Infectious Diseases Flashcards
(62 cards)
1
Q
What is the definition of meningitis?
How is this different to encephalitis?
A
meningitis is inflammation of the leptomeningeal coverings (pia mater & arachnoid) of the brain
it affects the extremes of age due to impaired immunity
encephalitis involves inflammation of the brain parenchyma
2
Q
What are the typical causative agents of meningitis?
A
BACTERIA
- Streptococcus pneumoniae
- Neisseria meningitidis
- Haemophilus influenzae type B
- there are also some viral, fungal, parasitic and non-infectious causes
3
Q
What are the typical causative agents of encephalitis?
A
there are infectious and non-infectious causes
it is typically caused by VIRUSES
the main cause is the herpesvirus
4
Q
What are the typical symptoms associated with meningitis?
A
- photophobia
- neck stiffness
- headache
- fever
5
Q
What are the typical symptoms of encephalitis?
A
- altered state of consciousness
- seizures
- personality changes
- cranial nerve palsies
- speech problems
- motor and sensory deficits
6
Q
What investigations are performed for meningitis and encephalitis?
A
Meningitis:
- lumbar puncture is performed to obtain CSF
Encephalitis:
- blood cultures
- neuroimaging via MRI scan
- CSF analysis
7
Q
What is involved in the initial management of meningitis?
A
empirical antimicrobial therapy should be started promptly until the causative agent is identified
this involves ceftriaxone / vancomycin
8
Q
What organisms tend to cause meningitis in neonates?
Which one occurs straight after birth and which one is a delayed infection?
A
- Group B streptococcus is associated with infection in previous pregnancy and/or extended labour
this infection occurs early on in the life of the infant
- E. coli tends to cause late neonatal infection
- Listeria monocytogenes can also cause meningitis in neonates
9
Q
What organisms tend to cause meningitis in children & teenagers?
A
-
Haemophilus influenzae tends to cause meningitis in people who are unvaccinated
- this tends to be someone from a poor country or who’s parents don’t believe in vaccines
- Neisseria meningitides is a gram-negative diplococci that can also be responsible
10
Q
What organism most commonly causes meningitis in adults and the elderly?
A
Streptococcus pneumoniae
11
Q
When does Listeria monocytogenes typically cause meningitis?
A
- the elderly
- alcoholics
- consuming cheese / unpasteurised milk
- it likes cold environments and grows on refridgerator items
12
Q
What are the 2 demonstratable signs associated with meningitis?
A
- Brudzinski’s sign
- Kernig’s sign
13
Q
What is Brudzinski’s sign?
A
- severe neck stiffness causes a patient’s hips and knees to flex when the neck is flexed
14
Q
What is Kernig’s sign?
A
- Severe stiffness in the hamstrings causes an inability to straighten the leg when the hip is flexed to 90 degrees
15
Q
What are the signs of infection that are specific to meningitis?
A
- fever
- tachycardia
- hypotension
-
skin rash - petechiae - think meningococcal septicaemia
- if there is a skin rash, think Neisseria meningitidis
- altered mental state
16
Q
What 3 investigations are performed for suspected meningitis and why?
A
Bloods:
- two sets of blood cultures
Imaging:
- CT scan to exclude bleeding & raised intracranial pressure
Lumbar puncture:
- to obtain CSF which is sent for MC&S and Gram staining
17
Q
When should lumbar puncture be avoided as an investigation for meningitis?
A
- if there are neurological signs suggesting raised ICP
- if there is a superficial infection over LP site
- coagulopathy
18
Q
In normal CSF, what is the:
- appearance
- white cell count
- protein
- glucose
- Gram stain
A
- it has a clear appearance
- it has very low white cell count
- it has normal levels of protein and glucose
- Gram stain is normal
19
Q
How do the following characteristics of CSF change if there is bacterial infection?
