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Infection Control infection control JANICE CARR The above photo depicts an E.coli (ATCC 11775) biofilm grown on PC (polycarbonate) coupons using a CDC biofilm reactor. Microorganisms often colonize, and adhere strongly to living and non-living surfaces forming biofilms, and at times, demonstrate an increased resistance to antimicrobials. Biofilms on indwelling medical devices pose a serious threat to public health. BIOFILMS:BIOFILMS: Friend or Foe? By NICOLE KENNY, B.Sc, Assoc.Chem., Director of Professional & Technical Services, Virox Technologies Inc 38 Sanitation Canada - SEPTEMBER / OCTOBER 2006 JANICE CARR Scanning electron micrograph of a Staphylococcus biofilm on the inner surface of a needleless connector. A distinguishing characteristic of biofilms is the presence of extracellular polymeric substances, primarily polysaccharides, surrounding and encasing the cells. Here, there polysaccharides have been visualized by scanning electron microscopy. Picture yourself a con- “Why didn’t I listen to my mother and take Biofilms can be dangerous or benefi- testant on Jeopardy. Alex more science courses?” But in that split cial depending on where they are found Tribec has just asked you second you also remember a documen- and of which organisms they are com- to choose the category. tary you watched on CNN about whirl- prised. In industry, biofilms are responsi- You’re lagging behind the pool tubs and you know the answer. ble for billions of dollars in lost produc- leader by $400. All but “Alex, what are BIOFILMS?” tivity due to equipment damage, notori- one of the $500 questions ously famous for causing pipes to plug or Phave been taken, and the last category has THE ISSUE corrode. However, in biotechnology, had extremely difficult and often perplex- Biofilms are nothing new to our world. biofilms are used for treating environmen- ing questions. With as much confidence As described in the Jeopardy question, tal wastes such as sewage, contaminated as you can muster you blurt out, “Alex, I’ll they can be evident in any environment ground water or soil. They are also used take Natural Phenomena for $500.” that has a flow of water and a surface to to produce a variety of biochemicals that You take a deep breath as Alex reads which to stick. In fact, since 1684 scien- can be used for manufacturing medicines the question: “What does the plaque on tists have been striving to determine how or food additives. Even Mother Nature your teeth, the slippery slime on river to manage biofilms. More than three cen- makes use of biofilms. Some biofilms at- stones, the gel-like film on the inside of a turies ago, Antonie van Leeuwenhoek tach to the plant roots of crops, and help flower vase, the unsightly stains in toilet studied dental plaque (which he referred cycle nutrients to and from the plant, bowls, the gunk that clogs your drains, to as scurf), and made the following con- which results in improved agricultural pro- otitis media (ear infections) and bacterial clusions: “From whence I conclude, that ductivity. As a society, however, we most endocarditis (infection of the inner sur- the vinegar with which I washed my teeth, commonly associate biofilms with their face of the heart) have in common?” killed only those animals which were on related infections. Examples of these are Your brain goes blank, your heart the outside of the scurf, but did not pass otitis media and bacterial endocarditis, stops, your mouth goes dry and you think, thro the whole substance of it.”1 Continued On Page 41 Sanitation Canada - SEPTEMBER / OCTOBER 2006 39 PG. 40 KARCHER AD TO PLACE 40 Sanitation Canada - SEPTEMBER / OCTOBER 2006 infection control Continued From Page 39 which are caused by bacteria entering a fluid-filled part of the body. Most nota- ble, however, are the healthcare related infections where biofilms can develop on medical device surfaces such as catheters, medical implants or wound dressings.2 By the way, biofilms happily colonize on many household surfaces such as toi- lets, sinks, countertops, cutting boards and coffee pots. Poor disinfection practices and ineffective cleaning products may in- crease the incidence of illness associated with the pathogenic organisms commonly found around the home. THE COMPOSITION The literal meaning of Biofilm is “life- slime.” The scientific definition of Biofilm is “the film or thin layer com- JANICE CARR posed of cells of microorganisms The above low-mag SEM shows surface irregularities in biofilm culture material (polycarbonate) growing P. mirabilis bacteria. Biofilms, or the colonization of bacteria on living and non-living surfaces, are cultured in the laboratory to investigate the link between biofilm forma- such as bacteria, fungi, yeasts, pro- tion, infection and the development of antimicrobial resistance. tozoa and other mircoorganisms that are attached to a surface.”3 When the bacte- (technically called extracellular