Improved Acid Pretreatment for the Detection of Legionella Species from Environmental Water Samples Using the Plate Culture Method

Abstract

Acid treatment is performed in the detection of Legionella species from environmental water samples using the plate culture method. The acid treatment functions to eliminate the nontarget heterotrophic bacteria. Usually, an HCL-KCL buffer is used for the acid treatment of samples. However, the buffering capacity of the HCL-KCL buffer is not sufficient to maintain a constant low-pH in highly alkaline samples or highly buffered samples such asthose from cooling towers or spas. Our results show that the pH of various water samples ranged from 2.4 to 7.2 after treatment with an HCL-KCL buffer. We demonstrate here that an acid-phosphate buffer produces a low pH in highly alkaline samples or highly buffered samples. The pH of the water samples ranged from 2.2 to 2.5 after treatment with an acid-phosphate buffer. In the re-sults of the examination of 161 samples, the use of an acid-phosphate buffer instead of an HCL-KCL buffer decreased the effect of non-target heterotrophic bacteria from 3.1% to 1.2%. Therefore, efficient detection of Legionella from samples of varying water quality can be achieved following pretreatment with an acid-phosphate buffer.