Legionella bacteria was first discovered in 1976 in Philadelphia when people became ill and suffered from a type of unidentified pneumonia. It was later coined as Legionnaires disease. Legionella is a gram negative bacteria and can be easily identified when viewed through a microscope by using Gram staining technique. The legionella bacteria occurs naturally in fresh water bodies and in soil but in those conditions they don’t pose a serious threat because the conditions are not ideal for their growth. They became a threat when they establish themselves in water systems that are weakened immune systems where the conditions are ideal for their growth and nourishment. The water systems in large complexes and water coolers for hospital are ideal medium for legionella bacteria.

Testing for the Presence of Legionella Growth in Hospitals

The main source of Legionella in hospitals are the water systems. If the water is not treated with uv purifiers, the Legionella are capable of multiplying at a quick pace. The infection does not spread from one person to another. The water purification companies can help in legionella testing by using any one of the following methods :

  1. DNA Amplification

This method uses a polymerase chain reaction process that amplifies and detects genetic materials and DNA that are specifically associated with Legionella bacteria. This is comparatively faster than other methods and the results are yielded in a day.

  1. Direct Fluorescence Antibody

This method is used to determine the total number of organisms that are present in the water body. This method uses direct fluorescence antibody that leaves a stain on the organisms with a fluorescent dye. The results are yielded in one or two days but it is not capable to differentiate the live and dead organisms.

  1. Legionella Culture Of Water Sample

In this method, the sample water is cultured by using charcoal yeast extract. The medium is cultured for about 2 weeks after which time, legionella bacteria can be observed directly through the microscope.

Signs and Symptoms of Legionella Disease


Chest pain



Shortness of breath

Diagnosis of Legionnaire Disease

Legionnaire disease is a form of pneumonia and the victim suffering from the disease will have severe pneumonia accompanied man-made fever. There are two renowned tests to diagnose Legionnaire disease.

  1. Urine test for Legionella Antigen

This is a preliminary test used for diagnosing legionella disease. The results are obtained in the same day but this test does not show the effect or severity of the disease.

  1. Legionella Culture of Respiratory sample

This test is used to identify the severity of the infection by culturing the lung fluid of the victim. This method gives precise information about the disease such as the species of the Legionella bacteria, source of infection, severity, etc…

Risk factors

Legionnaire disease does not affect every person that come in contact with the bacteria. There are certain factors that induce the infection in human beings.  They are as follows :

  1. Weak immune system

If your immune system is weak, then you are vulnerable to all types of infections and legionnaire disease is not any different. Having a strong immune system offers resistance to our body from Legionnaire infection.

  1. Smoking

Smoking affects your lungs and is the primary risk factor for all types of lung infections. Legionnaire infects the lungs and smoking greatly favors legionnaire infection.

  1. Lung infections

Having any other lung infections such as tuberculosis, emphysema, etc.. can also favor and make it an ideal host for legionella bacteria.

  1. Old age

Old age people are prone to all types of diseases due to the weakened immune system and other organ functions.

Disinfection of legionella bacteria

Hospitals are one of the areas where there is a higher risk for the growth of legionella bacteria. The water systems that are used in hospitals can become an ideal medium for the growth of legionella bacteria. The patient safety in hospitals is very important and many hospitals have adopted legionella prevention plan and disinfectant methods to ensure it. The water purification companies will help you in developing a water management program to reduce legionella growth and spread in buildings. The water purification companies make use of the following disinfection methods :

UV radiation – Ultraviolet rays are passed into the water that kills the legionella bacteria

Thermal conditioning – Water is heated to excess of 60 degree celsius

Hyperchlorination – Chlorine is a powerful oxidising and is used widely as a disinfectant

The patient safety in hospitals has to be considered top priority as they will have weakened immune systems and are vulnerable to infections. The above mentioned can also be incorporated in the water coolers for hospital ensuring the water is free from contamination.