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Medicine > Infectious > Flashcards

Infectious Flashcards

0
Q

Which groups in the UK are most likely to be at risk from TB? (3)

A

Asian immigrants and their children.
Homeless
HIV patients

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1
Q

Is tuberculosis a notifiable disease? (1)

Why? (2)

A

Yes to public health authority for contact tracing and screening.

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2
Q

What is a Ghon focus? (2)

How is it characterised? (2)

A 
Primary TB (first infection with M. Tuberculosis) usually occurs as a subpleural lesion in the upper region of the lung called the Ghon focus. It can also appear in the GI tract at the ileocaecal region.
The Ghon focus is characterised by exudation and infiltration with neutrophil granulocytes which are then replaced by macrophages that engulf the bacilli leaving caseating granulomas.
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3
Q

What is a Ghon complex? (2)

A

Ghon focus accompanied by caseating lesions in the mediastinal and cervical lymph nodes.

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4
Q

What are the symptoms of primary TB? (2)

A

Usually asymptomatic.

May have erythema nodosum or a small pleural effusion.

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5
Q

What is miliary TB? (2)

What symptoms might you expect ? (2)

A

Acute dissemination of the primary infection of tubercle bacilli via the bloodstream.
Symptoms may be vague of ill-health, fever of unknown origin, weight loss. May present at TB meningitis.
Usually caused by delayed reactivation rather than secondary infection.

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6
Q

How should a patient with suspected TB be managed? (3)

Not great q

A

Side room to prevent transmission.
CXR
Sputum staining with Ziehl-Neelsen for acid fast bacilli.
CSF sample for TB if miliary TB suspected.

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7
Q

What is the treatment of TB? (4)

In which situations is treatment extended and for how long? (2)

A

6 months total
2 months of RIPE (rifampicin, isoniazid, pyrazinamide, ethambutol) then
4 months of RI (rifampicin and isoniazid)

Treatment is 12 months in TB meningitis and 9 months in bone TB.

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8
Q

Why is pyridoxine given in treatment of TB? (2)

A

Reduce the risk of Isoniazid peripheral neuropathy.

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9
Q

Name 2 side effects for each of the drugs commonly used in the treatment of TB? (8)

A

Rifampicin- bodily fluids turn red/pink, induces liver enzymes, elevated aminotransferases and hepatitis, thrombocytopenia.
Isoniazid- polyneuropathy, allergic response.
Pyrazinamide- hepatitis, rash, gout.
Ethambutol- eyes (optic neuritis, visual changes)

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10
Q

In TB what is the infective agent? (1)

A

Mycobacterium tuberculosis

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11
Q

What is a tuberculin test? (1)

A

Mantoux test, intradermal injection of protein derivative of M. tuberculosis.

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13
Q

Rajeev has RA and is about to start treatment with methotrexate and prednisolone. However he had TB as a child but is now fully recovered.
What is the main issue? (2)
How should he be managed? (1)

A

Even after healing, the primary focus may contain tubercle bacilli. If the host defence mechanism is compromised (eg immunosuppression) the remaining bacilli may reactivate.
Chemoprophylaxis with isoniazid.

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14
Q

What is the difference between bacteraemia and septicaemia? (2)

A

Bacteraemia: transient presence of organisms in the blood, generally without symptoms as a result of local infection or penetrating injury.
Septicaemia: Reserved for clinical picture of SIRS response to infection.

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15
Q

What is Waterhouse-Friderichsen syndrome? (3)

A

Commonly caused by Neisseria meningitidis.
Rapidly fatal illness without treatment
Purpuric skin rash and shock
Adrenal haemorrhage and hypoadrenalism may be present

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16
Q

What is the period of infectivity of measles? (1)

A

4 days before and up to 4 days after onset of rash.

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17
Q

Roger is 6 years old and presents with mumps.

When can he return to school? (1)

A

5 days after onset of parotid gland swelling.

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18
Q

Rachel has rubella, when can she return to school? (1)

A

6 days after onset of rash

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19
Q

Which virus most commonly causes cold sores? (1)

A

HSV-1

20
Q

What is the cause of infectious mononucleosis? (1)

A

aka glandular fever is caused by EBV

21
Q

EBV can have cause several conditions.

name 3. (3)

A 
Infectious mononucleosis (glandular fever)
Hairy leukoplakia in AIDS patients
Burkitt's lymphoma
Nasopharyngeal carcinoma
post-transplant lymphoma
22
Q

What is Lyme disease? (2)

A

Multisystem inflammatory disease caused by a spirochete Borrelia burgdorferi. Infection is spread by ticks, mainly in north america and europe in the summer or spring.

23
Q

What are the stages of Lyme disease? (3)

A

First: 7-10 days after infection. Characterised by erythema migrans at the site of the bite (bull’s eye appearance), associated with fever, malaise, headache, myalgia.
Second: weeks to months later when some develop neurological, cardiac problems or arthritis.
Chronic: some continue to have fatigue and musculoskeletal pain for months to years after infection.

24
Q

How can Lyme disease be diagnosed? (2)

A

Serology: IgM in first month, IgG antibodies later.

