Cinco años de experiencia en conservación de streptococcus agalactiae: comparación de dos metodologías alternativas

Abstract

Streptococcus agalactiae (SGB) es responsable de enfermedad neonatal severa entre otras patologias. Actualmente existe la necesidad de la conservacion para investigaciones que incluyan: busqueda de genes de virulencia y resistencia antimicrobiana, estudios epidemiologicos, desarrollos biotecnologicos y envios a centros de referencia. El objetivo de este trabajo fue comparar dos metodos de conservacion: Tripteina Soya Agar al 7‰ a temperatura ambiente y oscuridad (ATS-S) y leche descremada al 20% a -80 .C (LD-80). Ciento cincuenta cepas fueron evaluadas a los tres, doce y sesenta meses. Luego del tiempo de conservacion se comprobo su viabilidad, pureza, estabilidad antigenica y genetica. Para cada periodo estudiado, los porcentajes de recuperacion fueron: 100%, 80% y 15,33% para ATS-S y 100%, 100% y 98,66% para LD-80. A partir de los 12 meses existieron diferencias significativas (p<0,05) entre ambos metodos. Concluimos que LD-80 es altamente eficaz para conservar cepas de SGB con porcentajes de recuperacion cercanos al 100%.

Streptococcus agalactiae (GBS) is responsible for severe neonatal disease and other pathologies. Currently, there is a need to conserve it to carry on studies involving the search for genes of virulence and antimicrobial resistance, epidemiological studies, biotechnological developments and shipments to referral centers. The aim of this study was to compare two methods of conservation of Streptococcus agalactiae: Trypticase Soy Agar (ATS-S) to 7‰ at room temperature and darkness and skim milk at 20% at -80 .C (LD-80). One hundred and fifty strains were evaluated at three, twelve to sixty months. After shelf viability, purity, antigenic and genetic stability were verified. Recovery rates were: 100%, 80% and 15.33% for ATS-S and 100%, 100% and 98.66% for LD-80 for each period studied. Significant differences (p <0.05) were found between the two methods after the twelfth month. We conclude that LD-80 is highly effective to conserve GBS strains with recovery rates nearly a 100%.