RESUMO
A pesar del aumento de infecciones invasoras por Streptococcus pyogenes: fasceitis necrozante (FN) y síndrome de shock tóxico (SST) en nuestro medio, su caracterización generalmente se limita a identificación de especie y prácticamente no existen estudios moleculares. La literatura describe diversos métodos para tipificar S pyogenes (MLEE, PFGE y secuenciación de emm) que resultan complejos. Una alternativa es la técnica basada en el polimorfismo del regulón vir (emm, emm I, scp A, vir R) que es más sencilla y permite correlacionar los virRLFP con los serotipos M. Objetivo: caracterizar S. pyogenes aislados de cuadros invasores mediante vir-RFLP para establecer relaciones entre cepas locales y extranjeras. Materiales y Métodos: se estudiaron 30 cepas de S. pyogenes aisladas de pacientes con cuadros invasores (SST/FN: 8; infecciones de piel y tejidos blandos: 13; infecciones de cavidades estériles: 9) mediante Long PCR-RFLP (amplificación regulón vir con partidores VUF y SBR, seguido de digestión con HaeIII). Resultados: 28/30 (93 por ciento) cepas presentaron regulones entre 4,2 - 7,8 Kb y dos entre 1,5 -1,6 Kb. Se establecieron 14 patrones vir-RFLP y 3 grupos génicos. Dos grupos génicos presentaron patrones similares a los descrito para los serotipos M y se asociaron a una determinada evolución clínica: grupo I, similar a M1 y asociado a infecciones de cavidades estériles; grupo III, similar a M3 y asociado a SST/FN. El grupo II fue heterogéneo en relación a los serotipos, pero concentró las cepas aisladas de infecciones de piel y tejidos blandos. Conclusiones: Las cepas de S. pyogenes aisladas de cuadros severos presentan gran diversidad génica. Sin embargo, tienden a agruparse según serotipos y a asociarse a una determinada evolución clínica destacándose la asociación entre vir-RFLP, tipo serotipo M3 y SST/FN. Las dos cepas con amplicones pequeños constituyen un hallazgo interesante, que requiere mayor investigación
Assuntos
Humanos , Regulon , Streptococcus pyogenes , Técnicas de Tipagem Bacteriana , Fasciite Necrosante , Polimorfismo Genético/genética , Choque Séptico/etiologia , Choque Séptico/microbiologia , Streptococcus pyogenesRESUMO
Background: The virulence of Streptococcus pyogenes is determined by a variety of structural molecules, toxins and complex enzymes. Pyrogenic exotoxins cause fever, erythematous reactions, cytotoxic and immunological effects. Aim: To assess the frequency of speA, speB and speC genes in Chilean Streptococcus pyogenes strains and their association with the invasiveness of infections. Material and methods: The genes for pyrogenic exotoxins SpeA, SpeB and SpeC were determined by polymerase chain reactions in 114 strains of group A Streptococcus pyogenes isolated from Chilean patients with invasive or non invasive infections. Results: The gene for SpeA was present in 30.7 percent of isolates, the gene for SpeB was present in 69.3 percent and the gen for SpeC in 44.7 percent of isolates. The gene for SpeA was present in 20 of 33 invasive infections and in 15 of 81 non invasive infections (p <0.0001). On the contrary, the gene for SpeC was present in 11 of 33 invasive infections and in 41 of 81 non invasive infections (p <0.05). The frequency of speB was similar in invasive and non invasive infections. Conclusions: There is a clear relationship between the presence of SpeA genes and the severity of infections caused by Streptococcus pyogenes
Assuntos
Streptococcus pyogenes/genética , Técnicas In Vitro , Reação em Cadeia da Polimerase , Exotoxinas/genética , Frequência do Gene , GenótipoRESUMO
Background: During the last decade, there has been a progressive increase in the resistance of gram (+) cocci to betalactamics and other antimicrobials. Therefore, vancomycin and teicoplanin have incorporated as alternative antimicrobial drugs. Aim: To assess the susceptibility of gram (+) cocci to different antimicrobials including vancomycin and teicoplanin. Material and methods: We studied 447 strains of gram (+) cocci coming from ambulatory and hospitalized patients. These included 308 enterococcus sp strains, 99 staphycoccus aureus strains and 40 coagulase negative staphylococci strains. Enterococci susceptibility was measured using minimal inhibitory concentrations in agar and that of staphylococci, through diffusion. Susceptibility to vancomycin and teicoplanin was measured using minimal inhibitory concentrations in all strains. Results: Enterococcus faecalis was 100 percent susceptible to ampicillin, penicillin, vancomycin and teicoplanin, 23 percent susceptible to tetracyclin and 47 percent to chloramphenicol. Susceptibility of E faecium was 61 percent to penicillin, 49 percent to chloramphenicol, 41 percent to tetracyclin, 100 percent to vancomycin and teicoplanin. Of 19 enterococcus spp strains, 90 percent were susceptible to ampicillin, 80 percent to penicillin, 55 percent to chloramphenicol and 45 percent to tetracyclin. Only one E casseiflavus strain had a low level resistance to vancomycin and was susceptible to teicoplanin. No staphylococcus aureus strain was resistant to vancomycin or teicoplanin. Conclusions: A permanent surveillance of gram (+) cocci antimicrobial susceptibility is required to update therapeutic schemes