CDC Culture Method: The culture method remains the "gold standard" for detecting Legionella from environmental sources. This technique requires 7-10 days to get a detailed result. The result could pinpoint Legionella sources, distinguish between live and dead cells, and prevent additional exposures.
PCR Method: Polymerase Chain Reaction (PCR) method is a technique using DNA segments to determine the bacteria. This method could show the result in a short time. With expedited processing service, our customers can receive the results as fast as the same day. Although this method cannot distinguish if cells are alive or dead, it can rapidly identify potential sources, facilitate disinfection processes, and help to prevent further exposures. In order to determine the viability of the Legionella bacteria, customers need to confirm via the conventional culture method.
| What is Legionella Bacteria? |
| Illness caused by the gram-negative bacteria in the genus Legionella is referred to as legionellosis. Legionellosis consists of two distinct clinical syndromes, Legionnaires’ disease and Pontiac fever. Legionnaires' disease is characterized by pneumonia whereas Pontiac fever is self-limiting, nonpneumonic, influenza-like illness. Inhalation of aerosols containing the bacterium is presumed to be the primary means of acquiring legionellosis. Aerosolized waters from cooling towers evaporative condensers, showers, and humidifiers have been identified as sources of infection. Legionella species have been recovered from a wide variety of domestic water systems and are ubiquitous in freshwater environments. Although once considered transient contaminants of natural and domestic waters, legionellae are now known to be free-living organisms surviving as natural component of freshwater ecosystems. Domestic systems are complex environments in which concentrations of legionellae can fluctuate considerably depending upon water temperature, biocide levels, and presence of natural hosts (i.e. protozoa) for legionellae to parasitize. The choice of a procedure used to recover legionellae from water samples is dependent upon the expected degree of bacterial contamination in a particular water source. Potable waters generally have low bacterial densities and are either cultured directly or concentrated to detect legionellae. Nonpotable waters, such as those from cooling towers, generally do not require concentration because of their high bacterial concentrations. |
| Sample Types |
| For both CDC Culture Method and PCR Method, the sample types could be:Bulk SampleSwab SampleWater Sample |
| Sample Equipment |
| Clean collection bottles with neutralizer (e.g. thiosulfate) for halogenated water. For routine monitoring 250ml sample size is sufficient; for recovery of isolates for case investigations multiple samples per outlet or larger sample volumes (1 liter) are recommended. Non-cotton tip sterile swab. |
| Places for Sample Collection |
| Samples should not be collected from sites that demonstrate periodic drying, because Legionella does not survive in dry environments. Common location where Legionella can be found include cooling towers, evaporative condensers, fluid coolers that use evaporation to dissipate heat and, domestic hot water systems with water heaters that operate below 60°C (140°F) and deliver water to taps below 50°C (122°F). Data collected from swab samples are qualitative if no area is given, and quantitative if an area is given. Air sampling is not often conducted since it generally results in a low recovery of Legionella species from the environment. |
| Sampling Protocols |
| Sampling for Legionella species typically involves collecting water samples and swabs from potential sources. Collection sites range from taps and faucets to water storage reservoirs. Please remember that it is important not to flush water outlets before taking a sample for Legionella analysis because the end section of the water system may be a contaminated site. For potable water collect 500ml of water for routine monitoring and if possible larger volumes or several samples for isolate recovery in case investigations. For non-potable water, a minimum of 250 ml is appropriate. |
| How to Sample? |
| Make a sampling plan, check this video. Sample Potable Water, check this video. Sample Cooling Towers, check this video. Sample Spas and Fountains, check this video. |
| What is Turnaround Time? |
| Culture Method (LC200): Standard (usually takes 7-10 business days) PCR Method (PCR20.1): StandardNext Day ExpediteSame Day Expedite |
| Shipping Instruction |
| Samples must be shipped to the Legionella testing laboratory for overnight delivery, as it is recommended to begin analysis within 24 hours from sampling. Thus, we suggest to choose FedEx overnight with 10:30 AM option shipping method. Shipping temperatures should be kept between 2°C (35.6°F) and 18°C (64.4°F). During hot weather, it is recommended to add cold packs or ice in a cooler containing the sample containers. |
