Dataset Information

Specific blaCTX-M-8/IncI1 Plasmid Transfer among Genetically Diverse Escherichia coli Isolates between Humans and Chickens.

ABSTRACT: We investigated the genetic backbones of 14 blaCTX-M-8-positive Escherichia coli isolates recovered from human stool samples and chicken meat. All isolates carried IncI1 plasmids with blaCTX-M-8 (blaCTX-M-8/IncI1), and most (9/14) belonged to a specific genetic lineage, namely, plasmid sequence type 113 (pST113). The genetic contexts of the nine blaCTX-M-8/IncI1 pST113 plasmids were similar, regardless of the source. These results suggest the probable local transfer of blaCTX-M-8/IncI1 between humans and chickens with genetically diverse E. coli.

SUBMITTER: Norizuki C

PROVIDER: S-EPMC5444161 | biostudies-literature | 2017 Jun

REPOSITORIES: biostudies-literature

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Specific blaCTX-M-8/IncI1 Plasmid Transfer among Genetically Diverse Escherichia coli Isolates between Humans and Chickens.

Norizuki Chihiro C Wachino Jun-Ichi JI Suzuki Masahiro M Kawamura Kumiko K Nagano Noriyuki N Kimura Kouji K Arakawa Yoshichika Y

Antimicrobial agents and chemotherapy 20170524 6

We investigated the genetic backbones of 14 blaCTX-M-8-positive Escherichia coli isolates recovered from human stool samples and chicken meat. All isolates carried IncI1 plasmids with blaCTX-M-8 (blaCTX-M-8/IncI1), and most (9/14) belonged to a specific genetic lineage, namely, plasmid sequence type 113 (pST113). The genetic contexts of the nine blaCTX-M-8/IncI1 pST113 plasmids were similar, regardless of the source. ...[more]

PMID: 28396551

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Project description:The spread of antibiotic resistant bacteria worldwide presents a major health threat to human health care that results in therapy failure and increasing costs. The transfer of resistance conferring plasmids by conjugation is a major route by which resistance genes disseminate at the intra- and interspecies level. High similarities between resistance genes identified in foodborne and hospital-acquired pathogens suggest transmission of resistance conferring and transferrable mobile elements through the food chain, either as part of intact strains, or through transfer of plasmids from foodborne to human strains. To study the factors that affect the rate of plasmid transfer, the transmission of an extended-spectrum ?-lactamase (ESBL) plasmid from a foodborne Escherichia coli strain to the ?-lactam sensitive E. coli MG1655 strain was documented as a function of simulated environmental factors. The foodborne E. coli isolate used as donor carried a CTX-M-1 harboring IncI1 plasmid that confers resistance to ?-lactam antibiotics. Cell density, energy availability and growth rate were identified as factors that affect plasmid transfer efficiency. Transfer rates were highest in the absence of the antibiotic, with almost every acceptor cell picking up the plasmid. Raising the antibiotic concentrations above the minimum inhibitory concentration (MIC) resulted in reduced transfer rates, but also selected for the plasmid carrying donor and recombinant strains. Based on the mutational pattern of transconjugant cells, a common mechanism is proposed which compensates for fitness costs due to plasmid carriage by reducing other cell functions. Reducing potential fitness costs due to maintenance and expression of the plasmid could contribute to persistence of resistance genes in the environment even without antibiotic pressure. Taken together, the results identify factors that drive the spread and persistence of resistance conferring plasmids in natural isolates and shows how these can contribute to transmission of resistance genes through the food chain.

Project description:Multidrug-resistant (MDR) Escherichia coli strains are a major global threat to human health, wherein multidrug resistance is primarily spread by MDR plasmid acquisition. MDR plasmids are not widely distributed across the entire E. coli species, but instead are concentrated in a small number of clones. Here, we test if diverse E. coli strains vary in their ability to acquire and maintain MDR plasmids and if this relates to their transcriptional response following plasmid acquisition. We used strains from across the diversity of E. coli strains, including the common MDR lineage sequence type 131 (ST131) and the IncF plasmid pLL35, carrying multiple antibiotic resistance genes. Strains varied in their ability to acquire pLL35 by conjugation, but all were able to stably maintain the plasmid. The effects of pLL35 acquisition on cefotaxime resistance and growth also varied among strains, with growth responses ranging from a small decrease to a small increase in growth of the plasmid carrier relative to the parental strain. Transcriptional responses to pLL35 acquisition were limited in scale and highly strain specific. We observed transcriptional responses at the operon or regulon level-possibly due to stress responses or interactions with resident mobile genetic elements (MGEs). Subtle transcriptional responses consistent across all strains were observed affecting functions, such as anaerobic metabolism, previously shown to be under negative frequency-dependent selection in MDR E. coli Overall, there was no correlation between the magnitudes of the transcriptional and growth responses across strains. Together, these data suggest that fitness costs arising from transcriptional disruption are unlikely to act as a barrier to dissemination of this MDR plasmid in E. coli IMPORTANCE Plasmids play a key role in bacterial evolution by transferring adaptive functions between lineages that often enable invasion of new niches, including driving the spread of antibiotic resistance genes. Fitness costs of plasmid acquisition arising from the disruption of cellular processes could limit the spread of multidrug resistance plasmids. However, the impacts of plasmid acquisition are typically measured in lab-adapted strains rather than natural isolates, which act as reservoirs for the maintenance and transmission of plasmids to clinically relevant strains. Using a clinical multidrug resistance plasmid and a diverse collection of E. coli strains isolated from clinical infections and natural environments, we show that plasmid acquisition had only limited and highly strain-specific effects on bacterial growth and transcription under laboratory conditions. These findings suggest that fitness costs arising from transcriptional disruption are unlikely to act as a barrier to transmission of this plasmid in natural populations of E. coli.

Dataset Information

Specific blaCTX-M-8/IncI1 Plasmid Transfer among Genetically Diverse Escherichia coli Isolates between Humans and Chickens.

Publications

Specific <i>bla</i><sub>CTX-M-8</sub>/IncI1 Plasmid Transfer among Genetically Diverse Escherichia coli Isolates between Humans and Chickens.

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