Burkholderia cepacia in the Environment
Dear Editor
I recently heard from a friend with CF that Burkholderia cepacia can be found in some foods, waste material, and even in drinking water or in the air we breathe. Is this the case?
I already take the precautions necessary to minimise risk of cross-infection around my friends who have CF, and avoid other people with infections, colds, etc. My hospital also has a good segregation policy for B cepacia and MRSA.
Should I be concerned about this information I have heard, or has this been exaggerated? And even if only partly true, what can I do to minimise coming into contact with
B cepacia in my every day environment?
Lucinda Carruthers
South Africa
Dr Dieter Rossboth, a Microbiology advisor to CFW replies:
Today, bacterial taxonomy (the system of giving names to bacteria) is quickly changing, due to various new methods of classification and re-classification of bacteria (such as genetic fingerprinting, molecular-biology methods, etc.). Since 1992 the genus of Burkholderia bacteria also contains B. cepacia (formerly Pseudomonas cepacia).
Environmental Organisms
Burkholderia is a bacterial genus grouped within other closely related bacteria with names such as Stenotrophomonas, Ralstonia, Brevundimonas, Comamonas, and Acidovorax. The sum of those bacterial genera is described best as environmental organisms. They can be found in water, in soil, and on plants, including fruits and vegetables.
Burkholderia – as a genus of bacteria (a genus is a greater class of various bacterial species) – includes several species. Some of them are named for their co-existence in plants, e.g. B. plantarii.
B. cepacia – The Exception
HOWEVER, in that list B. cepacia is the exception, because it is not frequently cultivated in environmental samples! At least this is true for sinks, swimming pools, pond water, showers, salad bars, etc.
Nevertheless B. cepacia is probably the one bacterium that has been well researched, due to its importance in infecting CF patients and also the remarkable capabilities of B. cepacia with respect to bioremediation of soils contaminated with toxic wastes.
B. cepacia exhibits some amazing capabilities, such as metabolism of nitroaromatic compounds and degradation of chlorinated solvents, e.g. monochlorethene. In particular, the latter the latter property of B. cepacia was already used for bioaugmentation purposes, which means the injection of bacteria into ground-water to remove these chemical compounds (in these cases using B. cepacia).
Sources for B. cepacia infection
To sum up, one should remember that – to the best of our knowledge today – the most frequent way for acquiring B. cepacia infection is person-to-person transmission, especially with ‘hypertransmissible’ B. cepacia strains.
Hence all routes of possible person-to-person transmission of bacteria must be suggested and appropriate infection control measures should be established to protect CF patients. Direct transmission, and indirect transmission via ‘vectors’ such as utensils, fluids (drugs), etc. should also be taken into consideration. Also, airborne transmission might be of great importance, especially in lung-physiotherapy units. Therefore, segregation policy for B. cepacia patients and B. cepacia free patients is highly recommended.
The source of infection for non person-to-person transmission with B. cepacia patients is still not elucidated. Plants, corn, maize, etc. have been described to harbour B. cepacia, but one should remember that those reports are very, very rare. Hence, there might be a possibility for plants for being source to B. cepacia infection, but the probability is – to the generally accepted knowledge – not of great concern. If one is really worried about this route of infection, the ‘peel it, boil it, cook it – or forget it’ rule might help.
Drinking water is not normally a source for bacterial or viral infection, as water quality management including chlorination of drinking water offers water of the highest quality in industrial countries.
Conclusion
- bacteria of the genus Burkholderia are typically environmental, however B. cepacia is the exception to this rule
- person-to-person transmission has the highest impact/risk from B. cepacia infection
- main routes of transmission of B. cepacia infections (other than person-to-person) still needs further clarification
- the role of environmental sources of B. cepacia transmission needs to be better determined, however some vegetables may play a minor role
- boiling is the accepted, basic infection control measure in food-borne
bacterial infections
