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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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Bacterial load of specific serotypes/serogroups of pneumococcus in ARI cases and healthy children.Bacterial load of ARI cases (denoted by “1” in each serotype/serogroup) in red and healthy children (denoted by “0” in each serotype/serogroup) in blue, showed that the common serotypes 19F, 14, 23F, 6A/6B, 15B/15C had high bacterial load.
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pone-0110777-g003: Bacterial load of specific serotypes/serogroups of pneumococcus in ARI cases and healthy children.Bacterial load of ARI cases (denoted by “1” in each serotype/serogroup) in red and healthy children (denoted by “0” in each serotype/serogroup) in blue, showed that the common serotypes 19F, 14, 23F, 6A/6B, 15B/15C had high bacterial load.

Mentions: Higher bacterial load was associated with hospitalization due to ARI. The median bacterial load (total) was 6.61 log10/ml in ARI cases and 4.36 log10/ml in healthy children (OR = 9.96, 95%CI: 6.39–15.52; P<0.0001 and aOR = 9.07, 95%CI: 5.69–14.4; P<0.0001). There was no difference in median bacterial load between males and females both in ARI cases (6.62 log10 in male Vs. 6.59 log10 in female; p-value: 0.76) and healthy children (4.36 log10 in male Vs. 4.32 log10 in female; p-value: 0.86). Bacterial loads of specific serotypes/serogroups were higher in ARI cases than healthy children in all detected serotypes (Figure 3). Serotypes 14, 19F, 23F, 6A/6B had higher median bacterial load than other serotypes in ARI cases while serotypes 14, 19F, 23A, 23F had higher load in healthy children. The bacterial load of serotype 6C/6D was found to be lower than other common serotypes in ARI cases.


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)

Bacterial load of specific serotypes/serogroups of pneumococcus in ARI cases and healthy children.Bacterial load of ARI cases (denoted by “1” in each serotype/serogroup) in red and healthy children (denoted by “0” in each serotype/serogroup) in blue, showed that the common serotypes 19F, 14, 23F, 6A/6B, 15B/15C had high bacterial load.
© Copyright Policy
Related In: Results  -  Collection

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

pone-0110777-g003: Bacterial load of specific serotypes/serogroups of pneumococcus in ARI cases and healthy children.Bacterial load of ARI cases (denoted by “1” in each serotype/serogroup) in red and healthy children (denoted by “0” in each serotype/serogroup) in blue, showed that the common serotypes 19F, 14, 23F, 6A/6B, 15B/15C had high bacterial load.
Mentions: Higher bacterial load was associated with hospitalization due to ARI. The median bacterial load (total) was 6.61 log10/ml in ARI cases and 4.36 log10/ml in healthy children (OR = 9.96, 95%CI: 6.39–15.52; P<0.0001 and aOR = 9.07, 95%CI: 5.69–14.4; P<0.0001). There was no difference in median bacterial load between males and females both in ARI cases (6.62 log10 in male Vs. 6.59 log10 in female; p-value: 0.76) and healthy children (4.36 log10 in male Vs. 4.32 log10 in female; p-value: 0.86). Bacterial loads of specific serotypes/serogroups were higher in ARI cases than healthy children in all detected serotypes (Figure 3). Serotypes 14, 19F, 23F, 6A/6B had higher median bacterial load than other serotypes in ARI cases while serotypes 14, 19F, 23A, 23F had higher load in healthy children. The bacterial load of serotype 6C/6D was found to be lower than other common serotypes in ARI cases.

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