9. a. Salmonella Flashcards
What are the virulence factors of salmonella?
Peritrichous flagellae
Stay alive within macrophages
How is salmonella spread?
Faecal-oral
Contaminated food and water
In typhoidal salmonella, what events lead up to the primary bacteraemia?
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
How does typhoidal salmonella cause a secondary bacteraemia?
Invade and multiply in liver, gall bladder, spleen and bone marrow
Secondary bacteraemia occurs during week 3
How does typhoid fever progress after the secondary bacteraemia?
From the gallbladder the bacteria reinfects the intestinal tract and causes necrosis of Peyer’s patches
What are the clinical features of typhoid fever during the first week?
Slowly rising temperature
Headache
Bradycardia
Constipation or diarrhoea
What are the clinical features of typhoid fever during the second week?
High fever
Distended abdomen and splenomegaly
Pea soup diarrhoea
Rose spots
What are rose spots?
Bacteria embolise to dermis
Found on flanks, buttocks and costal margin
Resolve within 2-5 days
Salmon coloured blanching maculopapules
What are the clinical features of typhoid fever during the third week?
Hepatic, renal and bone marrow dysfunction
Bowel perforation
Osteomyelitis of spine and long bones if sickle cell
What are the clinical features of typhoid fever during the fourth week and beyond?
Symptoms improve but bowel may still perforate
Weight loss and debilitating weakness for months
What is chronic carriage of typhoidal salmonella defined as?
Positive stool cultures 12 months after overcoming the disease
What is the management of a chronic carrier of typhoidal salmonella?
Ciproflaxin for 1 month
Can’t work in the food industry until negative stool
Increased risk of gallbladder cancer
What samples can be cultured to diagnose typhoid fever?
Blood in first week
Faeces in second
Urine in third
Bone marrow
What is the treatment for typhoid fever?
10-14 days of ceftriaxone
Check susceptibility for ciprofloxacin and azithromycin
What vaccines are available for typhoidal salmonella?
Polysaccharide subunit
Live attenuated oral