This medium was originally described by Slanetz and
Bartley for the enumeration of enterococci from wa
ter samples using a membrane
filtration technique, but it may also be used as a
spread plate for the examination of other sample ty
pes. Enterococci reduce tetrazolium
chloride to the insoluble red dye formazan, produci
ng colonies which are dark red or maroon on the sur
face of the membrane or agar. This
reaction is not exclusive to enterococci, and the c
ount at this stage should be considered presumptive
. Colonies may be confirmed as
enterococci by demonstrating aesculin hydrolysis us
ing Kanamycin Aesculin Azide Agar LAB 106.
Dipotassium hydrogen phosphate
2,3,5 Tetrazolium chloride
Method for reconstitution
Weigh 43.5 grams of powder and mix with 1 litre of
deionised water. Bring to the boil with frequent st
irring to dissolve completely. Cool
to 47°C and pour into sterile Petri dishes. DO NOT
AUTOCLAVE, OVERHEAT, OR LEAVE FOR GREATER THAN 4hr
Rose coloured gel.
7.2 ± 0.2
Minimum QC organisms:
WDCM 00013 (inhibition)
Plates – up to 7 days at 2-8°C. Storage in bottles
is not recommended as re-melting the medium will ca
Water: Filter 100ml of the water through a suitable
membrane, and place this on the surface of a prope
rly dried Slanetz and Bartley plate.
Other samples: Dilute as necessary and spread 0.5ml
over the surface of the plate using a spreader, an
d allow to soak into the agar.
Water: at 37°C for 48hr if testing potable waters o
r processed foods. At 37°C for 4hr then 44°C for 44
hr if testing untreated waters or raw
Count all red and maroon colonies as presumptive en
terococci. Confirmation of isolates can be achieved
by demonstration of a positive
aesculin reaction on KAAA LAB106.
Slanetz, L.W., and Bartley, C.H. (1957) J.Bact.
Environment Agency: The Microbiology of Drinking Wa
ter (2002). Methods for the Examination of Water an
d Associated Materials.