Abstract
Infections caused by Legionella spp. are considered an emerging public health problem and are linked to high rates of mortality and morbidity, if not properly treated. This study analyzes 76 samples of water in Guangzhou with the aim of obtaining a more efficient means based on culture to isolate the genus Legionella. A comparative assessment of techniques recommended was performed on monitoring Legionella spp. in environmental water samples. Fourteen (14) sampling methods included in four categories based on concentration (filtration or centrifugation), acid buffer treatment (no acid treatment, treatment for 10 min), thermal treatment (no thermal treatment or treated for 30 min in 50°C) and heat enrich the samples in 37°C for 72 h were tested to identify their sensitivity. The four categories methodologies were assembled by different procedures and 14 methods were obtained to compare the efficiency for isolating Legionella in 76 water samples and in which Legionella were isolated from 42 water samples through these 14 methods. Merit and demerit of each single method was evaluated. Results suggest that a single category methodology for water sampling was insufficient to isolate Legionella spp. from water samples. Some Legionella positive water samples were missed through a single category methodology which made the results mistranslation. PSF category methods in this study were recommended methods and they could isolate Legionella species from 78.6% Legionella positive water samples; and if time was enough, PSF category methods combined with ERCT category methods to isolate Legionella from water samples are strongly recommended. Legionella were isolated from 41 water samples through these two category methods, it only missed 2.4% positive water sample. The results obtained, highlighted the importance of improving culture method for the identification of Legionella in water samples.
Key words: Legionella, environmental water samples, sampling methods.
Abbreviation
CT, Centrifugation for water concentration; ER, pre-treat samples in 37°C for 72 h for heat enrich; SF, sucking filtration for water concentration; PSF, sucking filtration and then add sterile water and scrape the membranes to collect bacteria; A, acid treatment; H, thermal treatment; AH, acid treatment and then thermal treatment; HA, thermal treatment and then acid treatment.
