Ana J Choi, Daniel J Bennison, Esha Kulkarni, Hibah Azar, Haoyu Sun, Hanqi Li, Jonathan Bradshaw, Hui Wen Yeap, Nicholas Lim, Vishwas Mishra, Anna Crespo-Puig, Ewurabena A Mills, Frances Davies, Shiranee Sriskandan, Avinash R Shenoy
{"title":"Aminoglycoside heteroresistance in <i>Enterobacter cloacae</i> is driven by the cell envelope stress response.","authors":"Ana J Choi, Daniel J Bennison, Esha Kulkarni, Hibah Azar, Haoyu Sun, Hanqi Li, Jonathan Bradshaw, Hui Wen Yeap, Nicholas Lim, Vishwas Mishra, Anna Crespo-Puig, Ewurabena A Mills, Frances Davies, Shiranee Sriskandan, Avinash R Shenoy","doi":"10.1128/mbio.01699-24","DOIUrl":null,"url":null,"abstract":"<p><p><i>Enterobacter cloacae</i> is a Gram-negative nosocomial pathogen of the ESKAPE (<i>Enterococcus, Staphylococcus, Klebsiella, Acinetobacter, Pseudomonas</i>, and <i>Enterobacter</i> spp.) priority group with increasing multi-drug resistance via the acquisition of resistance plasmids. However, <i>E. cloacae</i> can also display forms of antibiotic refractoriness, such as heteroresistance and tolerance. Here, we report that <i>E. cloacae</i> 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 <i>cpxRA</i> 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 <i>cpxA</i> led to high aminoglycoside MICs<i>,</i> consistent with cell envelope stress response driving these behaviors in <i>E. cloacae</i>. 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 Δ<i>cpxRA</i> 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 <i>E. cloacae</i> strains. Altogether, we establish that <i>E. cloacae</i> relies on transcriptional reprogramming via the envelope stress response pathway for transient resistance to a major class of frontline antibiotic.IMPORTANCE<i>Enterobacter cloacae</i> is a bacterium that belongs to the WHO high-priority group and an increasing threat worldwide due its multi-drug resistance. <i>E. cloacae</i> can also display heteroresistance, which has been linked to treatment failure. We report that <i>E. cloacae</i> shows heteroresistance to aminoglycoside antibiotics. These are important frontline microbicidal drugs used against Gram-negative bacterial infections; therefore, understanding how resistance develops among sensitive strains is important. We show that aminoglycoside resistance is driven by the activation of the cell envelope stress response and transcriptional reprogramming via the CpxRA two-component system. Furthermore, heterologous activation of envelope stress via copper, typically a heavy metal with antimicrobial actions, also increased aminoglycoside MICs of the <i>E. cloacae</i> type strain and clinical strains isolated from bloodstream infections. Our study suggests aminoglycoside recalcitrance in <i>E. cloacae</i> could be broadly conserved and cautions against the undesirable effects of copper.</p>","PeriodicalId":18315,"journal":{"name":"mBio","volume":null,"pages":null},"PeriodicalIF":5.1000,"publicationDate":"2024-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"mBio","FirstCategoryId":"99","ListUrlMain":"https://doi.org/10.1128/mbio.01699-24","RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"MICROBIOLOGY","Score":null,"Total":0}
引用次数: 0
Abstract
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 behaviors 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.IMPORTANCEEnterobacter cloacae is a bacterium that belongs to the WHO high-priority group and an increasing threat worldwide due its multi-drug resistance. E. cloacae can also display heteroresistance, which has been linked to treatment failure. We report that E. cloacae shows heteroresistance to aminoglycoside antibiotics. These are important frontline microbicidal drugs used against Gram-negative bacterial infections; therefore, understanding how resistance develops among sensitive strains is important. We show that aminoglycoside resistance is driven by the activation of the cell envelope stress response and transcriptional reprogramming via the CpxRA two-component system. Furthermore, heterologous activation of envelope stress via copper, typically a heavy metal with antimicrobial actions, also increased aminoglycoside MICs of the E. cloacae type strain and clinical strains isolated from bloodstream infections. Our study suggests aminoglycoside recalcitrance in E. cloacae could be broadly conserved and cautions against the undesirable effects of copper.
期刊介绍:
mBio® is ASM''s first broad-scope, online-only, open access journal. mBio offers streamlined review and publication of the best research in microbiology and allied fields.