Natural History of Drug-Resistant Clones of<i>Streptococcus pneumoniae</i>Colonizing Healthy Children in Portugal

Mato, R.; Sanches, Ilda Santos; Simas, C.; Nunes, Sónia; Carriço, João André; Sousa, Natacha G.; Frazão, Nelson; Saldanha, Joana; Brito-Avô, António; Almeida, Jonas S.; Lencastre, Hermı́nia de

doi:10.1089/mdr.2005.11.309

Cited by 24 publications

(24 citation statements)

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“…Antibioticresistant isolates obtained between 1996 and 2003 were characterized before (19,21,33,37). Isolates obtained in 2006 were partially described (according to their serotypes) before (29), and isolates obtained in 2007 are first described in this study.…”

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

“…Signed informed consent was obtained from the parents or guardians of participating children. This study design for sampling has been maintained for several years, allowing direct comparisons over time (19,21,33).To evaluate clonal changes among antibiotic-resistant pneumococci colonizing healthy children following introduction of PCV7, three time periods were considered: (i) 1996 to 2001, the pre-PCV7 era; (ii) 2002 to 2003, the low-PCV7-uptake era, when 17.5% of the children enrolled in our studies had received at least one dose of the vaccine; and (iii) 2006 and 2007, the high-PCV7 uptake era, when 67.1% of the children had received at least one PCV7 dose. In the last period, 30.7% had received four doses and 20.0% were appropriately vaccinated for age but had not yet reached the four doses.…”

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confidence: 99%

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Clonal Evolution Leading to Maintenance of Antibiotic Resistance Rates among Colonizing Pneumococci in the PCV7 Era in Portugal

et al. 2011

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The introduction of the seven-valent pneumococcal conjugate vaccine (PCV7) in Portugal led to extensive serotype replacement among carriers of pneumococci, with a marked decrease of PCV7 types. Although antimicrobial resistance was traditionally associated with PCV7 types, no significant changes in the rates of nonsusceptibility to penicillin, resistance to macrolides, or multidrug resistance were observed. This study aimed to investigate the mechanisms leading to maintenance of antimicrobial resistance, despite marked serotype replacement. We compared, through molecular typing, 252 antibiotic-resistant pneumococci recovered from young carriers in 2006 and 2007 (era of high PCV7 uptake) with collections of isolates from 2002 and 2003 (n ‫؍‬ 374; low-PCV7-uptake era) and 1996 to 2001 (n ‫؍‬ 805; pre-PCV7 era). We observed that the group of clones that has accounted for antimicrobial resistance since 1996 is essentially the same as the one identified in the PCV7 era. The relative proportions of such clones have, however, evolved substantially overtime. Notably, widespread use of PCV7 led to an expansion of two Pneumococcal Molecular Epidemiology Network (PMEN) clones expressing non-PCV7 capsular variants of the original strains: Sweden 15A ST63 (serotypes 15A and 19A) and Denmark 14 ST230 (serotypes 19A and 24F). These variants were already in circulation in the pre-PCV7 era, although they have now become increasingly abundant. Emergence of novel clones and de novo acquisition of resistance contributed little to the observed scenario. No evidence of capsular switch events occurring after PCV7 introduction was found. In the era of PCVs, antimicrobial resistance remains a problem among the carried pneumococci. Continuous surveillance is warranted to evaluate serotype and clonal shifts leading to maintenance of antimicrobial resistance.Streptococcus pneumoniae is a Gram-positive bacterium that frequently colonizes asymptomatically the nasopharynx of young children. However, it is also an important human pathogen that can cause a wide range of diseases, from otitis media to pneumonia and meningitis. Worldwide, it has been estimated that 14.5 million episodes of serious pneumococcal disease and 826,000 deaths per year occur in children aged less than 5 years (23).In 2000, a seven-valent pneumococcal conjugate vaccine (PCV7) targeting the seven most common serotypes (4, 6B, 9V, 14, 18C, 19F, and 23F) causing invasive disease among young children in the United States became available. Since then, in countries where the vaccine has been introduced in the universal vaccination plan, a dramatic reduction in the incidence of invasive disease caused by PCV7 serotypes has been observed in all age groups (11,17,35). This extended phenomenon beyond the target group, known as herd immunity, has been attributed to decreased transmission of pneumococci from children to other age groups. Indeed, the nasopharynx of children is the main reservoir of pneumococci, and a decrease in carriage of PCV7 serotypes has been observed in vaccina...

