Microbiology Flashcards

1
Q

Which organism is the commonest cause of food poisoning?

A

Campylobacter

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2
Q

Which organisms are more likely to cause outbreaks of food poisoning?

A

Salmonella

E. coli 0157

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3
Q

What is the incubation period for Staph. aureus and Bacillus cereus?

A

Short

1-6 hours

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4
Q

Staph. aureus produces a toxin which is rapidly absorbed by the stomach. True/False?

A

True

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5
Q

What is the incubation period for Salmonella and Cl. perfringens?

A

Medium

12-48 hours

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6
Q

What is the incubation period for Campylobacter and E. coli 0157?

A

Long

2-14 days

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7
Q

Which foods does Campylobacter mainly colonise?

A

Poultry
Raw milk
Poor food preparaiton

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8
Q

Is Campylobacter likely to spread from person to person?

A

No

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9
Q

Which foods does Salmonella mainly colonise?

A

Poultry
Raw egg
Meat, animal guts

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10
Q

What is the significance of the antigens found on Salmonella?

A

Different antigens on different strains, so specific antibodies will agglutinate

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11
Q

Which foods does E. coli 0157 colonise?

A

Beef
Raw milk, water
Wide variety really

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12
Q

Is E. coli 0157 likely to spread from person to person?

A

Yes

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13
Q

Who is most at risk of complications from E. coli 0157 infection?

A

Children + elderly

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14
Q

What is the name of the toxin produced by E. coli 0157?

A

Verotoxin (VTEC)

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15
Q

Which syndrome can result due to verotoxin?

A

Haemolytic uraemic syndrome

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16
Q

What are the sites of action of antibiotics in a cell?

A

Cell wall
Cell membrane
Cytoplasm
DNA

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17
Q

What is the main class of antibiotic which acts on the beta-lactam ring on the cell wall of bacteria?

A

Pencillins

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18
Q

Does antibiotic use lead to antibiotic resistance?

A

Yes

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19
Q

How does antibiotic use have public health consequences for other people, in terms of resistance?

A

Resistant bacteria are selected out in presence of antibiotic, and can spread between patients

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20
Q

What is meant by antimicrobial stewardship?

A

Prescribing optimum dosage and duration of antimicrobial treatment that results in best clinical outcome, prevention of infection and minimal resistance

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21
Q

What is gastroenteritis and what is the consequence regarding absorption?

A

Inflammation of stomach and small intestine

Limits absorption of nutrients and water

22
Q

Which out of bacteria, viruses and parasites is the most common cause of gastroenteritis?

A

Viruses

23
Q

What is meant by toxin-mediated food poisoning?

A

Toxin has been preformed by the bacteria on the host before ingestion of food, leading to acute symptoms once the food has been eaten

24
Q

List common organisms that produce preformed toxins

A

Stap. aureus
Clostridium perfringens
Bacillus cereus
E. coli 0157

25
Q

Acute enteritis often presents with fever, diarrhoea, vomiting and abdo pain. Is the diarrhoea usually bloody?

A

No

26
Q

Acute colitis often presents with fever, diarrhoea and abdo pain. Is the diarrhoea usually bloody?

A

Yes

27
Q

What are the main organisms that cause bloody diarrhoea?

A

Campylobacter
Shigella
E. coli 0157
Amoebas

28
Q

What is the usual duration of Campylobacter infection?

A

5-14 days

29
Q

Typhoid is an enteric fever like illness caused by which organism?

A

Salmonella

30
Q

Which type of culture - urine, stool or blood - is key to diagnosing typhoid?

A

Blood

Stool and urine would be done too though

31
Q

Name the 4 main stool investigations for infectious organisms, from most used to least

A

Stool culture
Stool microscopy
Stool toxin
Stool PCR

32
Q

Which stool investigation is appropriate for Salmonella, Campylobacter and Shigella?

A

Stool culture

33
Q

Which stool investigation is appropriate for Giardia, Amoebas and parasitic infections?

A

Stool microscopy

34
Q

Which stool investigation is appropriate for Clostridium Difficile and E. coli 0157?

A

Stool toxin

35
Q

Which stool investigation is appropriate for Norovirus?

A

Stool PCR

36
Q

Which 3 markers assess the severity of C. difficile infection?

A

Suspicion of pseudomembranous colitis/toxic megacolon/ileus
WCC greater than 15
High creatinine

37
Q

What is first line treatment for gastroenteritis?

A

Oral rehydration or IV fluids

38
Q

Which antibiotic is commonly used for non-severe C. diff?

A

Oral metronidazole

39
Q

Which antibiotic is used for severe C. diff?

A

Oral vancomycin

NEVER IV

40
Q

Which antibiotic is used for first recurrence of C. diff infection?

A

Fidaxomycin

41
Q

Which organism is the most common cause of traveller’s diarrhoea?

A

E. coli 0157 (produces VTEC)

42
Q

Which antibiotic is used for amoeba and giardia infections?

A

Metronidazole

43
Q

What is the commonest cause of viral diarrhoea in kids under 3 years old?

A

Rotavirus

44
Q

How is rotavirus spread?

A

Faeco-oral

45
Q

Which virus is known as the winter vomiting bug?

A

Norovirus

46
Q

How is norovirus spread?

A

Faeco-oral

Droplets

47
Q

Describe the nature of vomiting that comes with norovirus

A

Explosive and sudden

Lead to environmental contamination

48
Q

What is the diagnostic test for rotavirus and norovirus?

A

PCR, on stool or vomit

49
Q

Define SIRS (systemic inflammatory response syndrome)

A

More than 2 of
Temperature over 38 or less than 36
RR over 20
WCC less than 4k or over 12k

50
Q

Define sepsis

A

SIRS + suspected/confirmed underlying infectious process

51
Q

What is involved in the sepsis 6 treatment?

A

Take blood cultures + FBC + urine output

Give fluids + antibiotics + oxygen

52
Q

Which antibiotics are given for peritonitis/biliary tract intra-abdominal infection?

A

IV amoxicillin + metronidazole + gentamicin

vancomycin if pen-allergic