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2a > Infectious Diseases > Flashcards

Infectious Diseases Flashcards

1
Q

What is meningitis?

A

Inflammation of the meninges of the brain. Can be a bacterial, viral or fungal cause.

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2
Q

What are the bacterial causes of meningitis in neonates?

A

E.coli
Group B Strep
Listeria monocytogenes

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3
Q

What are the bacterial causes of meningitis in infants?

A

Neisseria meningitidis
H.influenzae
Strep pneumoniae

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4
Q

What are the bacterial causes of meningitis in young adults?

A

N.meningitidis

Strep pneumoniae

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5
Q

What are the bacterial causes of meningitis in the elderly?

A

Strep pneumoniae
N.meningitidis
Listeria

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6
Q

What are the viral causes of meningitis?

A 
Mumps virus
Echo virus
Coxsackie virus
Other enterovirus
Herpes simplex virus
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7
Q

Risk factors for meningitis?

A 
Immunocompromised
Elderly
Pregnant
Malignancy
Diabetes
Bacterial endocarditis
Crowding
Intrathecal drug administration
IVDU
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8
Q

How does meningitis present?

A

TRIAD

  1. headache
  2. neck stiffness
  3. fever

Other:

  • meningismus (photophobia, neck stiffness)
  • reduced GCS
  • papilloedema
  • intense malaise, fever, riggers, vomiting
  • irritable + prefers to lie still
  • meningococcal septicaemia (rash)
  • seizures
  • progressive drowsiness
  • positive Kernig’s + Brudzinki’s sign

If viral may be less signs and more self-limiting

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9
Q

How do you diagnose meningitis?

A 
Blood cultures
Bloods: FBC, U+E, CRP, serum glucose
CT head
Lumbar puncture
Throat swabs
Serum PCR (pneumococcal + meningococcal)
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10
Q

When do you do a CT before LP?

A
  • > 60 years
  • immunocompromised
  • Hx of CNS disease
  • new onset/recent seizures
  • decreasing conscious levels
  • focal neurological signs
  • papilloedema
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11
Q

What are the LP results for bacterial meningitis?

A

Cells: polymorphs (neutrophils)
Protein: raised
Glucose: low

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12
Q

What are the LP results for viral meningitis?

A

Cells: lymphocytes
Protein: normal/raised
Glucose: normal

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13
Q

What are the LP results for TB meningitis?

A

Cells: lymphocytes
Protein: raised
Glucose: low/normal

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14
Q

How do you treat meningitis?

A

If non-blanching petechial or purpuric rash = meningococcal septicaemia
> immediate IM benzylpenicillin (community)
> immediate IV cefotaxime (hospital)
+ do not perform LP, confirm diagnosis by blood culutres

If bacterial meningitis:
> IV cefotaxime or IV ceftriazone 2-3g QID
(if Hx of anaphylaxis with penicillin, give IV chloramphenicol)

If viral:
> self-limiting
> aciclovir if cause is HSV

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15
Q

When would you add IV amoxicillin to meningitis treatment? And why?

A 
If bacterial cause and patient is:
- immunocompromised
- >50 years
- pregnant 
In order to cover listeria.
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16
Q

If the cause is likely pneumoccocal for bacterial meningitis, what could you add to the treatment and why?

A

Oral dexamethasone to reduce cerebral oedema

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17
Q

What do you do with contacts of meningitis patients?

A

Prophylaxis for close contacts
> oral ciprofloxacin stat (all ages + pregnancy)
> oral rifampicin (all ages but NOT pregnancy)

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18
Q

What are some complications of meningitis?

A

Hearing loss
Seizures
Developmental problems

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19
Q

What is encephalitis?

A

Infection and inflammation of the brain parenchyma which affects the extremes of age (children + elderly.)

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20
Q

What causes encephalitis?

A

Mainly viral:

  • herpes simplex virus 1 + 2
  • varicella zoster
  • EBV, CMV, HIV
  • mumps, measles

Non-viral:

  • bacterial meningitis
  • TB
  • malaria
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21
Q

Clinical presentation of encephalitis?

A

TRIAD

  1. fever
  2. headache
  3. altered mental status

Begins with features of viral infection (fevers, headache, myalgia, fatigue, nausea) and progresses to personality and behavioural changes, decreased consciousness, confusion + drowsiness

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22
Q

How is encephalitis diagnosed?