- appearance
- white cell count
- protein
- glucose
- Gram stain
A
- appearance is turbid
- white cell count is VERY HIGH with many NEUTROPHILS
- protein is massively increased
- glucose is massively decreased
- this is because bacterial infections take up sugar for nutrition, whereas viral infections do not
- Gram stain is positive
20
Q
How are the following characteristics of CSF changed in viral infections?
- appearance
- white cell count
- protein
- glucose
A
- the appearance is clear/cloudy
- white cell count is high with lots of LYMPHOCYTES
- protein is slightly raised
- glucose is normal
21
Q
How are the following characteristics of CSF changed in TB/fungal infection?
- appearance
- white cell count
- protein
- glucose
A
- the appearance is clear/cloudy
- the white cell count is high with lots of LYMPHOCYTES
- protein is slightly raised
- glucose is slightly decreased
22
Q
What infection is suspected if someone has a non-blanching rash?
What is the treatment for this?
A
- Neisseria meningitidis infection is suspected
- if someone has a non-blanching rash OR meningococcal septicaemia, they need to be admitted
- they are given a single dose of IV benzylpenicillin
23
Q
What is the general treatment for bacterial meningitis?
A
- IV ceftriaxone (3rd generation cephalosporin)
-
oral corticosteroids are considered as they reduce inflammation of the meninges
- this is dexamethasone usually
- OCS should NOT be given if meningococcal septicaemia is suspected
24
Q
If you are thinking of treating bacterial meningitis but the patient’s consciousness is affected, what other treatment should be considered and why?
A
- if consciousness is affected, consider IV aciclovir
- this covers encephalitis, as the most common cause of encephalitis is viral (herpes virus)
25
What treatment should be given to close contacts of someone with bacterial meningitis?
* **prophylaxis** should be given to close contacts
* this involves **_rifampicin_** or **ciprofloxacin**
26
What is the definition of infective endocarditis?
How common is it?
* it is the **infection of _endocardial structures_**
* this mainly involves **heart valves**
* it involves **life-threatening inflammation** of the endocardium (innermost layer of the heart)
* it is quite uncommon
27
What are the 4 causative organisms of infective endocarditis?
* ***Streptococci***
* ***Staphylococci***
* ***Enterococci***
* other organisms (HACEK organisms)
* these will have a negative blood culture
28
What are the risk factors for infective endocarditis?
* having **_abnormal heart valves_**
* e.g. congenital
* post-rheumatic
* calcification / degeneration
* **prosthetic** heart valves
* **IV drug use**
* **_turbulent_ blood flow** (e.g. PDA or VSA)
* recent **dental work**
29
What is the difference in the way in which streptococci and staphylococci affect the heart valves in infective endocarditis?
* **streptococci** need a **_damaged heart valve_** in order to attack
* there needs to be abnormal heart valves
* **staphylococci** doesn't need damaged valves to infect the heart, but it is **harder for them to enter** the body
30
What valve would you expect to be affected if an IVDU gets infective endocarditis?
* you would expect an **infection of the first valve** that is encountered from their venous system
* this would be the **_tricuspid valve_**
* infective endocarditis of the tricuspid valve - think IVDU
31
What are the symptoms of infective endocarditis?
* fever with **sweats / chills / rigors**
* malaise
* **arthralgia** (pain in a joint)
* **myalgia** (pain in a muscle / group of muscles)
* confusion
32
What are the signs of infective endocarditis?
* pyrexia
* tachycardia
* signs of anaemia
* finger **_clubbing_**
* **new murmur**
* frequency mitral \> aortic \> tricuspid \> pulmonary
* **splenomegaly**
* vasculitic lesions
33
What are the 3 types of vasculitic lesion associated with infective endocarditis?
* **_Osler's nodes_**
* these are **tender, painful lesions** on the **_fingers and toes_**
* they are red-purple, slightly raised and often have a pale centre
* **_Roth's spots_**
* red spots with white or pale centres that are found on the **_retina_**
* **_Janeway lesions_**
* these are **non-tender, haemorrhagic lesions** that occur on the **_thenar and hypothenar eminences_**
34
What mnemonic is used to remember the features of infective endocarditis?
