Typhoid fever

Question 1

Basis of serotyping

Answer 1

1. Somatic O antigen (LPS cell wall components)
2. Surface Vi antigen (restricted to S. typhi and S. paratyphi C)
3. Flagellar H antigen

Question 2

Characteristic of salmonella

Answer 2

produce acid on glucose fermentation, reduce nitrates, and do not produce cytochrome oxidase

Question 3

a systemic disease characterized by fever and abdominal pain caused by dissemination of S. typhi and S. paratyphi

Answer 3

Enteric (typhoid) fever

Question 4

Risk factor for typhoid fever

Answer 4

1. contaminated water/ice
2. flooding
3. food & drinks purchased from street vendors
4. raw fruits and vegetables grown in fields fertilized with sewage
5. ill household contacts
6. lack of hand washing and toilet access
7. evidence of prior H.pylori infection

Question 5

Multi-drug resistant (MDR) strains of S. typhi

Answer 5

contain plasmids encoding resistance to chloramphenicol, ampicillin, and trimethoprim

Question 6

incubation period of S. typhi

Answer 6

10-14 days but ranges from 5-21 days

Question 7

Most prominent symptom of typhoid fever

Answer 7

prolonged fever (38.5-40.5) which can continue up to 4 weeks if untreated

Question 8

Early physical findings of enteric fever

Answer 8

RAsh (“rose spots”), hepatosplenomegaly, epistaxis and relative bradycardia at the peak of high fever

Question 9

faint , salmon-colored, blanching maculopapular rash located primarily on the trunk and chest

Answer 9

Rose spots

Question 10

Timeline when GI bleeding and intestinal perforation occur in typhoid fever

Answer 10

3rd-4th week

Question 11

Neurologic manifestations of typhoid fever

Answer 11

meningitis, GBS, neuritis, and neuropsychiatric symptoms (“muttering delirium” or “coma vigil”)

Question 12

Relapse

Answer 12

within 2-3 weeks of fever resolution

Question 13

Chronic asymptomatic carriage

Answer 13

shed S. typhi in either urine or stool for >1 year

• common among women, infants, and persons who have biliary abnormalities or concurrent bladder infection with Schistosoma hematobium
• increased risk fo gallbladder cancer

Question 14

Definitive diagnosis of typhoid fever

Answer 14

isolation of S. typhi or S. paratyphi from blood, bone marrow, other sterile sites, rose spots, stool, or intestinal secretions

Question 15

yield not reduced by up to 5 days of prior antibiotic therapy

Answer 15

Bone marrow culture

Question 16

can be positive despite a negative bone marrow culture

Answer 16

Intestinal secretions

Question 17

can be come positive during the 3rd week of infection in untreated patients

Answer 17

Stool cultures

Question 18

most effective in the treatment of drug-susceptible typhoid fever

Answer 18

Fluoroquinolones (Ciprofloxacin)

Question 19

Treatment of drug-resistant strains of typhoid fever

Answer 19

Ceftriaxone, cefotaxime, and oral cefixime, oral azithromycin

Question 20

Duration of treatment of typhoid fever

Answer 20

at least 10 days or for 5 days after fever resolution

Question 21

Role of glucocorticoids

Answer 21

administration of dexamethasone (an initial dose of 3 mg/kg followed by eight doses of 1 mg/kg every 6h) with chloramphenicol was associated with substantially lower mortality rate than was treatment with chloramphenicol alone

-indicated in severe enteric fever

Question 22

Treatment of chronic carriage stage

Answer 22

4 weeks with oral ciprofloxacin or other fluoroquinolones

Question 23

Treatment in cases of anatomic abnormality (biliary or kidney stones)

Answer 23

eradication often requires both antibiotic therapy and surgical correction

Question 24

Antibiotic therapy for enteric fever in adults

Answer 24

Question 25

Answer 25

Rose spots

Question 26

Role of typhoid vaccines

Answer 26

should be considered for persons planning to travel to high risk areas

Commercially available
1. Ty21a - oral live attenuated S. typhi vaccine (days 1,3,5, and 7, with revaccination of full 4-dose series every 5 years)

2. Vi CPS - a parenteral vaccine consisting of purified Vi polysaccharide from the bacterial capsule (single dose,, booster every 2 years)