A

MRI
EEG
LP
Blood + CSF serology

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23
Q

How is encephalitis treated?

A

Viral:
> IV aciclovir immediately (don’t wait for results)

Anti seizure medication
e.g. primdone

If suspected meningitis: IM benzylpenicillin

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24
Q

What causes tetanus?

A

Clostridium tetani

  • soil organism, terminal spores
  • gram positive anaerobe
  • infects via dirty wounds, releasing toxin which translate via peripheral nerve and enter CNS and bind to GABA receptors of inhibitory inter-neurones.
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25
Q

What are the clinical features of tetanus?

A
  • Paraesthesia of wound
  • Trismus (lockjaw)
  • Opisthotonus (sustained muscle contraction)
  • Risus sardonic (involvement of facial muscles)
  • Paroxysmal generalied spasms
  • Autonomic dysfunction
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26
Q

How do you diagnose tetanus?

A

Wound culture

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27
Q

How do you treat tetanus?

A
  • debride wound quickly
  • benzylpenicilin
  • human tetanus immunoglobulin
  • spasms: dantolene, baclofen
  • control HTN/tachdysrythmia
  • ITU/airway mx
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28
Q

How do you prevent tetanus?

A

Tetanus toxoid

  • 3 doses (primary immunisation)
  • single booster dose (after wounds if >5 years since primary course or booster)
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29
Q

What is botulism?

A

Caused by clostridium botulinum, a powerful neurotoxin

  • assoc with home-canned fruit/veg or fish products
  • IVDU
  • descending paralysis with cranial neuropathy first
  • diplopia, dysarthria, dysphagia, peripheral weakness

Tx: equine or human antitoxin

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30
Q

What is pneumonia?

A

Inflammation of the lung tissue and fluid collection within the lungs that results from infection.

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31
Q

What causes pneumonia?

A

Bacterial

  • strep pneumonia (90% of cases)
  • staph aureus
  • legionella’s
  • jirovecci

Viral
- h.influenza

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32
Q

What are the different types of pneumonia?

A

Community acquired
Hospital acquired
Aspiration (inhaled foreign objects that bring in bacteria)

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33
Q

Who is at risk of pneumonia?

A
  • infants + elderly
  • COPD + other chronic lung conditions
  • HIV, AIDS
  • nursing home residents
  • impaired swallowing
  • diabetics
  • congestive heart disease
  • alcoholics and IVDU
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34
Q

Clinical features of pneumonia?

A

Symptoms

  • confusion
  • tired
  • pleuritic chest pain
  • SOB
  • headache

Signs

  • low BP
  • fever
  • tachycardia
  • high RR
  • sputum
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35
Q

Ix for pneumonia?

A 
CXR
Auscultation
Sputum sample
Blood culture
Legionella's urinary antigen test (ELISA)
Thoracentesis
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36
Q

What is CURB-65?

A

Assess the severity of CAP and increased likelihood of a patient’s 30 day mortality rate:

  • Confusion
  • Urea >7
  • RR >/30
  • BP <90/60
  • > /65 years

1 point for each

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37
Q

How do you treat a pt who scores 0-2 on curb65?

A

Oral amoxicillin as an outpatient

38
Q

How do you treat a pt who scores 3-4 on curb65?

A

Oral amoxicillin + clarithromycin

39
Q

How do you treat a pt who scores 5 on curb65?

A

IV co-amoxiclav + clarithromycin

40
Q

How do you treat a pt with legionellas pneumonia?

A

Fluoroquinolone + clarithromycin

41
Q

What causes TB?

A

Mycobacterium tuberculosis

Mycobacterium bovis

42
Q

What is a Gohn focus?

A

A lung lesion that forms in primary TB composed of tubercle-laden macrophages. It becomes a Gohn complex when it’s: Gohn focus + hilar lymph nodes.
Usually heals by fibrosis.

43
Q

Clinical features of TB?

A 
Weight loss
Night sweats
Fever
Cough
Haemoptysis
  • lymph node swelling + discharge
  • painful swollen joints (Potts)
  • ascites
  • epididymitis, dysuria, haematuria
44
Q

Ix for TB?

