title: Penicillin-induced killing and postantibiotic effect in oral streptococci are enhanced by platelet microbicidal proteins.
abstract: Thrombin-induced platelet microbicidal proteins (tPMP) are alpha-granule-derived cationic antimicrobial proteins released from platelets by stimulation with thrombin. tPMP has potent microbicidal activities against a broad spectrum of common microbial pathogens in infective endocarditis. We studied in vitro interactions of tPMP with penicillin against oral streptococci, Streptococcus rattus BHT (a tPMP-susceptible organism) and Streptococcus gordonii DL1 (a tPMP-insusceptible organism). tPMP was prepared by stimulating rabbit platelets with thrombin. tPMP plus penicillin showed a synergistic bactericidal effect on both S. rattus BHT and S. gordonii DL1, in contrast to either agent alone. Sequential exposure of both S. rattus BHT and S. gordonii DL1 to tPMP followed by exposure to penicillin at 10x the MICs resulted in a significant extension of the postantibiotic-effect duration compared with antibiotic exposure alone. The combined data indicate that tPMP exerts cooperative bactericidal and growth-inhibiting effect in concert with penicillin.
authors.affiliation: Department of Oral Microbiology, College of Dentistry, Research Institute of Oral Science, Kangnung National University, Kangnung 210-702, Republic of Korea. siyoung@knusun.kangnung.ac.kr
authors.forename: Si Young
authors.initials: SY
authors.lastname: Lee
authors.forename: Son-Jin
authors.initials: SJ
authors.lastname: Choe
mesh_terms: D000818:Animals; D000890:Anti-Infective Agents / Q000494:pharmacology; D001792:Blood Platelets / Q000378:metabolism; D001798:Blood Proteins / Q000302:isolation & purification / Q000494:pharmacology*; D015169:Colony Count, Microbial; D004357:Drug Synergism; D008826:Microbial Sensitivity Tests; D010406:Penicillins / Q000494:pharmacology*; D011817:Rabbits; D013291:Streptococcus / Q000187:drug effects* / Q000254:growth & development; D013917:Thrombin / Q000378:metabolism
chemical_list: D000890:Anti-Infective Agents; D001798:Blood Proteins; D010406:Penicillins; C077150:platelet microbicidal protein, Oryctolagus cuniculus; D013917:Thrombin