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My MRCP > Infectious diseases > Flashcards

Infectious diseases Flashcards

1
Q

Name 5 main live attenuated vaccines

A

BCG
MMR
oral polio
yellow fever
oral typhoid

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2
Q

HIV testing

When is p24 indicated?
What is better in testing asymptomatic individuals with signs of chronic infection?

A

P24 test
* Present in newly infected individuals during infection and seroconversion

HIV-1/2 Ab/Ag immunoassay
* screening for chronic HIV infection (most sensitive)

HIV RNA
* For neonatal HIV infection, screening blood donors

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3
Q

Malaria treatment

Non-falciparum malaria

A

Chloroquine sensitive area
* ACT or chloroquine
Chloroquine resistant area
* Artemisin based combination therapy like artemther-lumefantrine

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4
Q

Malaria treatment

Ovale, vivax

Describe the features distinguishing between vivax/ovale & malariae

A

Give chloroquine after initial treatment to destroy liver hypnozoites and prevent relapse

Features
* general features of malaria: fever, headache, splenomegaly
* Plasmodium vivax/ovale: cyclical fever every 48 hours.
* Plasmodium malariae: cyclical fever every 72 hours, is associated with nephrotic syndrome.

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5
Q

Malaria treatment

When is IV artesunate indicated?

A

IV artesunate - parasite count >2%
Give ACT for uncomplicated falciparum malaria
>10% parasitaemia - exchange transfusion

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6
Q

Fever in the returning traveller

Three days ago
Muscle ache
Headache
Maculopapular rash
Thrombocytopenia

A

Dengue fever
Remember break-bone fever
Virus induced bone marrow suppression and liver derangements
Facial flushing

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7
Q

Dengue - management

A

No drug treatment, just supportive

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8
Q

Botulism - describe features of presentation

A

Features
* patient usually fully conscious with no sensory disturbance
* flaccid paralysis
* diplopia
* ataxia
* bulbar palsy

Risk factors - eating tinned food, IVDU

Can mimic Guillian barre syndrome

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9
Q

Management of strongyloidosis

A

Ivermectin

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10
Q

Diarrhoea in traveller

What are the differences between shigella, giardia, campylobacter, entamoeba histolytica

A

Shigella dysenteriae
* Incubation period 1-3 days
* Bloody diarrhoea
Campylobacter jejuni
* Bloody diarrhoea - incubation period 2-4 days
Giardia lamblia
* Incubation 3-40 days
* Non bloody diarrhoea
Entamoeba histolytica
* Amoebiasis 2-4 weeks incubation
* Entamoeba - months to years
* Bloody diarrhoea

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11
Q

Syphilis investigations

Non-treponemal tests

A

Not specific for syphilis
* RPR
* VDRL
* Will become negative after treatment, will show repeat infection

Treponemal specific tests
* Qualitative results - reactive vs non-reactive
* Remain positive after the first infection
* TPHEA, TP-EIA

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12
Q

Campylobacter vs Salmonella

A

Campylobacter
* Bloody diarrhoea
* Barbecues

Salmonella typhi
* Abdo pain
* Constipation
* Vomiting

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13
Q

Antibiotic for cryptosporidiosis
Only for immunocompromised

A

Nitazoxanide

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14
Q

Management of multibacillary leprosy (>6 lesions)

A

This man has multibacillary leprosy (>6 lesions) so should have triple therapy with rifampicin, dapsone and clofazimine for 12 months. For paucibacillary leprosy (5 or less lesions) you should give rifampicin and dapsone for 6 months.

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15
Q

CSF analysis
Describe analysis of bacterial, viral, tuberculosis - appearance, glucose, protein, white cells

A
  • Bacterial - cloudy, low glucose, high protein, WCC high in polymorphs
  • Viral - clear or cloudy with slightly low glucose, normal prtein, lymphocytes WCC high
  • Tuberculosis - slight cloudy with fibrin web, low glucose, high protein with high lymphocytes
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16
Q

What is used to confirm tuberculous?

