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Streptococcus pneumoniae serotype 19A in children, South Korea.

Choi EH, Kim SH, Eun BW, Kim SJ, Kim NH, Lee J, Lee HJ - Emerging Infect. Dis. (2008)

Bottom Line: Overall, the proportion of serotype 19A isolates increased but serotype 19F decreased.Among children <5 years of age, the proportion of serotype 19A isolates in invasive pneumococcal disease increased from 0% in 1991-1994 to 8%-10% in 1995-2000, reached 26% in 2001-2003, and remained at 20% in 2004-2006 when vaccine coverage did not exceed 25% (p = 0.005 for trend).This study demonstrates that the expansion of multidrug-resistant ST320 was responsible for the increase in serotype 19A before PCV7 use.

View Article: PubMed Central - PubMed

Affiliation: Seoul National University College of Medicine, Seoul, South Korea.

ABSTRACT
Despite the concern of replacement disease, notably by serotype 19A after 7-valent conjugate vaccine (PCV7) use, serotype 19A was increasingly recognized in Korean children before the introduction of PCV7. To understand the dynamics of serogroup 19 prevalence from 1991-2006, we serotyped 538 pediatric pneumococcal isolates. Serogroup 19 isolates (n = 126) were characterized by antimicrobial drug susceptibility, presence of mefA/ermB, and multilocus sequence typing. Overall, the proportion of serotype 19A isolates increased but serotype 19F decreased. Among children <5 years of age, the proportion of serotype 19A isolates in invasive pneumococcal disease increased from 0% in 1991-1994 to 8%-10% in 1995-2000, reached 26% in 2001-2003, and remained at 20% in 2004-2006 when vaccine coverage did not exceed 25% (p = 0.005 for trend). This study demonstrates that the expansion of multidrug-resistant ST320 was responsible for the increase in serotype 19A before PCV7 use.

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Distributions of sequence types (STs) of serotypes 19A and 19F during five 3-or 4-year periods from 1991 through 2006, South Korea. A) Invasive isolates. B) Noninvasive isolates. *Indicates 11 different STs that contained 1 isolate of serotype 19F.
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Figure 4: Distributions of sequence types (STs) of serotypes 19A and 19F during five 3-or 4-year periods from 1991 through 2006, South Korea. A) Invasive isolates. B) Noninvasive isolates. *Indicates 11 different STs that contained 1 isolate of serotype 19F.

Mentions: ST320 was the only ST found among serotypes 19A and 19F; ST320 was the most common ST (n = 52, 90% of total 19A isolates) among serotype 19A. ST320 was observed in only 9% (n = 6) of serotype 19F isolates. The genetic structure of serotype 19A comprised primarily ST1374 during periods 1 and 2 (1991–1997), but ST1374 isolates were not recovered after 2001. In contrast, ST320 was the most common sequence type from 1998, and all 19A isolates from 2002–2006 were of ST320. The numbers of 19A isolates increased consistently from 1996 through 2003, which suggests that single clonal expansion of ST320 was responsible for the increase of serotype 19A isolates during this period (Figure 4).


Streptococcus pneumoniae serotype 19A in children, South Korea.

Choi EH, Kim SH, Eun BW, Kim SJ, Kim NH, Lee J, Lee HJ - Emerging Infect. Dis. (2008)

Distributions of sequence types (STs) of serotypes 19A and 19F during five 3-or 4-year periods from 1991 through 2006, South Korea. A) Invasive isolates. B) Noninvasive isolates. *Indicates 11 different STs that contained 1 isolate of serotype 19F.
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Related In: Results  -  Collection

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Figure 4: Distributions of sequence types (STs) of serotypes 19A and 19F during five 3-or 4-year periods from 1991 through 2006, South Korea. A) Invasive isolates. B) Noninvasive isolates. *Indicates 11 different STs that contained 1 isolate of serotype 19F.
Mentions: ST320 was the only ST found among serotypes 19A and 19F; ST320 was the most common ST (n = 52, 90% of total 19A isolates) among serotype 19A. ST320 was observed in only 9% (n = 6) of serotype 19F isolates. The genetic structure of serotype 19A comprised primarily ST1374 during periods 1 and 2 (1991–1997), but ST1374 isolates were not recovered after 2001. In contrast, ST320 was the most common sequence type from 1998, and all 19A isolates from 2002–2006 were of ST320. The numbers of 19A isolates increased consistently from 1996 through 2003, which suggests that single clonal expansion of ST320 was responsible for the increase of serotype 19A isolates during this period (Figure 4).

Bottom Line: Overall, the proportion of serotype 19A isolates increased but serotype 19F decreased.Among children <5 years of age, the proportion of serotype 19A isolates in invasive pneumococcal disease increased from 0% in 1991-1994 to 8%-10% in 1995-2000, reached 26% in 2001-2003, and remained at 20% in 2004-2006 when vaccine coverage did not exceed 25% (p = 0.005 for trend).This study demonstrates that the expansion of multidrug-resistant ST320 was responsible for the increase in serotype 19A before PCV7 use.

View Article: PubMed Central - PubMed

Affiliation: Seoul National University College of Medicine, Seoul, South Korea.

ABSTRACT
Despite the concern of replacement disease, notably by serotype 19A after 7-valent conjugate vaccine (PCV7) use, serotype 19A was increasingly recognized in Korean children before the introduction of PCV7. To understand the dynamics of serogroup 19 prevalence from 1991-2006, we serotyped 538 pediatric pneumococcal isolates. Serogroup 19 isolates (n = 126) were characterized by antimicrobial drug susceptibility, presence of mefA/ermB, and multilocus sequence typing. Overall, the proportion of serotype 19A isolates increased but serotype 19F decreased. Among children <5 years of age, the proportion of serotype 19A isolates in invasive pneumococcal disease increased from 0% in 1991-1994 to 8%-10% in 1995-2000, reached 26% in 2001-2003, and remained at 20% in 2004-2006 when vaccine coverage did not exceed 25% (p = 0.005 for trend). This study demonstrates that the expansion of multidrug-resistant ST320 was responsible for the increase in serotype 19A before PCV7 use.

Show MeSH