Differential Circulation of
            <i>Streptococcus pneumoniae</i>
            Serotype 6C Clones in Two Israeli Pediatric Populations

Porat, Nurith; Nahm, Moon H.; Dagan, Ron

doi:10.1128/jcm.01600-10

Cited by 9 publications

(8 citation statements)

References 15 publications

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“…Genotyping methods showed the same trend. Previous studies from our group have already shown the differential circulation of non-PCV7 clones among Jewish and Bedouin children in AOM cases (8,26,28). The current study expands this observation also to IPD cases.…”

Section: Discussionsupporting

confidence: 71%

Clonal Distribution of Common Pneumococcal Serotypes Not Included in the 7-Valent Conjugate Vaccine (PCV7): Marked Differences between Two Ethnic Populations in Southern Israel

et al. 2012

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This study aimed to compare the clonal distribution of common pneumococcal strains not included in the 7-valent pneumococcal conjugate vaccine (PCV7) that were isolated from cases of acute otitis media (AOM) and invasive pneumococcal disease (IPD) in two distinct ethnic populations in southern Israel during the decade (1999 to 2008) preceding PCV7 implementation. Isolates recovered from Jewish and Bedouin children <5 years old were characterized by antibiotic resistance and molecular epidemiology using pulsed-field gel electrophoresis and multilocus sequence typing. Of 5,236 AOM and 425 IPD isolates, 43% and 57% were from Jewish and Bedouin children, respectively. PCV7 accounted for 54% and 45% of the AOM and IPD episodes, respectively. Eleven major non-PCV7 serotypes (1, 3, 5, 6A, 7F, 12F, 15B/C, 19A, 21, 33F, and 35B) constituted 31% and 42% of the AOM and IPD episodes, respectively. The clonal distributions of the 11 non-PCV7 serotypes and their antibiotic susceptibilities were significantly different among the two ethnic populations in both the AOM and IPD groups. About half of the AOM and IPD cases resulted from non-PCV7 pneumococci, even before PCV7 implementation. The significant differences between the two ethnic populations suggest that lifestyle and microenvironment are major determinants in the clonal distribution of diseasecausing pneumococci. Post-PCV7 surveillance is important in understanding non-PCV7 clonal expansion in the two distinct populations.

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Section: Discussionsupporting

confidence: 71%

Clonal Distribution of Common Pneumococcal Serotypes Not Included in the 7-Valent Conjugate Vaccine (PCV7): Marked Differences between Two Ethnic Populations in Southern Israel

et al. 2012

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“…Serotype 6C strains share more multilocus sequence typing alleles with serotype 6A strains than either serotype 6B or 19A strains in the www.mlst.net database [23], providing indirect evidence that the serotype 6C capsular locus preferentially inserts into the serotype 6A background. The circulation of some of these serotype 6C clones can vary by population and location [24][25][26][27]. In Spain, two-thirds (142 of 213) of the serotype 6C strains causing IPD were related to a single clonal group (ST224-complex) [27].…”

Section: Molecular Epidemiology Of Serotype 6cmentioning

confidence: 99%

Novel Pneumococcal Serotypes 6C and 6D: Anomaly or Harbinger

McEllistrem¹,

Nahm²

2012

Clinical Infectious Diseases

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Clinical use of the 7-valent pneumococcal protein conjugate (PCV7) vaccine, which includes serotypes 4, 6B, 9V, 14, 18C, 19F, and 23F, dramatically reduced invasive pneumococcal disease (IPD); however, the effectiveness was diminished due to serotype shift. Although shift due to known serotypes was anticipated, shift by misidentified serotypes was unexpected. We describe the experience with newly recognized serotypes 6C and 6D, which were mistyped as serotypes 6A and 6B, respectively. Although serotype 6D caused only occasional infections, IPD due to serotype 6C disease expanded in the PCV7 era. Subsequent studies showed that PCV7 provided cross-protection against serotype 6A but not serotype 6C. The 13-valent pneumococcal protein conjugate (PCV13) vaccine, which includes PCV7 serotypes plus serotypes 1, 3, 5, 6A, 7F, 19A, may provide protection against IPD due to serotypes 6C and 6D. Regardless, this narrative illustrates the potential impact of unrecognized serotypes on the efficacy of a serotype-specific vaccine.

