Affiliation:
1. Department of Medical Microbiology, University College London, Royal Free Campus, London NW3 2PF, United Kingdom
2. Tanganyika Planting Company
3. Clinical Laboratory, Kilimanjaro Christian Medical College, Tumaini University, Moshi, Tanzania
Abstract
ABSTRACT
The need to design effective
Streptococcus pneumoniae
vaccines and to monitor resistance means that it is essential to have efficient methods to determine carriage rates. Two liquid media, consisting of skim milk, glycerol, glucose, and tryptone soya broth (STGG) or skim milk, glycerol, and glucose (SGG) alone, were evaluated for their ability to maintain pneumococcal viability. Optimal recovery of
S. pneumoniae
was achieved when swabs were transferred to STGG medium prior to plating onto blood agar-gentamicin selective plates (22%) compared to 7% when plated out directly (
P
< 0.0001 by Fisher's exact test). Both STGG and SGG media are appropriate for the long-term storage of pneumococci and primary swab samples at −70°C, with no decrease in viable count observed following repeated freeze-thaw cycles. Samples could be stored refrigerated for up to 3 days in either STGG or SGG medium with no significant loss of viability. Viability decreased progressively in storage at 20 to 30°C, with greater losses of viability occurring at the higher temperatures. There were no significant differences in viability between isolates in the two media. STGG preserved pneumococci significantly better (about twofold) than SGG medium at 21°C (
P
< 0.0001) and 30°C (
P
< 0.0001). Samples can be stored for 4 and 2.5 days at 6 to 8°C, 28 and 17 h at 21°C, and 15 and 7 h at 30°C in STGG and SGG media, respectively. For field studies undertaken in resource-limited environments, SGG medium can be prepared by using locally available materials. The quantitative data reported in this study will enable researchers to plan appropriate transport and storage protocols.
Publisher
American Society for Microbiology
Reference23 articles.
1. Evaluation of sampling sites for detection of upper respiratory tract carriage of Streptococcus pneumoniae and Haemophilus influenzae among healthy Filipino infants
2. Coffey, T. J., M. C. Enright, M. Daniels, J. K. Morona, R. Morona, W. Hryniewicz, J. C. Paton, and B. G. Spratt. 1998. Recombinational exchanges at the capsular polysaccharide biosynthetic locus lead to frequent serotype changes among natural isolates of Streptococcus pneumoniae.Mol. Microbiol.27:73-83.
3. Fairchok, M. P., W. S. Ashton, and G. W. Fischer. 1996. Carriage of penicillin-resistant pneumococci in a military population in Washington, DC: risk factors and correlation with clinical isolates. Clin. Infect. Dis.22:966-972.
4. Gherna R. L. 1981. Preservation p. 208-217. In P. Gerhardt R. G. E. Murray R. N. Costilow E. W. Nester W. A. Wood N. R. Krieg and G. B. Philips (ed.) Manual for methods for general microbiology. American Society for Microbiology Washington D.C.
5. Gibson, L. F., and J. T. Khoury. 1986. Storage and survival of bacteria by ultra-freeze. Lett. Appl. Microbiol.3:127-129.
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