First report of IMP-1 in a clinical isolate of Escherichia coli in Latin America

Multidrug resistance plasmids commonly reprogram the expression of metabolic genes in Escherichia coli

Multidrug-resistant Escherichia coli is a leading cause of global mortality. Transfer of plasmids carrying genes encoding beta-lactamases, carbapenamases, and colistin resistance between lineages is driving the rising rates of hard-to-treat nosocomial and community infections. Multidrug resistance (MDR) plasmid acquisition commonly causes transcriptional disruption, and while a number of studies have shown strain-specific fitness and transcriptional effects of an MDR plasmid across diverse bacterial lineages, fewer studies have compared the impacts of different MDR plasmids in a common bacterial host. As such, our ability to predict which MDR plasmids are the most likely to be maintained and spread in bacterial populations is limited. Here, we introduced eight diverse MDR plasmids encoding resistances against a range of clinically important antibiotics into E. coli K-12 MG1655 and measured their fitness costs and transcriptional impacts. The scale of the transcriptional responses varied substantially between plasmids, ranging from >650 to <20 chromosomal genes being differentially expressed. However, the scale of regulatory disruption did not correlate significantly with the magnitude of the plasmid fitness cost, which also varied between plasmids. The identities of differentially expressed genes differed between transconjugants, although the expression of certain metabolic genes and functions were convergently affected by multiple plasmids, including the downregulation of genes involved in L-methionine transport and metabolism. Our data show the complexity of the interaction between host genetic background and plasmid genetic background in determining the impact of MDR plasmid acquisition on E. coli.

IMPORTANCE

The increase in infections that are resistant to multiple classes of antibiotics, including those isolates that carry carbapenamases, beta-lactamases, and colistin resistance genes, is of global concern. Many of these resistances are spread by conjugative plasmids. Understanding more about how an isolate responds to an incoming plasmid that encodes antibiotic resistance will provide information that could be used to predict the emergence of MDR lineages. Here, the identification of metabolic networks as being particularly sensitive to incoming plasmids suggests the possible targets for reducing plasmid transfer.

Escherichia coli carrying blaNDM-1 obtained from a migratory penguin (Spheniscus magellanicus) in the Brazilian seacoast

The reservoirs for NDM-producing Enterobacterales are increasing, not only in hospitals, but also in the environment and in the community, challenging the therapeutic efficacy of carbapenems. We aimed to characterize an isolate of Escherichia coli harboring the bla_NDM-1 gene recovered from the bloodstream of a penguin (Spheniscus magellanicus) in Southern Brazil. A total of 74 bacterial isolates recovered from arterial blood samples from dead birds were submitted to species identification and antibiotic susceptibility evaluation. One isolate presented resistance to carbapenems (E. coli 89PenNDM) and proved to harbor the bla_NDM-1 gene by multiplex high-resolution melting real-time PCR (PCR-HRM). Conjugation experiments indicated that the bla_NDM-1 was transmissible to E. coli J53. Whole genome sequencing (WGS) confirmed the presence of the bla_NDM-1 gene in a conjugative plasmid (IncA/C₂ plasmid) in both the E. coli 89PenNDM and its transconjugants. The isolate was classified as ST 156 and many other resistance genes (e.g., sul1, sul,2, strA, floR, tet(A)) were identified, all carried in the same IncA/C2 plasmid. This is the first report of bla_NDM-1-producing E. coli isolated from a penguin in the Brazilian seacoast. The presence of a carbapenemase gene in wildlife animals is of concern as they may become reservoirs of multidrug-resistant bacteria and disseminate them to the environment.