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Streptococcus pneumoniae is desiccation tolerant and infectious upon rehydration.

Walsh RL, Camilli A - MBio (2011)

Bottom Line: Desiccation tolerance has been to shown to be essential for long-term survival on dry surfaces.Every year, there are approximately 7 million cases of pneumococcus-based otitis media in the United States alone, while pneumococcal invasive diseases are responsible for more than 1 million deaths globally.Our results suggest that desiccation tolerance is an inherent trait of this genetically variable species and that fomites may be a source of transmission.

View Article: PubMed Central - PubMed

Affiliation: Graduate Program in Molecular Microbiology, Sackler School of Graduate Biomedical Science, Howard Hughes Medical Institute and Department of Molecular Biology and Microbiology, School of Medicine, Tufts University, Boston, Massachusetts, USA.

ABSTRACT

Unlabelled: Streptococcus pneumoniae (pneumococcus) is a frequent colonizer of the nasopharynx and one of the leading causative agents of otitis media, pneumonia, and meningitis. The current literature asserts that S. pneumoniae is transmitted person to person via respiratory droplets; however, environmental surfaces (fomites) have been linked to the spread of other respiratory pathogens. Desiccation tolerance has been to shown to be essential for long-term survival on dry surfaces. This study investigated the survival and infectivity of S. pneumoniae following desiccation under ambient conditions. We recovered viable bacteria after all desiccation periods tested, ranging from 1 h to 4 weeks. Experiments conducted under nutrient limitation indicate that desiccation is a condition separate from starvation. Desiccation of an acapsular mutant and 15 different clinical isolates shows that S. pneumoniae desiccation tolerance is independent of the polysaccharide capsule and is a species-wide phenomenon, respectively. Experiments demonstrating that nondesiccated and desiccated S. pneumoniae strains colonize the nasopharynx at comparable levels, combined with their ability to survive long-term desiccation, suggest that fomites may serve as alternate sources of pneumococcal infection.

Importance: Even with the advent of multivalent capsular polysaccharide conjugate vaccines, S. pneumoniae continues to be a major cause of morbidity and mortality worldwide. Every year, there are approximately 7 million cases of pneumococcus-based otitis media in the United States alone, while pneumococcal invasive diseases are responsible for more than 1 million deaths globally. It is believed that the human upper respiratory tract is the sole niche of S. pneumoniae and, thus, that spread occurs via close contact with an infected individual. In this study, we characterized the desiccation tolerance of S. pneumoniae and found that it can survive for many weeks postdehydration and retain infectivity. Our results suggest that desiccation tolerance is an inherent trait of this genetically variable species and that fomites may be a source of transmission.

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Related in: MedlinePlus

Desiccation tolerance of S. pneumoniae D39 (encapsulated) and its acapsular derivative AC326. Bacteria were recovered 4 to 168 hours after desiccation. Data for D39 with the capsule (white) and without the capsule (gray) are shown as the median values (n = 4), and bars represent the ranges.
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f3: Desiccation tolerance of S. pneumoniae D39 (encapsulated) and its acapsular derivative AC326. Bacteria were recovered 4 to 168 hours after desiccation. Data for D39 with the capsule (white) and without the capsule (gray) are shown as the median values (n = 4), and bars represent the ranges.

Mentions: As research has indicated that Gram-positive bacteria survive desiccation better than their Gram-negative counterparts (28–30), we wondered if the polysaccharide capsule of S. pneumoniae contributes to its ability to withstand desiccation. A capsule is present in essentially all S. pneumoniae clinical isolates and is required for efficient host colonization as well as invasive disease (4, 31, 32). To assess the role of the capsule in desiccation tolerance, we compared the survival of D39 to that of an acapsular derivative, AC326. We saw no significant difference in bacterial viability at any time point at up to 1 week of desiccation (Fig. 3), leading us to conclude that the capsule is not an important factor in surviving desiccation. An anti-type 2 capsule Western blot demonstrated the presence of the capsule in cells desiccated for 1, 2, or 7 days, confirming that the lack of phenotypic difference between D39 and the acapsular strain is not due to D39 downregulating production of the capsule, and thus appearing acapsular, during desiccation (data not shown).


