Evaluation of a medium for the conservation of Streptococcus pneumoniae in nasopharyngeal isolates

Abstract

The World Health Organization (WHO) reached a consensus on a core methodology for pneumococcal carrier studies in 1998. This methodology included a new medium to transport and to store nasopharyngeal samples, called skim milk-tryptone-glucose-glycerin (STGG). This medium was evaluated by our laboratory in March 1999 in a group of 15 children less than 5 years old attending a daycare center in Santa Fe de Bogotá. The nasopharyngeal samples were placed in the STGG medium and. subsequently, S. pneumoniae growih was semiquantified at 4 different times: 0, 5, 10 and 30 days. The initial recovety of S. pneumoniae was 73% (11/15). In the 11 samples with initial growth it was possible to isolate S. pneumoniae in all the different times of observation, even in samwles with individual colonies. At time O and 30 days after. 7 of 11 samples showed moderate and abundant growth. The data obtained in this study proved that STGG medium has the ability to maintain the S. peumoniae viable over time from nasopharyngeal samples collected from children carriers.