Infectious diseases Flashcards

1
Q

How is meningitis investigated?

A
  • lumbar puncture if no signs of raised ICP (ZN stain, cytology, virology, glucose, protein, culture PCR)
  • FBC, CRP, coag, culture, glucose, gases, U&E, lactate, meningococcal and pneumococcal PCR
  • throat swabs
  • sometimes a CT scan
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2
Q

How is meningitis without signs of shock, severe sepsis or signs suggesting brain shift managed?

A
  • dexamethoasone 10mg IV
  • ceftriaxone IV
  • careful fluid restriction
  • Follow SEPSIS6
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3
Q

What signs suggest raised ICP and so you should delay LP in meningitis?

A
  • severe sepsis or rapidly evolving rash
  • severe resp/ cardiac compromise
  • focal neurological signs
  • papillodema
  • continuous or uncontrollable seizures
  • GCS<13
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4
Q

List 5 potential complications of meningitis

A

septic shock, DIC, septic arthritis, haemolytic anaemia, pericardial effusion, subdural effusion, SIADH, seizures, hearing loss, cranial nerve dysfunction

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5
Q

How should suspected TB be investigated?

A
  • CXR
  • 3 sputum samples for MC&S and ZN stain (may need todo bronchial washing)
  • biopsy and needle aspiration for non resp TB
  • HIV, Hep B and C serology
  • FBC, U&E, CRP, coag
  • MRI for leptomeningeal involvement
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6
Q

How is TB screened for?

A

Mantoux test + interferon gamma test

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7
Q

How is active TB managed?

A
  • 6 months isoniazid and rifampicin and 2 months of pyranzinamide and ethambutol
    + pyridoxine with the iso
  • check vision baseline with snellen chart
  • Do LFTs and U&Es to check baseline before starting therapy
  • neg pressure room and PPI
  • notify public health
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8
Q

How is latent TB managed?

A

6 months isoniazid or 3 months rifampicin and isoniazid + pyridoxine
notify public health

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9
Q

Give at least 1 adverse effect for each TB drug?

A

R: hepatotoxic, GI upset, autoimmune reactions, orange urine
I: hepatotoxic, peripheral neuritis, psychotic changes and epilepsy
P: hepatotoxic, GI upset,
E: Optic neuritis, hyperuricemia, GI upset, colourblindness
All: allergic reactions

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10
Q

List 5 common/ important diseases which could cause fever in a returing traveller?

A

malaria, dengue, typhoid, amoeba, viral haemorrhagic fever,

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11
Q

How does malaria present?

A
  • travel history to area of high humidity, rural location, cheap accom, outdoors at night roughly 2 weeks ago
  • non specific symptoms: fever, chills, headaches, cough, myalgia, GI upset
  • signs: hepatomegaly, jaundice, abdo tenderness
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12
Q

What are features of late/ severe malaria?

A

Impaired consciousness, SOB, bleeding, fits, hypovolaemia, hypoglycaemia, AKI, resp distress syndrome

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13
Q

What are the 3 causative organisms of malaria and what are their incubations?

A

Plasmodium falciparum: 7-14 days (most common in africa)
Plasmodium vivax: 12-17 days w/ relapses common due to dormant parasites in liver
Plasmodium ovale: 15-18 days, also relapsing

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14
Q

How should suspected malaria be investigated? (4)

A
  • 3x thick and thin blood films with giemsa stain
  • rapid antigen test
  • FBC, U&E, LFT, G6PD activity (prior to giving primaquine), blood glucose, gases, clotting, lactate (if severe)
  • head CT
  • CXR
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15
Q

How is p. falciparum treated?

A

IV quinine initially (needs ECG monitoring) then oral quinine and doxy for 7 days when they can swallow.
Supportive treatment also
Artesunate may be used in fututre

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16
Q

How is p vivax and ovale malaria treated?

A

Cholorquine (3-4 days) and primaquine (14 days)

Supportive treatment also

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17
Q

How does dengue fever present?

