Transcript Salmonella - IISME Community Site

Salmonella
Salmonellosis
Microbe Name:
Salmonella
Associated Disease in Humans:
• Salmonellosis
1. Enteric Fever (Typhoid Fever) – bacterial invasion of
the blood stream
2. Acute Gastroenteritis – food borne infection
Bacterial Structure and Classification
• Rod-shaped (Bacillus)
• Gram-negative
• Family: Enterobacteriaceae
• Species: Enterica
• S. Enteritidis belongs to the
species of S. Enterica.
• Facultative anaerobe – can survive in both aerobic
and anaerobic conditions
• Replicate through binary fission
Salmonella serotype Enteritidis
• Salmonella serotype Enteritidis (SE) is one of
the most common serotypes of pathogenic
Salmonella bacteria.
• Enteritidis is enteric and infects the small
intestine, rather than the whole body.
Method of Infection
• Enteric strains are food borne and must be
ingested
Once in the small intestine,
salmonella causes
inflammation of the
epithelial
layer by entering epithelial
cells and releasing an
enterotoxin (endotoxin).
Method of Infection (cont.)
Salmonella Antigens
Three kinds of antigens:
1. Somatic (O) are Cell Wall Antigens
2. Surface (Envelope) Antigens
3. Flagellar (H) Antigens
– Different flagellar antigens give patterns of
agglutination (with bacteria loosely attached to
each other using their flagella). Also, antiflagellar
antibodies can immobilize bacteria with
corresponding H antigens.
Discovery of Salmonella
• 1880s: Bacillus bacteria causing typhoid fever was first observed
by Eberth.
• 1884: Gaffky, one of Koch’s assistants, cultured
Salmonella typhi
• 1885: Dr. Daniel Salmon identified the first specific
strain
• 1896: Serodiagnosis of typhoid was made possible
Named “Salmonella” in 1990 after Dr. Daniel
Salmon
Symptoms
•
•
•
•
Fever
Abdominal Cramps/Pain
Vomiting and nausea
Diarrhea
– Electrolyte deficiency
– Dehydration
Remaining Complications
• Spread throughout the body
• Reactive Arthritis
Mortality Rate: Enteritidis - 3.6% mortality
Modes of Transmission
• Salmonella Enteritidis is zoonotic.
• Salmonella bacteria live in the intestinal tracts of
warm and cold blooded animals.
• Some species infect a specific host, but some are
ubiquitous (can infect other hosts).
• S. Enteritidis can establish an infection in animals
that isn’t apparent  animal carriers 
contaminated food
Common Sources of SE Infection
Most common:
• Poultry
Less frequent:
• raw milk
• pork
• beef
• sprouts
• raw almonds.
Non-Food Sources:
• International travel and contact with reptiles have
also been associated with SE infection.
Geography and Endemic Areas
Trends in the United States
• Salmonella was emerging in the U.S. in the
1980’s and 90’s and now commonly occurs in
most regions of the country.
Recent Outbreaks
•
•
•
•
1994 – Ice Cream
2005-6 – Raw Tomato
2006-7 – Peanut Butter
2012 – Raw Tuna
Raw Tomato Outbreak
Peanut Butter Outbreak
Drug Resistance in Salmonella
• Some of the serotypes of Salmonella are
thought to have originated due to drugs used
on chickens to prevent them from illness
Current Prevention Efforts
• Surveillance – organizations trace the source of
outbreaks to isolate and study them
• Monitoring of food animals – Government
agencies and food industries take steps to identify
and remove infected animals.
• Pasteurization
• Researching a vaccine
• (Antibacterial Drugs)
How can you prevent infection?
• Keep food like eggs refrigerated
• Wash hands often when cooking so
that cross-contamination does not
occur.
• Thoroughly cook food
S.E.A.R.
Salmonella Enteritidis Awareness Raising
• Education is perhaps the most effective
method of prevention is raising awareness
• If people cook contaminated food adequately,
they still won’t get infected because cooking
kills the bacteria.
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Sources (cont.)
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