Acute infectious diarrheal disease - Nontyphoidal salmonellosis - DONE

Question 1

Nontyphoidal Salmonellae can be aquired from….

Answer 1

animal reservoirs

Question 2

Transmission is most commonly associated with:

Nontyphoidal salmonellosis

Answer 2

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

2. contact with animals or their environments

Question 3

Risk factors and risk group:

Nontyphoidal salmonellosis

Answer 3

• 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

Question 4

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Answer 4

SLIDE 3

Question 5

Nontyphoidal salmonellosis - Symptoms - acute gastroenteritis:

Answer 5

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

Question 6

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

Answer 6

• bacteremia
• meningitis
• osteomyelitis
• septic arthritis

Question 7

Nontyphoidal salmonellosis - diagnosis:

Answer 7

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

Question 8

Nontyphoidal salmonellosis - treatment:

Answer 8

• 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.

Question 9

Nontyphoidal salmonellosis - prevention:

Answer 9

• 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

Question 10

Shigellosis:

Answer 10

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

Question 11

Shigella:

Answer 11

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

Question 12

The genus Shigella includes four species:

Answer 12

• S. dysenteriae
• S. flexneri
• S. boydii
• S. sonnei

Question 13

What kind of diarrhea does Shigella cause?

Answer 13

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

Question 14

Which Shigella species cause relatively mild illness?

Answer 14

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

Question 15

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

Answer 15

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

Question 16

S. dysenteriae type 1:

Answer 16

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.

Question 17

Shigella reservoir:

Answer 17

Humans and a few primates are the only reservoir of Shigella

Question 18

How is Shigella transmitted?

Answer 18

• 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.

Question 19

What is the dose required for infection?

Shigella

Answer 19

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

Question 20

Where does most infections caused by Shigella occur?

Answer 20

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

Question 21

Who is most likely to be infected by Shigella?

Answer 21

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

Question 22

Where does the outbreaks of Shigella occur in industrialized world?

Answer 22

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

Question 23

Who usually gets the sporadic cases of Shigella?

Answer 23

Sporadic cases occur among travelers returning from endemic areas

Question 24

Pathogenesis of Shigella:

Answer 24

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.

Question 25

What happens to Shigella once excreted?

Answer 25

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

Question 26

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

Answer 26

• incubation
• watery diarrhea
• dysentery
• postinfectious phase

Question 27

Shigella - incubation:

Answer 27

1-4 days, maybe up to 8 days

Question 28

Shigella - watery diarrhea:

Answer 28

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

Question 29

Shigella - dysentery:

Answer 29

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

Question 30

Shigella - postinfectious phase

Answer 30

reactive arthritis can occur

Question 31

Shigella - Diagnosis:

Answer 31

• 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.

Question 32

How can definitive diagnosis of Shigella infection be made?

Answer 32

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

Question 33

Shigellosis - Treatment:

Answer 33

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