
Q

What is the pathology of meningitis?

A

inflammation of the meninges/ brain parenchyma

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9
Q

What is the most frequent cause of meningitis and encephalitis?

A

viral infection - HSV most likely

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10
Q

Would you perform an LP on a patient with a suspected brain abcess?

A

no because of increased intracranial pressure

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11
Q

What are the symptoms of upper respiratory tract infections?

A

cold, sore throat, ear infections

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12
Q

What are the symptoms of lower respiratory tract infections?

A

bronchitis, pneumonia

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13
Q

What are the symptoms of community acquired pneumonia?

A

shortness of breath, cough, sputum, fever

-changes on chest X-ray confirm pneumonia

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14
Q

What is atypical pneumonia?

A
  • can present with some unusual symptoms - arthralgia, myalgia
  • if patient has failed usual antibiotic treatment or radiological features are unusual
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15
Q

Which viruses can we test for using PCR?

A
  • COVID-19
  • influenza A/B
  • parainfluenza
  • RSV
  • adenovirus
  • metapneumovirus
  • rhinovirus
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16
Q
What are:
1. typical pneumonia
2. atypical pneumonia
3. viral pneumonia
caused by?
A
  1. bacterial infection
  2. bacterial infection
  3. viruses
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17
Q

Which tests tell us if a patient has had TB in the past, even if they are not showing symptoms?

A
  • mantoux
  • IGRA’s
  • T-spot/ quantiferon
18
Q

What is the mode of transmission of TB?

A

Requires exposure then reactivation

19
Q

Which fungal infections are common in an immunocompromised host?

A
  • aspergillus fumigatus
  • crytococcosis
  • mucormycosis
20
Q

Which bacterial infections are common in an immunocompromised host?

A

nocardia sp

gram negatives - resistant

21
Q

Name 3 localised skin and soft tissue infection?

A
  • impetigo - spots on face and back
  • erysipelas - deep tissue infection
  • cellulitis
22
Q

Name 2 severe/extensive skin and soft tissue infection?

A
  • necrotising fasciitis

- diabetic foot infection

23
Q

What are the 4 types of urinary tract infections?

A
  • lower UTI
  • upper UTI
  • prostatitis
  • epididymo-orchitis
24
Q

Which 3 antibiotics increase resistance?

A
  • amoxicillin
  • trimethoprim
  • nitrofurantoin
25
What is prostatitis?
- bacterial inflammation in the prostate | - suspect in men with recurrent UTIs
26
What is epididymo-orchitis?
inflammation of the epididymis and/or testicles
27
What are some examples of GI tract infections?
- infectious diarrhoea - viral gastroenteritis, bacterial, parasitic infection, C-difficile - liver abscess - biliary tract infection - diverticulitis
28
What are some bacterial causes of community acquired gastroenteritis?
``` salmonella sp sigella sp E.coli campylobacter sp C.difficile ```
29
What are some viral causes of community acquired gastroenteritis?
rotavirus, norovirus
30
What are some parasitic causes of community acquired gastroenteritis?
cryptosporidium, giardia
31
What is a self-limiting disease?
a disease that can resolve without treatment
32
What are the signs of diverticulitis?
fever abdo pain diarrhoea
33
How can you test for HIV?
HIV Ab/Ag combined test | HIV PCR
34
how do we test for Hep C?
- look for antibody to see if patient has been exposed to virus - then do PCR if antibody test is +ve - to see if they have active infection
35
What is the positive predicted value?
the probability that people with a positive test truly have the disease
36
What is the negative predicted value?
the probability that people with a negative test truly don't have the disease
37
Name an organism that is a cuase of 'atypical pneumonia'
legionella pneumonphila
38
What are the most appropriate tests for a patient with suspected TB?
Chest X-ray and 3 sputum samples for AAFB MC&S
39
What tests would you perform if a patient presents to A&E with headache, neck stiffness, fever, photophobia
blood cultures, throat swabs (can pick up neisseria meningitidis), CSF, blood for PCR
40
How do we diagnose UTIs?
- go off symptoms | - antibiotics are not necessary if there are no symptoms