RESUMEN
Immunity to group A streptococci (GAS) is thought to be related to the acquisition of type-specific antibody directed against the M protein. However, recent work suggests that immunity may only be strain and not M-type specific. Therefore, susceptibility of 70 different GAS M-1 strains to opsonization and killing by convalescent sera was compared by using a highly sensitive chemiluminescence assay and by standard bactericidal assay. Sequencing of the emm1 gene in 10 strains with variable susceptibility to opsonization revealed 100% homology in 9 strains. Several substitutions in the N-terminal and 2 in the A3 repeat regions of strain CS-190 were associated with profound resistance to opsonization. Thus amino acid substitutions within different regions of the M-1 protein molecule may adversely affect opsonization by immune sera. In addition, non-M protein factors from identical M types influence susceptibility to phagocytosis. These findings may in part explain the persistently high prevalence of M-1 strains worldwide over the last 15 years.
Asunto(s)
Antígenos Bacterianos , Proteínas de la Membrana Bacteriana Externa , Proteínas Bacterianas/inmunología , Proteínas Portadoras/inmunología , Sueros Inmunes/inmunología , Proteínas Opsoninas/inmunología , Fagocitosis/inmunología , Streptococcus pyogenes/inmunología , Secuencia de Aminoácidos , Sustitución de Aminoácidos , Proteínas Bacterianas/química , Proteínas Bacterianas/genética , Actividad Bactericida de la Sangre , Proteínas Portadoras/química , Proteínas Portadoras/genética , Proteínas del Sistema Complemento/inmunología , Humanos , Mediciones Luminiscentes , Datos de Secuencia Molecular , Análisis de Secuencia de ADN , Serotipificación , Infecciones Estreptocócicas/microbiología , Streptococcus pyogenes/clasificaciónRESUMEN
The extent to which Emergency Medical Service personnel are placed in situations in which difficult cardiopulmonary resuscitation decisions must be made has been poorly explored. Further, it is not known whether this kind of decision making is troubling to emergency medical technicians. Although it is likely that emergency medical service systems handle withholding cardiopulmonary resuscitation in a variety of ways, the authors chose to examine a cross-section of New Mexico emergency medical technicians. Using a survey instrument, emergency medical technicians of all training levels, representing several emergency medical service systems around the state were asked how many times in their career they had been in a situation in which cardiopulmonary resuscitation had been withheld without a direct physician order. Of 310 individuals surveyed, 211 (66.8%) responded that this had occurred at least once. When asked whether they had been troubled by one of these situations, 86 of 211 (41%) individuals responded "yes." When a variety of demographic factors were evaluated, only training to the paramedic level was identified as being an independent predictor of those who were troubled (P = .019). Emergency medical technician training, protocols, and do not resuscitate programs may need to be expanded to give further guidance to prehospital personnel when making difficult resuscitation decisions.
Asunto(s)
Reanimación Cardiopulmonar , Toma de Decisiones , Auxiliares de Urgencia , Privación de Tratamiento , Adulto , Auxiliares de Urgencia/educación , Femenino , Humanos , Masculino , Negativa al Tratamiento , Órdenes de Resucitación , Factores Socioeconómicos , Factores de TiempoAsunto(s)
Amoxicilina/uso terapéutico , Ácidos Clavulánicos/uso terapéutico , Penicilina V/uso terapéutico , Faringitis/tratamiento farmacológico , Infecciones Estreptocócicas/tratamiento farmacológico , Niño , Ácido Clavulánico , Humanos , Faringitis/microbiología , Infecciones Estreptocócicas/microbiología , Streptococcus pyogenes/efectos de los fármacos , Streptococcus pyogenes/aislamiento & purificaciónRESUMEN
Studies of group A, M type 49 streptococci from England, Trinidad and Alaska indicate that isolates of this serotype often differ with respect to phage subtype from one geographical area to another, but are generally homogeneous in one place at one time. The findings support the conclusion that acute glomerulonephritis can be associated with a variety of phage subtypes of M type 49 streptococci. In outbreaks of skin sepsis without nephritis in England, the phage subtypes of M type 49 streptococci isolated from skin lesions of meat handlers were the same as those recovered from skin lesions of non-meat handlers in the same community. The findings on the Trinidad isolates suggest that M type 49 streptococci of one phage subtype may persist in a population for 9 years and may result in a second outbreak of acute glomerulonephritis. In an Alaska Eskimo population in whom acute glomerulonephritis was occurring, most of the M type 49 isolates available for testing were of a single phage subtype. Equally prevalent in this population were group A streptococci that exhibited the same T antigen as the type 49 isolates but differed in their serum opacity reaction and phage subtype. This apparently related strain was not typable with available M antisera but showed functional evidence of M protein and is probably a new M type.