The studied microorganisms included reference (from
the American Type Culture Collection) and clinical
(Laboratory collection) strains of Providencia stuartii,
Pseudomonas aeruginosa, Klebsiella pneumoniae, Escherichia coli, Enterobacter aerogenes and Enterobacter cloacae
The bacterial strains and their features were previously
reported [5]. The preliminary treatment of these organisms as well as the culture media were conducted as previously described [5].