Biology subjects

Haeberle, A. L.

Publications and source records attributed to Haeberle, A. L..

4 recordsLinked to original sources

bioRxiv2024

Genotypic and phenotypic characterization of Enterococcus faecalis isolates from periprosthetic joint infections

Over 2.5 million prosthetic joint implantation surgeries occur annually in the United States. Periprosthetic joint infections (PJIs), though occurring in only 1-2% of patients receiving replacement joints, are challenging to diagnose and treat and are associated with significant morbidity. The Gram-positive bacterium Enterococcus faecalis, which can be highly antibiotic resistant and is a robust biofilm producer on indwelling medical devices, accounts for 2-11% of PJIs. E. faecalis PJIs are understudied compared to those caused by other pathogens, such as Staphylococcus aureus. This motivates the need to generate a comprehensive understanding of E. faecalis PJIs to guide future treatments for these infections. To address this, we describe a panel of E. faecalis strains isolated from the surface of prosthetic joints in a cohort of individuals treated at Mayo Clinic in Rochester, MN. Here, we present the first complete genome assemblage of E. faecalis PJI isolates. Comparative genomics shows differences in genome size, virulence factors, antimicrobial resistance genes, plasmids, and prophages, underscoring the genetic diversity of these strains. These isolates have strain-specific differences in in vitro biofilm biomass, biofilm burden, and biofilm morphology. We measured robust changes in biofilm architecture and aggregation for all isolates when grown in simulated synovial fluid (SSF). Lastly, we evaluated antibiotic efficacy of these isolates and found strain specific changes across all strains when grown in SSF. Results of this study highlight the existence of genetic and phenotypic heterogeneity among E. faecalis PJI isolates which will provide valuable insight and resources for future E. faecalis PJI research. ImportancePeriprosthetic joint infections (PJIs) affect [~]1-2% of those who undergo joint replacement surgery. Enterococcus faecalis is a Gram-positive opportunistic pathogen that causes [~]10% of PJIs in the United States each year, but our understanding of how and why E. faecalis causes PJIs is limited. E. faecalis infections are typically biofilm associated and can be difficult to clear with antibiotic therapy. Here, we provide complete genomes for four E. faecalis PJI isolates from the Mayo Clinic. These isolates have strain-specific differences in biofilm formation, aggregation, and antibiotic susceptibility in simulated synovial fluid. These results provide important insight into genomic and phenotypic features of E. faecalis isolates from PJI.

microbiology↗

bioRxiv2022

Non-redundant dimethyl sulfoxide reductases influence Salmonella enterica serotype Typhimurium anaerobic growth and virulence

Facultative anaerobic enteric pathogens can utilize a diverse array of alternate electron acceptors to support anaerobic metabolism and thrive in the hypoxic conditions within the mammalian gut. Dimethyl sulfoxide (DMSO) is produced by methionine catabolism and can act as an alternate electron acceptor to support anaerobic respiration. The DMSO reductase complex consists of three subunits, DmsA, DmsB, and DmsC, and allows bacteria to grow anaerobically with DMSO as an electron acceptor. The genomes of non-typhoidal S. enterica encode three putative dmsABC operons, but the impact of the apparent genetic redundancy in DMSO reduction on fitness of non-typhoidal S. enterica during infection remains unknown. We hypothesized that DMSO reduction would be needed for S. enterica serotype Typhimurium (S. Typhimurium) to colonize the mammalian gut. We demonstrate a S. Typhimurium mutant with loss of function in all three putative DMSO reductases ({Delta}dmsA3) poorly colonizes the mammalian intestine when the microbiota are intact and when inflammation is absent. DMSO reduction enhances anaerobic growth through non-redundant contributions of two of the DMSO reductases. Furthermore, DMSO reduction influences the expression of the type-3 secretion systems needed for virulence. Collectively, our data demonstrate that the DMSO reductases of S. Typhimurium are functionally non-redundant and suggest DMSO is a physiologically relevant electron acceptor that supports S. enterica fitness in the gut.

microbiology↗

bioRxiv2022

Group B Streptococcus Adaptation Promotes Survival in a Hyper-inflammatory Diabetic Wound Environment

Diabetic wounds have poor healing outcomes due to the presence of numerous pathogens and a dysregulated immune response. Group B Streptococcus (GBS) is commonly isolated from diabetic wound infections, but the mechanisms of GBS virulence during these infections have not been investigated. Here, we develop a murine model of GBS diabetic wound infection, and using dual RNA-sequencing, demonstrate that GBS infection triggers an inflammatory response. GBS adapts to this hyperinflammatory environment by upregulating virulence factors including those known to be regulated by the two-component system covRS, such as the surface protein pbsP, and the cyl operon which is responsible for hemolysin/pigmentation production. We recover hyperpigmented/hemolytic GBS colonies from the murine diabetic wound which we determined encode mutations in covR. We further demonstrate that GBS mutants in cylE and pbsP are attenuated in the diabetic wound. This foundational study provides insight into the pathogenesis of GBS diabetic wound infections. TeaserThe Fight for Survival by the Bacterium Group B Streptococcus in the Diabetic Wound.

microbiology↗

bioRxiv2021

Niche-specific profiling reveals transcriptional adaptations required for the cytosolic lifestyle of Salmonella enterica

Salmonella enterica serovar Typhimurium (S. Typhimurium) is a zoonotic pathogen that causes diarrheal disease in humans and animals. During salmonellosis, S. Typhimurium colonizes epithelial cells lining the gastrointestinal tract. S. Typhimurium has an unusual lifestyle in epithelial cells that begins within an endocytic-derived Salmonella-containing vacuole (SCV), followed by escape into the cytosol, epithelial cell lysis and bacterial release. The cytosol is a more permissive environment than the SCV and supports rapid bacterial growth. The physicochemical conditions encountered by S. Typhimurium within the cytosol, and the bacterial genes required for cytosolic colonization, remain unknown. Here we have exploited the parallel colonization strategies of S. Typhimurium in epithelial cells to decipher the two niche-specific bacterial virulence programs. By combining a population-based RNA-seq approach with single-cell microscopic analysis, we identified bacterial genes/sRNAs with cytosol-specific or vacuole-specific expression signatures. Using these genes/sRNAs as environmental biosensors, we defined that Salmonella is exposed to iron and manganese deprivation and oxidative stress in the cytosol and zinc and magnesium deprivation in the SCV. Furthermore, iron availability was critical for optimal S. Typhimurium replication in the cytosol, as well as entC, fepB, soxS and sitA-mntH. Virulence genes that are typically associated with extracellular bacteria, namely Salmonella pathogenicity island 1 (SPI1) and SPI4, had a cytosolic-specific expression profile. Our study reveals that the cytosolic and vacuolar S. Typhimurium virulence gene programs are unique to, and tailored for, residence within distinct intracellular compartments. Therefore, this archetypical vacuole-adapted pathogen requires extensive transcriptional reprogramming to successfully colonize the mammalian cytosol. Author SummaryIntracellular pathogens reside either within a membrane-bound vacuole or are free-living in the cytosol and their virulence programs are tailored towards survival within a particular intracellular compartment. Some bacterial pathogens (such as Salmonella enterica) can successfully colonize both intracellular niches, but how they do so is unclear. Here we have exploited the parallel intracellular lifestyles of S. enterica in epithelial cells to identify the niche-specific bacterial expression profiles and environmental cues encountered by S. enterica. We have also discovered bacterial genes that are required for colonization of the cytosol, but not the vacuole. Our results advance our understanding of pathogen-adaptation to alternative replication niches and highlight an emerging concept in the field of bacteria-host cell interactions.

microbiology↗