A

The Ziehl-Neelsen stain is only 20% sensitive in the detection of tuberculous meningitis and therefore PCR is sometimes used (sensitivity = 75%)

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17
Q

What would be the result for mumps meningitis

A

*mumps is unusual in being associated with a low glucose level in a proportion of cases. A low glucose may also be seen in herpes encephalitis
evidence of viral features of CSF sample

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18
Q

Which HPV serotypes increase risk of cervical cancer

A

Human papillomavirus (HPV), particularly serotypes 16,18 and 33, is by far the most important factor in the development of cervical cancer.

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19
Q

HIV management

Antiretroviral therapy

Describe a typical HIV regimen and rationale

A

Antiretroviral therapy (ART) involves a combination of at least three drugs, typically two nucleoside reverse transcriptase inhibitors (NRTI) and either a protease inhibitor (PI) or a non-nucleoside reverse transcriptase inhibitor (NNRTI). This combination both decreases viral replication but also reduces the risk of viral resistance emerging

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20
Q

HIV management

Describe MOA of entry inhibitors
Give 2 examples

A
  • Prevents HIV from entering immune cells
  • CCR5 antagonist - maraviroc
  • Fusion inhibitor - enfuvirtide
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21
Q

HIV management

Nucleoside analogue reverse transcriptase inhibitors
MOA
General SE
Give examples

A

examples:
zidovudine (AZT),
abacavir,
emtricitabine,
didanosine,
lamivudine,
stavudine,
zalcitabine,
tenofovir
general NRTI side-effects: peripheral neuropathy

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22
Q

HIV management

Specific SE for NRTI
Tenofovir
Zidovudine
Didanosine

A
  • Tenofovir - renal impairment and ostesoporosis
  • Zidovudine- anaemia, myopathy, black nails
  • Didanosine - pancreatitis
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23
Q

Give 2 examples of NNRTI
SE

A

Non-nucleoside reverse transcriptase inhibitors (NNRTI)
examples: nevirapine, efavirenz
side-effects: P450 enzyme interaction (nevirapine induces), rashes

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24
Q

HIV management

Give 4 examples of protease inhibitors
Give 6 SE

A

Protease inhibitors (PI)
examples: indinavir, nelfinavir, ritonavir, saquinavir
side-effects: diabetes, hyperlipidaemia, buffalo hump, central obesity, P450 enzyme inhibition

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25
Q

Integrase inhibitors
MOA
Examples

A

Integrase inhibitors
* block the action of integrase, a viral enzyme that inserts the viral genome into the DNA of the host cell
* examples: raltegravir, elvitegravir, dolutegravir

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26
Q

HHV-5 infection
Also known as…
Treatment of CMV post renal transplant

A

Human herpes virus 5 (HHV 5), is cytomegalovirus (CMV).

In patients who are post-transplant, CMV infections can occur from reactivation of latent infection, infection via the transplanted organ, or because of a new primary infection.

‘Treatment is with IV ganciclovir, and where there is ganciclovir resistance, foscarnet or cidofovir are alternative options.

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27
Q

Tuberculosis management

Describe initial phase of treatment
Describe the continuation phase of treatment

A

Initial phase - first 2 months (RIPE)
* Rifampicin
* Isoniazid
* Pyrazinamide
* Ethambutol (the 2006 NICE guidelines now recommend giving a ‘fourth drug’ such as ethambutol routinely - previously this was only added if drug-resistant tuberculosis was suspected)

Continuation phase - next 4 months
* Rifampicin
* Isoniazid

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28
Q

Tuberculosis management

Latent tuberculosis

A

The treatment for latent tuberculosis is 3 months of isoniazid (with pyridoxine) and rifampicin OR 6 months of isoniazid (with pyridoxine)

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29
Q

Tuberculosis management

Management of meningeal TB

A

Patients with meningeal tuberculosis are treated for a prolonged period (at least 12 months) with the addition of steroids

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30
Q

Anti-viral agents

Aciclovir
MOA
Indications
SE

A

Name of drug: Aciclovir
Mechanism of action: Guanosine analog, phosphorylated by thymidine kinase which in turn inhibits the viral DNA polymerase
Indications: HSV, VZV
Adverse effects/toxicity: Crystalline nephropathy

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31
Q

Anti-viral agents

Galcanciclovir
MOA
Indications
SE

A

Name of drug: Ganciclovir
Mechanism of action: Guanosine analog, phosphorylated by thymidine kinase which in turn inhibits the viral DNA polymerase
Indications: CMV
Adverse effects/toxicity: Myelosuppression/agranulocytosis

