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13 Cards in this Set
- Front
- Back
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The Enterobacteriaceae |
- Ubiquitious - Found in soil, water, vegetation, and intestinal tracks of animals - Facultative anaerobes - Responsible for many diseases in humans |
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Potential human pathogens |
- part of the normal microbiota of the gastrointestinal tract - can cause opportunistic infections. |
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True pathogens |
- not normal microbiota - always associated with human disease |
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E. Coli |
- important opportunistic pathogen - normally in the colon - coliforms (gram-negative organisms that can ferment lactose) - motile, produce indole, unable to use citrate as a carbon source. - many strains produce a toxin that damages blood vessels and causes severe diarrhea |
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Coliforms |
Gram-negative organisms that can ferment lactose. - E. Coli, Enterobacter, Citrobacter, Klebsiella, Serratia. |
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E. Coli 0157:H7 |
Virulent strain that is associated with contaminated foods and many deaths. |
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Proteus |
- opportunistic pathogens not normally in the intestinal tract and considered harmless, but can cause infection outside the intestines. - motile, produce many different fimbriae - produce large amounts of urease - cannot ferment lactose, but can ferment glucose |
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Salmonella |
- gasteroenteritis, septicemia, and typhoid fever. - can exist in patients for a year. - transmitted through poultry and dairy products. - non-lactose fermenting - hydrogen sulfide production - flagella (motile) - negative for indole and urease |
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True intestinal pathogens of the Enterobacteriaceae |
Salmonella, Shigella, and Yersinia |
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Shigella |
- dysentery - humans only known reservoir - don't ferment lactose or hydrolyze urea - non-motile and do not produce hydrogen sulfide. |
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Yersinia |
- highly fatal systemic disease known as bubonic plague. - infection happens through ingestion of contaminated animals or the handling of contaminated animal tissues. - non-lactose fermenter - do not produce hydrdogen sulfide - non-motile and urease positive. |
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Media used for isolation of intestinal pathogens: |
MacConkey agar, Hektoen Enteric agar (HE), and Eosin Methylene Blue agar (EMB). - contain bile salts/sodium desoxycholate to inhibit gram-positive bacteria. - contain lactose and a dye so if an organism is a lactose fermenter it will take on a color characteristic. |
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Kligler's iron agar |
Contains glucose and lactose as well as phenol red to indicate when acid is produced (fermentation) and iron salts for the detection of H2S. - Non-lactose fermenters will create a red slant and yellow butt. - Lactose fermenters produce yellow slants and yellow butts. - Hydrogen-sulfide produce will turn it black. |
