Salmonella Infections

Question 1

Which two strains of salmonella cause enteric fever?

Answer 1

Salmonella typhi

Salmonella paratyphi

Question 2

How can people contract NTS (non-typhoidal salmonella) infections?

Answer 2

Broad range of animals can be carriers - especially reptiles**
Contaminated food including poultry, eggs, dairy products, ground beef, or produce
Produce with thick peel if not washed, sprouts, tomatoes that soak up contaminated water

Question 3

What is the incubation period for NTS?

Answer 3

12 to 48 hours but up to 7 days

Question 4

How do patients present with NTS?

Answer 4

Non-bloody diarrhea +/- vomiting and fever

Question 5

What populations are at risk of disseminated disease with NTS?

Answer 5

Immunocompromised
Asplenic patients
<3 months in age

Question 6

How can people contract typhoid/paratyphoid fever?

Answer 6

Water or food contamination with feces from carrier
Direct person to person spread
**travel history to Asia, less commonly Africa

Question 7

What is the incubation period for typhoid/paratyphoid fever?

Answer 7

Usually 7-14 days

Can be 3 to 60 days

Question 8

How can typhoid/paratyphoid fever present?

Answer 8

Bacteremia that can progress to sepsis and multi-organ failure

Question 9

List three clinical manifestations of NTS

Answer 9

Common to be asymptomatic*

1) Most patients have nausea, vomiting and diarrhea (non-bloody – persists 3 to 7 days) +/− fever
2) Bacteremia* up to 8% of patients across all age groups * rarely progresses to shock
3) Endocarditis/arteritis* more common in adults
4) Meningitis or brain abscess - mainly within the first year of life

Question 10

What are three RARE complications of NTS?

Answer 10

GI bleed
Intestinal perforation
Reactive arthritis (in children)
Neonatal infection from perinatal transmission

Question 11

What are children with sickle cell disease at higher risk of with NTS?

Answer 11

Osteomyelitis
Septic arthritis

*only with NTS not typhoidal infections

Question 12

Can children be chronic carriers of NTS?

Answer 12

Very rare in children* gallstones are a risk factor

Question 13

List three clinical manifestations of typhoid/paratyphoid fever?

Answer 13

1) Acute gastroenteritis* constipation history with recent diarrhea and associated abdominal pain
2) GI bleed- occurs in 10% of hospitalized patients
3) Bacteremia*** seen in 80% of cases but presumably
4) Encephalopathy

Question 14

What are three RARE complications of typhoid/paratyphoid fever?

Answer 14

1) Intestinal perforation* if occurs will happen at the terminal ileum
2) Brain abscess
3) Myocarditis/endocarditis
4) Osteomyelitis
5) Septic arthritis
6) UTI* can rarely lead to stones

Question 15

How is NTS diagnosed?

Answer 15

Stool cultures

- Cultures should be done in any child with blood diarrhea, persistent or severe non-bloody diarrhea

Question 16

When should be blood cultures be completed with NTS?

Answer 16

If child is:
Febrile
Immunocompromised

If afebrile: if <3 months and up to 6 months of age

Question 17

How is typhoid/paratyphoid fever diagnosed?

Answer 17

Blood cultures

• Should be done in any child returning from endemic regions (within 2 months of travel)
• *important to remember that bacteremia is low grade so higher yield two blood cultures are collected

Question 18

What is the yield of stool cultures in suspected typhoid/paratyphoid fever?

Answer 18

• Only 30%

Usually GI involvement has resolved by the time of presentation

Question 19

Should antibiotics be used in the treatment of NTS?

Answer 19

ONLY* with proven bacteremia OR signs of invasive disease

Do not decrease the incidence of diarrhea and increase the risk of carriage

Question 20

What is the antibiotic of choice of NTS?

Answer 20

Azithromycin

Question 21

What are strategies to limit the spread of NTS?

Answer 21

• Avoid work which would require contact with food if having diarrhea
• Find source* remove reptiles from the home or avoid exposure to kitchen or bathtub
• Notify public health

Question 22

Why is ciprofloxacin no longer recommended as a step down oral therapy? What is the first line treatment choice?

Answer 22

• Increased resistance

- Azithroymycin- good intracellular killing and less resistance

Question 23

What is the recommended duration of antimicrobial treatment for typhoidal infection?

Answer 23

Controversial
- Uncomplicated typhoid/paratyphoid fever are 7 days for azithromycin, 3 to 7 days for quinolones, 7 to 14 days for cefixime, 10 to 14 days for ceftriaxone and 14 days for amoxicillin or TMP-SMX [9]
The total duration is unclear for patients who are stepped down to oral therapy

Question 24

What is the rate of relapse for typhoid/paratyphoid infections?

Answer 24

17% within 4 weeks

- Thought to be due to residual disease within the reticuloendothelial system rather than antibiotic resistance

Question 25

How long can fever persist after initiation of antibiotics?

Answer 25

Fever typically persists 6 to 8 days from the start of antibiotics [4]
Fever is not a contraindication to switch to oral antibiotics or to hospital discharge, providing the child is otherwise well.

Question 26

When can patients with typhoid/paratyphoid infection return to work?

Answer 26

Guidelines may vary depending on region**
Food handlers, health care workers and diapered children must have two or three negative stool tests 24 h apart over a variable number of days following completion of antibiotics before returning to work or to child care.

Question 27

When are urine cultures indicated with typhoid/paratyphoid infection?

Answer 27

Urine cultures may be required if patients have been in an area endemic for schistosomiasis, because Salmonella- Schistosoma binding promotes long-term survival of S Tyhpi or S Paratyphi, with intermittent bacteriuria

Question 28

What are some strategies to prevent infection with NTS?

Answer 28

Safe food handling within the home

Handwashing after contact with animals (especially reptiles, baby poultry, frogs)

Question 29

What are some strategies to prevent infection with typhoid or paratyphoid?

Answer 29

Careful selection of food and travel when travelling to endemic regions
Good hand hygiene
Immunization

Question 30

For whom is immunization recommended to prevent typhoid or paratyphoid infection?

Answer 30

All children ≥24 months old travelling to South Asia (Afghanistan, Bangladesh, Bhutan, India, Nepal, Maldives, Pakistan and Sri Lanka) should receive typhoid vaccine

Immunization should be considered for travellers to other resource-poor countries when they are likely to be exposed to contaminated food or water OR when they have achlorhydria, asplenia or sickle cell disease or are immunocompromised
Household contacts of carriers should also be immunized

Question 31

Which vaccines are available?

Answer 31

Oral, live vaccine: Vivotif – licensed for children age 5 years and up, with a booster recommended after 7 years.
Parenteral inactivated vaccine: TYPHERIX or TYPHIM Vi – licensed for age 2 years and up, with a booster recommended after 3 years.
Parenteral inactivated vaccine combined with hepatitis A vaccine: ViVAXIM – licensed for age 16 years and up, with a typhoid booster recommended after 3 years.

All three vaccines have only about 50% efficacy for S Typhi.
Only oral vaccine is thought to provide some protection against S Paratyphi.

Question 32

What symptoms are suggestive of disseminated disease with salmonella infections?

Answer 32

Bacteremia
CNS involvement
Osteomyelitis
Septic arthritis