EXERCISE 1

Question 1

rationale of foodborne pathogens

Answer 1

1. Do not occur in aquatic environment naturally
2. Initially abundant in feces from warm-blooded animals
3. If absent, high probability that other harmful organisms are not present

Question 2

Desired characteristics of potable water:

Answer 2

1. Should not be contaminated with chemical or biological hazards which can cause risk to public health
2. Free of turbidity, color, and disagreeable
   taste or odor

Question 3

Give the top 6 coliforms

Answer 3

E. coli
Enterobacter
Klebsiella
Citrobacter
Serratia
Streptococcus

Question 4

what are the fecal coliforms

Answer 4

Escherichia coli
Enterobacter
Klebsiella

Question 5

what can enterococcus cause?

Answer 5

cystitis, pyometritis, endocarditis

Question 6

Used as an Indicator of water contamination in EU

Answer 6

enterobacter

Question 7

Importance: when sodium hypochlorite was added to water before getting a sample

Answer 7

when sodium hypochlorite mixes with water, produced hypochlorous acid (form of chlorine) which has high germicidal activity

Question 8

methods of water testing

Answer 8

MPN and HPC/SPC

Question 9

T/F MPN is useful when there are many contaminants

Answer 9

T

Question 10

assumptions of MPN

Answer 10

1. Random distribution of bacteria within the sample
2. Separated bacteria
3. Individual tubes are independent.

Question 11

allowable limits in presumptive test

Answer 11

<1.1 MPN or CFU/100mL

Question 12

medium for confirmatory test

Answer 12

EMB

Question 13

source of nutrient of non-lactose fermenting bacteria

Answer 13

Peptic digest of animal tissue

Question 14

purpose of methylene blue

Answer 14

inhibits G+ bacteria

Question 15

composition of EMB agar

Answer 15

peptic digest of animal, dipotassium phosphate, lactose, sucrose, eosin, meth blue, AGAR

Question 16

why is completed test performed?

Answer 16

to test for the strain / genotyoe of e.coli

Question 17

IMVIC can be a completed test for e.coli

Answer 17

no, same results as P. vulgaris

Question 18

Nutrient agar

Answer 18

general use medium for non-fastidious

Question 19

standard limit on HPC

Answer 19

<500 CFUs/mL

Question 20

what does HPC isolate?

Answer 20

facul aerobes and anaerobes