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Bacterial load of pneumococcal serotypes correlates with their prevalence and multiple serotypes is associated with acute respiratory infections among children less than 5 years of age.

Dhoubhadel BG, Yasunami M, Nguyen HA, Suzuki M, Vu TH, Thi Thuy Nguyen A, Dang DA, Yoshida LM, Ariyoshi K - PLoS ONE (2014)

Bottom Line: The dominant serotype in the co-colonization had a 2 log10 higher bacterial load than the subdominant serotype, both in ARI cases (P<0.001) and healthy children (P<0.05).High bacterial load in the nasopharynx may help transmit pneumococci among hosts, and increase the chance of successful acquisition and colonization.Co-colonization of multiple serotypes of pneumococci is linked with ARI, which infers the interactions of multiple serotypes may increase their pathogenicity; however, they may compete for growth in number.

View Article: PubMed Central - PubMed

Affiliation: Department of Clinical Medicine, Institute of Tropical Medicine, Nagasaki University, Nagasaki, Japan; Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan.

ABSTRACT

Background: Among pneumococcal serotypes, some serotypes are more prevalent in the nasopharynx than others; determining factors for higher prevalence remain to be fully explored. As non-vaccine serotypes have emerged after the introduction of 7-valent conjugate vaccines, study of serotype specific epidemiology is in need. When two or more serotypes co-colonize, they evolve rapidly to defend host's immune responses; however, a clear association of co-colonization with a clinical outcome is lacking.

Methods: Children less than 5 years old who were admitted to hospital due to acute respiratory infections (ARI) (n = 595) and healthy children (n = 350) were recruited. Carriage of pneumococcus was determined by culture and lytA PCR in the nasopharyngeal samples. Serotype/serogroup detection and its quantification were done by the nanofluidic real time PCR system. Spearman's correlation and logistic regression were used to examine a correlation of serotype/serogroup specific bacterial load with its prevalence and an association of co-colonization with ARI respectively.

Results: Serotype/serogroup specific bacterial load was correlated with its prevalence, both in ARI cases (Spearman's rho = 0.44, n = 186; P<0.0001) and healthy children (Spearman's rho = 0.41, n = 115; P<0.0001). The prevalence of multiple serotypes was more common in ARI cases than in healthy children (18.5% vs 7.1%; aOR 2.92, 95% CI: 1.27-6.71; P = 0.01). The dominant serotype in the co-colonization had a 2 log10 higher bacterial load than the subdominant serotype, both in ARI cases (P<0.001) and healthy children (P<0.05).

Conclusions: High bacterial load in the nasopharynx may help transmit pneumococci among hosts, and increase the chance of successful acquisition and colonization. Co-colonization of multiple serotypes of pneumococci is linked with ARI, which infers the interactions of multiple serotypes may increase their pathogenicity; however, they may compete for growth in number.

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Relationship between bacterial load of specific serotypes/serogroups and their prevalence.Bacterial load of each of specific serotypes/serogroups was plotted against its prevalence. Both in ARI cases (red) and in healthy children (blue), a positive correlation was found. Each dot represents an ARI case or a healthy child in the plot, and the red and blue lines are the fitted values for ARI cases and healthy children respectively. Spearman's rho was 0.44 (n = 186; P<0.0001) and 0.41 (n = 115; P<0.0001) for ARI cases and healthy children respectively.
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pone-0110777-g004: Relationship between bacterial load of specific serotypes/serogroups and their prevalence.Bacterial load of each of specific serotypes/serogroups was plotted against its prevalence. Both in ARI cases (red) and in healthy children (blue), a positive correlation was found. Each dot represents an ARI case or a healthy child in the plot, and the red and blue lines are the fitted values for ARI cases and healthy children respectively. Spearman's rho was 0.44 (n = 186; P<0.0001) and 0.41 (n = 115; P<0.0001) for ARI cases and healthy children respectively.

Mentions: Serotype/serogroup specific bacterial load was positively correlated with serotype/serogroup prevalence. Serotype/serogroup specific bacterial load of individual NPS samples from ARI cases and healthy children were plotted against the prevalence of individual serotype/serogroup (i.e., proportion of the serotypes/serogroups in carriage positive samples). We found that the serotype/serogroup specific bacterial load had positive correlation with its prevalence, both in ARI cases (Spearman's rho = 0.44, n = 186, P<0.0001) and healthy children (Spearman's rho = 0.41, n = 115, P<0.0001) (Figure 4).


