rationale of foodborne pathogens
- Do not occur in aquatic environment naturally
- Initially abundant in feces from warm-blooded animals
- If absent, high probability that other harmful organisms are not present
Desired characteristics of potable water:
- Should not be contaminated with chemical or biological hazards which can cause risk to public health
- Free of turbidity, color, and disagreeable
taste or odor
Give the top 6 coliforms
E. coli
Enterobacter
Klebsiella
Citrobacter
Serratia
Streptococcus
what are the fecal coliforms
Escherichia coli
Enterobacter
Klebsiella
what can enterococcus cause?
cystitis, pyometritis, endocarditis
Used as an Indicator of water contamination in EU
enterobacter
Importance: when sodium hypochlorite was added to water before getting a sample
when sodium hypochlorite mixes with water, produced hypochlorous acid (form of chlorine) which has high germicidal activity
methods of water testing
MPN and HPC/SPC
T/F MPN is useful when there are many contaminants
T
assumptions of MPN
- Random distribution of bacteria within the sample
- Separated bacteria
- Individual tubes are independent.
allowable limits in presumptive test
<1.1 MPN or CFU/100mL
medium for confirmatory test
EMB
source of nutrient of non-lactose fermenting bacteria
Peptic digest of animal tissue
purpose of methylene blue
inhibits G+ bacteria
composition of EMB agar
peptic digest of animal, dipotassium phosphate, lactose, sucrose, eosin, meth blue, AGAR
why is completed test performed?
to test for the strain / genotyoe of e.coli
IMVIC can be a completed test for e.coli
no, same results as P. vulgaris
Nutrient agar
general use medium for non-fastidious
standard limit on HPC
<500 CFUs/mL
what does HPC isolate?
facul aerobes and anaerobes