Otherwise clinical diagnosis following time in endemic area.

25
Q

What is the causative agent in Lyme disease? (1)

What is the management? (2)

A

Spirochete: Borrelia burgdorferi.

Antibiotics eg amoxicillin or doxycycline.

26
Q

How is leptospirosis contracted? (2)

A

Excreted in animal urine and enters host through skin abrasions or intact mucosal membranes.
Animal workers, or water sports are at risk.

27
Q

Name 3 causes of fever in the traveller returning from the tropics. (3)

A

*Malaria
*Viral hepatitis
*Febrile illness unrelated to foreign travel
*Dengue fever
*Enteric fever (typhoid)
Gastroenteritis
Leptospirosis
Schistosomiasis
Amoebic liver abscess
TB
Acute HIV

28
Q

What mosquito transmits the malaria protozoa? (1)

A

female anopheles mosquito

29
Q

Name the 4 types of malaria that affects humans. (4)

A

Plasmodium faciparum, vivax, ovale, malariae

30
Q

Describe the pathogenesis of malaria. (5)

A
  • Infective form of the parasite (sporozites) pass through the skin and via the blood to the liver.
  • They multiply inside hepatocytes as merozoites
  • Few days later the hepatocytes rupture and release merozoites into the blood stream.
  • In the blood, merozoites enter erythrocytes and develop further, until the red blood cell ruptures.
  • Rupture of RBCs cause anaemia and fever
  • RBCs infected with falciparum adhere to endothelium causing vascular occlusion and organ damage
  • P. ovale and vivax remain latent in the liver so may relapse
31
Q

What is different about plasmodium malariae? (1)

A

May run chronic course over months to years.

32
Q

What is cerebral malaria? (1)

A

Complication of P. falciparum.

Diminished consciousness, confusion, convulsions, coma and eventually death.

33
Q

What is blackwater fever? (1)

A

dark brown-black urine (haemoglobinuria) from severe intravascular haemorrhage.

34
Q

What is the conventional method for diagnosing malaria? (1)

How many should be performed before malaria can be ruled out? (1)

A

Thick and thin blood films
(thick for diagnosis, thin for quantifying % of parasitised red cells and species identification)

Three smears should be taken over 48 hours before ruling out malaria.

35
Q

Name 3 complications associated with plasmodium falciparum infection. (3)

A 
Cerebral malaria (impaired consciousness, convulsions)
Blackwater fever (haemoglobinuria)
ATN
Anaemia
DIC
Bleeding
Tachypnoea
ARDS
Hypoglycaemia
Metabolic acidosis
Diarrhoea
Jaundice
Splenic rupture
Hyperpyrexia
Shock
36
Q

What are the clinical features of malaria? (3)

A

Abrupt onset of fever (>40’c), tachycardia, rigors, profuse sweating

37
Q

Name 3 elements of malaria prevention. (3)

A

Awareness of risk
Bite avoidance: mosquito repellents, mosquito nets, permethrin impregnated sheets.
Chemoprophylaxis: for one week before travel and 4 weeks after.

38
Q

How long should malaria prophylaxis tablets be taken? (1)

A

One week before travel and 4 week after return

39
Q

What is Dengue fever? (2)

A

Virus transmitted by infected mosquitoes in asia, africa and south america.
Symptoms include: abrupt onset of fever, headache, retro-orbital pain and severe myalgia.

40
Q

What is enteric fever? (1)

How is it spread? (1)

A

Typhoid

faecal-oral

41
Q

Describe the clinical features of typhoid. (3)

A

insidious onset of intermittent fever, headache and dry cough.
In second week there is maculopapular rash (rose spots) on upper abdomen and thorax, splenomegaly, hepatomegaly, cervical lymphadenopathy.

42
Q

How is clostridium difficile diagnosed? (1)

A

By demonstration of toxins A and B on stool sample.

43
Q

How is an acute episode of clostridium difficile treated? (3)

A

Prevent cross infection (side room and barrier nurse)
Stop causative antibiotics where possible
Treat with metronidazole for 10-14 days
If severe treat with vancomycin

44
Q

Name 3 causes of traveller’s diarrhoea. (3)

A

Bacteria (70-90%): e. coli, shigella, salmonella, campylobacter
Viral (10%): rotavirus, norovirus
Protozoa (<5%): giardia intestinalis

45
Q

Give 2 pieces of advice to a patient wishing to minimise the risk of developing traveller’s diarrhoea. (2)

A

Avoid salads (may be washed in contaminated water)
Drink bottled water only
Peel fruit before eating it

Ciprofloxacin prophylaxis is sometimes given to those with an underlying medical condition such as CKD or ileostomy.

46
Q

Tim has profuse watery diarrhoea (rice water stools), you suspect cholera.
What is the mode of transmission? (2)

A

faecal-oral. Most commonly Tim has ingested water that has been contaminated with human faeces.

47
Q

What is the cause of giardiasis? (1)

A

Flagellated protozoa
Causes damage to small intestine with severe cases causes subtotal villous atrophy. Symptoms include abdominal pain, distension, diarrhoea and nausea.

Medicine (14 decks)

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