Total Coliform and Ecoli

Question 1

Length of time for record retention - Microbiology

Answer 1

5 years

Question 2

How is sunlight an interference

Answer 2

may hydrolyze indicator compounds resulting in a false positive

Question 3

Bleach concentration for sample collection

Answer 3

1 oz per gallon

Question 4

Shelf life of raw TSB media

Answer 4

unopened - 2 years
opened - 6 months (1 year in dessicator)

Question 5

TSB weight/ volume prep ratio

Answer 5

30 +/- 0.01g to 1000 mL DI water

Question 6

TSB autoclave time and temp

Answer 6

119-121*C 12-15 min on slow
must NOT sit in autoclave for more than 45 min from door closing

Question 7

final pH of TSB

Answer 7

7.3 +/- 0.2

Question 8

shelf life of prepared TSB pre sterilization

Answer 8

3 months R, 1 week RT

Question 9

Sterilization of Neg Control Water

Answer 9

119-121*C for 30 min on slow

Question 10

Sample Collection steps

Answer 10

Flush tap for about 1 min
Sanitize tap for about 2 min
Fully open and flush tap for 3-5 min
Take chlorine reading (free and total)
Aseptically collect sample

Question 11

What is the preservative used to remove chlorine?

Answer 11

Sodium Thiosulfate

Question 12

Maximum holding time for Bacteria samples

Answer 12

30 hours refrigerated

Question 13

Volume/ headspace of collection

Answer 13

100 mL with 1 inch of headspace

Question 14

Over 100 mL sample?
Under 100 mL sample?

Answer 14

over - aseptically adjust volume to 100 mL
under - sample rejected due to insufficient volume (re-collect)

Question 15

For potable bacteria samples, Colilert or Colisure?

Answer 15

Colisure

Question 16

What is a sample set defined as?

Answer 16

up to 60 samples who have an inclusive incubation time of 4 hrs, with one POS and one NEG control

Question 17

After the addition of Colisure, how long can samples sit prior to incubation?

Answer 17

30 min

Question 18

Incubation temp and time

Answer 18

35.0 +/- 0.5 *C
Colilert- 24 to 28 hrs
Colisure- 24 to 48 hrs

Question 19

Colisure result interpretations for Total Coliform:

Answer 19

No Color Change - Neg. for Total Coliform
Color Change - Yellow to Magenta, Pos. for total Coliform

Question 20

Colisure result interpretations for E. Coli:

Answer 20

No Fluorescence - Neg. for E. Coli
Fluorescence - Pos. for E. Coli

Question 21

Analyst QC requirements

Answer 21

Certified analysts are required to preform test at least once a month

Question 22

Total number of bottles for TSB sterility check

Answer 22

1%, no more than 4

Question 23

Autoclave time and temp for contaminated bacteria materials

Answer 23

119-121*C for 45 min

Question 24

Autoclave sterility testing is required how often and by what method?

Answer 24

once every 3 months, by either commercially manufactured check solution or by TSB inoculation

Question 25

What does TSB stand for?

Answer 25

Tryptic Soy Broth

Question 26

How often should thermometers be calibrated?

Answer 26

annually

Question 27

How often should timers be calibrated?

Answer 27

every three months

Question 28

pH linearity acceptance criteria

Answer 28

-56 to -62 mV