A
  • abrupt onset high fever, severe headache behind eyes, myalgia, N+V, abdo pain
  • macropapular blanching trunchal rash
  • signs of bleeding, organ failure, hypovolaemia in severe disease
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18
Q

What countries is dengue common in and how long is the incubation period?

A

africa/ thailand/ americas
4-10 day incubation
carried by day biting mosquito

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19
Q

How is dengue investigated?

A
  • FBC (high PCV, low platelets, leukopenia), clotting studies (prolongs APTT and PT), U&Es, LFTs
  • Serum IgM and IgG antibody detection by ELISA
  • CXR if pleural effusion suspected
  • blood cultures
  • malaria films
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20
Q

How is dengue managed?

A
  • All supportive:
  • Fever control w/ paracetamol/ tepid sponge/ fans
  • Iv fluid resus and fluid balance monitoring
  • haemorrhage and shock require FFP, platelets and sometimes infusion
  • severe dengue may need ITU
21
Q

How does typhoid present? What is the relevance of their tongue?

A

Gradually increasing fever, malaise, headache, dry cough, abdo pain, diarrhoea, furred tongue with red edges and tip, bradycardia

22
Q

What organism causes thyphoid, what is incubation period and how does it spread?

A

Salmonella typhi
Incubation period is 10-20 days for S typhi and 1-10 days for S paratyphi
Spreads through contaminated water and food

23
Q

How is typhoid investigated?

A
  • Blood cultures (gram neg bacillus)
  • FBC, U&E, LFT
  • blood films for malaria
24
Q

How is typhoid managed? (4)

A
  • IV ceftriaxone or azithromycin
  • steroids in severe disease
  • supportive
  • side room, PPE, careful handwashing and faeces disposal
  • surgery if bowl perforates
25
Q

What organism causes amoeba and what country is it prevalent in?

A

entamoeba histolytica

south and central america, west africa, SE asia

26
Q

How long is incubation period and how does amoeba present?

A

Incubation 7 days- 4 months
Usually presents as dysentery (severe diarrhoea with blood and mucus).
Liver amoebiasis presents later w/ pyrexia, sweating, RUQ pain and abdo tenderness, hepatomegaly, weight loss, cough

27
Q

How do you diagnose amoeba?

A

History+Specific stool E. histolytica testing (culture, antigen testing or PCR- 4-6 samples may be needed before a positive result)
USS or CT looking for liver abscesses

28
Q

What is uses to treat dysentery and liver amoeba?

A

both PO metronidazole

29
Q

Give 3 causes of viral haemorrhagic fever (VHF)?

A

All subtypes of RNA virus eg ebola, zika, dengue, yellow fever, crimean congo etc

30
Q

How does VHF present?

A
  • incubation of 2-21 days
  • flushing, conjunctival injection, fever, malaise, flu like illness, petechial haemorrhages
  • later mucous membrane haemorrhage, hypovolaemia, hypotension, shock, circulatory collapse
31
Q

How should VHF be investigated?

A
  • clotting studies
  • FBC: leukopenia and thrombocytopenia
  • LFTs, U&Es, LFTs (raised)
  • D Dimers often high
  • antibody test to identify virus
32
Q

How should VHF be managed?

A
  • notify public health
  • barrier nursing, side rooms, visitor restriction (v contagious)
  • supportive management (keep FFP on standby)
  • monitor and support major organs
  • no specific management
33
Q

Give 4 common bacterial causes of pyrexia with unknown origin

A
  • TB where dissemination has occurred there may be no localising signs and normal CXR
  • Endocarditis (can be culture negative)
  • Abcesses can have no localising symptoms, but may be from previous surgery, trauma, perinephric abcesses can have normal urinalysis
  • hepatobillary infections
  • osteomyelitis (usually causes pain)
  • discitis
34
Q

Give 3 viral causes of pyrexia of unknown origin

A
  • CMV
  • EBV
  • HIV
    Can all cause prolonged febrile illness with no prominent organ manifestation esp in elderly
35
Q

State 2 factors that predispose you to disseminate fungal infections

A

immunosurpression, broad spectrum abx, IV devices and paraenteral nutrition

36
Q

Which cancers are most associated with pyrexia of unknown origin?

