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Stress adaptation within the host effects antibiotic tolerance and treatment outcome in Staphylococcus aureus infections

ABSTRACT: Staphylococcus aureus can cause severe invasive infections that require prolonged antibiotic treatment. Although S. aureus can easily acquire antibiotic resistance, even fully susceptible bacteria can persist and survive antibiotic therapy, thus complicating treatment. These so-called persisters are phenotypic variants of bacteria characterized by an arrested-growth phenotype that can tolerate high concentrations of chemotherapeutics and are associated with chronic and recurrent infections. Here, we show that S. aureus recovered directly from infection sites, displayed an increased bacterial lag-phase heterogeneity, forming more non-stable small colonies, indicating the presence of dormant bacteria. Infection modelling showed that host-mediated stress, including acidic pH, neutrophil exposure and murine abscesses, as well as antibiotic treatment, promoted formation of persisters both in vitro and in vivo. Proteomics and RNA sequencing revealed stress-response reactions in bacteria leading to an overall more virulent population. However, after persister-enrichment, S. aureus displayed down-regulation of pathways involved in virulence, cell division, and DNA replication, while ribosomal proteins, nucleotide-, and amino acid- metabolic pathways were up-regulated, suggesting their requirement to fuel and maintain the persister phenotype. We demonstrate that decreased aconitase activity and ATP-levels as well as accumulation of insoluble proteins correlated with dormancy and growth reactivation cycles. Combination of antibiotics with retinoid derivatives, especially CD1530, significantly reduced both persisters and total bacterial load in a murine infection model. Our study provides an in-depth characterization of S. aureus persisters and shows that treatment failure due to antibiotic persistence could be addressed by using retinoid derivatives in combination with conventional antibiotics.

INSTRUMENT(S): Q Exactive

ORGANISM(S): Bacteria Staphylococcus Aureus

DISEASE(S): Epidural Abscess

SUBMITTER: Markus Huemer

LAB HEAD: Annelies S. Zinkernagel

PROVIDER: PXD018332 | Pride | 2021-02-12

REPOSITORIES: Pride

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Project description:Staphylococcus aureus causes invasive infections and easily acquires antibiotic resistances. Even antibiotic susceptible S. aureus can survive antibiotic therapy and persist, requiring prolonged treatment and surgical interventions. These so-called persisters display an arrested-growth phenotype, tolerate high antibiotic concentrations and are associated with chronic and recurrent infections. To characterize these persisters, we assessed S. aureus recovered directly from a patient suffering from a persistent infection. We show that host-mediated stress, including acidic-pH, abscesses-environment, and antibiotic exposure promoted persister formation in-vitro and in-vivo. Multi-omics analysis identified molecular changes in S. aureus in response to acid-stress leading to an overall virulent population. However, further analysis of a persister-enriched population revealed major molecular reprogramming in persisters including downregulation of virulence and cell division, and upregulation of ribosomal proteins, nucleotide-, and amino acid- metabolic pathways, suggesting their requirement to fuel and maintain the persister phenotype and highlighting that persisters are not completely metabolically inactive. Additionally, decreased aconitase activity and ATP-levels and accumulation of insoluble proteins involved in transcription, translation and energy-production correlated with persistence in S. aureus, underpinning the molecular mechanisms that drive the persister phenotype. Upon regrowth, these persisters regained their virulence potential and metabolically active phenotype including reduction of insoluble proteins, exhibiting a reversible state, crucial for recurrent infections. We further show that a targeted anti-persister combination therapy using retinoid derivatives and antibiotics significantly reduced lag-phase heterogeneity and persisters in a murine infection model. Our results provide molecular insights into persisters and help explain why persistent S. aureus infections are so difficult-to-treat.

Project description:Kaiser2014 - Salmonella persistence after ciprofloxacin treatment The model describes the bacterial tolerance to antibiotics. Using a mouse model for Salmonella diarrhea, the authors have found that bacterial persistence occurs in the presence of the antibiotic ciprofloxacin because Salmonella can exist in two different states. One, the fast-growing population that spreads in the host's tissues and the other, slow-growing "persister" population that hide out inside dendritic cells of the host's immune system and cannot be attacked by the antibiotics. However, this can be killed by adding agents that directly stimulate the host's immune defense. This model is described in the article: Cecum lymph node dendritic cells harbor slow-growing bacteria phenotypically tolerant to antibiotic treatment. Kaiser P, Regoes RR, Dolowschiak T, Wotzka SY, Lengefeld J, Slack E, Grant AJ, Ackermann M, Hardt WD. PLoS Biol. 2014 Feb 18;12(2):e1001793. Abstract: In vivo, antibiotics are often much less efficient than ex vivo and relapses can occur. The reasons for poor in vivo activity are still not completely understood. We have studied the fluoroquinolone antibiotic ciprofloxacin in an animal model for complicated Salmonellosis. High-dose ciprofloxacin treatment efficiently reduced pathogen loads in feces and most organs. However, the cecum draining lymph node (cLN), the gut tissue, and the spleen retained surviving bacteria. In cLN, approximately 10%-20% of the bacteria remained viable. These phenotypically tolerant bacteria lodged mostly within CD103⁺CX₃CR1⁻CD11c⁺ dendritic cells, remained genetically susceptible to ciprofloxacin, were sufficient to reinitiate infection after the end of the therapy, and displayed an extremely slow growth rate, as shown by mathematical analysis of infections with mixed inocula and segregative plasmid experiments. The slow growth was sufficient to explain recalcitrance to antibiotics treatment. Therefore, slow-growing antibiotic-tolerant bacteria lodged within dendritic cells can explain poor in vivo antibiotic activity and relapse. Administration of LPS or CpG, known elicitors of innate immune defense, reduced the loads of tolerant bacteria. Thus, manipulating innate immunity may augment the in vivo activity of antibiotics. This model is hosted on BioModels Database and identified by: MODEL1312170001. To cite BioModels Database, please use: BioModels Database: An enhanced, curated and annotated resource for published quantitative kinetic models. To the extent possible under law, all copyright and related or neighbouring rights to this encoded model have been dedicated to the public domain worldwide. Please refer to CC0 Public Domain Dedication for more information.

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Stress adaptation within the host effects antibiotic tolerance and treatment outcome in Staphylococcus aureus infections

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