Selective medium for Pseudomonas aeruginosa that uses 1,10-phenanthroline as the selective agent.

The MIC of 1,10-phenanthroline for 35 Pseudomonas aeruginosa strains was 128 micrograms/ml, whereas 32 micrograms or less per ml inhibited all other microorganisms tested. On the basis of these results, a selective agar for P. aeruginosa which contained 15 g of Trypticase soy broth (BBL Microbiology Systems), 15 g of agar, and 0.1 g of phenanthroline per liter was formulated. Forty-four P. aeruginosa strains yielded a mean efficiency of plating on this medium of 79% of the counts obtained on Trypticase soy agar, which was significantly higher than that obtained with pseudomonas isolation agar or Pseudosel agar. Pseudomonas cepacia, Pseudomonas fluorescens, Pseudomonas putida, Pseudomonas stutzeri, representatives of 13 other genera (including gram-negative rods, gram-positive rods, and cocci), and a yeast were not recovered within 48 h at 35 degrees C when approximately 10(7) CFU were plated on this medium. Only small colonies from one strain each of P. fluorescens and P. putida could be seen at 3 and 7 days, respectively, and they had an efficiency of plating of only less than 0.001%. When 10(7) CFU of either of these strains was plated with 10(2) CFU of P. aeruginosa, it did not interfere with the quantitative recovery of P. aeruginosa

Ototoxicity and tolerance assessment of a TrisEDTA and polyhexamethylene biguanide ear flush formulation in dogs

Clinically healthy mixed breed dogs (n = 20) were used to determine if a Tris (tromethamine)-buffered test solution, Otinide((R)) (Trademark of Dermcare-Vet Pty-Ltd, Australia), containing disodium ethylenediamine tetraacetic acid (EDTA; 1.21 g/L) and polyhexamethylene biguanide (PHMB; 0.22 g/L) caused ototoxicity or vestibular dysfunction. The dogs were randomly assigned to either a control group (group A, n = 10) receiving saline, or a treatment group (group B, n = 10) receiving the test solution. Phase 1 of the study consisted of applying 5.0 mL of saline to both ears of the control group (group A) and 5 mL of test solution to both ears of the test group (group B), for 21 days. A bilateral myringotomy was then performed on each dog under deep sedation. Phase 2 of the study then consisted of applying 2.0 mL of the saline to both ears of the control group (group A) and 2.0 mL of the test solution to both ears of the test group (group B), for 14 days. Throughout the study, dogs were examined for clinical health, and underwent otoscopic, vestibular and auditory examinations. The auditory examinations included brainstem auditory evoked potential (BAEP) threshold and supra-threshold assessments using both click and 8 kHz tone burst stimuli. The absence of vestibular signs and effects on the BAEP attributable to the test solution suggested the test solution could be applied safely to dogs, including those with a damaged tympanic membrane

Tonometers and infectious risk: myth or reality? Efficacy of different disinfection regimens on tonometer tips.

Purpose To evaluate the adequacy of common disinfection regimens for disposable tonometer tips and assess if disinfection of reusable prisms or the use of disposable tips is preferable. Methods We used disposable tonometer tips, using the same material and tip diameter of standard Goldmann tonometer prism. Strains of Pseudomonas aeruginosa, Staphylococcus aureus, Bacillus subtilis and Candida albicans were tested according to the European standard guidelines for disinfectants test. Antimicrobial effectiveness of the following disinfection practices has been assessed: dry wipe, Minuten wipes (Alpros), soaking in 3% hydrogen peroxide, 0.5% benzalkonium chloride, and 0.5% Pantasepts for 1, 5, and 15 min. All tests have been performed three times and all conditions tested in duplicate. Results Dry wiping and 1 min soak in 3% hydrogen peroxide were ineffective on all microrganisms. Minuten wipes, 1 min soak in 0.5% benzalkonium chloride or 3% hydrogen peroxide were ineffective on B. subtilis. 0.5% Pantasepts soak was effective in 1 min for all microrganisms tested, whereas 3% hydrogen peroxide and 0.5% benzalkonium chloride soaks were effective when performed for at least 5 min. B. subtilis was the most resistant organism to disinfectant regimes at 1 min time. Conclusions Results of our study demonstrate a relative disinfection efficacy for the different evaluated regimens, provided that correct exposure times are adopted for the chosen disinfectants, a condition difficult to ensure in a busy clinic setting. We conclude that disposable prism tonometry provides a safe alternative to Goldmann tonometry