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32
Q

Anti-viral agents

Ribavirin
MOA
Indications
SE

A

Mechanism of action: Guanosine analog which inhibits inosine monophosphate (IMP) dehydrogenase, interferes with the capping of viral mRNA
Indications: Chronic hepatitis C, RSV
Adverse effects/toxicity: Haemolytic anaemia

33
Q

Antiviral agents

Amantadine
MOA
Indications
SE

A

Mechanism of action: Inhibits uncoating (M2 protein) of virus in cell. Also releases dopamine from nerve endings
Indications: Influenza, Parkinson’s disease
Adverse effects/toxicity: Confusion, ataxia, slurred speech

34
Q

Anti-viral agents

Oseltamivir
MOA
Indications

A

Mechanism of action: Inhibits neuraminidase
Indications: Influenza

35
Q

Anti-viral agents

Foscarnet

A

Name of drug: Foscarnet
Mechanism of action: Pyrophosphate analog which inhibits viral DNA polymerase
Indications: CMV, HSV if not responding to aciclovir
Adverse effects/toxicity: Nephrotoxicity, hypocalcaemia, hypomagnesaemia, seizures

36
Q

Anti-viral agents

Interferon alpha

A

Name of drug: Interferon-α
Mechanism of action: Human glycoproteins which inhibit synthesis of mRNA
Indications: Chronic hepatitis B & C, hairy cell leukaemia
Adverse effects/toxicity: Flu-like symptoms, anorexia, myelosuppression

37
Q

Anti viral agents

Interferon alpha

A

Name of drug: Interferon-α
Mechanism of action: Human glycoproteins which inhibit synthesis of mRNA
Indications: Chronic hepatitis B & C, hairy cell leukaemia
Adverse effects/toxicity: Flu-like symptoms, anorexia, myelosuppression

38
Q

Anti-viral agents

Cidofovir

A

Name of drug: Cidofovir
Mechanism of action: Acyclic nucleoside phosphonate, and is therefore independent of phosphorylation by viral enzymes (compare and contrast with aciclovir/ganciclovir)
Indications: CMV retinitis in HIV
Adverse effects/toxicity: Nephrotoxicity

39
Q

Helminths: roundworms

Strongyloides Stercoralis
Presentation
Treatment

A

Features include diarrhoea, abdominal pain, papulovesicular lesions where the skin has been penetrated by infective larvae e.g. soles of feet and buttocks, larva currens
Treatment - ivermectin, bendazoles

40
Q

Helminths: roundworms

What helminth infection can cause elephantiasis?
What is the vector? What is the treatment?

A
  • Wuchereria bancrofti
  • Transmission by female mosquito
  • causing blockage of lymphatics
  • Treatment: diethylcarbamazine
41
Q

Helminths: roundworms

What is Lofflers syndrome

A

This is when helminths like ascaris lumbricoides migrate to the lung

42
Q

Helminths: tapeworms

Echinococcus granulosus
* Features
* How is it transmitted
* Which occupation is this more common??

A
  • Fetaures - liver cysts causing anaphylaxis in rupture
  • Transmitted through ingestion of eggs in dog faeces
  • Often seen in farmers

Treatment is bendazoles

43
Q

Helminths: tapeworms

Cysticerosis and neurocysticercosis

A

Ingesting undercooked pork
Mass lesions in brain with swiss cheese appearances

Treatment is bendazoles

44
Q

Helminths: Trematodes

Schistosoma haematobium

A
  • host: snails
  • cercariae penetrate the skin
  • swimmers itch manifests with frequency, haematuria
  • Risk factor for squamous bladder cancer
  • treated with praziquantel
45
Q

Helminths: Trematodes

Which organism is transmitted by ingsting
Undercooked crabmeat
Undercooked fish

A
  • Undercooked crabmeat - paragonimus westermani
  • Undercooked fish - features include biliary tract inflammation, rf for cholagniocarcinoma
  • Both are treated with praziquantel
46
Q

What organism is also known as the liver fluke

A

Fasciola hepatica
Causes biliary obstruction
Treated with triclabendazole

47
Q

Coxiella burnetti
Q fever

A
  • Associated with abbatoir workers, cattle/sheep based jobs
  • Prodromal illness - fever, malaise
  • PUO
  • Transaminitis
  • Atypical pneumonia
  • Endocarditis culture negative
  • Treated with doxycycline
48
Q

