Horizontal Transfer of Antibiotic Resistance Genes on Abiotic Touch Surfaces: Implications for Public Health

Abstract

Horizontal gene transfer (HGT) is largely responsible for increasing the incidence of antibiotic-resistant infections worldwide. While studies have focused on HGT in vivo, this work investigates whether the ability of pathogens to persist in the environment, particularly on touch surfaces, may also play an important role. Escherichia coli, virulent clone ST131, and Klebsiella pneumoniae harboring extended-spectrum-β-lactamase (ESBL) blaCTX-M-15 and metallo-β-lactamase blaNDM-1, respectively, exhibited prolonged survival on stainless steel, with approximately 104 viable cells remaining from an inoculum of 107 CFU per cm2 after 1 month at 21°C. HGT of bla to an antibiotic-sensitive but azide-resistant recipient E. coli strain occurred on stainless steel dry touch surfaces and in suspension but not on dry copper. The conjugation frequency was approximately 10 to 50 times greater and occurred immediately, and resulting transconjugants were more stable with ESBL E. coli as the donor cell than with K. pneumoniae, but blaNDM-1 transfer increased with time. Transconjugants also exhibited the same resistance profile as the donor, suggesting multiple gene transfer. Rapid death, inhibition of respiration, and destruction of genomic and plasmid DNA of both pathogens occurred on copper alloys accompanied by a reduction in bla copy number. Naked E. coli DNA degraded on copper at 21°C and 37°C but slowly at 4°C, suggesting a direct role for the metal. Persistence of viable pathogenic bacteria on touch surfaces may not only increase the risk of infection transmission but may also contribute to the spread of antibiotic resistance by HGT. The use of copper alloys as antimicrobial touch surfaces may help reduce infection and HGT.

Surface-attached cells, biofilms and biocide susceptibility: implications for hospital cleaning and disinfection

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“…Copper alloys acting on abiotic surfaces showed that besides the rapid death of antibiotic resistant strains, it caused destruction of plasmid and genomic DNA, which has an implication in preventing the spread of infections and gene transfer (Warnes et al, 2013& Bagchi et al, 2013. Copper surfaces or their alloys are able to eliminate 99.9 % of pathogenic bacteria in hours, including methicillin-resistant Staphylococcus aureus (MRSA), Escherichia coli, Pseudomonas aeruginosa, Listeria monocytogenes, Salmonella enterica, Campylobacter jejuni, Legionella pneumophila, Clostridium difficile and Mycobacterium tuberculosis.…”

Controlling Hospital-Acquired Infection: Focus on the Role of the Environment and New Technologies for Decontamination

“…Microorganisms will exploit an inadequately cleaned niche to exchange genetic material coding for antimicrobial resistance and other survival mechanisms (156)(157)(158). This could include resistance or tolerance to disinfectants.…”