Affiliation:
1. Centre for Biological Sciences, University of Southampton, Highfield Campus, Southampton, United Kingdom
Abstract
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)
bla
CTX-M-15
and metallo-β-lactamase
bla
NDM-1
, respectively, exhibited prolonged survival on stainless steel, with approximately 10
4
viable cells remaining from an inoculum of 10
7
CFU per cm
2
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
bla
NDM-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.
IMPORTANCE
Horizontal gene transfer (HGT) conferring resistance to many classes of antimicrobials has resulted in a worldwide epidemic of nosocomial and community infections caused by multidrug-resistant microorganisms, leading to suggestions that we are in effect returning to the preantibiotic era. 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. Here we show prolonged (several-week) survival of multidrug-resistant
Escherichia coli
and
Klebsiella pneumoniae
on stainless steel surfaces. Plasmid-mediated HGT of β-lactamase genes to an azide-resistant recipient
E. coli
strain occurred when the donor and recipient cells were mixed together on stainless steel and in suspension but not on copper surfaces. In addition, rapid death of both antibiotic-resistant strains and destruction of plasmid and genomic DNA were observed on copper and copper alloy surfaces, which could be useful in the prevention of infection spread and gene transfer.
Publisher
American Society for Microbiology
Cited by
126 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献