Limits...
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.

Show MeSH

Related in: MedlinePlus

Distribution of co-colonization of multiple serotypes of pneumococcus.In ARI cases (red) co-colonization was detected in 36 samples out of 194 lytA positive samples (18.5%), while in healthy children (blue) it was detected in 10 samples out of 140 (7.1%) lytA positive samples. The odds ratio, adjusted for age, sex and daycare, was 2.92 (95%CI 1.27–6.71; P = 0.012). The serotypes/serogroups were positioned first and second according to their bacterial load.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4216008&req=5

pone-0110777-g005: Distribution of co-colonization of multiple serotypes of pneumococcus.In ARI cases (red) co-colonization was detected in 36 samples out of 194 lytA positive samples (18.5%), while in healthy children (blue) it was detected in 10 samples out of 140 (7.1%) lytA positive samples. The odds ratio, adjusted for age, sex and daycare, was 2.92 (95%CI 1.27–6.71; P = 0.012). The serotypes/serogroups were positioned first and second according to their bacterial load.

Mentions: Co-colonization of multiple serotypes of pneumococci was associated with ARI. Co-colonization of multiple-serotypes was detected in 18.5% (n = 36/194) in ARI cases and 7.1% (n = 10/140) in healthy children (OR 2.96, 95%CI 1.41–6.19; P = 0.004). When adjusted for age, sex and daycare, the adjusted odds ratio (aOR) was 2.92 (95%CI 1.27–6.71; P = 0.012). Co-colonization of serotypes 19F and 11, 19F and 15B/15C, 23F and 6A/6B occurred more frequently in ARI cases. We observed none of the serotypes involved in co-colonization were 19A or 35B (Figure 5). Co-colonization of pneumococcus occurred in 18.56% (18/97) of ARI cases when pre-hospital antibiotics had been used and 38.71% (12/31) when no antibiotics were used (P = 0.002) [Unknown antibiotic status in 9.09% (6/66) of ARI cases]. The prevalence of co-colonization was found to be higher 32.5% (13/40) in age group of less than 6 months of age than 14.94% (23/154) in age group of 6 or more than 6 months of age in ARI cases (P = 0.01). But, we did not find any such difference in healthy children among these age groups, 0% (0/16) versus 7.04% (10/124) (P = 0.60).


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)

Distribution of co-colonization of multiple serotypes of pneumococcus.In ARI cases (red) co-colonization was detected in 36 samples out of 194 lytA positive samples (18.5%), while in healthy children (blue) it was detected in 10 samples out of 140 (7.1%) lytA positive samples. The odds ratio, adjusted for age, sex and daycare, was 2.92 (95%CI 1.27–6.71; P = 0.012). The serotypes/serogroups were positioned first and second according to their bacterial load.
© Copyright Policy
Related In: Results  -  Collection

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

pone-0110777-g005: Distribution of co-colonization of multiple serotypes of pneumococcus.In ARI cases (red) co-colonization was detected in 36 samples out of 194 lytA positive samples (18.5%), while in healthy children (blue) it was detected in 10 samples out of 140 (7.1%) lytA positive samples. The odds ratio, adjusted for age, sex and daycare, was 2.92 (95%CI 1.27–6.71; P = 0.012). The serotypes/serogroups were positioned first and second according to their bacterial load.
Mentions: Co-colonization of multiple serotypes of pneumococci was associated with ARI. Co-colonization of multiple-serotypes was detected in 18.5% (n = 36/194) in ARI cases and 7.1% (n = 10/140) in healthy children (OR 2.96, 95%CI 1.41–6.19; P = 0.004). When adjusted for age, sex and daycare, the adjusted odds ratio (aOR) was 2.92 (95%CI 1.27–6.71; P = 0.012). Co-colonization of serotypes 19F and 11, 19F and 15B/15C, 23F and 6A/6B occurred more frequently in ARI cases. We observed none of the serotypes involved in co-colonization were 19A or 35B (Figure 5). Co-colonization of pneumococcus occurred in 18.56% (18/97) of ARI cases when pre-hospital antibiotics had been used and 38.71% (12/31) when no antibiotics were used (P = 0.002) [Unknown antibiotic status in 9.09% (6/66) of ARI cases]. The prevalence of co-colonization was found to be higher 32.5% (13/40) in age group of less than 6 months of age than 14.94% (23/154) in age group of 6 or more than 6 months of age in ARI cases (P = 0.01). But, we did not find any such difference in healthy children among these age groups, 0% (0/16) versus 7.04% (10/124) (P = 0.60).

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