Bromocresol-purple Azide Broth

Bromocresol Purple Azide Broth

EMD Cat. No. 1.03032.0500

500 g

For confirming the presence of enterococci, particularly in the bacteriological analysis of water according to HAJNA and PERRY (1943 an HAJNA (1951).

This broth should be employed after performing a preliminary test with Azide Dextrose Broth.

Additives

EMD Cat. No.	Product	Pack Size
1.01590.0500	Azide Dextrose Broth	500 g
GX0195-1	Glycerol (about 87 %)	500 ml

Mode of Action	Preparation
Experimental Procedure and Evaluation	Quality Control
Typical Composition (g/liter)	Literature
Picture/Image

Mode of Action
Sodium azide inhibits the entire accompanying bacterial flora including those species which may have grown in the preliminary test. Enterococci ferment the glucose present in the medium to give acid which is detected by the pH indicator bromocresol purple - the acid causes the indicator to change its color to yellow. According to HAJNA (1951), enterococcal glucose fermentation is improved by the addition of glycerol.

Typical Composition (g/liter)
Peptone from casein 10.0; yeast extract 10.0; D(+)glucose 5.0; sodium chloride 5.0; di-potassium hydrogen phosphate 2.7; potassium dihydrogen phosphate 2.7; sodium azide 0.5, bromocresol purple 0.032.

Preparation
Suspend 36 g in 1 liter of purified water, adding 5 ml/liter glycerol if desired, dispense into test tubes, autoclave under mild conditions
(15 min at 115°C).
pH: 7.0 ± 0.2 at 25°C.
The prepared broth is clear and violet.

Experimental Procedure and Evaluation
Inoculate the culture medium massively on account of the high degree of inhibition.
Incubation: up to 48 hours at 35 °C aerobically.

Colony growth with turbidity and a change in color to yellow: Enterococci.

Quality control

Test strains	Growth	color change to yellow
Streptococcus agalactiae ATCC 13813	none / poor	-
Enterococcus faecalis ATCC 11700	good / very good	+
Enterococcus faecalis ATCC 19433	good / very good	+
Enterococcus hirae ATCC 8043	good / very good	+
Streptococcus bovis DSM 20065	good / very good	+ (poor)
Staphylococcus aureus ATCC 25923	none
Escherichia coli ATCC 25922	none
Pseudomonas aeruginosa ATCC 27853	none

Literature

HAJNA, A.A.: A buffered azide glucose-glycerol broth for presumptive and confirmative tests for fecal Streptococci. - Publ. Health Lab., 9; 80-81 (1951).
HAJNA, A.A., a. PERRY, C.A.: Comparative Study of Presumptive and Confirmative Media for Bacteria of the Coliform Group and for Fecal Streptococci. - Am. J. Publ. Health, 33; 550-556 (1943).

Bromcresol-purple Azide Broth - Enterococcus hirae