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These flashcards cover key concepts, definitions, and distinctions related to the Enterobacteriaceae family and Gram negative rods discussed in the lecture.
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What is the family of gut-associated gram-negative rods discussed in the lecture?
Enterobacteriaceae.
What does 'Enterobacteriaceae' refer to in bacteriology?
It refers to a family of enteric organisms associated with the gut.
Name two pathogens from the Enterobacteriaceae family that are not normal flora.
Salmonella and Shigella.
Which organism is the most isolated from different microbiology cultures?
Escherichia coli (E. coli).
What is the distinguishing characteristic of Enterobacteriaceae regarding their oxygen requirements?
They are facultative anaerobes, meaning they can grow with or without oxygen.
Which test is used to differentiate between lactose fermenters and non-lactose fermenters on MacConkey agar?
The color change to pink for lactose fermenters indicates acid production.
What are some major infections caused by members of the Enterobacteriaceae family?
Urinary tract infections, respiratory infections, and wound infections.
What is the appearance of E. coli on MacConkey agar?
It forms pink colonies due to lactose fermentation.
What reaction would you expect from Proteus on a TSI slant?
It would show K/A (alkaline slant with acidic butt) with H2S production.
What distinguishes Shigella from Salmonella in laboratory tests?
Shigella is H2S negative, whereas Salmonella is H2S positive.
What does a positive indole test indicate?
The presence of tryptophanase enzyme that breaks down tryptophan.
In terms of colony morphology, how do enteric gram-negative rods typically present on agar?
They are generally larger than gram-positive colonies and can be medium to large in size.
Name the three sugars present in TSI agar.
Lactose, sucrose, and glucose.
What does an alkaline (red) slant with an acid (yellow) butt indicate in a TSI test?
It indicates that the organism is a non-lactose fermenter using only glucose.
Why must antibiotics be used cautiously in treating Salmonella infections?
Using antibiotics can lead to the development of antibiotic resistance and may worsen the infection in the gut.
What is a virulence factor for E. coli?
The presence of endotoxin (LPS), capsule, flagella, and various toxins.
What is the family characteristic that allows differentiation on oxidase testing?
Most members of this family (Enterobacteriaceae) are oxidase negative.
How can one isolate Salmonella from stool samples?
By using selective media such as Hektoen enteric agar or XLD agar.
Which organism is recognized for swarming growth on blood agar?
Proteus.
What is the primary virulence factor associated with Shigella?
The production of shiga toxin.
What common method is used to diagnose bacterial infections in clinical microbiology?
Culture and isolation of microorganisms from patient samples.
What is the importance of knowing the different serotypes of E. coli?
Different serotypes can have varying pathogenic properties and virulence factors.
Name one characteristic that differentiates Enterobacter from Klebsiella in a microbiology lab.
Indole test: Klebsiella is typically indole negative while Enterobacter can be positive.
What is the relationship between the presence of Salmonella in food animals and human infections?
Foodborne illness results from consuming contaminated animal products, leading to infections.