Streptococcus pneumoniae is desiccation tolerant and infectious upon rehydration.

Walsh RL, Camilli A - MBio (2011)

Desiccation tolerance of S. pneumoniae D39 (encapsulated) and its acapsular derivative AC326. Bacteria were recovered 4 to 168 hours after desiccation. Data for D39 with the capsule (white) and without the capsule (gray) are shown as the median values (n = 4), and bars represent the ranges.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3101785&req=5

f3: Desiccation tolerance of S. pneumoniae D39 (encapsulated) and its acapsular derivative AC326. Bacteria were recovered 4 to 168 hours after desiccation. Data for D39 with the capsule (white) and without the capsule (gray) are shown as the median values (n = 4), and bars represent the ranges.
Mentions: As research has indicated that Gram-positive bacteria survive desiccation better than their Gram-negative counterparts (28–30), we wondered if the polysaccharide capsule of S. pneumoniae contributes to its ability to withstand desiccation. A capsule is present in essentially all S. pneumoniae clinical isolates and is required for efficient host colonization as well as invasive disease (4, 31, 32). To assess the role of the capsule in desiccation tolerance, we compared the survival of D39 to that of an acapsular derivative, AC326. We saw no significant difference in bacterial viability at any time point at up to 1 week of desiccation (Fig. 3), leading us to conclude that the capsule is not an important factor in surviving desiccation. An anti-type 2 capsule Western blot demonstrated the presence of the capsule in cells desiccated for 1, 2, or 7 days, confirming that the lack of phenotypic difference between D39 and the acapsular strain is not due to D39 downregulating production of the capsule, and thus appearing acapsular, during desiccation (data not shown).

Bottom Line: Desiccation tolerance has been to shown to be essential for long-term survival on dry surfaces.Every year, there are approximately 7 million cases of pneumococcus-based otitis media in the United States alone, while pneumococcal invasive diseases are responsible for more than 1 million deaths globally.Our results suggest that desiccation tolerance is an inherent trait of this genetically variable species and that fomites may be a source of transmission.

View Article: PubMed Central - PubMed

Affiliation: Graduate Program in Molecular Microbiology, Sackler School of Graduate Biomedical Science, Howard Hughes Medical Institute and Department of Molecular Biology and Microbiology, School of Medicine, Tufts University, Boston, Massachusetts, USA.

ABSTRACT

Unlabelled: Streptococcus pneumoniae (pneumococcus) is a frequent colonizer of the nasopharynx and one of the leading causative agents of otitis media, pneumonia, and meningitis. The current literature asserts that S. pneumoniae is transmitted person to person via respiratory droplets; however, environmental surfaces (fomites) have been linked to the spread of other respiratory pathogens. Desiccation tolerance has been to shown to be essential for long-term survival on dry surfaces. This study investigated the survival and infectivity of S. pneumoniae following desiccation under ambient conditions. We recovered viable bacteria after all desiccation periods tested, ranging from 1 h to 4 weeks. Experiments conducted under nutrient limitation indicate that desiccation is a condition separate from starvation. Desiccation of an acapsular mutant and 15 different clinical isolates shows that S. pneumoniae desiccation tolerance is independent of the polysaccharide capsule and is a species-wide phenomenon, respectively. Experiments demonstrating that nondesiccated and desiccated S. pneumoniae strains colonize the nasopharynx at comparable levels, combined with their ability to survive long-term desiccation, suggest that fomites may serve as alternate sources of pneumococcal infection.

Importance: Even with the advent of multivalent capsular polysaccharide conjugate vaccines, S. pneumoniae continues to be a major cause of morbidity and mortality worldwide. Every year, there are approximately 7 million cases of pneumococcus-based otitis media in the United States alone, while pneumococcal invasive diseases are responsible for more than 1 million deaths globally. It is believed that the human upper respiratory tract is the sole niche of S. pneumoniae and, thus, that spread occurs via close contact with an infected individual. In this study, we characterized the desiccation tolerance of S. pneumoniae and found that it can survive for many weeks postdehydration and retain infectivity. Our results suggest that desiccation tolerance is an inherent trait of this genetically variable species and that fomites may be a source of transmission.

Show MeSH
Related in: MedlinePlus