lab 9

Portable

water source stars at mountain picks to revers that mixed with washes. All of these sources are exposed to human/animal fecal contamination and other pollutants.

• All enterobacterceae
• All ferment lactose
• All gram negative rods
• All anaerobe facultatives
• All produce gas

• They all cause GI tract infections
• diarrhea, dysentery, and vomiting.

Because it inhibit the growth of gram positive bacteria and select the growth of gram negative

It differentiate between lactose fermenting coliforms from other gram negative that do not ferment lactose.

• A quick test of coliforms in 100 mL of water.
• The water will change color blue/green and participials will glow under 360 nm UV light if coliforms are present

• E. coli produce a lot of acid turn media color green shean
• Other lactose fermenters produce less acid turn the media pink to red/purple

• Because it selects gram negative growth only
• Some dyes in this media inhibit gram +

• Selective: Contains bile salt that inhibits G+
• Deferential:
• E. coli turn agar color to pink, yellow or orange
• Shigella: blue green
• Salmonella produce H₂S black

• Selective: Bile salt & crystal violet inhibit G+
• Differential:
• Lactose frementer turn media pink.

• Members of enterobactriaceae, facultative anaerobes, produce gas, ferment lactose.
• Because they can cause GI tract infections

Dysentery, diarrhea, and vomiting, cholera

• Grow form:  cluster
• Colony color: Golden yellow
• Catalase test: positive
• Infection: MRSA (Methicillin resistance staphylococcus aureus)
  

• Growth form: Chains
• Colony color: white
• Catalase test: negative
• Infection: VRE (vancomycin resistance enterococcus)

Enzyme produced by Staphylococcus that break down oxygen radicals

• halotolorant
• normal residents of the body
• opportunists can become pathogenic under certain conditions

Mannitol is used as sugar

• Differential media : Because it will turn yellow if mannitol is fermented (S. saprophyticus & S. aureus)
• Selective media: because it selects for only halotolorant bacteria

• All are halotolorant
• S. epidermis; cause (endocarditis inflammation of the heart lining), Cannot ferment mannitol
• S. saprophyticus cause UT infection,
• S, aureus: cause MRSA,

• S.epidermis: gamma hemolysis (non hemolysis)
• S. saprophyticus : gamma hemolysis
• S. aureus: Beta hemolysis (complete hemolysis)