RESUMO
We report the successful purification of a cloned lysin encoded by the novel Staphylococcus aureus bacteriophage phi MR11. The lysin, designated MV-L, rapidly and completely lysed cells of a number of S. aureus strains tested, including methicillin-resistant S. aureus (MRSA) and vancomycin-resistant S. aureus and a subset of vancomycin-intermediate S. aureus (VISA) in growing conditions. MV-L-mediated killing is specific to S. aureus and not to other species, except for S. simulans. MV-L exerted its staphylocidal effect synergistically with glycopeptide antibiotics against VISA. MV-L efficiently eliminated MRSA that had been artificially inoculated into the nares of mice. The intraperitoneal administration of MV-L also protected mice against MRSA septic death, without any harmful effects. Although MV-L evoked detectable levels of a humoral response in mice, the antibodies did not abolish the bacteriolytic activity. These results indicate that MV-L might be useful as a powerful therapeutic agent against multidrug-resistant S. aureus infections.
Assuntos
Antibacterianos/administração & dosagem , Toxinas Bacterianas/administração & dosagem , Farmacorresistência Bacteriana Múltipla/efeitos dos fármacos , Proteínas Hemolisinas/administração & dosagem , Proteínas Recombinantes/biossíntese , Fagos de Staphylococcus/metabolismo , Staphylococcus aureus/efeitos dos fármacos , Administração Intranasal , Administração Tópica , Animais , Antibacterianos/isolamento & purificação , Toxinas Bacterianas/isolamento & purificação , Modelos Animais de Doenças , Endopeptidases/administração & dosagem , Endopeptidases/biossíntese , Feminino , Proteínas Hemolisinas/isolamento & purificação , Resistência a Meticilina/efeitos dos fármacos , Camundongos , Proteínas Recombinantes/isolamento & purificação , Staphylococcus aureus/virologia , Resistência a Vancomicina/efeitos dos fármacosRESUMO
We intended to clarify the influence of student academic ability on the effectiveness of CAI, using data of a study to assess the effectiveness of a new type of CAI software, cyberPatient (CP), at Kochi Medical School (KMS). A total of 59 third-year students were randomly assigned to four groups: Group-1 used a textbook for self-instruction, Group-2 used CP, Group-3 used both types of learning materials, and Group-4 did not learn. Learning performance was evaluated by multiple-choice examination and OSCE. In order to clarify the influence of students' academic ability on the effectiveness of CAI, statistical analyses were conducted, assigning students as either high or medium or low performance students. High performance students from Group-1, -2 and -3 did not differ significantly in test performance after self-instruction. However, low performance students in Group-1 scored significantly lower than those in Group-2 and -3. All students in Group-2 and -3 reported that CP stimulated willingness to learn and assisted understanding. The present analysis suggested that effectiveness of CAI might be associated with the academic ability of students.
