Platelet microbicidal proteins (PMPs), small cationic peptides released at sites of endovascular damage, kill common bloodstream pathogens in vitro. Our group previously showed that in vitro resistance of clinical staphylococcal and viridans group streptococcal bacteremic strains to PMPs correlated with the diagnosis of infective endocarditis (IE) (Wu et al., Antimicrob. Agents Chemother. 38:729–732, 1994). However, that study was limited by (i) the small number of Staphylococcus aureus isolates from IE patients, (ii) the retrospective nature of the case definitions, and (iii) the diverse geographic sources of strains. The present study evaluated the in vitro PMP susceptibility phenotype of a large number of staphylococcemic isolates (n = 60), collected at a single medical center and categorized by defined and validated clinical criteria. A significantly higher proportion of staphylococcemic strains from patients with IE was PMP resistant in vitro than the proportion of strains from patients with soft tissue sepsis (83% and 33%, respectively; P < 0.01). Moreover, the levels of PMP resistance (mean percent survival of strains after 2-h exposure to PMP in vitro) were significantly higher for isolates from patients with IE and with vascular catheter sepsis than for strains from patients with abscess sepsis (P < 0.005 and P < 0.01, respectively). These data further support the concept that bloodstream pathogens that exhibit innate or acquired PMP resistance have a survival advantage with respect to either the induction or progression of endovascular infections.

Platelet microbicidal proteins (PMPs) are believed to be integral to host defense against endovascular infection. We previously demonstrated that susceptibility to thrombin-induced PMP 1 (tPMP-1) in vitro negatively influences Candida albicans virulence in the rabbit model of infective endocarditis (IE). This study evaluated the relationship between in vitro tPMP-1 susceptibility (tPMP-1 s ) or resistance (tPMP-1 r ) and efficacy of fluconazole (FLU) therapy of IE due to C. albicans. Candida IE was established in rabbits with either tPMP-1 s or tPMP-1 r strains. Treatment groups received FLU (100 mg/kg/day) intraperitoneally for 7 or 14 days; control animals received no therapy. At these time points, cardiac vegetations, kidneys, and spleens were quantitatively cultured to assess fungal burden. At both 7 and 14 days and in all target tissues, the extent of candidal clearance by FLU was greater in animals infected with the tPMP-1 s strain than in those infected with the tPMP-1 r strain. These differences were statistically significant in the spleen and kidney. Corroborating these in vivo data, FLU (a candidastatic agent), in combination with tPMP-1, exerted an enhanced fungicidal effect in vitro against tPMP-1 s and tPMP-1 r C. albicans, with the extent of this effect greatest against the tPMP-1 s strain. Collectively, these results support the concept that tPMP-1 susceptibility contributes to the net efficacy of FLU against C. albicans IE in vivo, particularly in tissues in which platelets and tPMP-1 likely play significant roles in host defense.

A previously developed two‐component model was used to estimate the magnitude of interference from tetrapropylene‐based alkylbenzenes (TABs) in measuring linear alkylbenzene (LAB) concentrations in a sediment core collected from the Palos Verdes Shelf (Los Angeles, CA, USA). The magnitude of such interference generally increased with increasing sediment core depth and was fairly high in deeper sediments, where TABs were abundant relative to LABs. Usage of LABs as sewage markers in sediments is generally valid as long as the approximate ratio of TAB to LAB concentration is less than 10.

Abstract-A previously developed two-component model was used to estimate the magnitude of interference from tetrapropylenebased alkylbenzenes (TABs) in measuring linear alkylbenzene (LAB) concentrations in a sediment core collected from the Palos Verdes Shelf (Los Angeles, CA, USA). The magnitude of such interference generally increased with increasing sediment core depth and was fairly high in deeper sediments, where TABs were abundant relative to LABs. Usage of LABs as sewage markers in sediments is generally valid as long as the approximate ratio of TAB to LAB concentration is less than 10.