The antibiotic-resistant Acinetobacter baumannii bacterium presents a major concern to healthcare systems. For this reason, the organism is the subject of considerable research into finding ways to combat the risks posed.
The organism is also associated with developing resistance to commonly used antimicrobials, which increases its challenge to healthcare environments.
In a new development, researchers at the University of Turku have discovered that the bacterium spreads by attaching to surfaces using ultrathin stretchy fibres. The fibres are involved in ways through which the bacterium colonizing medical devices and potentially infecting patients.
The focus of was with unravelling of the molecular mechanisms governing the interplay between microbial pathogens and their hosts.
These fibres are formed on the bacterial surface and hence this mechanism can present an avenue for new approaches to prevent bacterial infections.
In addition, the findings could also help medical researchers to combat the risk posed by other pathogens, like Pseudomonas aeruginosa.
Specifically, A. baumannii is capable of colonizing medical devices by means of archaic chaperone-usher (ACU) pili. ACU pili are hair-like protein fibres found on the surface of several species of pathogenic bacteria.
By using cryo-electron microscopy, scientists discovered that the pili have a special ultrathin zigzag architecture. Through this, the fibres firmly attach the bacterium to various biotic and abiotic surfaces via tiny sticky finger-like structures at their ends. Once the sticky fingers grip the surface, the fibre is difficult to detach because it can stretch by changing its conformation from the zigzag to linear shape.
The zigzag structure of the fibres also plays an important role in the secretion to the bacterial surface. Fibres are secreted from the inside of the bacterium through its outer membrane in the extended linear conformation. On the surface, these change in their conformation to a zigzag shape, which prevents them from slipping back into the bacterium.
The researchers hope that drugs can be developed to prevent this conformational change from occurring. This process would block fibre biogenesis, halting bacterial attachment.
The research appears in the journal Nature, titled “Archaic chaperone-usher pili self-secrete into superelastic zigzag springs.”
