9. a. Salmonella Flashcards

1
Q

What are the virulence factors of salmonella?

A

Peritrichous flagellae

Stay alive within macrophages

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2
Q

How is salmonella spread?

A

Faecal-oral

Contaminated food and water

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3
Q

In typhoidal salmonella, what events lead up to the primary bacteraemia?

A

Bacteria adheres to and penetrates epithelium over Peyer’s patches using fimbriae
Ingested by macrophages and brought to mesenteric lymph nodes
Multiply in lymph nodes
Primary bacteraemia occurs at days 10-14

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4
Q

How does typhoidal salmonella cause a secondary bacteraemia?

A

Invade and multiply in liver, gall bladder, spleen and bone marrow
Secondary bacteraemia occurs during week 3

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5
Q

How does typhoid fever progress after the secondary bacteraemia?

A

From the gallbladder the bacteria reinfects the intestinal tract and causes necrosis of Peyer’s patches

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6
Q

What are the clinical features of typhoid fever during the first week?

A

Slowly rising temperature
Headache
Bradycardia
Constipation or diarrhoea

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7
Q

What are the clinical features of typhoid fever during the second week?

A

High fever
Distended abdomen and splenomegaly
Pea soup diarrhoea
Rose spots

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8
Q

What are rose spots?

A

Bacteria embolise to dermis
Found on flanks, buttocks and costal margin
Resolve within 2-5 days
Salmon coloured blanching maculopapules

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9
Q

What are the clinical features of typhoid fever during the third week?

A

Hepatic, renal and bone marrow dysfunction
Bowel perforation
Osteomyelitis of spine and long bones if sickle cell

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10
Q

What are the clinical features of typhoid fever during the fourth week and beyond?

A

Symptoms improve but bowel may still perforate

Weight loss and debilitating weakness for months

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11
Q

What is chronic carriage of typhoidal salmonella defined as?

A

Positive stool cultures 12 months after overcoming the disease

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12
Q

What is the management of a chronic carrier of typhoidal salmonella?

A

Ciproflaxin for 1 month
Can’t work in the food industry until negative stool
Increased risk of gallbladder cancer

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13
Q

What samples can be cultured to diagnose typhoid fever?

A

Blood in first week
Faeces in second
Urine in third
Bone marrow

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14
Q

What is the treatment for typhoid fever?

A

10-14 days of ceftriaxone

Check susceptibility for ciprofloxacin and azithromycin

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15
Q

What vaccines are available for typhoidal salmonella?

A

Polysaccharide subunit

Live attenuated oral

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16
Q

What are the sources of salmonella gastroenteritis?

A

GIT of animals and reptiles
Foodborne in meat and animal products
Faecal-oral

17
Q

What is the incubation period of salmonella gastroenteritis?

A

18-72 hours

18
Q

What are the clinical features of salmonella gastroenteritis?

A

3-7 days of diarrhoea, nausea, headache

Danger of dehydration

19
Q

What is chronic excretion of salmonella gastroenteritis?

A

Up to 4 weeks after the infection

20
Q

What factors increase the likelihood a patient will chronically excrete salmonella?

A

Antibiotics
HIV
IBD
Diverticulosis

21
Q

What complications are associated with salmonella gastroenteritis?

A
BSI
Osteomyelitis
Meningitis
Infect prosthetics, grafts and valves
Reactive arthritis
22
Q

When should antibiotics be given in salmonella gastroenteritis?

A

younger than 1 or older than 50
Immunocompromised
Risk factors for endocarditis or joint disease

23
Q

What are the lab features of salmonella?

A

Gram negative bacilli
Non-lactose fermenting
Black colonies on XLD

24
Q

Why does salmonella produce black colonies on XLD?

A

Hydrogen sulphide production

25
Q

What is used to track salmonella outbreaks?

A

Whole genome sequencing