Nanofibre paint that kills MRSA

MRSA, the antibiotic resistant form of Staphylococcus aureus is a major problem in hospitals. The antibiotic resistance makes it hard to erradicate, not just from patients, but in the surounding environment, on surfaces, on medical equipment, on the walls of the hospital. In order to minimise the numbers of dangerous bacteria found in hospital surroundings, quite a lot of research has gone into creating antibacterial coverings or coatings that would reduce the number of bacteria p. Currently however, many of these coating substaces work by either using biocides (such as silver) or releasing antibiotics and antimicrobials, which doesn't work on bacteria that have gained resistance.

Scanning electron microscope picture of clusters of Staph aureus

However medical scientists aren't the only ones trying to kill bacteria, virus's known as bacteriophages are also interested in breaking open bacterial cells and they do it using a cocktail of different enzymes to break open the cell wall. Many of these enzymes feature a two-domain structure with bacteria-specific cell wall targeting and catalytic domains. The enzymes Lst was found to be particularly good at breaking apart Staph aureus cell walls with one end of the enzyme (C terminus) recognising and binding to the bacterial cell wall while the other end (the N terminus) breaks the protein bridges between the sugar componants of the peptidoglycan layer, which is a major componant of the cell wall.

Schematic of the cell wall

Work from the Rensselaer’s Center for Biotechnology has been looking at incorporating these enzymes into nanofibres to create stable bactericidal paint films. The molecular-level curvature of carbon nanotubes stabilizes a wide range of enzymes and the lab was able to successfully create Lst-containing nanocomposite films which achieved >99.9% killing of MRSA upon contact within 2 h. They also explored incorporating these into a latex paint, which retained the bactericidal properties of the nanofibres. This paint could theoretically be spread over hospital surfaces to reduce the numbers of Staph aureus within the hospital environment. Incorporating this enzyme into the nanofibres (rather than directly mixing with the latex) gives added stability and helps the enzyme stay within the coating for longer. Films which were stored dry at room temperature showed >99% bactericidal activity against S. aureus after 30 days.

It remains to be seen how effective this technique will be outside of a laboratory setting but at the moment it looks like a highly promising step to help reduce the incidence of a dangerous pathogen. The speed and likelihood of resistance also remains to be seen, but it's heartening that bacteriophages have been using these enzymes against the bacteria for far longer than we've been using antibiotics. This is unlikely to be any kind of magical anti-MRSA cure, but it could certainly be very useful in helping to reduce the incidence of the disease.

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Pangule RC, Brooks SJ, Dinu CZ, Bale SS, Salmon SL, Zhu G, Metzger DW, Kane RS, & Dordick JS (2010). Antistaphylococcal nanocomposite films based on enzyme-nanotube conjugates. ACS nano, 4 (7), 3993-4000 PMID: 20604574
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