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“…A striking clonal segregation was found between the two study populations; e.g., ST6984, the major S. pneumoniae serotype 6D clone, which constituted 31% of the strains, was found only among Bedouin children, whereas ST8599, which constituted 16% of the strains, was found mostly (16/17, 94%) among Jewish children. The differential clonal distribution between the two study populations was already shown by us for additional serotypes (13,(18)(19)(20), suggesting that lifestyle and microenvironment are major determinants in child-to-child transmission of pneumococci.…”

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confidence: 87%

Baseline Epidemiology and Genetic Structure of Streptococcus pneumoniae Serotype 6D in Southern Israel Prior to Introduction of Pneumococcal Conjugate Vaccines

et al. 2013

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We characterized Streptococcus pneumoniae serotype 6D from among previously identified S. pneumoniae serotype 6B strains from Jewish and Bedouin children in southern Israel during a decade before vaccination. S. pneumoniae serotype 6D isolates constituted 6.7% of the presumed S. pneumoniae serotype 6B isolates. S. pneumoniae serotype 6D strains belonged to 20 sequence types that were differentially distributed between the two ethnic groups.T he discovery of a new Streptococcus pneumoniae serotype, serotype 6C, led to the logical suggestion that recombination might also produce a new member of the serogroup 6 family which would have the wciP serotype 6B (wciP 6B ) allele that differentiates S. pneumoniae serotype 6B from S. pneumoniae serotype 6A and the wciN 6C allele (1, 2). This serotype, designated S. pneumoniae serotype 6D, has been detected in both nasal carriage and invasive isolates (2-11).The 7-and 13-valent pneumococcal conjugate vaccines (PCV7 and PCV13, respectively) were introduced into the Israeli national immunization program in 2009 and 2010, respectively. Preliminary in vitro data suggest that the S. pneumoniae serotype 6B component of these vaccines elicits antibodies that are cross-opsonic to S. pneumoniae serotype 6D (12). However, clinical data are not yet available to confirm these findings. Evaluation of the prevalence of S. pneumoniae serotype 6D before and after PCV implementation would indirectly determine whether these vaccines provide protection against S. pneumoniae serotype 6D. The aim of this study was therefore to identify S. pneumoniae serotype 6D strains from among previously characterized S. pneumoniae serotype 6B isolates, explore their molecular epidemiology, and determine the circulation of S. pneumoniae serotype 6D clones among the members of two distinct ethnic subpopulations.This retrospective study was conducted in southern Israel during the decade (1999 to 2008) preceding PCV7 implementation. The study population included children Ͻ5 years of age: Jewish children with lifestyles resembling those of populations in developed countries and Muslim Bedouin children with standards of living resembling those of populations in developing countries (13). Contact between children of the two populations is rare. S. pneumoniae was cultured from four isolation sites: blood/cerebrospinal fluid (CSF), middle ear fluid (MEF), conjunctiva, and nasopharynx (14). Identification, antimicrobial susceptibility testing, and serotyping were performed as previously described (13). A PCR system targeting both wciN 6C (wciN ␤ ) and wciP 6B (wciP584a) was used to segregate S. pneumoniae serotype 6D from S. pneumoniae serotype 6B (2).Of 1,628 presumed S. pneumoniae serotype 6B isolates, 1,593 (97.9%) pneumococci, isolated from 1,201 children, were available for S. pneumoniae serotype 6D typing by PCR. S. pneumoniae serotype 6D was identified in 98/1,201 (8.2%) individuals, of which 41 individuals also presented S. pneumoniae serotype 6B during the study period. Overall, S. pneumoniae serotype 6D con...

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Differential Circulation of Streptococcus pneumoniae Serotype 6C Clones in Two Israeli Pediatric Populations

Cited by 9 publications

References 15 publications

Clonal Distribution of Common Pneumococcal Serotypes Not Included in the 7-Valent Conjugate Vaccine (PCV7): Marked Differences between Two Ethnic Populations in Southern Israel

Clonal Distribution of Common Pneumococcal Serotypes Not Included in the 7-Valent Conjugate Vaccine (PCV7): Marked Differences between Two Ethnic Populations in Southern Israel

Novel Pneumococcal Serotypes 6C and 6D: Anomaly or Harbinger

Baseline Epidemiology and Genetic Structure of Streptococcus pneumoniae Serotype 6D in Southern Israel Prior to Introduction of Pneumococcal Conjugate Vaccines

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