Bacterial load of pneumococcal serotypes correlates with their prevalence and multiple serotypes is associated with acute respiratory infections among children less than 5 years of age.

Dhoubhadel BG, Yasunami M, Nguyen HA, Suzuki M, Vu TH, Thi Thuy Nguyen A, Dang DA, Yoshida LM, Ariyoshi K - PLoS ONE (2014)

Relationship between bacterial load of specific serotypes/serogroups and their prevalence.Bacterial load of each of specific serotypes/serogroups was plotted against its prevalence. Both in ARI cases (red) and in healthy children (blue), a positive correlation was found. Each dot represents an ARI case or a healthy child in the plot, and the red and blue lines are the fitted values for ARI cases and healthy children respectively. Spearman's rho was 0.44 (n = 186; P<0.0001) and 0.41 (n = 115; P<0.0001) for ARI cases and healthy children respectively.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4216008&req=5

pone-0110777-g004: Relationship between bacterial load of specific serotypes/serogroups and their prevalence.Bacterial load of each of specific serotypes/serogroups was plotted against its prevalence. Both in ARI cases (red) and in healthy children (blue), a positive correlation was found. Each dot represents an ARI case or a healthy child in the plot, and the red and blue lines are the fitted values for ARI cases and healthy children respectively. Spearman's rho was 0.44 (n = 186; P<0.0001) and 0.41 (n = 115; P<0.0001) for ARI cases and healthy children respectively.
Mentions: Serotype/serogroup specific bacterial load was positively correlated with serotype/serogroup prevalence. Serotype/serogroup specific bacterial load of individual NPS samples from ARI cases and healthy children were plotted against the prevalence of individual serotype/serogroup (i.e., proportion of the serotypes/serogroups in carriage positive samples). We found that the serotype/serogroup specific bacterial load had positive correlation with its prevalence, both in ARI cases (Spearman's rho = 0.44, n = 186, P<0.0001) and healthy children (Spearman's rho = 0.41, n = 115, P<0.0001) (Figure 4).

Bottom Line: The dominant serotype in the co-colonization had a 2 log10 higher bacterial load than the subdominant serotype, both in ARI cases (P<0.001) and healthy children (P<0.05).High bacterial load in the nasopharynx may help transmit pneumococci among hosts, and increase the chance of successful acquisition and colonization.Co-colonization of multiple serotypes of pneumococci is linked with ARI, which infers the interactions of multiple serotypes may increase their pathogenicity; however, they may compete for growth in number.

View Article: PubMed Central - PubMed

Affiliation: Department of Clinical Medicine, Institute of Tropical Medicine, Nagasaki University, Nagasaki, Japan; Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan.

ABSTRACT

Background: Among pneumococcal serotypes, some serotypes are more prevalent in the nasopharynx than others; determining factors for higher prevalence remain to be fully explored. As non-vaccine serotypes have emerged after the introduction of 7-valent conjugate vaccines, study of serotype specific epidemiology is in need. When two or more serotypes co-colonize, they evolve rapidly to defend host's immune responses; however, a clear association of co-colonization with a clinical outcome is lacking.

Methods: Children less than 5 years old who were admitted to hospital due to acute respiratory infections (ARI) (n = 595) and healthy children (n = 350) were recruited. Carriage of pneumococcus was determined by culture and lytA PCR in the nasopharyngeal samples. Serotype/serogroup detection and its quantification were done by the nanofluidic real time PCR system. Spearman's correlation and logistic regression were used to examine a correlation of serotype/serogroup specific bacterial load with its prevalence and an association of co-colonization with ARI respectively.

Results: Serotype/serogroup specific bacterial load was correlated with its prevalence, both in ARI cases (Spearman's rho = 0.44, n = 186; P<0.0001) and healthy children (Spearman's rho = 0.41, n = 115; P<0.0001). The prevalence of multiple serotypes was more common in ARI cases than in healthy children (18.5% vs 7.1%; aOR 2.92, 95% CI: 1.27-6.71; P = 0.01). The dominant serotype in the co-colonization had a 2 log10 higher bacterial load than the subdominant serotype, both in ARI cases (P<0.001) and healthy children (P<0.05).

Conclusions: High bacterial load in the nasopharynx may help transmit pneumococci among hosts, and increase the chance of successful acquisition and colonization. Co-colonization of multiple serotypes of pneumococci is linked with ARI, which infers the interactions of multiple serotypes may increase their pathogenicity; however, they may compete for growth in number.

Show MeSH
Related in: MedlinePlus