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Updated: May 4, 2026
Microtiter Dish Biofilm Formation Assay
Published on: January 30, 2011
Biofilm formation enhances fomite survival of Streptococcus pneumoniae and Streptococcus pyogenes
Laura R Marks1, Ryan M Reddinger, Anders P Hakansson
1Department of Microbiology and Immunology, University at Buffalo, State University of New York, Buffalo, New York, USA.
Abstract:
Both Streptococcus pyogenes and Streptococcus pneumoniae are widely thought to rapidly die outside the human host, losing infectivity following desiccation in the environment. However, to date, all literature investigating the infectivity of desiccated streptococci has used broth-grown, planktonic populations. In this study, we examined the impact of biofilm formation on environmental survival of clinical and laboratory isolates of S. pyogenes and S. pneumoniae as both organisms are thought to colonize the human host as biofilms. Results clearly demonstrate that while planktonic cells that are desiccated rapidly lose viability both on hands and abiotic surfaces, such as plastic, biofilm bacteria remain viable over extended periods of time outside the host and remain infectious in a murine colonization model. To explore the level and extent of streptococcal fomite contamination that children might be exposed to naturally, direct bacteriologic cultures of items in a day care center were conducted, which demonstrated high levels of viable streptococci of both species. These findings raise the possibility that streptococci may survive in the environment and be transferred from person to person via fomites contaminated with oropharyngeal secretions containing biofilm streptococci.
Insights
Biofilm formation enhances survival of Streptococcus pyogenes and Streptococcus pneumoniae outside the human host. Biofilm bacteria remain viable and infectious on surfaces, unlike planktonic cells.
Area of Science:
- Microbiology
- Environmental Science
- Infectious Diseases
Background:
- Streptococcus pyogenes and Streptococcus pneumoniae are typically considered fragile outside the human host.
- Previous studies on environmental survival used planktonic (free-floating) bacterial cells.
Purpose of the Study:
- To investigate the impact of biofilm formation on the environmental survival and infectivity of Streptococcus pyogenes and Streptococcus pneumoniae.
- To assess natural streptococcal contamination levels in a daycare setting.
Main Methods:
- Culturing clinical and laboratory isolates of S. pyogenes and S. pneumoniae in biofilm and planktonic forms.
- Assessing viability of desiccated bacteria on hands and abiotic surfaces.
- Testing infectivity in a murine colonization model.
- Conducting bacteriologic cultures of fomites in a daycare center.
Main Results:
- Planktonic streptococci rapidly lost viability upon desiccation on hands and surfaces.
- Biofilm-grown streptococci remained viable for extended periods on surfaces.
- Biofilm bacteria retained infectivity in a murine model.
- Daycare fomites showed high levels of viable streptococci.
Conclusions:
- Biofilm formation significantly enhances the environmental survival of S. pyogenes and S. pneumoniae.
- Streptococci in biofilms may persist on fomites and contribute to person-to-person transmission.
- Findings challenge the notion of rapid streptococcal death outside the host.
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