Influence of in vitro susceptibility phenotype against thrombin-induced platelet microbicidal protein on treatment and prophylaxis outcomes of experimental Staphylococcus aureus endocarditis
Vk. Dhawan et al., Influence of in vitro susceptibility phenotype against thrombin-induced platelet microbicidal protein on treatment and prophylaxis outcomes of experimental Staphylococcus aureus endocarditis, J INFEC DIS, 180(5), 1999, pp. 1561-1568
Thrombin-induced platelet microbicidal protein-1 (tPMP-1) is a small, catio
nic staphylocidal peptide from rabbit platelets. In the current study, the
outcomes of vancomycin treatment and prophylaxis were compared in experimen
tal infective endocarditis (IE) caused by an isogenic Staphylococcus aureus
strain pair differing in tPMP-1 susceptibility (tPMP(S)) or resistance (tP
MP(R)) in vitro (ISP479C and ISP479R, respectively). Vancomycin therapy (se
lected for its intrinsically slow bactericidal activity) reduced ISP479C (b
ut not ISP479R) densities in vegetations compared with controls (P <.01), I
n contrast, prophylactic administration of vancomycin yielded no difference
s in efficacies for the 2 challenge strains. These data suggest that the tP
MPR phenotype in vitro has a negative effect on the antimicrobial therapy (
but not the prophylaxis) of experimental S. aureus IE. These disparate resu
lts may be explained in part by the requirement for microbicidal effects in
the treatment of established IE, whereas prophylactic efficacy depends mor
e on growth inhibitory and antiadhesion effects.