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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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Dominance of one serotype/serogroup over the other in co-colonization of multiple serotypes/serogroups.Among two serotypes/serogroups present in a co-colonization, one serotype/serogroup (red) was found to be dominant by having 100 folds (2 log10) higher bacterial load than the other subdominant (blue) serotype/serogroup both in ARI cases and healthy children.
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pone-0110777-g006: Dominance of one serotype/serogroup over the other in co-colonization of multiple serotypes/serogroups.Among two serotypes/serogroups present in a co-colonization, one serotype/serogroup (red) was found to be dominant by having 100 folds (2 log10) higher bacterial load than the other subdominant (blue) serotype/serogroup both in ARI cases and healthy children.

Mentions: One serotype/serogroup dominated the other serotype/serogroups in co-colonization. In co-colonization, the serotype/serogroup specific bacterial load was 2.45 log10 higher in the dominant serotypes than the subdominant serotypes in ARI cases, while it was 2.04 log10 higher in healthy children (Figure 6). The dominant serotype was a vaccine serotype in 100% (10/10) of co-colonization in healthy children (P = 0.003); while it was vaccine serotypes only in 72.22% (26/36) of co-colonization in ARI cases (P = 0.76). The median total bacterial load was higher, 4.81 log10 versus 4.31 log10 (P = 0.03), when co-colonization of multiple serotypes was present as compared to single serotype colonization in healthy children; however, no significant difference was found among them in ARI cases (6.65 log10 versus 6.58 log10, P = 0.59).


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)

Dominance of one serotype/serogroup over the other in co-colonization of multiple serotypes/serogroups.Among two serotypes/serogroups present in a co-colonization, one serotype/serogroup (red) was found to be dominant by having 100 folds (2 log10) higher bacterial load than the other subdominant (blue) serotype/serogroup both in ARI cases and healthy children.
© Copyright Policy
Related In: Results  -  Collection

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

pone-0110777-g006: Dominance of one serotype/serogroup over the other in co-colonization of multiple serotypes/serogroups.Among two serotypes/serogroups present in a co-colonization, one serotype/serogroup (red) was found to be dominant by having 100 folds (2 log10) higher bacterial load than the other subdominant (blue) serotype/serogroup both in ARI cases and healthy children.
Mentions: One serotype/serogroup dominated the other serotype/serogroups in co-colonization. In co-colonization, the serotype/serogroup specific bacterial load was 2.45 log10 higher in the dominant serotypes than the subdominant serotypes in ARI cases, while it was 2.04 log10 higher in healthy children (Figure 6). The dominant serotype was a vaccine serotype in 100% (10/10) of co-colonization in healthy children (P = 0.003); while it was vaccine serotypes only in 72.22% (26/36) of co-colonization in ARI cases (P = 0.76). The median total bacterial load was higher, 4.81 log10 versus 4.31 log10 (P = 0.03), when co-colonization of multiple serotypes was present as compared to single serotype colonization in healthy children; however, no significant difference was found among them in ARI cases (6.65 log10 versus 6.58 log10, P = 0.59).

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