A
  • lymphoma
  • leukaemia
  • renal cell carcinoma
  • mets from breast, liver, colon, pancreas
37
Q

Name 2 drugs which could cause a pyrexia

A

B lactam abx
procainamide
isoniazid
phenytoin

38
Q

Which autoimmune diseases could cause pyrexia of unknown origin?

A
  • RA
  • crohns and sarcoidosis (granulomatoid diseases)
  • vasculitis (GCA, PMR)
39
Q

Give 2 non infective, non neoplastic, non autoimmune causes of pyrexia of unknown origin?

A
  • hyperthyroidism
  • peripheral pulmonary emboli
  • thrombophlebitis
  • kikuchis disease (necrotising lymphadenitis- self limiting)
40
Q

What specific investigations could be done to investigate pyrexia of unknown origin?

A
  • Labelled white cell scan
  • blood, urine, sputum, stool, CSF cultures
  • hybrid PET CT
  • skin biopsies or rashes
  • lymph node aspirations or biopsies
41
Q

What are the 3 principles of antimicrobial stewardship? give an eg of each

A
  • persuasive (education, consensus, opinion leaders)
  • restrictive (formulary restriction, prior authorisation, automatic stop orders)
  • structural (computerised records, rapid lab tests, quality monitoring, expert systems)
42
Q

Define pyrexia of unknown origin

A

temp of >38 on multiple occasions for 3 weeks with no identified cause despite 1 week in patient investigations

43
Q

How should suspected HIV be investigated?

A
  • HIV test (antigen and antibody testing, positive a few weeks after infection and get results on same day)
  • CD4 count
  • HIV viral load (PCR)
  • HIV resistance profile
  • syphillis and hep abc serology
  • routine bloods
  • taxoplasma, measles, varicella and rubellla IgG
  • TB cultures often
44
Q

Name 4 conditions and infections associated with severe HIV infection?

A
  • kaposi sarcome
  • TB
  • PCP (pneumocystis jiroveci pneumonia)
  • taxoplasmosis
  • CMV
  • lymphoma
  • herpes
  • candida
  • cryptococcal meningitis
45
Q

How is HIV managed?

A

Nucleoside receptor transcriptase inhibitor x2 (tenofovir, lamivudine)
+
non NRTI
or
protease inhibitor
or
integrase inihbitor
or
CCR5 (entry) inhibitor
AND hep B, pneumococcal and flu vaccines AND co trimoxazole for PCP prophylaxis if your CD4 is <200 AND opthalmology assesment for CMV retinitis if your CD4 count is <50
Also education about condoms etc is important

46
Q

What extra is needed to treat TB if there is pericardial, meningeal or spinal involvement?

A

Steroids- the start of the anti TB meds will cause bacteria death and inflammation which will be bad in these places

47
Q

Describe the pathogenesis of TB

A
  • inhaled infectious droplets
  • engulfed by alveolar macrophages and primary ghon focus forms
  • some may get taken around body and to lymph nodes where t mediated immunity will contain the infection
  • 5% will progress to active primary disease soon after
  • latent infection then heals or self cures or lays dormant until reactivation due to immunocompromise causing post primary TB
48
Q

Describe the differences between active and latent TB

A

active- cxr abnormal, sputum samples positive, symptoms (cough, fever, weightloss, nightsweats), infectious, mantoux and IFN gamma positive
latent- mantoux and IFN gamma positive, cxr usually normal, sputum cultured negative, no symptoms, not infectious

49
Q

How is meningitis with signs of raised ICP, severe sepsis or a rapidly evolving rash managed?

A
  • critical care input
  • secure airway
  • bloods and culutres
  • fluid resus
  • dexamethasone and ceftriaxone IV
  • neuro imaging when stable
  • delay LP
  • catheter
  • blood gasses
  • source isolation until ceftriaxone for 24 hrs
  • notify microbio and public health