**_FROM JANE with \<3_**
* **F** - Fever
* **R** - Roth spots
* **O** - Osler nodes
* **M** - Murmur
* **J** - Janeway lesions
* **A** - Anaemia
* **N** - Nail-bed haemorrhage
* **E** - Emboli
* occasionally it can present with **haematuria** (which tends to be microscopic) due to emboli travelling to the kidneys
35
What are the 6 buzzwords to remember when thinking about infective endocarditis?
* **_prosthetic valves_**
* previous / recent **dental procedure**
* **new onset murmur**
* **vegetation** present on Echo
* **right heart** (this is usually due to IVDU)
* **indwelling catheter** (another point of introducing infection)
36
What investigations are conducted for suspected infective endocarditis?
***_Bloods:_***
* FBC - showing **_high neutrophils_** & **_normocytic anaemia_**
* ESR / CRP
* U&Es
* Rheumatoid factor positive
***_Duke Criteria:_***
* in order to determine this **_3 blood cultures_ are needed, each _1 hour apart_ within _24 hours_** for diagnosis
***_Urgent Echo_***
37
What is needed for the diagnosis of infective endocarditis?
What treatment is given in the meantime?
* **_3 blood cultures_** are needed, each **_at least 1 hour apart_** and all need to be taken **_within 24 hours_**
* **broad spectrum antibiotics** are given until sensitivity is reported
38
What are the possible complications of infective endocarditis?
* congestive heart failure
* valve incompetence
* aneurysm formation
* systemic embolisation
* renal failure
* glomerulonephritis
39
What is the management for infective endocarditis affecting native valves?
antibiotics are given for **_4 - 6 weeks_**
* for penicillin-sensitive ***Streptococcus viridans*** the treatment is **_benzylpenicillin + gentamicin_**
* for ***Staphylococcus aureus***, the treatment is **_flucloxacillin_**
* if resistant or penicillin-allergic, then **_vancomycin_** is given instead
40
What is the treatment for infective endocarditis in someone with prosthetic valves?
* this is usually caused by ***Staphylococci***
* the treatment is **_flucloxacillin_** **_+_** **_rifampicin_** **_+_** **_gentamicin_**
* if the patient is allergic to penicillin then **_vancomycin_** is given instead of flucloxacillin
41
What is the definition of gastroenteritis?
**_acute inflammation_ of the _lining of the GI tract_,**
manifested by **nausea**, **vomiting**, **diarrhoea** and **abdominal discomfort**
42
What are the viral causes of gastroenteritis?
* **rotavirus**
* ****this was the most common cause in children
* they are now vaccinated against it, so it is not as common
* adenovirus
* astrovirus
* calcivirus
43
What are the bacterial causes of gastroenteritis?
* ***Campylobacter jejuni***
* ***Escherichia coli*** (particularly 0157)
* **Salmonella**
* Shigella
* *Vibrio cholerae*
* Listeria
* *Yersinia enterocolitica*
44
What are the protozoal causes of gastroenteritis?
* *Entamoeba histolytica*
* *Cryptosporidium parvum*
* *Giardia lamblia*
45
What is dysentry and how is it different from diarrhoea?
* it involves **intestinal inflammation** that primarily involves the **colon**
* it involves **mild to severe stomach cramps** and **severe diarrhoea**
* the diarrhoea associated with dysentry **_contains blood_**
46
What mnemonic can be used to remember the organisms which cause dysentry?
**_CHESS_**
* **C** - Campylobacter / Clostridium difficile
* **H** - Haemorrhagic *E. coli*
* **E** - Entamoeba histolytica
* **S** - Shigella
* **S** - Salmonella
47
What are the causes of gastroenteritis that present with diarrhoea and not dysentry?
