At the Hamilton, Montana Performing Arts Center, Vincent speaks with three local high school graduates and two high school teachers about how Rocky Mountain Laboratories influenced school science programs and opened up career opportunities.
Bacteria frequently grow in communities called biofilms, which are aggregates of cells and polymers. An example of a biofilm is the dental plaque on your teeth. Biofilms are medically important as they can allow bacteria to persist in host tissues and on catheters, and confer increased resistance to antibiotics and dessication. Therefore understanding how biofilms form is crucial for controlling microbial infections. An advance in our understanding of biofilms formation is the observation that filamentous phages help them assemble, and contribute to their fundamental properties.
Pseudomonas aeruginosa is an important human pathogen which is a particular problem in patients with cystic fibrosis. The ability of this bacterium to form biofilms in the lung is linked to its ability to cause chronic infections. Pseudomonas aeruginosa biofilms contain large numbers of filamentous Pf bacteriophages (pictured; image credit). These viruses lyse cells and release DNA, which becomes one component of the biofilm matrix.
Mixing supernatants of P. aeruginosa cultures with hyaluronan, which is present in airways of cystic fibrosis patients, resulted in the formation of a biofilm – in the absence of bacteria. A major component of P. aeruginosa biofilms was found to be Pf bacteriophages. When purifed Pf bacteriophages were mixed with hyaluronan, biofilms formed. Similar biofilms also formed when the filamentous bacteriophage fd of E. coli was mixed with hyaluronan. Mixtures of Pf bacteriophages and various polymers (alginate, DNA, hyaluronan, polyethylene glycol) formed liquid crystals (matter in a state between a liquid and a solid crystal).
Pf phages were detected in sputum from patients with cystic fibrosis, but not in uninfected patients. Addition of Pf phage to sputum from patients infected with P. aeruginosa made the samples more birefringent, a property of liquid crystals. Compared with a strain of P. aeruginosa that does not produce Pf phage, colonies of virus-producing strains formed liquid crystals. These observations indicate that Pf phage help organize the bacteria into a biofilm matrix.
Some features of biofilms include their ability to adhere to surfaces, to protect bacteria from dessication, and to increase resistance to antibiotics. Addition of phage Pf increased biofilm adhesion and tolerance against dessication. Such addition also made the biofilm more resistant to aminoglycoside antibiotics, because these were sequestered in the biofilm. No phage-mediated increased resistance to ciprofloxacin was observed, probably because this antimicrobial does not interact with polyanions of the biofilm as do aminoglycosides.
These results show that presence of bacteriophage in a biofilm of P. aeruginosa helps organize the matrix while contributing to some of its fundamental properties. It seems likely that filamentous phages of other bacteria will play roles in biofilm formation, suggesting that targeting the phages in these matrices could be effectie strategies for treating biofilm infections.
I usually don’t post TWiM episodes here, but #90 has a lot of virology. In this episode, recorded in La Jolla, CA at the annual meeting of the Southern California Branch of the American Society for Microbiology, I first speak with Laurene Mascola, Chief of Acute Communicable Diseases at the Los Angeles County Department of Public Health. Dr. Mascola talks about how Los Angeles county has prepared for an outbreak of Ebola virus. Next up is David Persing, Executive Vice President and Chief Medical and Technology Officer at Cepheid. His company has developed an amazing, modular PCR machine that is brining rapid diagnosis everywhere, including the United States Post Office. And it might even be available on your refrigerator one day.
Scientists for Science are confident that biomedical research on potentially dangerous pathogens can be performed safely and is essential for a comprehensive understanding of microbial disease pathogenesis, prevention and treatment. The results of such research are often unanticipated and accrue over time; therefore, risk-benefit analyses are difficult to assess accurately.
If we expect to continue to improve our understanding of how microorganisms cause disease we cannot avoid working with potentially dangerous pathogens. In recognition of this need, significant resources have been invested globally to build and operate BSL-3 and BSL-4 facilities, and to mitigate risk in a variety of ways, involving regulatory requirements, facility engineering and training. Ensuring that these facilities operate safely and are staffed effectively so that risk is minimized is our most important line of defense, as opposed to limiting the types of experiments that are done.
In contrast to recombinant DNA research at the time of Asilomar in 1975, studies on dangerous pathogens are already subject to extensive regulations. In addition to regulations associated with Select Agent research, experimental plans on other pathogens are peer reviewed by scientists and funding agencies, and the associated risk assessments are considered by biosafety experts and safety committees. Risk mitigation plans are proposed and then considered and either approved or improved by safety committees.
If there is going to be further discussion about these issues, we must have input from outside experts with the background and skills to conduct actual risk assessments based on specific experiments and existing laboratories. Such conversations are best facilitated under the auspices of a neutral party, such as the International Union of Microbiological Societies or the American Society for Microbiology, or national academies, such as the National Academy of Sciences, USA. We suggest they should organize a meeting to discuss these issues.
Scientists for Science have a range of opinions on how risk is best assessed. However, maintaining dogmatic positions serves no good purpose; only by engaging in open constructive debate can we learn from one another’s experience. Most importantly, we are united as experts committed to ensuring public health is not compromised and the reputation of science in general, and microbiology in particular, is defended.
There are also bacteria, such as this collection (with some viruses) from Clare:
You can find more by searching for ‘microbe’ at Ravelry (login required), where you’ll also find the patterns to reproduce these wonderful creations. Microbes are clearly inspiring and fascinating to fiber artists!
Do you make fiber viruses? If so let me know and we can include a photograph here.
On TWiM #55 we discussed the remarkable ability of copper to reduce hospital acquired infections. Now you can watch Michael Schmidt, TWiM co-host and a co-author on this work, discuss the findings at a recent TEDx talk in Charleston, South Carolina.
During my visit to Berkeley, CA to record TWiV #228, I met Deb Sklut, an artist who is inspired by the power of science. I recorded a brief conversation with Deb which you can view below. Her work can be found at Screenology (formerly SqueakySqueegeeArt).
On episode #53 of the science show This Week in Microbiology, Vincent, Laura, David, Kalin and Paul get together at the Society for General Microbiology meeting in Manchester, England to talk about next-generation approaches to antimicrobial therapy.
You can find the audio for TWiM #53, along with show notes, at microbeworld.org/twim. Watch video of the episode below.
On episode #41 of the science show This Week in Microbiology, Vincent and Michael travel to San Francisco for the 52nd Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC), where they meet with Bill, John, and Victor to discuss tuberculosis, monitoring infectious disease outbreaks with online data, and outside-the-box approaches to antibacterial therapy.
You can view video of this episode below, or download audio or video files at microbeworld.org.