Use of a new alginate film test to study the bactericidal efficacy of the high-level disinfectant ortho-phthalaldehyde.

OBJECTIVES To evaluate the merit of a new alginate efficacy film test to determine the bactericidal activity of the high-level disinfectant ortho-phthalaldehyde (OPA). METHODS The efficacy of OPA was investigated using a new sodium alginate surface film test against Mycobacterium chelonae NCIMB 1474 and Epping, and Pseudomonas aeruginosa NCIMB 10421 under different test conditions. RESULTS OPA was highly bactericidal against P. aeruginosa but its mycobactericidal efficacy was seriously reduced and produced >or=5 log reductions only at a concentration of 0.5% (w/v) within 30-60 min without organic load. CONCLUSIONS The sodium alginate film efficacy was reproducible between repeats. Inactivation results depended upon the concentration of OPA, contact time, the presence of an organic load and the bacterial genera.