Molecular assessment of invasive Streptococcus pneumoniae serotype 1 in Brazil: evidence of clonal replacement

Abstract

In Brazil, serotype 1 Streptococcus pneumoniae is one of the most prevalent causes of severe infection. This study investigated the genetic relatedness of 134 serotype 1 isolates obtained from invasive diseases during the period . Molecular typing by PFGE revealed two major lineages using visual inspection and computer analysis. Type A comprised 94 isolates (70.2 %) with four subtypes, whereas type B comprised 40 isolates (29.8 %) with eight subtypes. Subtype A3, the most frequent genotype, accounting for 65 % of the total isolates, was identified as a representative of clone Sweden 1 -40 (ST304). Type B was predominant in the period [1977][1978][1979][1980][1981][1982][1983][1984][1985][1986][1987][1988]. In contrast, an increase in the type A lineage was detected from 1990 in Brazil, significantly associated with isolates recovered from pneumonia cases and from young patients. This study clearly established a temporal switch between two lineages of S. pneumoniae serotype 1 in Brazil, with a wide dispersion of clone Sweden 1 -40 in recent years. INTRODUCTIONThe polysaccharide capsule of Streptococcus pneumoniae can be used to define more than 90 pneumococcal serotypes, in addition to acting as the primary virulence determinant for this organism. Some serotypes are mostly associated with nasopharyngeal carriage, whilst others are more likely to be the causative agents of invasive disease (Alannee et al., 2007;Hausdorff et al., 2005).Serotype 1 ranks among the most prevalent invasive serotypes in many countries (Garcia et al., 2006;Konradsen & Kaltoft, 2002;McChlery et al., 2005;Porat et al., 2001). In Brazil, since 1977, serotype 1 has been identified as one of the most frequent pneumococci causing severe infections in both adult and paediatric patients (Brandileone et al., 2003). In the period 2000-2005, serotype 1 isolates were ranked fourth (5.6 %) among the principal serotypes identified in Brazilian children up to 6 years of age, preceded by serotypes 14 (35.9 %), 6B (11 %) and 18C (6.1 %) (Pan-American Health Organization, 2007).Serotype 1 has specific epidemiological features, including: (i) a low colonization frequency, even in populations in which serotype 1 is a frequent cause of pneumococcal infections (Laval et al., 2006;Normark et al., 2001;Nunes et al., 2008); (ii) the ability to cause outbreaks in communities and in crowded and closed institutions (Dagan et al., 2000;Leimkugel et al., 2005); (iii) an association with severe episodes of pneumonia and empyema in children (Byington et al., 2006); and (iv) susceptibility to most antimicrobial agents (Klugman & Koornhof, 1988). Recently, some authors have speculated that isolates of serotype 1, which are known to have a highly invasive potential, behave as primary pathogens, whereas other capsular types demonstrate opportunistic features (Garau & Calbo, 2007;Hausdorff, 2007). Molecular typing studies have greatly contributed to epidemiological investigations of pneumococci, mostly focusing on the global spread of penicillin-resistant clones (Brueggem...

Phenotypic and Molecular Characterization of Optochin-Resistant Streptococcus pneumoniae Isolates from Brazil, with Description of Five Novel Mutations in the atpC Gene

“…1). Among these, four (Spain 6B -2, Spain 9V -3, Colombia 23F -26, and Sweden 1 -40) are known to be prevalent in Brazil (31,36,37). Except for one, those five Opt r S. pneumoniae strains were recovered from cases of invasive pneumococcal disease, and two of them were nonsusceptible to penicillin, with one being multidrug resistant.…”

What is Different About Serotype 1 Pneumococci?

“…While in the case of New Caledonia, the predominant clone of serotype 1 remained constant over time, this has not been observed elsewhere. Clonal replacement was observed in Brazil [34] and Scotland [35]. In these locales, a background population of several clones identified on pulsed-field gel electrophoresis of serotype 1 were replaced over several years by a single clone (ST304 in Brazil and ST306 in Scotland).…”

Spatial exploration of Streptococcus pneumoniae clonal clustering in São Paulo, Brazil

“…2,3 Furhermore, due to its ability in differentiating isolates of same species and correlating them with endemic clones, it has also been one of the most frequently used methods for S. pneumoniae molecular typing. [4][5][6][7] Spatial analysis based on geographical information systems (GIS) is useful for understanding disease epidemiology. However, it has not been frequently used for understanding the patterns of specific bacterial infections and their related risk factors, despite the fact that spatial aspects are probably linked to many factors influencing antimicrobial resistance patterns.…”