Epidemiology of infectious
endocarditis has changed in last decades,
endocarditis associated to hospital practices, sustained by multiresistant pathogens being highly increased. In particular, methicillin-resistant staphylococci (MRSA), almost resistant to a number of other antimicrobial classes, often exhibit a reduced susceptibility to
vancomycin (h-VISA) with MICs' values more e than 1 mg/l, leading to suppose a reduced therapeutic efficacy of this
drug. Thirty-one percent of MRSA strains in the
ICE study, which prospectively collected more than 5000
endocarditis, were h-VISA.
Daptomycin shows a rapid bactericidal activity against both
methicillin-susceptible staphylococcci (MSSA) and MRSA, included those strains with reduced susceptibility to
vancomycin.
Daptomycin shows a good therapeutic efficacy in staphylococcal
endocarditis: MRSA 71%, MSSA 75%. These data suggest the use of
daptomycin as initial
therapy for treatment of staphylococcal
endocarditis, independently from methcillin susceptibility. Some experimental data showed that
daptomycin efficacy can diminish, if it is used as a rescue
therapy after
vancomycin failure. The thickness of bacterial cell-wall recognized in h-VISA strains can represent a physical and electrical barrier to reach both the
vancomycin and
daptomycin target site. However, the reduced efficacy of
daptomycin following
vancomycin exposure is an extremely rare event in the clinical practice. It is preferrable to use
daptomycin as first line
therapy, at a proper dosage. As far as
endocarditis is concerned, recent data proved the excellent
daptomycin tolerability, with dosages up to 8-10 mg/kg/die. During the treatment, CPK values must be always monitored. For
endocarditis sustained by vancomycin-resistant enterococci, therapeutic choices are based on
linezolid or
ampicillin-
ceftriaxone combination
therapy.
Daptomycin alone, or in association with
gentamycin and
rifampin, can represent a promising therapeutic alternative.