Horizontal transfer of the blaNDM-1 gene to Pseudomonas aeruginosa and Acinetobacter baumannii in biofilms

Abstract

Horizontal gene transfer has contributed to the global spread of the blaNDM-1 gene. Multiple studies have demonstrated plasmid transfer of blaNDM-1 between Gram-negative bacteria, primarily Enterobacteriaceae species, but conjugational transfer of natural blaNDM-1 plasmids from Enterobacteriaceae into Pseudomonas aeruginosa and Acinetobacter baumannii has not previously been shown. As P. aeruginosa and A. baumannii are both typically strong biofilm formers, transfer of natural blaNDM-1 plasmids could potentially occur more readily in this environment. To determine whether natural blaNDM-1 plasmids could transfer to P. aeruginosa or A. baumannii in biofilms, three clinical and environmental Enterobacteriaceae strains carrying NDM-1-encoding plasmids of different incompatibility types were mated with E. coli J53, producing E. coli J53- blaNDM-1 transconjugants. Subsequently, dual-species biofilms were created using the E. coli J53 transconjugants as plasmid donors and either P. aeruginosa or A. baumannii as recipients. Biofilm transfer of NDM-encoding plasmids to P. aeruginosa and A. baumannii was successful from one and two E. coli J53- blaNDM-1 transconjugants, respectively. This demonstrates the potential for the spread of blaNDM-1, genes to P. aeruginosa and A. baumannii in clinical and environmental settings.

<em>Acinetobacter baumannii</em> biofilms: effects of physicochemical factors, virulence, antibiotic resistance determinants, gene regulation, and future antimicrobial treatments

“…The ability of a dual-species biofilm to spread bla NDM-1 between both clinical and environmental settings was reported. 173 The study confirmed that Enterobacte- riaceae strains could transfer bla NDM-1 readily to strong biofilm-producing P. aeruginosa and A. baumannii in the environment. 173 …”

Real time monitoring of Aeromonas salmonicida evolution in response to successive antibiotic therapies in a commercial fish farm

“…The efficacy of combination or alternation therapy is therefore critically dependent upon whether resistance primarily emerges via mutation or the horizontal acquisition of MGEs from exogenous sources (Hughes and Andersson, ). Hence, for some critically resistant pathogens, such as Escherichia coli , Klebsiella pneumoniae , Acinetobacter baumannii and Pseudomonas aeruginosa where the spread of resistance is primarily driven by the transfer of MGEs (McGann et al ., ; Tanner et al ., ), the simultaneous or cyclic use of different antibiotics is unlikely to be an efficient strategy.…”

“It Takes a Village”: Mechanisms Underlying Antimicrobial Recalcitrance of Polymicrobial Biofilms

“…There have been multiple reports of HGT of antibiotic resistance genes between species within polymicrobial biofilms. One study found that a plasmid harboring a carbapenemase resistance gene (bla NDM-1 ) can be transferred from E. coli to either P. aeruginosa or Acinetobacter baumannii via conjugation within dual-species biofilms (119), which was not observed between these organisms in planktonic settings (120). These results highlight the enhanced propensity of genetic exchange within biofilms.…”