Extraction and Detection of Legionella DNA From Cooling Tower Water Samples Using InnuPure C16 touch and qTOWER3 Application Note · qTOWER³, innuDETECT Water Assays

Introduction

Bacteria of the genus Legionella are the cause of Legionnaires‘ disease as well as Pontiac fever. A common source of Legionnaires‘ disease outbreaks are cooling towers. The bacteria are spread via aerosols and infect alveolar macrophages upon inhalation. Legionnaires‘ disease is most commonly caused by Legionella pneumophila (L. pneumophila). However, other species of Legionella (Legionella spp.) can also cause legionellosis.

According to the 42. Bundesimmissionsschutzverordnung (BImSchV), the German Federal Immission Control Ordinance, operators of evaporative cooling systems, cooling towers and wet separators must regularly monitor the parameter Legionella spp. to assess the hygienic quality of service water. If specific limit values are exceeded, the additional differentiation into the L. pneumophila species is mandatory.

In addition, monitoring the general bacterial load in cooling towers is mandatory as well. Conventional detection methods reliant on bacterial plating and cultivation are challenging due to complex nutritional demands of these bacteria as well as interference by accompanying flora. Cultivation also requires at least a couple of days to generate conclusive results. Detection of general bacterial DNA and/or Legionella DNA by means of real-time PCR, however, is a matter of hours.

As little as a 1 mL water sample from a cooling tower is sufficient for extraction of bacterial DNA using Analytik Jena‘s InnuPure C16 touch. The usage of the innuPREP Bacteria Lysis Booster (by IST Innuscreen GmbH), an optimized mix of several lytic enzymes, ensures efficient nonmechanical pre-lysis of a wide range of bacteria. The lysis of the bacteria was included in the automated protocol, making external lysis and subsequent manual addition of the lysate to the reagent plate obsolete.