rocks, implanted medical devices and even ria or fungi adhere to surfaces, they begin polysaccride) that helps them stick to all tissue. This slime layer also provides a to excrete a slimy, glue-like substance kinds of surfaces such as metals, plastics, Continued On Page 43 Sanitation Canada - SEPTEMBER / OCTOBER 2006 41 PG. 42 SCA TISSUE AD GARRY TO PLACE *CD ENCLOSED 42 Sanitation Canada - SEPTEMBER / OCTOBER 2006 infection control Continued From Page 41 protective environment in which to live. makes it a significantly different organ- infection of hundreds of asthmatics. The In fact the general structure of a biofilm ism to deal with. Studies conducted to date infections were caused by contaminated consists of 85 per cent polysaccride and have shown that an antibiotic dose suffi- inhalers, which contained pieces of 15 per cent microorganisms. That’s a cient to kill free-floating bacteria needs biofilm containing a bacterium known as whole lot of slime! to be increased as much as 1000 times to Pseudomonas aeruginosa. The bacterium, in The bacteria and slime layer can now kill a biofilm colony.4 its biofilm state, was able to survive the trap other materials such as clay, organic Herein lies the problem. A biofilm disinfection process during manufactur- materials, dead cells or any other particle colony provides a number of advantages ing of the inhalant, and when used by the that floats over the biofilm, which adds for microorganisms including environ- unsuspecting asthmatics, was transported to the size and diversity of the biofilm mental protection from adverse elements directly to the lung tissue where it flour- colony. Much like a snowball rolling down like UV light, drying and antimicrobials. ished. At least 100 people died from the hill, getting ever larger, this growing It also acts to attract nutrients based upon biofilm infection. biofilm serves as a magnet for attachment its negative charge. Many nutrients (par- An example closer to home is the May and growth of other organisms, thus in- ticularly cations) are attracted to the 2000 E.coli O157:H7 outbreak in creasing its size and diversity. biofilm surface. This provides bacteria Walkerton, Ont., that killed seven people It is interesting to note, that more than cells within the biofilm with a nutrient and sickened some 2500 residents, many 99 per cent of all bacteria in the world supply greater than that found in the sur- of them children. Walkerton’s water sys- exists as part of a biofilm community al- rounding water. In essence this verifies the tem was contaminated with E.coli though, historically, microbiologists have results that van Leeuwenhoek reported in O157:H7 following heavy rains in early only studied free-floating (planktonic) 1684 when he studied dental plaque. May 2000. The source of the E.coli bacteria. This may not seem entirely sig- O157:H7 was traced back to a field where nificant, but research has shown that once THE RISKS manure had been spread. Because the a microorganism attaches to the surface Biofilms are a hot topic. The first case water treatment system was inadequately of a biofilm, it “turns on” a previously that moved Biofilms to the forefront of maintained and did not have the appro- unused set of genes. This effectively microbiology was in 1994 – involving the Continued On Page 44 Sanitation Canada - SEPTEMBER / OCTOBER 2006 43 infection control Continued From Page 43 priate levels of residual chlorine that dislodged.7 There are two real hazards from would have killed the bacteria and Another area where biofilms are a biofilm in one of these tubs or spas. First, stopped, or at least lessened, the level of growing concern is with the use of whirl- bacteria are shed from the biofilm and contamination. Following the outbreak, pool tubs, hydrotherapy tubs or foot spa from other bathers, and are present in the during the restoration program of the baths. In North America there is a large water. Sores or breaks in the skin may town’s water-mains, flushing and swabbing number of tubs in use in various become infected as a result of this expo- of the 41 kilometres of water-mains was healthcare, educational and hospitality sure. The more significant hazard is not completed. It was noted that while the facilities, not to mention the number of in the water at all. When a tub’s jet system swabbing program was underway, there such tubs used in the Spa industry. The is turned on, small segments of biofilm were increased levels of Coliform and design of many of these tubs allows wa- can break free and become aerosolised, heterotrophic bacteria populations in the ter to accumulate and pool in the pump bouncing along on the haze above the system due to biofilm material from the and other piping, ideal conditions for water surface. Inhaling biofilm bacteria inner surface of the water-mains being biofilm growth. from whirlpools could do a significant amount of pulmonary damage.
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