Microbio Lab Quiz

Staphylococcus epidermidis

Gram positive coagulase negative staphylococcus bacteria. This is a member of normal skin flora that becomes a opportunistic pathogen in the immunosupressed or in pt w/ broken skin. Virulence: biofilm formation to resist the immune system/antibiotics. ID'd by seeing gram positive cocci, a neg coagulase test, and a no growth on mannitol salt agar

S. epidermidis is a gram _______________ staphylococcus bacteria.

gram positive

S. epidermidis is distinguised from S. aureus by:

a negative coagulase test and a negative mannitol test. S. aureus possesses the coagulase enzyme and ferments mannitol

Biofilm

A microbial community that usually forms as a slimy layer on a surface. These form on catheters, implants, etc and provide a physical barrier between the immune system or antibiotics and the infection.

Pseudomonas aeruginosa is a gram ____________ bacteria with a single polar flagellum for motility.

gram negative

Pseudomonas aeruginosa is a environmental organism that thrives in what kind of areas?

Warm & moist areas (water bowls, drains, poorly cleaned surfaces)

What virulence factors are associated with P. aeruginosa?

Exotoxins, enzymes (proteases and elastases), biofilm formation, and production of pyocanin- a blue/green pigment that generates reactive oxygen to damage host and immune cells

P. aeruginosa is a frequent cause of ______ infections, especially in dogs.

ear

Pseudomonas aeruginosa

Gram negative bacilli known for creating a pigment (pyocanin) that causes a characteristic blue/green color in cultures. This bacteria contain efflux pumps and a outer membrane that increase drug resistance. Commonly found in the environment- especially in warm and moist areas. This is a opportunistic pathogen associated with several virulence factors: exotoxins, enzymes, biofilms, and pigment formation.

How do you identify P. aeruginosa?

Gram staining a sample and viewing gram negative rods, production of a fruity odor and a blue-green pigment on nutrient agar, a positive oxidase test, and growth thriving on selective media (like cetrimide agar)

Where is E. coli typically found in animals?

the lower intestine- e. coli is a part of the normal gut microbiome

What are the major types of pathogenic E. coli bacteria?

Enterotoxigenic (ETEC), enteropathogenic (EPEC), shiga toxin producing e.coli (STEC), & uropathogenic (UPEC)

UPEC strains of E. coli are a common cause of UTIs in what species?

dogs

What infections are associated with E. coli bacteria?

Neonatal diarrhea (ETEC & EPEC), UTIs (UPEC), mastitis, and septicemia

What strain of E.coli is known for transmission from animal to human?

O157:H7

What bacteria grows well on MacConkey agar and produces colonies that are pink in color?

Escherichia coli

E. coli in a sample appears as gram ______________ rods after gram staining.

gram negative

How is E. coli identified?

the appearance of gram-negative rods, good growth on MacConkey agar that appears pink, positive for lactose and glucose fermentation, and through serotyping

Serotyping

Identifying specific pathogenic strains of E. coli based on antigenic markers (O, H, & K antigens)

E. coli colonies on EMB agar appear what color?

Blue/black colonies with a characteristic metallic green sheen

Escherichia coli (E. coli)

Gram negative rod shaped bacteria that has flagella for motility. This bacteria is naturally found in the lower intestine and is excreted in feces, where it commonly contaminates the environment/water. Strains are categorized based on virulence. This bacteria ferments lactose so it produces pink colonies on MacConkey agar. ID can be from staining, serotyping, and testing for specific toxins