Metalloacid surfaces may be answer to hospital-acquired infections

By Helen Albert, Senior medwireNews Reporter

Coating surfaces in metalloacids may help control the spread of hospital-acquired infections, suggest study findings.

The metalloacid material, molybdenum trioxide, produces oxonium ions that are acidic and create an effective, nonspecific antimicrobial environment, explain the researchers.

"A molybdenum trioxide coating may be an effective and permanent means of minimizing microbial contamination between hospital cleaning procedures, particularly against multidrug-resistant organisms," suggested lead investigator Nathalie van der Mee-Marquet (University of Tours, France) in a press statement.

As reported in Antimicrobial Resistance and Infection Control, the team assessed the biocidal abilities of molybdenum trioxide by exposing uncoated surfaces and those coated with the metalloacid to 11 types of microorganism.

The micro-organisms were selected based on their ability to cause hospital-acquired infections and included vancomycin-resistant Enterococcus faecium, Pseudomonas aeruginosa, multidrug-resistant Acinetobacter baumannii, and two fungal strains of Candida albicans, as well as two strains of methicillin-resistant Staphylococcus aureus.

The researchers found that compared with the noncoated surfaces, the molybdenum trioxide-coated surfaces exhibited considerable biocidal activity, with all nonspore-forming micro-organisms showing significantly lower bacterial counts on the coated than the noncoated surfaces after 24 hours.

The fastest biocidal effect was seen against the Staphyloccus species, which decreased from over 1280 colony-forming units (cfu) to less than 800 in 2 hours, and against E. faecium, which decreased from over 1200 to less than 200 cfu in this time, whereas the counts of Gram-negative micro-organisms only began to dip significantly after 4 hours' exposure.

Of note, the metalloacid coating had no effect on the number of colony-forming units of the spore-forming strain of Clostridium difficile and the two strains of fungi present.

"The variations in susceptibility between Gram-positive and Gram-negative microorganisms, and the resistance exhibited by the spore-forming ones, suggest that the differences among micro-organisms with respect to their susceptibility to the biocidal surface may be due to the [oxonium] ion permeability of their cell wall and/or cell membrane," write the authors.

The researchers believe that their results suggest that coating certain hospital surfaces with molybdenum trioxide could be an effective way of minimizing bacterial contamination with minimal human risks, although they concede that further research is needed to confirm their findings.

"In contrast to disinfectants and antibiotics, microbial resistance to metalloacids may not emerge, and they should be safe for human use," said van der Mee-Marquet.

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