Metabolic changes associated with adaptive resistance to daptomycin in Streptococcus mitis-oralis

Background: Viridans group streptococci of the Streptococcus mitis-oralis subgroup are important endovascular pathogens. They can rapidly develop high-level and durable non-susceptibility to daptomycin both in vitro and in vivo upon exposure to daptomycin. Two consistent genetic adaptations associated with this phenotype (i.e., mutations in cdsA and pgsA) lead to the depletion of the phospholipids, phosphatidylglycerol and cardiolipin, from the bacterial membrane. Such alterations in phospholipid biosynthesis will modify carbon flow and change the bacterial metabolic status. To determine the metabolic differences between daptomycin-susceptible and non- susceptible bacteria, the physiology and metabolomes of S. mitis-oralis strains 351 (daptomycin-susceptible) and 351-D10 (daptomycin non-susceptible) were analyzed. S. mitis-oralis strain 351-D10 was made daptomycin non- susceptible through serial passage in the presence of daptomycin. Background: Viridans group streptococci of the Streptococcus mitis-oralis subgroup are important endovascular pathogens. They can rapidly develop high-level and durable non-susceptibility to daptomycin both in vitro and in vivo upon exposure to daptomycin. Two consistent genetic adaptations associated with this phenotype (i.e., mutations in cdsA and pgsA) lead to the depletion of the phospholipids, phosphatidylglycerol and cardiolipin, from the bacterial membrane. Such alterations in phospholipid biosynthesis will modify carbon flow and change the bacterial metabolic status. To determine the metabolic differences between daptomycin-susceptible and non- susceptible bacteria, the physiology and metabolomes of S. mitis-oralis strains 351 (daptomycin-susceptible) and 351-D10 (daptomycin non-susceptible) were analyzed. S. mitis-oralis strain 351-D10 was made daptomycin non- susceptible through serial passage in the presence of daptomycin. Conclusions: S. mitis-oralis metabolism is altered in daptomycin non-susceptible bacteria relative to the daptomycin susceptible parent strain. As demonstrated in Staphylococcus aureus, inhibiting the metabolic changes that facilitate the transition from a daptomycin susceptible state to a non-susceptible one, inhibits daptomycin non- susceptibility. By preventing these metabolic adaptations in S. mitis-oralis, it should be possible to deter the formation of daptomycin non-susceptibility

Investigating Antibiotic Resistance in \u3ci\u3eStaphylococcus aureus\u3c/i\u3e and \u3ci\u3eStreptococcus mitis-oralis\u3c/i\u3e by Nuclear Magnetic Resonance Based Metabolomics

Metabolomics is rapidly growing in popularity as a valuable resource for drug discovery due to its ability to identify perturbations in metabolic pathways between healthy controls and drug treatment groups. Metabolomics can differentiate between different phenotypes resulting from genetic changes or in response to variations in environmental conditions. Conversely, genomics, transcriptomics, and proteomics can only provide insight into the outcome that could happen. Notably, metabolomics is commonly used to observe the effects of environmental stress on bacteria and between resistant and non-resistant strains of bacteria. The development of a protocol to grow Staphylococcus aureus in a blood-like environment was essential in identify the metabolic, growth, and survivability differences cause due to cultivation medium. The blood-like environment consist of tryptic soy broth without dextrose (TSB-DEX) with 55% Serum. Daptomycin-susceptible (DapS) and daptomycin-nonsusceptible (DapNS) strains of S. aureus were then cultured in the blood-like environment to identify metabolome differences. NMR and mass spectrometry were used in combination to provide a comprehensive characterization of metabolic perturbations. In this regards, adaptive metabolic differences between DapS and DapNS may be leveraged as potential therapeutic targets. NMR metabolomics was also used to characterize metabolic response for adaptive resistance strains of Streptococcus mitis-oralis to daptomycin. Advisor: Robert Power

Investigating Antibiotic Resistance in \u3ci\u3eStaphylococcus aureus\u3c/i\u3e and \u3ci\u3eStreptococcus mitis-oralis\u3c/i\u3e by Nuclear Magnetic Resonance Based Metabolomics

Metabolomics is rapidly growing in popularity as a valuable resource for drug discovery due to its ability to identify perturbations in metabolic pathways between healthy controls and drug treatment groups. Metabolomics can differentiate between different phenotypes resulting from genetic changes or in response to variations in environmental conditions. Conversely, genomics, transcriptomics, and proteomics can only provide insight into the outcome that could happen. Notably, metabolomics is commonly used to observe the effects of environmental stress on bacteria and between resistant and non-resistant strains of bacteria. The development of a protocol to grow Staphylococcus aureus in a blood-like environment was essential in identify the metabolic, growth, and survivability differences cause due to cultivation medium. The blood-like environment consist of tryptic soy broth without dextrose (TSB-DEX) with 55% Serum. Daptomycin-susceptible (DapS) and daptomycin-nonsusceptible (DapNS) strains of S. aureus were then cultured in the blood-like environment to identify metabolome differences. NMR and mass spectrometry were used in combination to provide a comprehensive characterization of metabolic perturbations. In this regards, adaptive metabolic differences between DapS and DapNS may be leveraged as potential therapeutic targets. NMR metabolomics was also used to characterize metabolic response for adaptive resistance strains of Streptococcus mitis-oralis to daptomycin. Advisor: Robert Power

Metabolic changes associated with adaptive resistance to daptomycin in Streptococcus mitis-oralis

Background: Viridans group streptococci of the Streptococcus mitis-oralis subgroup are important endovascular pathogens. They can rapidly develop high-level and durable non-susceptibility to daptomycin both in vitro and in vivo upon exposure to daptomycin. Two consistent genetic adaptations associated with this phenotype (i.e., mutations in cdsA and pgsA) lead to the depletion of the phospholipids, phosphatidylglycerol and cardiolipin, from the bacterial membrane. Such alterations in phospholipid biosynthesis will modify carbon flow and change the bacterial metabolic status. To determine the metabolic differences between daptomycin-susceptible and non- susceptible bacteria, the physiology and metabolomes of S. mitis-oralis strains 351 (daptomycin-susceptible) and 351-D10 (daptomycin non-susceptible) were analyzed. S. mitis-oralis strain 351-D10 was made daptomycin non- susceptible through serial passage in the presence of daptomycin. Background: Viridans group streptococci of the Streptococcus mitis-oralis subgroup are important endovascular pathogens. They can rapidly develop high-level and durable non-susceptibility to daptomycin both in vitro and in vivo upon exposure to daptomycin. Two consistent genetic adaptations associated with this phenotype (i.e., mutations in cdsA and pgsA) lead to the depletion of the phospholipids, phosphatidylglycerol and cardiolipin, from the bacterial membrane. Such alterations in phospholipid biosynthesis will modify carbon flow and change the bacterial metabolic status. To determine the metabolic differences between daptomycin-susceptible and non- susceptible bacteria, the physiology and metabolomes of S. mitis-oralis strains 351 (daptomycin-susceptible) and 351-D10 (daptomycin non-susceptible) were analyzed. S. mitis-oralis strain 351-D10 was made daptomycin non- susceptible through serial passage in the presence of daptomycin. Conclusions: S. mitis-oralis metabolism is altered in daptomycin non-susceptible bacteria relative to the daptomycin susceptible parent strain. As demonstrated in Staphylococcus aureus, inhibiting the metabolic changes that facilitate the transition from a daptomycin susceptible state to a non-susceptible one, inhibits daptomycin non- susceptibility. By preventing these metabolic adaptations in S. mitis-oralis, it should be possible to deter the formation of daptomycin non-susceptibility