Bacterial Biofilms Resist Key Host Defenses

B acteria have long intrigued, terrified, and baffled humans. Although most microorganisms are not pathogenic to humans, the thought of microbes existing everywhere can have a dramatic effect on the psyche. Once-specialized terms and acronyms, such as Staph, for Staphylococcus aureus, MRSA, for methicillin-resistant S. aureus, and XDR, for extensively drugresistant Mycobacterium tuberculosis, are now catchphrases in the news media. In light of this and of several recent outbreaks of foodborne illnesses, it is easy to trace the source of some of those psychological effects. Yet, even though scientists have been studying these pathogens for almost two centuries, more and more researchers believe that it is how these bacteria live that can really matter in terms of the diseases they cause. One key issue is whether they live as single-celled “planktonic” organisms or as complex communities called biofilms that cause chronic infections by withstanding standard antibiotic treatments and escaping the destructive forces of the host. Several bacterial pathogens form biofilms having complex interactions with components of the innate host defense system. Deciphering these interactions could lead to novel, biofilm-specific therapies.