test: Test tubes with lysine broth were inoculated with pure overnight isolate followed by incubation at 37[degrees]C for 4 days.
The stool sample was inoculated on MacConkey agar (Oxoid, UK) and xylose lysine decarboxylase
agar (XLD) (Oxoid, UK).
The isolates showed positive results for arginine dihydrolase, lysine decarboxylase
, ornithine decarboxylase, citrate utilization and HoS production.
Other tests included the glucuronidase, nitrate reduction, lysine decarboxylase
, orinithine decarboxylase, phenylalanine deamination, arabinose, oxidase and citrate utilization tests.
The biochemical tests showed positive results for O-nitrophenyl- b-D-galactopyranoside, arginine dehydrolyase, lysine decarboxylase
, citrate utilization, indole production, gelatinase and Voges Proskauer.
The strain was unusual because it was negative for the production of lysine decarboxylase
and b-galactosidase (ortho-nitrophenol test) and positive only for stx1.
The results of morphological, physiological and biochemical analyses showed that the isolates were Gram positive, motile, and positive for catalase, nitrate, citrate, methyl red (MR), lysine decarboxylase
, ornithine decarboxylase, methyl red (MR) and Ortho-Nitrophenyl-Beta-D-Galactosidase (ONPG) tests, but were negative for oxidase, urease, indole, H2S production, arginine dihydrolase, phenylalanine and tryptophan deaminase and Voges-Proskauer (VP) tests.
2]S - - - Gas + - - Gelatin Liquification + + + Starch Hydrolysis - - - ONPG - - - Lysine decarboxylase
+ + + Ornithine decarboxylase + + + Tentative identification Pseudomonas Bacillus Bacillus aeruginosa cereus cereus (St1) (St2) (St3) Isolates/Tests Iso 4 Iso 5 Gram stain - ve - ve Shape Short Rod Short Rod Endospore - - Motility + + Oxidase + + Catalase + + Urease + + Indole - + MR--VP - - Citrate + + Utilization TSI Butt A K Slant K K [H.
Organisms are oxidase and ONPG positive, and lysine decarboxylase
12129 13408 Serogroup O1 O22 Haemolysis on blood agar + + Indole + + Voges-Proskauer + + Lysine decarboxylase
+ + Arginine dihydrolase - - Ornithine decarboxylase + + Phage IV (lysis) - - Acid from: L-Arabinose - - Mannose + - Sucrose + + Growth in tryptone broth: 0% NaCl + + 3% NaCl + + Susceptibility to: O/129 (10 [micro]g disc) R R (150 [micro]g disc) R R Polymyxin B (50 U disc) R R Trimethoprim/sulphamethoxazole R R (1.
Key words: bacillus, aciduric, effervescence, spore-formers, lysine decarboxylase
Because some strains of lysine negative Escherichia hermanii will cross react with 0157 sera; we employed the lysine decarboxylase
test on candidate sorbitol nonfermenters and lactose fermenters (8): 13 x 100 mm serology tubes (VWR Scientific, San Francisco, Calif.