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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confidence: 99%

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Clonal Evolution Leading to Maintenance of Antibiotic Resistance Rates among Colonizing Pneumococci in the PCV7 Era in Portugal

et al. 2011

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“…Previous point prevalence studies conducted among Portuguese DCC attendees have found high pneumococcal and H. influenzae colonization rates (over 70%) (5,12) with abundant representation of international clones (22).…”

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confidence: 92%

High Rates of Transmission of and Colonization by Streptococcus pneumoniae and Haemophilus influenzae within a Day Care Center Revealed in a Longitudinal Study

Sá-Leão

Nunes

Brito-Avô³

et al. 2008

J Clin Microbiol

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Day care centers (DCCs) are unique settings where young children are at increased risk for colonization by pneumococci and Haemophilus influenzae. Although point prevalence studies in DCCs are frequent, only a few longitudinal studies on the dynamics of colonization have been published. We conducted a 1-year longitudinal study with 11 sampling periods on nasopharyngeal carriage of pneumococci and H. influenzae among 47 children who attended a single DCC. All isolates were antibiotyped and genotyped by pulsed-field gel electrophoresis. Pneumococci were also serotyped. Of the 414 samples obtained, 61.4% contained pneumococci, and 87% contained H. influenzae. Only 8.3% of the samples were negative for both species. Twenty-one pneumococcal clones and 47 H. influenzae clones were identified. Introduction of clones occurred during all year. Ninety-eight percent and 96% of all pneumococcal and H. influenzae isolates, respectively, belonged to clones shared by more than one child. Children were sequentially colonized with up to six pneumococcal clones (mean, 3.6) and five serotypes and nine H. influenzae clones (mean, 7.1). Clones with increased capacity for transmission and/or prolonged colonization were identified in both species. These two fitness properties appeared to be independent. In conclusion, among DCC attendees, a high rate of acquisition and turnover of strains was observed, and all children were overwhelmingly colonized by clones shared with others. DCCs are units where permanent introduction of new clones occurs, and attendees, as a whole, provide a pool of hosts where the fittest clones find privileged opportunities to persist and expand.Studies conducted during the last decade have highlighted the important role of day care centers (DCCs) as unique places where young children with immature immune systems and poor hygienic behavior are crowded together, resulting in an increased risk for colonization and transmission of upper respiratory tract pathogens such as Streptococcus pneumoniae and Haemophilus influenzae (1,4,5,10,23,30).While point prevalence studies in DCCs to study colonization by these bacteria have been conducted in several countries (reviewed in reference 7), longitudinal studies are less frequent and have often focused on the individual host and not on a particular epidemiological setting (9,14,16). By looking at the DCC as a unit, one would expect to obtain additional information on the fitness capacities (for transmission and persistence) of individual clones, as they would be exposed to the same pool of hosts (the attendees). To our best knowledge, extended longitudinal studies that have systematically applied genotyping techniques to study pneumococci and H. influenzae in DCCs with such objectives in mind are very scarce. Trottier et al. studied H. influenzae colonization among 38 DCC attendees for 4 months (29), and Yagupsy et al. conducted a 7-month study focusing on the transmission of drug-resistant pneumococci among 48 children from two DCCs (30). A third study by Raymond et al. f...

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“…Os principais fatores que influenciam a taxa de colonização nos portadores incluem: idade abaixo de dois anos, número de irmãos e condições de aglomerações, ou seja, condições de vida em pequenas áreas, particularmente em creches (MALFROOT et al, 2004;MATO et al, 2005).…”

Section: Colonização E Fatores De Riscounclassified

Desenvolvimento e avaliação da resposta imune humoral de uma vacina anti-pneumocócica conjugada: polissacarídeo capsular sorotipo 14 - proteína de superfície pneumocócica A.

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Natural History of Drug-Resistant Clones ofStreptococcus pneumoniaeColonizing Healthy Children in Portugal

Cited by 24 publications

References 35 publications

Clonal Evolution Leading to Maintenance of Antibiotic Resistance Rates among Colonizing Pneumococci in the PCV7 Era in Portugal

Clonal Evolution Leading to Maintenance of Antibiotic Resistance Rates among Colonizing Pneumococci in the PCV7 Era in Portugal

High Rates of Transmission of and Colonization by Streptococcus pneumoniae and Haemophilus influenzae within a Day Care Center Revealed in a Longitudinal Study

Desenvolvimento e avaliação da resposta imune humoral de uma vacina anti-pneumocócica conjugada: polissacarídeo capsular sorotipo 14 - proteína de superfície pneumocócica A.

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