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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 versus nutrient deprivation. Bacteria were recovered 6, 24, or 48 hours after desiccation or starvation on PBS agar, and viability was determined. Closed circles represent desiccated samples, open circles represent starved samples, and bars show the medians. The probability that medians differ at each time point is shown by asterisks. *, P < 0.05; **, P < 0.001 (two-way ANOVA with Bonferroni posttest correction).
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f2: S. pneumoniae D39 survival after desiccation versus nutrient deprivation. Bacteria were recovered 6, 24, or 48 hours after desiccation or starvation on PBS agar, and viability was determined. Closed circles represent desiccated samples, open circles represent starved samples, and bars show the medians. The probability that medians differ at each time point is shown by asterisks. *, P < 0.05; **, P < 0.001 (two-way ANOVA with Bonferroni posttest correction).

Mentions: Numerous forces that contribute to bacterial cell death over time are at work during desiccation (21, 22, 27). It is possible that cell death of S. pneumoniae is due primarily to nutrient deprivation, regardless of other factors. To test this, we conducted simultaneous experiments under two conditions, desiccation and starvation with maintenance of hydration. The desiccated samples were treated as described above, while the starved samples were spread onto phosphate-buffered saline (PBS) agar plates rather than polystyrene petri dishes. All samples were placed in the dark under ambient conditions for 6, 24, or 48 h prior to collection for comparison to the T0 viable count. We saw a significant difference in bacterial recovery between the desiccated and starved samples (Fig. 2), with the starved samples losing viability at a much higher rate than the desiccated samples. The starved samples underwent a shift from slightly higher survival after 6 h (P < 0.05) to lower survival at 24 h (P < 0.05) and 48 h (P < 0.001), confirming that nutrient deprivation is a different phenomenon than dehydration.


Streptococcus pneumoniae is desiccation tolerant and infectious upon rehydration.

Walsh RL, Camilli A - MBio (2011)

S. pneumoniae D39 survival after desiccation versus nutrient deprivation. Bacteria were recovered 6, 24, or 48 hours after desiccation or starvation on PBS agar, and viability was determined. Closed circles represent desiccated samples, open circles represent starved samples, and bars show the medians. The probability that medians differ at each time point is shown by asterisks. *, P < 0.05; **, P < 0.001 (two-way ANOVA with Bonferroni posttest correction).
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f2: S. pneumoniae D39 survival after desiccation versus nutrient deprivation. Bacteria were recovered 6, 24, or 48 hours after desiccation or starvation on PBS agar, and viability was determined. Closed circles represent desiccated samples, open circles represent starved samples, and bars show the medians. The probability that medians differ at each time point is shown by asterisks. *, P < 0.05; **, P < 0.001 (two-way ANOVA with Bonferroni posttest correction).
Mentions: Numerous forces that contribute to bacterial cell death over time are at work during desiccation (21, 22, 27). It is possible that cell death of S. pneumoniae is due primarily to nutrient deprivation, regardless of other factors. To test this, we conducted simultaneous experiments under two conditions, desiccation and starvation with maintenance of hydration. The desiccated samples were treated as described above, while the starved samples were spread onto phosphate-buffered saline (PBS) agar plates rather than polystyrene petri dishes. All samples were placed in the dark under ambient conditions for 6, 24, or 48 h prior to collection for comparison to the T0 viable count. We saw a significant difference in bacterial recovery between the desiccated and starved samples (Fig. 2), with the starved samples losing viability at a much higher rate than the desiccated samples. The starved samples underwent a shift from slightly higher survival after 6 h (P < 0.05) to lower survival at 24 h (P < 0.05) and 48 h (P < 0.001), confirming that nutrient deprivation is a different phenomenon than dehydration.

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