Acute infectious diarrheal disease - Nontyphoidal salmonellosis - DONE Flashcards Preview

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Flashcards in Acute infectious diarrheal disease - Nontyphoidal salmonellosis - DONE Deck (33)
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1
Q

Nontyphoidal Salmonellae can be aquired from….

A

animal reservoirs

2
Q

Transmission is most commonly associated with:

Nontyphoidal salmonellosis

A
  1. eating foods contaminated with small amounts of animal feces:
  • usually food products of animal origin: eggs, poultry, undercooked ground meat, dairy products
  • also fresh vegetables and fruits
  1. contact with animals or their environments
3
Q

Risk factors and risk group:

Nontyphoidal salmonellosis

A
  • Salmonella infection is more common in the summer months (June, July, and August) than winter.
  • children under 5 years
  • infants who are not breastfed
  • adults over 65 years old
  • people with weakened immune systems
  • certain medications (for example, medications which reduce stomach acid) can increase the risk of Salmonella infection
4
Q

IMAGE

A

SLIDE 3

5
Q

Nontyphoidal salmonellosis - Symptoms - acute gastroenteritis:

A
  • symptoms occur 6-48 hours after ingestion of contaminated food or water
  • nausea, vomiting
  • diarrhea: loose, nonbloody, of moderate volume stools
  • fever
  • abdominal cramping
6
Q

Invasive Salmonella infection - Occur in about 8 % of persons with laboratory- confirmed Salmonella infection as:

A
  • bacteremia
  • meningitis
  • osteomyelitis
  • septic arthritis
7
Q

Nontyphoidal salmonellosis - diagnosis:

A

is based on isolation of the organism from stool or blood, or otherwise sterile fluids
- stool cultures remain positive for 4-5 weeks after acute infection and in case of chronic carriage (<1% of patients) for more than one year

8
Q

Nontyphoidal salmonellosis - treatment:

A
  • gastroenteritis is usually self-limited within 3-7 days
    • antibiotics usually not recommended - may prolong fecal carriage
  • invasive disease
    • choices for antimicrobial therapy for severe infections often include fluoroquinolone, third generation cephalosporins, or ampicillin.
9
Q

Nontyphoidal salmonellosis - prevention:

A
  • don’t rinse raw chicken
  • cook chicken to 65F (always use thermometer)
  • wash your hands before all meal preparation
  • always use soap for effective hand washing
10
Q

Shigellosis:

A

Shigellosis is an infectious disease caused by a group of bacteria called Shigella

11
Q

Shigella:

A
  • Gram-negative
  • non-sporeforming
  • non-motile bacilli
  • belonging to the family Enterobacteriacae.
12
Q

The genus Shigella includes four species:

A
  • S. dysenteriae
  • S. flexneri
  • S. boydii
  • S. sonnei
13
Q

What kind of diarrhea does Shigella cause?

A

All species of Shigella cause acute bloody diarrhea. Immunity is serotype-specific.

14
Q

Which Shigella species cause relatively mild illness?

A

S. sonnei and S. boydii usually cause relatively mild illness in which diarrhea may be watery or bloody.

15
Q

Which Shigella species is the chief cause of endemic shigellosis in developing countries?

A

S. flexneri is the chief cause of endemic shigellosis in developing countries.

16
Q

S. dysenteriae type 1:

A

produces a potent cytotoxin (Shiga toxin)

  • „causes illness that is more severe, more prolonged, and more frequently
  • fatal than is illness caused by other Shigella
  • resistance to antimicrobials occurs more frequently than among other Shigella
  • it causes large, often regional, epidemics, frequently with high attack rates and high case fatality rates.
17
Q

Shigella reservoir:

A

Humans and a few primates are the only reservoir of Shigella

18
Q

How is Shigella transmitted?

A
  • Shigella are spread by direct contact with an infected person, or by eating contaminated food or drinking contaminated water.
  • Flies may also transmit the
    organism.
19
Q

What is the dose required for infection?

Shigella

A

The high level infectivity springs from low infective dose required for infection

20
Q

Where does most infections caused by Shigella occur?

A

Ninety-nine percent of infections caused by Shigella occur in developing countries

21
Q

Who is most likely to be infected by Shigella?

A

The majority of cases (~70%), and of deaths (~60%), occur among children less than five years of age.

22
Q

Where does the outbreaks of Shigella occur in industrialized world?

A

In the industralized world outbreaks can occur in day care centers and institiution for mentally retarded

23
Q

Who usually gets the sporadic cases of Shigella?

A

Sporadic cases occur among travelers returning from endemic areas

24
Q

Pathogenesis of Shigella:

A
  1. active secretion and abnormal water reabsorption - watery diarrhea precedes the dysenteric syndrome
  2. Shigella invade the colonic epithelium causing its destruction
  3. this leads to formation of micro-ulcers and inflammatory exudates
  4. inflammatory cells (polymorphonuclear leucocytes) and blood appear in the stool.
25
Q

What happens to Shigella once excreted?

A

Once excreted, the organism is very sensitive to environmental conditions and dies rapidly, especially when dried or exposed to direct sunlight.

26
Q

What are the four phases of the clinical manifestation of Shigella?

A
  • incubation
  • watery diarrhea
  • dysentery
  • postinfectious phase
27
Q

Shigella - incubation:

A

1-4 days, maybe up to 8 days

28
Q

Shigella - watery diarrhea:

A

watery diarrhea (may represent the only clinical manifestation): fever, limited watery diarrhea, abdominal pain, malaise, anorexia

29
Q

Shigella - dysentery:

A

frequent passage of small volume mucopurulent stools that contain visible blood, abdominal cramps and tenesmus (unproductive, painful straining)

30
Q

Shigella - postinfectious phase

A

reactive arthritis can occur

31
Q

Shigella - Diagnosis:

A
  • routine microscopy of fresh stool is a simple screening test to detect invasive bacterial diarrhea.
    The identification of numerous PMNs suggests a bacterial etiology, but does not distinguish shigellosis from disease caused by other invasive bacteria.
  • definitive diagnosis of Shigella infection can only be made by isolating the organism from stool and serotyping the isolate.
  • culture is required to determine antimicrobial sensitivity.
32
Q

How can definitive diagnosis of Shigella infection be made?

A

definitive diagnosis of Shigella infection can only be made by isolating the organism from stool and serotyping the isolate

33
Q

Shigellosis - Treatment:

A
  • Ciprofloxacin is a drug of choice for all patients , irrespective of their age.
  • Alternative treatment:
    • pivmecillinam
    • ceftriaxon
    • azithromycin