In vitro growth of pneumococcal isolates representing 23 different serotypes
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Published on: April 28, 2014
Hans-Christian Slotved1, Catherine Satzke
1Department of Microbiology and Infection Control, Statens Serum Institut, Copenhagen, Denmark. hcs@ssi.dk
Background:
Although there are established methodologies for pneumococcal carriage studies, recent studies have extended these by conducting a culture amplification step prior to pneumococcal identification or serotyping. However, few data are available comparing the growth of different serotypes.
Findings:
We compared the growth of individual isolates representing 23 serotypes in serum broth, and Todd-Hewitt broth from four different manufacturers. Following overnight incubation of low inocula, there were differences in the final growth densities of individual isolates. These can be minimised with the use of optimal media.
Conclusions:
These data caution against using broth culture amplification of nasopharyngeal samples for some applications.
Insights
Culture amplification for pneumococcal carriage studies can alter the growth of different Streptococcus pneumoniae serotypes. Optimal media selection is crucial to minimize growth differences, but caution is advised for some applications.
Area of Science:
- Microbiology
- Immunology
- Public Health
Background:
- Established methods for pneumococcal carriage studies exist.
- Recent studies incorporate culture amplification before identification or serotyping.
- Limited data compare the growth of different Streptococcus pneumoniae serotypes.
Purpose of the Study:
- To compare the in vitro growth of individual Streptococcus pneumoniae serotypes.
- To evaluate the impact of different broth media on pneumococcal growth.
- To inform the application of culture amplification in carriage studies.
Main Methods:
- Compared growth of 23 Streptococcus pneumoniae serotypes in serum broth and Todd-Hewitt broth from four manufacturers.
- Incubated low inocula overnight.
- Assessed final growth densities.
Main Results:
- Observed differences in final growth densities among individual Streptococcus pneumoniae serotypes.
- Growth differences were minimized using optimal media.
- Variability in growth was noted across different broth manufacturers.
Conclusions:
- Broth culture amplification may not be suitable for all applications in pneumococcal carriage studies.
- Serotype-specific growth characteristics can influence study outcomes.
- Careful selection of culture media is essential.
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