Enterobacteriaceae Flashcards
What organisms are part of the enterobacteriaceae family?
E.coli, shigella, salmonella, & yersinia pestis
Why are they referred to enterics?
Because they are found in the GI tract of humans & animals
T/F E.coli is part of the Enterobacteriaceae family?
True
Name the characteristics of E.coli
- gram negative bacilli
- oxidase negative
- ferment glucose to produce acid
- facultative anaerobes
What are the virulence factors for E.coli?
Depends on the strain of E.coli: enterotoxin( type of exotoxin), endotoxin, E .coli O157:H7 (shigella-like toxin)
What is E.coli O157:H7 ?
Is a strain of E.coli w/ a shigella like toxin that causes hemolytic uremic syndrome (HUS) & can lead to kidney failure. It is usually found in cattle
What is the reservoir for E.coli?
Humans or animals ( it’s part of the normal flora in the GI tract)
What is the mode of transmission for E.coli?
Vehicle transmission: eating contaminated food
What diseases does E.coli cause?
- HAIs
- UTIs
- Sepsis
- Wound infections
- Neonatal meningitis
- Gastroenteritis
- Enterotoxin causes infantiles & travelers diarrhea
What some test used for E.coli diagnosis ?
- gram stain
- glucose fermentation test
- isolation on selective media
- ELISA
- DNA
What is the treatment required for E.coli ?
Depends on the strain, in most cases of diarrheal diseases no antibiotics are prescribed. They best way to treat is rehydration & electrolytes.
Prevention for E.coli
Wash hands, sterile equipment, aseptic techniques etc.
What are the characteristics for Salmonella?
Gram negative bacilli, facultative anaerobe, ferment glucose to produce acid, & oxidase negative
What are the virulence factors of Salmonella?
Endotoxins —> lead to inflammation & septic shock
What is the reservoir for Salmonella?
Poultry (chicken) & reptiles (turtles)
Salmonella is a zoonotic disease meaning?
It is spread from animals to people
What diseases does Salmonella cause?
Often times causes food borne infections of the GI tract by ingesting contaminated food
What is the incubation time for Salmonella?
12-36 hours, depends of number of Salmonella ingested?
Treatment for Salmonella?
Oral rehydration, antibiotics will only be necessary for chronic carriers
T/F Shigella is more invasive than Salmonella
True
What are characteristics for Shigella?
Gram negative bacilli, facultative anaerobes, ferments glucose—> acid, & oxidase negative
Virulence factors for Shigella?
- Endotoxins
- Ability to attach to villi cells
- Enterotoxin( a type of exotoxin that affects the GI tract)
- shigella toxin —> hemolytic uremic syndrome (HUS) = lead to kidney failure & death
Infectious dose of Shigella?
200 pretty low compared to Salmonella(10,000)
What is the reservoir for Shigella?
Humans (found in the GI tract of infected humans)
Shigella pathway to infection
Ingestion —>invades villus cells —> inflammation response—>extensive tissue destruction—> bloody diarrhea —> mucus secretion
What disease does Yersinia pestis cause?
Black Death AKA “the plague”
What can Yersinia pestis be capable of causing?
Death & destruction
Do we still have the black plague today?
Yes but not as many cases (only 1 case in 2018 in the US)
When gram staining how can you distinguish Yersinia pestis?
Looks like a safety pin
How many forms of the plague is there?
Bubonic, pneumonia, & inhalation fever
What is the reservoir for Yersinia pestis?
Rodents (squirrels)
What is the mode of transmission for Yersinia pestis?
Transmitted via a biological vector (flea): you can get infected if you get bitten by a flea or if your pets come in contact w/ the fleas & become infected, also if they come in contact w/ the infected animal (squirrel)
What type of disease is Yersinia pestis?
Zoonotic disease ( transmitted from animal to person)
What are the virulence factors of Y. Pestis?
- Coagulase
- Capsule (prevents phagocytosis)
- Endotoxin —> part of the gram neg cell wall
What is the bubonic plague?
When the lymph nodes become infection (swollen b/c they are full of bacteria) & can burst open
What is septicemia (systemic) plague?
When the infection winds up in the bloodstream —> endotoxin can lead to inflammation & septic shock
Describe pneumonia plague
Via inhalation for example a person that’s infected can spread through respiratory secretions or droplets to another person
Which form of the plague has the highest fatality rate?
Pneumonia plague
Diagnosis of Y.pestis?
Culturing
Treatment for Y.pestis?
Antibiotics however a person can still die even w/ antibiotic therapy (the sooner it’s treated the better)
Prevention for the Black Death?
Rodent control & flea control
