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

Participants recruited into the study, and their nasopharyngeal samples.Half of the aliquot of nasopharyngeal samples were cultured overnight in 5% sheep blood agar with 5% CO2 at 37°C. DNA was extracted directly from the other half of the aliquot of the nasopharyngeal samples which yielded alpha hemolytic colonies and positive Optochin test. DNA was subjected to lytA PCR to confirm pneumococcus; and lytA positive samples were then processed for molecular serotyping in the nanofluidic real time PCR system.
© Copyright Policy
Related In: Results  -  Collection

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

pone-0110777-g001: Participants recruited into the study, and their nasopharyngeal samples.Half of the aliquot of nasopharyngeal samples were cultured overnight in 5% sheep blood agar with 5% CO2 at 37°C. DNA was extracted directly from the other half of the aliquot of the nasopharyngeal samples which yielded alpha hemolytic colonies and positive Optochin test. DNA was subjected to lytA PCR to confirm pneumococcus; and lytA positive samples were then processed for molecular serotyping in the nanofluidic real time PCR system.

Mentions: Pneumococcal carriage rate was 32.6% (194/595) in ARI cases and 40% (140/350) in healthy children (figure 1). The proportion of typeable serotypes in ARI cases and healthy children were 95.9% (186/194) and 82.1% (115/140) respectively. Thirteen serotypes/serogroups of pneumococcus were detected in ARI cases and healthy children (figure 2). Serotypes/serogroups 19F, 6A/6B, 23F and 6C/6D were more prevalent in hospitalized ARI cases while serotypes/serogroups 14, 6A/6B, 19F, 15B/15C, 11 and non-typeables (NT) were common in healthy children. The proportion of serotypes/serogroups covered by pneumococcal conjugate vaccines: 7-valent (PCV7), 10-valent (PCV10) and 13-valent (PCV13) were approximately equal to one another, which was about 74% in ARI cases and 55% in healthy children (this was an approximate estimation as a serogroup was treated as a serotype as required).


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)

Participants recruited into the study, and their nasopharyngeal samples.Half of the aliquot of nasopharyngeal samples were cultured overnight in 5% sheep blood agar with 5% CO2 at 37°C. DNA was extracted directly from the other half of the aliquot of the nasopharyngeal samples which yielded alpha hemolytic colonies and positive Optochin test. DNA was subjected to lytA PCR to confirm pneumococcus; and lytA positive samples were then processed for molecular serotyping in the nanofluidic real time PCR system.
© Copyright Policy
Related In: Results  -  Collection

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

pone-0110777-g001: Participants recruited into the study, and their nasopharyngeal samples.Half of the aliquot of nasopharyngeal samples were cultured overnight in 5% sheep blood agar with 5% CO2 at 37°C. DNA was extracted directly from the other half of the aliquot of the nasopharyngeal samples which yielded alpha hemolytic colonies and positive Optochin test. DNA was subjected to lytA PCR to confirm pneumococcus; and lytA positive samples were then processed for molecular serotyping in the nanofluidic real time PCR system.
Mentions: Pneumococcal carriage rate was 32.6% (194/595) in ARI cases and 40% (140/350) in healthy children (figure 1). The proportion of typeable serotypes in ARI cases and healthy children were 95.9% (186/194) and 82.1% (115/140) respectively. Thirteen serotypes/serogroups of pneumococcus were detected in ARI cases and healthy children (figure 2). Serotypes/serogroups 19F, 6A/6B, 23F and 6C/6D were more prevalent in hospitalized ARI cases while serotypes/serogroups 14, 6A/6B, 19F, 15B/15C, 11 and non-typeables (NT) were common in healthy children. The proportion of serotypes/serogroups covered by pneumococcal conjugate vaccines: 7-valent (PCV7), 10-valent (PCV10) and 13-valent (PCV13) were approximately equal to one another, which was about 74% in ARI cases and 55% in healthy children (this was an approximate estimation as a serogroup was treated as a serotype as required).

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