Biofilms And Infection: What You Should Know

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Biofilms And Infection: What You Should Know
In one study, researchers noted that the cells of the pathogens that cause osteomyelitis (as shown in the photo above) grew in enormous biofilms, consisting of millions of bacterial cells embedded in thick matrix material. (Photo courtesy of Lawrence Karl
Here one can see a Staphylococcus aureus infection. S. aureus is one of the bacteria commonly found in biofilms. (Photo courtesy of Mark Kosinski, DPM )
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Author(s): 
By Dave Nielson, DPM, FAPWCA and Guy Pupp, DPM, FACFAS

     The biofilm concept offers possible explanations to the following unusual circumstances.
     • Antibiotic coverage is not enough to eradicate the organism.
     • Swabs of an infected area will only propagate a few cells.
     • Blood cultures from patients with overt infectious signs are negative.

When You Suspect Biofilm Infection

Biofilms stimulate antibodies within 10 days of the initial colonization. One may use enzyme linked immunosorbent assay (ELISA) to detect antibodies against biofilm-specific epitopes common to all staphylococcal species. One can utilize phase-contrast microscopy to detect bacteria. Replacement of the implant with the use of aggressive perioperative antibiotic therapy is suggested.

     Biofilm engineering has contributed to new technologies of potential interest in the control of biofilm infections. Researchers have shown that biofilms are more susceptible to conventional antibiotics in direct current electric fields or when they are treated with ultrasonic radiation.8,9

     Bacteria that grow on tissue or implantable devices in the body may be well controlled by the host’s immune system. However, when the immune system is compromised, the equilibrium is tilted in favor of pathogens. Biofilms present a peculiar problem as they act as the source of disseminated planktonic bacteria that may cause a chronic inflammatory condition. Although antibiotic therapy will usually kill these planktonic bacteria, it cannot rid the body of the biofilm. For this reason, one needs to remove infected implantable devices. When devices cannot be removed, one may prescribe antibiotic therapy at low doses for the remainder of the patient’s life.

     In the future, we may look at biofilm as something that changed the way we evaluate and treat infection.

     Dr. Pupp (pictured) is a Fellow of the American College of Foot and Ankle Surgeons. He is the Clinical Director of the Foot and Ankle Clinic at the Southeast Michigan Surgical Hospital in Warren, Mich.

     Dr. Nielson is a third-year resident at Southeast Michigan Surgical Hospital.

     Dr. Burks is a Fellow of the American College of Foot and Ankle Surgeons, and is board certified in foot and ankle surgery. Dr. Burks practices in Little Rock, Ark.

     For related articles, see “Key Insights For Addressing Infected Hardware” in the August 2006 issue of Podiatry Today or “How To Differentiate Between Infected Wounds And Colonized Wounds” in the July 2005 issue.




References:

1. De Beer D, Stoodley P, Lewandowski Z. Liquid flow in heterogeneous biofilms. Biotechnol. Bioeng. 44:636-641, 1994.
2. Costeron JW, Stewart PS, Greenberg IP. Bacterial biofilms: A common cause of persistent infections. Science. 284:1318-1322, 1999.
3. Costerton JW, Geesey GG, and Cheng GK. How bacteria stick. Sci. Am. 238:86-95, 1978.
4. Veeh RH, et. al. Detection of Staphylococcus aureus biofilm on tampons and menses components. J. Infect. Dis. 188:519-530, 2003.
5. Khoury AE, Lam K, Ellis B, and Costerton JW. Prevention and control of bacterial infections associated with medical devices. ASAIO Transactions. 38:M174-M178, 1992.
6. Lambe DW Jr., Ferguson KP, Mayberry-Carson KJ, Tober-Meyer B, and Costerton JW. Foreign-body-associated experimental osteomyelitis induced with Bacteroides fragilis and Staphylococcus epidermidis in rabbits. Clin. Ortho. 266:285-294, 1991.
7. Saur K, Camper AK, Ehrlich GD, Costerton JW, and Davies DG. Pseudomonas aeruginosa displays multiple phenotypes during development as a biofilm. J. Gacteriol. 184:1140-1154, 2002.
8. Costerton JW, Ellis B, Lam K, Johnson F, and Khoury AE. Mechanisms of electrical enhancement of efficacy of antibiotics in killing biofilm bacteria. Antimicrob. Agents Chemother. 38:2803-2809, 1994.
9. Rediske AM, Hymas WC, Wilkinson R, and Pitt WG. Ultrasonic enhancement of antibiotic action on several species of bacteria. J. Gen. Appl. Microbiol. 44:283-288, 1998.







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