Efficacy of a mixture of colloidal silver-hydrogen peroxide and 2-bromo-2-nitropropan, 1,3-diol compounds against different Legionella pneumophila strains

Abstract number: P1175

Kimiran-Erdem A., Sanli-Yurudu N.O., Arslan-Aydogdu E.O., Zeybek Z., Gurun S., Cotuk A.

Objectives:Legionella pneumophila, the causative agent of Legionnaires' disease and Pontiac fever, can be isolated from a variety of potential human contact areas (cooling tower systems, potable water sources, etc.). Because of the potential for any water system to harbour, amplify and disseminate legionellae, control measures need to be considered for all water systems. Therefore, in order to prevent legionellosis outbreaks, contaminated water systems must be disinfected and the most effective and practical biocides need to be evaluated. The aim of this study is to determine the lethal activity of various concentrations of a mixture of colloidal silver-hydrogen peroxide (CSHP) and 2-bromo-2-nitropropan, 1,3-diol (BNPD) compounds on L. pneumophila. The susceptibility of environmental isolates [SG 1 and SG 2–14] and standard strain to biocides was assessed at different contact times.

Methods: In the current study, the qualitative suspension test method by Skaliy et al. was modified based The American Society for Testing Materials (ASTM) E 645–91 standard test method, which is used for determining the efficacy of microbicides used in cooling systems.

Results: CSHP compound was found effective at the recommended dosages (200–500 ppm) against legionellae, since these concentrations achieved >5 log reduction at 0 hour contact time. Furthermore, all strains were killed by lower doses (100 ppm and 50 ppm) in 3 hours contact time. Recommended BNPD concentration (100 ppm) for cooling towers killed SG 2–14 and standart strains at 3 hours contact time, however SG 1 strain was killed at 6 hours contact time. The antibacterial activity of lower doses BNPD (50 and 25 ppm) against SG 1 and standard strains required longer contact times than recommended dosages.

CSHP compound was found more effective than BNPD in terms of recommended dosages and contact times.

Conclusion: CSHP compound can be recommended for decontamination of legionellae. Since, several factors such as bacterial strains, biocides and conditions in the water sytems can affect efficiency of a biocide against bacteria, activity of the biocide needs to be evaluated in laboratory conditions before practical usage.

Session Details

Date: 19/04/2008
Time: 00:00-00:00
Session name: 18th European Congress of Clinical Microbiology and Infectious Diseases
Location: Barcelona, Spain
Presentation type:
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