A

Ziehl-Neelsen stain for acid fast bacilli

CXR

45
Q

What is seen on CXR in TB?

A
  • consolidation
  • cavitation
  • calcification
  • pleural effusion
46
Q

How do you treat TB?

A

Rifampicin (6months)
Isoniazid (6 months)
Pyranzinamide (2months)
Ethambutol (2months)

47
Q

SE of TB medication?

A

Rifampicin: red urine, hepatitis
Isoniazid: hepatitis, neuropathy
Pyranzinamide: hepatitis, arthralgia/gout, rash
Ethambutol: optic neuritis

48
Q

How do you screen for TB?

A 
Mantoux test (for latent TB)
Interferron gamma blood test
49
Q

What is infective endocarditis?

A

Infection of heart valves or other endocardial lined structures within the heart.

50
Q

RF for IE?

A
  • IVDU
  • poor dental hygiene
  • skin + soft tissue infection
  • dental treatment
  • IV cannula
  • cardiac surgery
  • pacemaker
  • prosthetic heart valve patients
51
Q

What organisms cause IE?

A 
Staph aureus!!
Pseudomonas aeruiginosa
Strep viridians (dental problems)
52
Q

Clinical presentation of IE?

A 
New valve lesion/regurgitate murmur
Fever
Valve dysfunction
Embolic events
Haematuria
Finger clubbing
Headache, malaise, confusion, night sweats
53
Q

Peripheral stigmata of IE?

A
  • splinter haemorrhages
  • osler nodes
  • laneway lesions
  • roth spots
  • petechiae
  • embolic skin lesions
54
Q

How do you diagnose IE?

A

DUKE’S CRITERIA is used

Blood cultures

  • 3 sets from different sites over 24hours
  • do this before Abx are started

Bloods

  • CRP + ESR (raised)
  • Normochromic normocytic anaemia
  • Neutrophilia
Transoesophageal echo (better at diagnosing)
Transthoracic echo

Urinalysis
- haematuria

CXR
- cardiomegaly

ECG
- long PR interval

55
Q

How do you treat IE?

A

Abx for 6 weeks
Staph: IV vancomycin + rifampicin
Non-staph: IV benzylpenicillin + gentamicin

Treat complications (arrhythmias, heart failure etc)

Surgery
- remove valve

Good oral health

56
Q

What is Duke’s criteria?

A 
Either need:
- 2 major
- 1 major + 3 minor
- 5 minor
to diagnose a definite IE
57
Q

What are some major criteria in dukes?

A
  • bugs grown from blood cultures

- evidence of endocarditis on echo, or new valve leak

58
Q

What are some minor criteria in dukes?

A
  • predisposing factors
  • fever
  • vascular phenomena
  • immune phenomena
  • equivocal blood cultures
59
Q

What is HIV?

A

A sexually transmitted disease. Often has a long, latent and dormant period which is very prone to mutations.
It is a retrovirus the contains RNA.

60
Q

How do you diagnose HIV?

A 
CD4 count (low)
Viral load (high)
61
Q

Why is the CD4 count used in HIV?

A

The CD4 cells are T-helper lymphocytes which are attacked by the HIV virus. Therefore a low CD4 count suggests it has been affected by the virus.

62
Q

What is AIDs?

A

Acquired Immune Deficiency Syndrome

- diagnosed when the CD4 count <200 or by presence of AIDS-defining illness

63
Q

What are the AIDs defining illnesses?

A
  • PCP
  • CMV
  • TB
  • Kapos’s sarcoma
  • Lymphoma
64
Q

How is HIV treated?

A

Anti-retroviral therapy
(HAART) started regardless of CD4 count.
- 2 NRTIs with an integrate inhibitor, an NNRTI or a PI

65
Q

What are some combination drugs made for HIV tx?

A

Truvada (tenofovir + emtricitabine)

Kivexa (abacavir + latitudine)

66
Q

What prophlyaxis is given to pt with CD4 count <200?

A

Co-timoxazole
Nebulised pentamidine
Azithromycin
Ganciclovir

67
Q

How is Hep B transmitted?

A 
Vertical
Horizontal
- sexual
- blood transfusions
- needles/sharps
- shared razors or toothbrushes
68
Q

Explain the different antigens in Hep B?

