Salmonella Infections Flashcards by Raman Chawla

Which two strains of salmonella cause enteric fever?

Salmonella typhi

Salmonella paratyphi

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

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

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What is the incubation period for NTS?

12 to 48 hours but up to 7 days

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How do patients present with NTS?

Non-bloody diarrhea +/- vomiting and fever

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What populations are at risk of disseminated disease with NTS?

Immunocompromised
Asplenic patients
<3 months in age

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How can people contract typhoid/paratyphoid fever?

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

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What is the incubation period for typhoid/paratyphoid fever?

Usually 7-14 days

Can be 3 to 60 days

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How can typhoid/paratyphoid fever present?

Bacteremia that can progress to sepsis and multi-organ failure

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List three clinical manifestations of NTS

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

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What are three RARE complications of NTS?

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

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

Osteomyelitis
Septic arthritis

*only with NTS not typhoidal infections

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Can children be chronic carriers of NTS?

Very rare in children* gallstones are a risk factor

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List three clinical manifestations of typhoid/paratyphoid fever?

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

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What are three RARE complications of typhoid/paratyphoid fever?

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

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How is NTS diagnosed?

Stool cultures

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

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When should be blood cultures be completed with NTS?

If child is:
Febrile
Immunocompromised

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

How is typhoid/paratyphoid fever diagnosed?

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

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

Only 30%

Usually GI involvement has resolved by the time of presentation

Should antibiotics be used in the treatment of NTS?

ONLY* with proven bacteremia OR signs of invasive disease

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

What is the antibiotic of choice of NTS?

Azithromycin

What are strategies to limit the spread of NTS?

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

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

Increased resistance

- Azithroymycin- good intracellular killing and less resistance

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

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

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

17% within 4 weeks

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

How long can fever persist after initiation of antibiotics?

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.

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

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.

When are urine cultures indicated with typhoid/paratyphoid infection?

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

What are some strategies to prevent infection with NTS?

Safe food handling within the home | Handwashing after contact with animals (especially reptiles, baby poultry, frogs)

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

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

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

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

Which vaccines are available?

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.

What symptoms are suggestive of disseminated disease with salmonella infections?

Bacteremia CNS involvement Osteomyelitis Septic arthritis