DIATABS ™
05-2007 Ch. 3
Page 29 of 130
3.5
ARGININE DIHYDROLASE (ADH) REF No. 56211
L-arginine is broken down in a two step process: first from l-arginine to l-citrulline (ADH) followed by a citrulline splitting system. The over-all reaction results in the formation of l-ornithine, CO2 and NH3 from the substrate l-arginine, resulting in an alcalinization of the medium and a change of colour of the indicator from yellow to red. Procedure Prepare a dense “milky” suspension (at least McFarland No. 4) from the strain to be tested in 0.25 ml saline in a tube. Add one ADH Diagnostic Tablet and 3 drops of sterile paraffin oil. Close the tube and incubate at 35-37 °C for 4 hours or up to 18-24 hours. Reading of the test Positive reaction: Negative reaction:
Red Yellow
After overnight incubation, positive reaction: strong red; negative reaction: yellow or orange. In most cases overnight incubation is necessary. Results 1) Enterobacter Positive: Usually negative:
Enterobacter cloacae Other Enterobacter spp. ADH 97 0 0 99 0
E. cloacae E. aerogenes E. intermedium E. sakazakii E. agglomerans
MR 5 5 100 5 50
Remarks
α-GLU + ODC 0
ADH = Arginine Dihydrolase D.T., MR = Methyl Red, α-GLU = Alpha-Glucosidase D.T., ODC = Ornithine Decarboxylase D.T. 2) Streptococci/Enterococci Positive: Negative:
E. faecalis, E. faecium, E. durans, E. gallinarum, E. casseliflavus. Group D streptococci (Strept. bovis, Strept. equinus) E. avium, E. raffinosus.
3) Non-fermenters Positive: Negative:
Ps. aeruginosa, Ps. fluorescens, Ps. putida, Ps. pseudoalcaligenes, Ps. alcaligenes, Ps. stutzeri, Cryseom. luteola (Ve-1). St. maltophilia, Sphing. paucimobilis, Shew. putrefaciens, Flavobacterium spp., Brev. vesicularis, Com. acidovorans, Com. testosteroni, Pasteurella multocida, Ralst. pickettii, Alcaligenes spp., Brev. diminuta, Burkh. cepacia, Oligella spp.
4) Staphylococci Usually positive: Usually negative:
S. aureus, S. haemolyticus, S. schleiferi, S. simulans, S. warneri, S. capitis. S. hominis, S. lugdunensis, S. saprophyticus, S. xylosus, S. cohnii, S. sciuri, S. lentus
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