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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

S. pneumoniae D39 survival after desiccation. Bacteria were rehydrated and plated after 1 hour to 28 days of desiccation to determine viability. Data were pooled from multiple biological replicate experiments. Open circles represent individual samples, and bars show the medians.
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f1: S. pneumoniae D39 survival after desiccation. Bacteria were rehydrated and plated after 1 hour to 28 days of desiccation to determine viability. Data were pooled from multiple biological replicate experiments. Open circles represent individual samples, and bars show the medians.

Mentions: To examine the ability of S. pneumoniae to withstand dehydration, we developed a desiccation protocol. Encapsulated S. pneumoniae strain D39 (serotype 2) was grown overnight on blood agar, scraped off the plate, evenly divided, and spread thinly onto four polystyrene petri dish lids. The bacteria from one lid were immediately resuspended in Todd-Hewitt broth supplemented with yeast extract (THY; initial time point [T0]), and the other three lids were desiccated in the dark under ambient conditions for predetermined times prior to rehydration. The number of viable cells per lid was determined by plating serial dilutions on blood agar and counting the resultant colonies, and the percent survival was calculated by dividing the time point by the T0 viable count. Our results show that S. pneumoniae survives desiccation periods of at least 4 weeks at ambient temperature and humidity (Fig. 1).


Streptococcus pneumoniae is desiccation tolerant and infectious upon rehydration.

Walsh RL, Camilli A - MBio (2011)

S. pneumoniae D39 survival after desiccation. Bacteria were rehydrated and plated after 1 hour to 28 days of desiccation to determine viability. Data were pooled from multiple biological replicate experiments. Open circles represent individual samples, and bars show the medians.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f1: S. pneumoniae D39 survival after desiccation. Bacteria were rehydrated and plated after 1 hour to 28 days of desiccation to determine viability. Data were pooled from multiple biological replicate experiments. Open circles represent individual samples, and bars show the medians.
Mentions: To examine the ability of S. pneumoniae to withstand dehydration, we developed a desiccation protocol. Encapsulated S. pneumoniae strain D39 (serotype 2) was grown overnight on blood agar, scraped off the plate, evenly divided, and spread thinly onto four polystyrene petri dish lids. The bacteria from one lid were immediately resuspended in Todd-Hewitt broth supplemented with yeast extract (THY; initial time point [T0]), and the other three lids were desiccated in the dark under ambient conditions for predetermined times prior to rehydration. The number of viable cells per lid was determined by plating serial dilutions on blood agar and counting the resultant colonies, and the percent survival was calculated by dividing the time point by the T0 viable count. Our results show that S. pneumoniae survives desiccation periods of at least 4 weeks at ambient temperature and humidity (Fig. 1).

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