PMID- 28049149 OWN - NLM STAT- MEDLINE DCOM- 20170628 LR - 20191227 IS - 2150-7511 (Electronic) VI - 8 IP - 1 DP - 2017 Jan 3 TI - RelA Mutant Enterococcus faecium with Multiantibiotic Tolerance Arising in an Immunocompromised Host. LID - 10.1128/mBio.02124-16 [doi] LID - e02124-16 AB - Serious bacterial infections in immunocompromised patients require highly effective antibacterial therapy for cure, and thus, this setting may reveal novel mechanisms by which bacteria circumvent antibiotics in the absence of immune pressure. Here, an infant with leukemia developed vancomycin-resistant Enterococcus faecium (VRE) bacteremia that persisted for 26 days despite appropriate antibiotic therapy. Sequencing of 22 consecutive VRE isolates identified the emergence of a single missense mutation (L152F) in relA, which constitutively activated the stringent response, resulting in elevated baseline levels of the alarmone guanosine tetraphosphate (ppGpp). Although the mutant remained susceptible to both linezolid and daptomycin in clinical MIC testing and during planktonic growth, it demonstrated tolerance to high doses of both antibiotics when growing in a biofilm. This biofilm-specific gain in resistance was reflected in the broad shift in transcript levels caused by the mutation. Only an experimental biofilm-targeting ClpP-activating antibiotic was able to kill the mutant strain in an established biofilm. The relA mutation was associated with a fitness trade-off, forming smaller and less-well-populated biofilms on biological surfaces. We conclude that clinically relevant relA mutations can emerge during prolonged VRE infection, causing baseline activation of the stringent response, subsequent antibiotic tolerance, and delayed eradication in an immunocompromised state. IMPORTANCE: The increasing prevalence of antibiotic-resistant bacterial pathogens is a major challenge currently facing the medical community. Such pathogens are of particular importance in immunocompromised patients as these individuals may favor emergence of novel resistance determinants due to lack of innate immune defenses and intensive antibiotic exposure. During the course of chemotherapy, a patient developed prolonged bacteremia with vancomycin-resistant Enterococcus faecium that failed to clear despite multiple front-line antibiotics. The consecutive bloodstream isolates were sequenced, and a single missense mutation identified in the relA gene, the mediator of the stringent response. Strains harboring the mutation had elevated baseline levels of the alarmone and displayed heightened resistance to the bactericidal activity of multiple antibiotics, particularly in a biofilm. Using a new class of compounds that modulate ClpP activity, the biofilms were successfully eradicated. These data represent the first clinical emergence of mutations in the stringent response in vancomycin-resistant entereococci. CI - Copyright (c) 2017 Honsa et al. FAU - Honsa, Erin S AU - Honsa ES AD - Department of Infectious Diseases, St. Jude Children's Hospital, Memphis, Tennessee, USA. FAU - Cooper, Vaughn S AU - Cooper VS AUID- ORCID: 0000-0001-7726-0765 AD - Department of Microbiology and Molecular Genetics, University of Pittsburgh, Pittsburgh, Pennsylvania, USA. FAU - Mhaissen, Mohammed N AU - Mhaissen MN AD - Department of Infectious Diseases, St. Jude Children's Hospital, Memphis, Tennessee, USA. FAU - Frank, Matthew AU - Frank M AD - Department of Infectious Diseases, St. Jude Children's Hospital, Memphis, Tennessee, USA. FAU - Shaker, Jessica AU - Shaker J AD - Department of Infectious Diseases, St. Jude Children's Hospital, Memphis, Tennessee, USA. FAU - Iverson, Amy AU - Iverson A AD - Department of Infectious Diseases, St. Jude Children's Hospital, Memphis, Tennessee, USA. FAU - Rubnitz, Jeffrey AU - Rubnitz J AD - Department of Oncology, St. Jude Children's Hospital, Memphis, Tennessee, USA. FAU - Hayden, Randall T AU - Hayden RT AD - Department of Pathology, St. Jude Children's Hospital, Memphis, Tennessee, USA. FAU - Lee, Richard E AU - Lee RE AD - Department of Chemical Biology and Therapeutics, St. Jude Children's Hospital, Memphis, Tennessee, USA. FAU - Rock, Charles O AU - Rock CO AD - Department of Infectious Diseases, St. Jude Children's Hospital, Memphis, Tennessee, USA. FAU - Tuomanen, Elaine I AU - Tuomanen EI AD - Department of Infectious Diseases, St. Jude Children's Hospital, Memphis, Tennessee, USA. FAU - Wolf, Joshua AU - Wolf J AD - Department of Infectious Diseases, St. Jude Children's Hospital, Memphis, Tennessee, USA Joshua.wolf@stjude.org jason.rosch@stjude.org. AD - Department of Pediatrics, University of Tennessee Health Science Center, Memphis, Tennessee, USA. FAU - Rosch, Jason W AU - Rosch JW AD - Department of Infectious Diseases, St. Jude Children's Hospital, Memphis, Tennessee, USA Joshua.wolf@stjude.org jason.rosch@stjude.org. LA - eng GR - R01 AI110618/AI/NIAID NIH HHS/United States GR - R01 AI111449/AI/NIAID NIH HHS/United States GR - R01 AI110578/AI/NIAID NIH HHS/United States GR - U01 AI124302/AI/NIAID NIH HHS/United States GR - R25 CA023944/CA/NCI NIH HHS/United States GR - R01 GM034496/GM/NIGMS NIH HHS/United States GR - R01 AI027913/AI/NIAID NIH HHS/United States PT - Journal Article PT - Research Support, N.I.H., Extramural PT - Research Support, Non-U.S. Gov't DEP - 20170103 PL - United States TA - mBio JT - mBio JID - 101519231 RN - 0 (Anti-Bacterial Agents) RN - 0 (Mutant Proteins) RN - 33503-72-9 (Guanosine Tetraphosphate) RN - EC 6.- (Ligases) RN - EC 6.- (guanosine 3',5'-polyphosphate synthetases) SB - IM CIN - MBio. 2017 Feb 21;8(1):null. PMID: 28223450 MH - Anti-Bacterial Agents/*pharmacology MH - Bacteremia/microbiology MH - Biofilms/drug effects/growth & development MH - *Drug Tolerance MH - Enterococcus faecium/*drug effects/genetics/isolation & purification/physiology MH - Female MH - Gram-Positive Bacterial Infections/*microbiology MH - Guanosine Tetraphosphate/metabolism MH - Humans MH - *Immunocompromised Host MH - Infant MH - Ligases/*genetics MH - Microbial Sensitivity Tests MH - Mutant Proteins/*genetics MH - Mutation, Missense MH - Sequence Analysis, DNA MH - Vancomycin-Resistant Enterococci/drug effects/genetics/isolation & purification PMC - PMC5210501 EDAT- 2017/01/04 06:00 MHDA- 2017/06/29 06:00 PMCR- 2017/01/03 CRDT- 2017/01/04 06:00 PHST- 2017/01/04 06:00 [entrez] PHST- 2017/01/04 06:00 [pubmed] PHST- 2017/06/29 06:00 [medline] PHST- 2017/01/03 00:00 [pmc-release] AID - mBio.02124-16 [pii] AID - mBio02124-16 [pii] AID - 10.1128/mBio.02124-16 [doi] PST - epublish SO - mBio. 2017 Jan 3;8(1):e02124-16. doi: 10.1128/mBio.02124-16.