A

Surface antigen

  • protein found in blood of pt that have CURRENT infection (diagnostic confirmation)
  • can be genetically produced to be used as a vaccine

Envelope antigen
- allows assessment of phase of infection

Core antigen
- not used diagnostically

69
Q

What are the different antibodies found in Hep B?

A

Surface antibody
- indicates immunity to hep B following immunisation or infection

Envelope antibody
- appears in later phase of both acute/chronic disease ad evidence of immune response

Core antibody

  • found in most people exposed to HBV
  • IgM = acute infection
  • IgG = chronic infection
70
Q

What is HBV DNA?

A

Measured and quantified by nucleic acid testing such as PCR.

Helps determine the grade of replication + activity of the virus.

71
Q

What treatments are used in Hep B?

A

Pegylated interferon alpha
- weekly injectable for 48 weeks

Oral agents (daily long term)

  • tenofovir
  • entecavir
72
Q

What is the main mode of transmission for hep C?

A

parenteral

- IVDU

73
Q

Clinical features of hep c?

A 
Mostly asymptomatic
Malaise
Nausea
RUQ apin
Jaundice
74
Q

How is hep C diagnosed?

A

Enzyme immunoassay serology
Immunoblot assay
PCR for HCV RNA

75
Q

What can chronic HCV infection develop into?

A

ESLD

76
Q

What other tests are done for HCV patients?

A

Liver fibrosis assessment
- fibroscan

Liver biopsy

HCC screening

OGD to look for varices if evidence of portal hypertension

77
Q

What is involved in hepatocellular carcinoma screening?

A

6 monthly AFP testing + liver USS

78
Q

Difference in tx aim in HBV + HCV?

A

HBV: control not cure
HCV: cure

79
Q

How is a cure defined in HCV?

A

Undetectable HCV RNA in blood 12 weeks after the end of treatment

80
Q

What is HCV treatment?

A

Direct acting antiviral drugs which act on specific HCV viral enzymes and prevent its replication

  • NS3/4A inhibition (-previr)
  • NS5A inhibitors (-asvir)
  • NS5B (-buvir)
81
Q

What are the 5 species that cause malaria?

A
  1. plasmodia falciparum (most common)
  2. plasmodia ovale
  3. plasmodia viva
  4. plasmodia malariae
  5. plasmodia knowlesi
82
Q

Clinical features of malaria?

A 
Fever
N+V+diarrhoea
Headache, myalgia, fatigue
Chills + sweats
Hepatosplenomegaly
Blood in urine
Anaemia + jaundice
83
Q

How do you diagnose malaria?

A

3 thin + thick blood films at least 24 hours apart

FBC, U+E, LFT, glucose, lactate + clotting
Blood cultures
Blood gas

84
Q

What does the thick film tell you in malaria testing?

A
  • determines whether the parasite is present

- calculate the parasitaemia %

85
Q

What does the thin film tell you in malaria testing?

A
  • determines morphology + plasmodium species present
86
Q

How is uncomplicated malaria treated?

A

PO riamet
or
PO quinine + doxycycline

87
Q

How is a benign malaria treated?

A

PO chloroquine

Give Primaquine for P.vivax and ovale hypnozoites

88
Q

How is complicated malaria treated?

A

IV Artesunate
Once patient improved and tolerating oral medications this can be switched to Artemether-lumefantrine (Riamet) or Quinine and doxycycline

89
Q

How would you monitor someone’s response to malaria treatment?

A
  1. Monitoring the patient clinically (routine observations, daily symptom review etc.)
  2. 12 hourly blood films to monitor the parasitaemia.
  3. Daily bloods to monitor for evidence of anaemia, clotting derrangements and developing end organ failure.
90
Q

What are some major features of complicated/severe malaria?

A
  • Imparied GCS or seizures
  • Renal impairment
  • Acidosis (pH <7.3)
  • Hypoglycaemia
  • Pulmonary oedema or ARDs
  • Haemoglobin (<80g/L)
  • Disseminated intravascular coagulation/ spontanous bleeding
  • Shock (BP <90/60)
  • Haemaglobinuria
  • Parasitaemia >10%
91
Q

What anti-malarials can be used for prophylaxis?

A 
Proguanil
Doxycycline
Mefloquine
Chloroquine and/or proguanil
Atovaquone/proguanil

2a (7 decks)

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