Necrotising fascititis
Type 1 and Type 2

A
  • type 1 is caused by mixed anaerobes and aerobes (often occurs post-surgery in diabetics). This is the most common type
  • type 2 is caused by Streptococcus pyogenes
49
Q

Necrotising fasciitis risk factors

A
  • skin factors: recent trauma, burns or soft tissue infections
  • diabetes mellitus
  • most common preexisting medical condition
  • particularly if the patient is treated with SGLT-2 inhibitors
  • intravenous drug use
  • immunosuppression
50
Q

How does necrotising fasciitis present?

A

acute onset
pain, swelling, erythema at the affected site
often presents as rapidly worsening cellulitis with pain out of keeping with physical features
extremely tender over infected tissue with hypoaesthesia to light touch
skin necrosis and crepitus/gas gangrene are late signs
fever and tachycardia may be absent or occur late in the presentation

51
Q

Leishmaniasis
Name the 3 types and the subtype that causes each one

A

Cutaneous leishmaniasis
* Leishmania tropica or Leishmania mexicana
Mucocutaneous leishmaniasis - mucosal ulceration of nose, pharynx
* Leishmania braziliensis
Visceral leishmaniasis
* mostly caused by Leishmania donovani

52
Q

Causes of false positive non-treponemal (cardiolipin) tests:

A

pregnancy
SLE, anti-phospholipid syndrome
tuberculosis
leprosy
malaria
HIV
yaws

53
Q

Infections that can result in viral haemorrhagic fever

A

Yellow fever
Dengue fever
Lassa fever
Ebola

54
Q

Viral Haemorrhagic fevers

What is plasma leak?
How do you manage discharging a patient with viral haemorrhagic fevers?

A

The plasma leak phase may occur anytime within the first 48 hours after the fever has broken and manifests with leakage into pleural and peritoneal spaces.
It may be accompanied by shock and in some cases haemorrhage.
Platelets and renal function may be falsely reassuring as they tend to improve after the febrile phase but rising haematocrit is a sensitive sign of plasma leak.
It is therefore essential to monitor patients for a full 48 hours after the febrile phase and ensure haematocrit is stable prior to discharge.
Platelets should be at least 50 * 109/l and rising prior to discharge.

55
Q

Yellow fever
Vector
Incubation period

A

zoonotic infection: spread by Aedes mosquitos
incubation period = 2 - 14 days

56
Q

Yellow fever
Presentation

A
  • may cause mild flu-like illness lasting less than one week
  • classic description involves sudden onset of high fever, rigors, nausea & vomiting.
  • Bradycardia may develop.
  • A brief remission is followed by jaundice, haematemesis, oliguria
  • If severe jaundice, haematemesis may occur
    Councilman bodies (inclusion bodies) may be seen in the hepatocyte
57
Q

Complications of mycoplasma pneumoniae

A
  • cold agglutins (IgM): may cause an haemolytic anaemia, thrombocytopenia
  • erythema multiforme, erythema nodosum
  • meningoencephalitis, Guillain-Barre syndrome and other immune-mediated neurological diseases
  • bullous myringitis: painful vesicles on the tympanic membrane
  • pericarditis/myocarditis
  • gastrointestinal: hepatitis, pancreatitis
  • renal: acute glomerulonephritis
58
Q

Pneumonias - worsening flu like symptoms with dry cough… diagnosis?

A

Mycoplasma pneumoniae

59
Q

Legionella and mycoplasma share some similarities in presentation and treatment, how do we differentiate them?

A
60
Q

Steps in screening for pulmonary TB for close contacts (asymptomatic)

A
  • You are testing for latent TB because the patient is asymptomatic
  • If asymptomatic and younger than 65 years then test for latent TB. If Mantoux-negative and unvaccinated then offer vaccination. If at risk of HIV then test for HIV first.
  • If asymptomatic and older than 65 years then assess with a chest X-ray.
61
Q

How to test for active TB?

