With further testing by spot indole, the positive isolates may be presumptively reported as Proteus vulgarisand the negative ones as Proteus mirabilis.
The result of this test would not necessarily indicate an absence of contamination.
The media used in this test is glucose phosphate broth, which contains buffered peptone water.
Additional biochemical testing using pure cultures is recommended for complete identification.
What is the purpose of the control vial? The growth of non-motile bacteria is restricted along the stab line and leaves the surrounding medium clear.
Tryptophan is an amino acid that can undergo deamination and hydrolysis by bacteria that express tryptophanase enzyme.