Project description:Recently, we have reported on a highly drug-resistant carbapenemase-producing isolate of Enterobacter cloacae (Nepal et al., Virulence. 2018; 9: 1377-1389). In the present study, we asked the question whether and, if so, how this isolate responds to a sub-inhibitory challenge with the antibiotic imipenem. To answer this question, we applied a SILAC proteomics approach that allowed the quantification of changes in the relative abundance of bacterial protein in response to imipenem. The results show that the investigated E. cloacae isolate mounts a highly specific response to counteract the detrimental effects of imipenem.
Project description:Enterobacter cloacae is a Gram-negative nosocomial pathogen of the ESKAPE (Enterococcus, Staphylococcus, Klebsiella, Acinetobacter, Pseudomonas, and Enterobacter spp.) priority group with increasing multi-drug resistance via the acquisition of resistance plasmids. However, E. cloacae can also display forms of antibiotic refractoriness, such as heteroresistance and tolerance. Here, we report that E. cloacae displays transient heteroresistance to aminoglycosides, which is accompanied with the formation of small colony variants (SCVs) with increased minimum inhibitor concentration (MIC) of gentamicin and other aminoglycosides used in the clinic, but not other antibiotic classes. To explore the underlying mechanisms, we performed RNA sequencing of heteroresistant bacteria, which revealed global gene-expression changes and a signature of the CpxRA cell envelope stress response. Deletion of the cpxRA two-component system abrogated aminoglycoside heteroresistance and SCV formation, pointing to its indispensable role in these processes. The introduction of a constitutively active allele of cpxA led to high aminoglycoside MICs, consistent with cell envelope stress response driving these behaviours in E. cloacae. Cell envelope stress can be caused by environmental cues, including heavy metals. Indeed, bacterial exposure to copper increased gentamicin MIC in the wild-type, but not in the ΔcpxRA mutant. Moreover, copper exposure also elevated the gentamicin MICs of clinical isolates from bloodstream infections, suggesting that CpxRA- and copper-dependent aminoglycoside resistance is broadly conserved in E. cloacae strains. Altogether, we establish that E. cloacae relies on transcriptional reprogramming via the envelope stress response pathway for transient resistance to a major class of frontline antibiotic.
2023-10-18 | GSE236124 | GEO
Project description:cefiderocol-resistance in NDM-producing Enterobacter cloacae complex
Project description:Biogenic amine-producing bacteria are responsible for the production of basic nitrogenous compounds, such as histamine, cadaverine, tyramine and putrescine, after foods spoil due to microorganisms. In the present work, we applied a shotgun proteomics approach to quickly and easily characterize 15 different foodborne strains of biogenic amine-producing bacteria. A total of 10673 peptide spectrum matches (PSMs) belonging to 4081 nonredundant peptides and corresponding to 1811 annotated proteins were identified. With the results, relevant functional pathways were determined and the strains were differentiated into different Euclidean hierarchical clusters. Moreover, a predicted protein‒protein interaction network of biogenic amine foodborne strains was created. The whole confidence network contains 260 nodes and 1973 interactions. Most of the identified proteins were related to pathways and networks of energy, putrescine metabolism and host‒virus interaction. In addition, a total of 556 nonredundant peptides were identified as virulence factors, and most of these peptides corresponded to functions such as toxins, antimicrobial compound production, antimicrobial resistance, additional resistances and tolerances, host colonization and immune evasion, ABC transporters, phage proteins, and alternative virulence factors and proteins involved in horizontal transfer. Potential species-specific peptide biomarkers were screened. Thus, 77 species-specific peptide biomarkers belonging to 64 different proteins were proposed to identify 10 species (Enterobacter aerogenes, Enterobacter cloacae, Hafnia alvei, Klebsiella oxytoca, Morganella morganii, Proteus mirabilis, Proteus penneri, Proteus vulgaris, Raoutella planticola, Stenotrophomonas maltophilia). All of these results constitute the first major dataset of peptides and proteins of seafood biogenic amine-producing strains. This repository may be useful for further studies, for the development of new therapeutic treatments for food intoxication and for tracking microbial sources in foodstuffs.