Water Bacteriology Flashcards
Contaminants of fecal origins ( because of unsanitary practices of that particular area)
Bacillary dysentery
Typhoid
Cholera
Parathypoid fever
Common water borne enterics
Shigella dysenteriae
Campylobacter jejuni
Salmonella typhi
Vibrio cholerae
Indicates the presence of e.coli
Coliform formation
Presumptive test
Lactose fermentation broth with inverted Durham tube
Confirmed test
EMB or ENDO agar
Completed test
Lactose broth and nutrient agar
Enterobacteriae, specifically your e-coli produces
Gas
used to detect production of gas
e.coli
Formation of e. coli under emb on ENDO agar
pink with a metallic sheen
utilized for completed test, which is used to completely identify your coli forms coming from presumptive and confirmed test
lactose broth and nutrient agar
for presumptive test, incubate sample ___ hours at 37 degree celsius
48 hours
positive result in presumptive test
presence of gas
for confirmatory test streak ___ from positive tube and incubate ___ hours, 37 degree celsius
EMB, 24 hours
positive confirmed test
- typical coliform colonies, water nonpotable
- gram neg short bacilli
the absence of gas in all lactose broth tubes indicates
coliforms are absent and water is safe to drink
if gas is present only after 48 hours
the gas is probably not due to coliforms. further testing
if gas occurs in the durham tube of one or more lactose broth after 24 hours
water is presumed unable to drink
pathogens that can contaminate water and cause disease
cholera (vibrio cholera)
typhoid fever (salmonella typhi)
dysentery (shigella dysenteriae)
types of bacteria used to detect and estimate the level of fecal contamination of water
indicator bacterium
characteristics of coliforms
gram negative
facultative anaerobic
non spore forming rods that ferment lactose
is the basis for determining the total coliform count in water sample
lactose fermentation with acid and gas
bacterial examination of water tests
presumptive test, confirmed test, completed test, IMViC tests
presumptive test is also used to determine ____ of coliforms present in 100 ml water
Most Probable Number (MPN)
plates of Levine EMB agar inoculated form positive tubes (gas producing tubes) to see if the organisms that are producing gas are gram neg (another coliform characteristic)
confirmed test
determines if organisms are gram negative (media inhibits (media inhibits gram pos bacteria)
confirmed test
coliforms in emb will inhibits what colonies?
large blue black colonies with a green metallic sheen for e. coli under
determines if the isolate from the agar plates match our definition of a coliform
completed test
if gas is produced and a slide is made from a slant, this confirms the presence of gram negative, non spore forming rods the presence of coliform is certain
completed test
- final test to separate e. coli and e.aerogenes
- previous tests just indicate that coliforms are present, not which organism
IMVic tests
