Biological Testing  Reg No. 2787

Cert No. 7176 – 10

Editor: Glen Pinna

26

August 2004

 

Issue No.

         A variety of micro-organisms that can cause illness have been found in water, these can be introduced into the body by drinking and inhalation, or by exposure to skin or mucous membrane. They include bacteria, protozoa, algae and viruses. This discussion will cover the description, significance, water treatment required for elimination and health significance where applicable.

 

         Pseudomonas aeruginosa

 

         No guideline value has been set for Pseudomonas aeruginosa in drinking water.

 

         Although Pseudomonas aeruginosa is commonly found in faeces, soil, water and sewage, it cannot be used as an indicator of faecal contamination, as in is not universally present in faecal matter and can also be found in many aquatic environments and on surfaces in contact with water. It’s presence can, however, be used to indicate poor general cleanliness in a water distribution system and the quality of bottled water. Pseudomonas aeruginosa can also be found in some foods.

 

         Pseudomonas aeruginosa is an opportunistic pathogen, meaning that it exploits some break in the host defences to initiate an infection.  It causes urinary tract infections, respiratory system infections, dermatitis, soft tissue infections, bacteremia, bone and joint infections, gastrointestinal infections and a variety of systemic infections, particularly in patients with severe burns and in cancer and AIDS patients who are immunosuppressed. Pseudomonas aeruginosa infection is a serious problem in patients hospitalized with cancer, cystic fibrosis, and burns. The case fatality rate in these patients is 50 percent.

 

         It is therefore obvious that contamination of hospital water supplies with high levels of Pseudomonas aeruginosa can be a serious situation, although a direct link between nosocomial infection and contaminated water supplies has yet to be conclusively proven.

 

         The control of Pseudomonas aeruginosa can generally be achieved by maintaining free available chlorine levels of 0.2 to 0.5 mg/L.

 

         It is commonly found in poorly disinfected swimming pools and spa pools, where cases of eye, ear and folliculitis (skin inflammation) have been reported. Although there are not guidelines for drinking water, acceptable limits in swimming and spa pools are generally less than one organism per 100mL. In bottled water, the levels are much more stringent and are less than one organism per 250mL.

 

 

         Despite the absence of drinking water acceptable limits, the presence of Pseudomonas aeruginosa in a water supply may indicate a serious deterioration in the overall bacterial quality. In these situations it is unlikely that Pseudomonas aeruginosa will be the only contaminating bacteria and numerous other bacteria groups are likely to be present. This will often be associated with a deterioration of other physical characteristics such as taste, odour and turbidity.

 

 

         The next BioTalk will deal with Salmonella.

 

Source: Australian Drinking Water Guidelines - 6: 1996. National Health and Medical Research Council of Australia & Agriculture and Resource Management Council of Australia and New Zealand.  Foodborne Microorganisms of Public Health Significance. 5th Edition. 1997. AIFST (NSW Branch Food Microbiology Group. And US. FDA Foodborne Pathogenic Microorganisms and Natural Toxins Handbook.