Daptomycin dose-ranging evaluation with single-dose versus multidose ceftriaxone combinations against streptococcus mitis/ oralis in an ex vivo simulated endocarditis vegetation model
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2019
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Antimicrobial agents and chemotherapy, 1098-6596, Vol. 63, Nro. 6, 2019, p. e00386-19
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American Society for Microbiology
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Abstract
T The viridans group streptococci (VGS) are a heterogeneous group of organisms which are important components of the normal human oral flora. Among
the VGS, the Streptococcus mitis/oralis subgroup is one of the most common causes
of infective endocarditis (IE). Daptomycin (DAP) is a potential alternative therapeutic
option for invasive S. mitis infections, given high rates of -lactam resistance and
vancomycin tolerance in such strains. However, the ability of these strains to rapidly
evolve high-level and durable DAP resistance (DAP-R) is problematic. Recent data
suggest that combination DAP--lactam therapy circumvents this issue. Humansimulated dose-escalating DAP-alone dose regimens (6, 8, 10, or 12 mg/kg/day times
4 days) versus DAP (6 mg/kg/day) plus ceftriaxone (CRO) (2 g once daily times 4 days
or 0.5 g, single dose) were assessed against two prototypical DAP-susceptible
(DAP-S) S. mitis/oralis strains (SF100 and 351), as measured by a pharmacokinetic/
pharmacodynamic (PK/PD) model of simulated endocardial vegetations (SEVs). No
DAP-alone regimen was effective, with regrowth of high-level DAP-R isolates observed for both strains over 96-h exposures. Combinations of DAP-CRO with either
single- or multidose regimens yielded significant reductions in log10 CFU/g amounts
within SEVs for both strains (6 log10 CFU/g) within 24 h. In addition, no DAP-R
strains were detected in either DAP-CRO combination regimens over the 96-h exposure. In contrast to prior in vitro studies, no perturbations in two key cardiolipin biosynthetic genes (cdsA and pgsA) were identified in DAP-R SEV isolates emerging
from strain 351, despite defective phospholipid production. The combination of
DAP-CRO warrants further investigation for treatment of IE due to S. mitis/oralis
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Estreptococos viridans
Endocarditis bacteriana
Resistencia betalactámica
Endocarditis bacteriana
Resistencia betalactámica