* Campylobacter / *Clostridium difficile*
* *Staphylococcus aureus*
* *Vibrio cholera*
* *E. coli*
* *Bacillus cereus*
* Salmonella
48
What clues might be in the history of someone presenting with diarrhoea due to *C. diff* or *Staph aureus* infection?
* ***C. diff*** is associated with the **_use of antibiotics_** and/or antiperistaltic drugs
* ***Staph aureus*** is associated with **food**
it comes on **_1 - 6 hours after eating_** and is **short-lived**
49
What clues might be in the history of someone presenting with diarrhoea due to *Vibrio cholera* and *E. coli*?
* ***Vibrio cholera*** is associated with **_rice water diarrhoea_**, **poor sanitation** and **shock**
* ***E. Coli*** is associated with consumption of **_leafy vegetables_**
50
What clues might be in the history of someone presenting with diarrhoea due to salmonella or *Bacillus cereus*?
***_Salmonella:_***
* mainly comes from **_eggs_** and can also come from **poultry**
* may present with **constipation**
* multiplies in Peyer's patches of the intestine
***_Bacillus cereus:_***
* associated with **_reheated rice_**
* can cause **cerebral abscess**
51
What clues might be in the history of someone presenting with diarrhoea due to haemorrhagic E. coli?
What does this infection cause?
* it is associated with consumption of **_leafy vegetables_**
* it is characterised by **bloody diarrhoea** followed by **_haemolytic uraemic syndrome_**
52
What clues might be in the history of someone presenting with diarrhoea due to *Entamoeba histolytica* or campylobacter?
* *Entamoeba histolytica* is associated with **poor sanitation**, **tropical places** and **MSM**
* Campylobacter is associated with **_uncooked poultry_**
53
What clues might be in the history of someone presenting with diarrhoea due to shigella?
* person-to-person contact
* poor sanitation
* MSM
54
What are the symptoms of gastroenteritis?
* sudden onset nausea
* vomiting
* anorexia
* diarrhoea (+/- blood)
* abdominal pain
* fever and malaise
55
What signs might be present on examination of someone with gastroenteritis?
* check **mucous membranes** for signs of **_dehydration_**
* assess **skin turgor** and **capillary refill**
* measure **HR** and **BP** to assess whether patient is in **_shock_**
* **temperature**
56
What other investigations are carried out for gastroenteritis?
***_Bloods:_***
* FBC
* ESR / CRP
* U&Es will be deranged - **_low potassium in severe D&V_**
***_Stool MC&S:_***
* bacterial pathogens
* ova cysts (eggs)
* parasites
57
What is the treatment for gastroenteritis when the patient has no systemic signs?
* systemic signs include **shock** and **dehydration**
* **_supportive therapy_** is given
* bed rest and **fluid** and **electrolyte replacement** with **_oral rehydration solution_**
* this is given due to loss of nutrients / vitamins through diarrhoea/vomiting
58
What is the treatment for gastroenteritis when there are signs of systemic illness?
How is systemic illness defined and what investigation is carried out?
* systemic illness is defined as:
* temperature **\> 39oC** or **dehydration**
* visible **blood**
* or duration **\> 2 weeks**
* patient is admitted and given **_oral fluids_**
* **__****_IV rehydration_** is required for **severe vomiting**
* **antibiotics** are given if the infective organism is identified
* a **_direct faecal smear_ then culture** is obtained
59
**_Hepatitis A_**
* **jaundice**, **RUQ pain** and **raised ALT & AST** are suggestive of hepatitis
* Jamaica is an endemic country and hepatitis A is **_faeco-orally_** transmitted
60
What signs and tests would point towards a diagnosis of hepatocellular carcinoma?
* combination of **jaundice**, **hepatomegaly** and **weight loss**
* when combined with a **_raised aFP_**
61
B - positive nitrites and Gram-negative bacilli
* this is an **_E. coli infection_**
* **nitrites are specific for E. coli**
* this is more common in women after sexual intercourse as their urethra is shorter
62
