- Posted April 8, 2014 by
Facts About Legionella
The Legionella organism is a gram negative, rod shaped bacterium which can cause pneumonia or Legionnaires' Disease. This was first identified to cause disease during its outbreak that happened in 1976 at Philadelphia. It has a specific growth requirement that must be met for it to survive and grow. Some of these requirements will include iron, L Cysteine, biofilm, and temperature above 68 degrees Fahrenheit.
As compared to other bacteria, it can actually survive at lower dissolved oxygen level. Also, it is somewhat resistance to chlorine disinfection. Some plastics and organics can provide nutrients for its growth while copper and silver ion concentrations can kill it.
Lab services that can detect the presence of Legionella
Legionella Culture Method – This culture method still remains to be the gold standard when it comes to detecting this bacterium from environmental sources. The negative side though when using this method is that it will require up to 10 days to be complete. Always be reminded that time is precious.
Legionella PCR Method – This method is otherwise known as the polymerase chain reaction method. This is a molecular technique that will offer a very sensitive process and will require a couple of hours to complete. This method will provide a very extreme powerful screening tool for fast Legionella detection in various environmental samples. The negative side though is that it cannot distinguish between living and dead cells. Indeed, this method can identify potential sources rapidly which can then facilitate disinfection processes and help to prevent exposures. And since this technique will not determine the viability of the bacterium, the PCR screen should only be considered presumptive and will indeed require confirmation through conventional culture techniques.
Here are some sampling methods
Swab sampling – First, you have to collect a surface sample through a sterile swab where there is scale formation or perhaps on water outlets. Swabs of faucet aerators as well as shower heads must be taken before the water sample from these areas with the aerator or shower head removed when possible. You must pre-wet the swab with water from the sampling site and submerge swab in 3-5 ml of water taken at the same time in order to prevent drying during transport.
Bottle Sampling – some of the equipment needed for this kind of sampling will include gloves, respirator, and sterile bottle with sodium thiosulfate preservative.
Understand that the number and types of sites that must be tested should be determined on a case-to-case basis. Because of the diversity of mechanical and plumbing systems within the building, you might need more than one sample from the suspect source.