A

CXR: upper lobe cavitation is classical finding for reactivated TB
+ 3 sputum sample smears for MC&S - ZN staining
+ Sputum culture is gold standard but can take 1-3 weeks
+ NAAT allows rapid dx 24-48h

62
Q

What is the first line agent for ESBL

A

Ertapenem
Extended spectrum B-lactamase (ESBL) producing organisms are typically resistant to penicillins and cephalosporins and as such the carbapenem class of antibiotics are typically first-line although nitrofurantoin or fosfomycin are also frequently effective.

63
Q

What are Calabar swellings a sign of?

A

Loiasis is a filarial infection caused by Loa Loa. It is transmitted by the Chrysops deerfly and tends to occur in rainforest regions of Western and Central Africa.

Clinical features
* pruritus
* urticaria
* Calabar swellings: transient, non-erythematous, hot swelling of soft-tissue around joints
* ‘eye worm’ - the dramatic presentation of subconjunctival migration of the adult worm.

64
Q

Viral haemorrhagic fevers

Triad of symptoms

A
  • Haemorrhage manifestations, platelets <100, evidence of plasma leakage
65
Q

Management of contacts of measles:
* in a child
* in an immunosuppressed patient

A
  • Unimmunized child that is exposed -then MMR should be offered (vaccine-induced measles antibody develops more rapidly than that following natural infection)- this should be given within 72 hours
  • Immunosuppressed patient - administer immunoglobulin following exposure will reduce risk of infection
66
Q

HIV medication

What is eviplera a combination of?

A
  • emtricitabine
  • rilpivirine
  • tenofovir
67
Q

How does ritonavir interact with steroids to cause Cushings?

A

Ritonavir is a protease inhibitor which are potent P450 inhibitors. Steroids are metabolised by P450 system. So addition of ritonavir will cause increased bioavailability of the drug.

68
Q

Clinicl pharmacology

Can you give first-line TB therapy to a patient on anti-retrovirals?

A

Rifampicin interacts with protease inhibitors. Rifampicin is a potent induer of p450 reducing concentration of ritonavir. Rifabutin is used as it is less potent inducer of P450.

69
Q

Pneumocystis Jiroveci

Indication for PJP prophylaxis in HIV patients
What is a common complication of PJP

A

Indication for PCP prophylaxis in HIV patients - CD4 count <200
Pneumothorax is a common complication of PCP.
CXR - bilateral interstitial pulmonary infiltrates
Sputum often negative so BAL needed to demonstrate silver staining showing characteristic cysts
Management - cotrimoxazole

70
Q

Pneumocystis Jirovecii

Management of severe PJP
When do you give steroids?

A

IV pentamidine
Aerolised pentamidine is also used but less effective with risk of pneumothorax
Steroids are used if hypoxia ie pO2<9 as it reduces risk of respiratory failure by 50% and death by a third

71
Q

How can meningitis type A, B, C be distinguished by geographic locations?

A

Type A - saudi arabia
Type B, C- Europe and South America

72
Q

Listeria meningitis

How is it usually spread?
Risk factors

A

Listeria monocytogenes is a Gram-positive bacillus which has the unusual ability to multiply at low temperatures. It is typically spread via contaminated food, typically unpasteurised dairy products.

Risk factors
elderly
neonates
immunosuppression
especially glucocorticoids
pregnancy

73
Q

Listeria infection

Presentation

A

gastroenteritis
diarrhoea
bacteraemia
flu-like illness
central nervous system infection
meningoencephalitis
ataxia
seizures

74
Q

Investigations

Listeria infection
Blood culture appearance
CSF findings - wcc, protein, glucose

A

blood cultures
* ‘tumbling motility’ on wet mounts
cerebrospinal fluid findings:
* pleocytosis, often lymphocytes (nontuberculous bacteria usually cause a rise in neutrophils)
* raised protein
* reduced glucose

75
Q

Rickettsial diseases

Typhus types

A

Endemic typhus - fleas on rats, relative brady
Epidemic typhus - body louse, prowazekii, Africa, South America
Spotted fever - Rocky Mountain, spread by ticks

76
Q

Presentation of typhus
Antibiotic for typhus

A

Maculopapular rash
Fever headache malaise
Exotic travel locations
Mx - doxycycline

77
Q

Management of multi drug resistant TB

A

multi-drug resistant TB requires 18-24 months of at least 5 drugs.

78
Q
A

My MRCP (43 decks)

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