Growth in a biofilm promotes conjugation of a bla _NDM-1 -bearing plasmid between Klebsiella pneumoniae strains

Abstract

Antimicrobial resistance (AMR) is a growing problem, especially in Gram-negative Enterobacteriaceae such as Klebsiella pneumoniae . Horizontal transfer of conjugative plasmids contributes to AMR gene dissemination. Bacteria such as K. pneumoniae commonly exist in biofilms, yet most studies focus on planktonic cultures. Here we studied the transfer of a multi-drug resistance plasmid in planktonic and biofilm populations of K. pneumoniae . We determined plasmid transfer from a clinical isolate, CPE16, which carried four plasmids, including the 119-kbp bla NDM-1 -bearing F-type plasmid pCPE16_3, in planktonic and biofilm conditions. We found that transfer frequency of pCPE16_3 in a biofilm was orders-of-magnitude higher than between planktonic cells. In 5/7 sequenced transconjugants (TCs) multiple plasmids had transferred. Plasmid acquisition had no detectable growth impact on TCs. Gene expression of the recipient and a transconjugant was investigated by RNA-sequencing in three lifestyles: planktonic exponential growth, planktonic stationary phase, and biofilm. We found that lifestyle had a substantial impact on chromosomal gene expression, and plasmid carriage affected chromosomal gene expression most in stationary planktonic and biofilm lifestyles. Furthermore, expression of plasmid genes was lifestyle-dependent, with distinct signatures across the three conditions. Our study shows that growth in biofilm greatly increased the risk of conjugative transfer of a carbapenem resistance plasmid in K. pneumoniae without fitness costs and minimal transcriptional rearrangements, thus highlighting the importance of biofilms in the spread of AMR in this opportunistic pathogen. IMPORTANCE Carbapenem-resistant K. pneumoniae is particularly problematic in hospital settings. Carbapenem resistance genes can transfer between bacteria via plasmid conjugation. Alongside drug resistance, K. pneumoniae can form biofilms on hospital surfaces, at infection sites and on implanted devices. Biofilms are naturally protected and can be inherently more tolerant to antimicrobials than their free-floating counterparts. There have been indications that plasmid transfer may be more likely in biofilm populations, thus creating a conjugation “hotspot”. However, there is no clear consensus on the effect of the biofilm lifestyle on plasmid transfer. Therefore, we aimed to explore the transfer of a plasmid in planktonic and biofilm conditions, and the impact of plasmid acquisition on a new bacterial host. Our data show transfer of a resistance plasmid is increased in a biofilm, which may be a significant contributing factor to the rapid dissemination of resistance plasmids in K. pneumoniae .

Natural products from food sources can alter the spread of AMR plasmids inEnterobacterales

“…Next, the effect of the four compounds was tested on a clinical urine isolate of K. pneumoniae , which we have shown carries and readily transmits a 120 kb IncF plasmid with a bla NDM-1 carbapenem resistance gene, termed pCPE16_3 (19). Each compound was tested at 100 µg/mL, with a one-hour co-incubation of donors and recipients.…”

“…The K. pneumoniae clinical isolate carrying pCPE16_3 bla NDM-1 plasmid (KP10) was paired with the hygromycin resistant K. pneumoniae ATCC 43816R recipient strain (KP20) in liquid broth as previously described (28). Briefly, KP10 and KP20 cultures were grown overnight, sub-cultures were prepared in 5 mL LB broth (1% inoculum) and grown to an OD 600 of ∼0.5.…”

Inorganic Polyphosphate Affects Biofilm Assembly, Capsule Formation, and Virulence of Hypervirulent ST23 Klebsiella pneumoniae

“…Biofilm formation is the primary lifestyle of bacteria in their natural state and serves as a successful strategy to thrive in niches subjected to various stressors and the most efficient way for the trafficking of mobile genetic elements. 51 There is a broad consensus in the literature regarding the ability of both classical and multidrug-resistant K. pneumoniae strains to form biofilms in various niches, particularly in immunocompromised individuals. 52−55 The f im and mrk operons, responsible for encoding type I and type III fimbriaes, respectively, play a crucial role in the initial adhesion to both biotic and abiotic surfaces.…”

“…Biofilm formation is the primary lifestyle of bacteria in their natural state and serves as a successful strategy to thrive in niches subjected to various stressors and the most efficient way for the trafficking of mobile genetic elements . There is a broad consensus in the literature regarding the ability of both classical and multidrug-resistant K.…”

Effects of Polyphosphate metabolism Mutations on Biofilm, Capsule Formation and Virulence Traits in Hypervirulent ST23Klebsiella pneumoniaeSGH10

“…Biofilm formation is the primary lifestyle of bacteria in their natural state and serves as a successful strategy to thrive in niches subjected to various stressors and the most efficient way for the trafficking of mobile genetic elements 58 . There is a broad consensus in the literature regarding the ability of both classical and multidrug-resistant Klebsiella pneumoniae strains to form biofilms in various niches, particularly in immunocompromised individuals [59][60][61][62] .…”