Persistence of Two Invasive Streptococcus pneumoniae Clones of Serotypes 1 and 5 in Comparison to That of Multiple Clones of Serotypes 6B and 23F among Children in Southern Israel

Abstract

We conducted a study to examine the clonal distribution of invasive serotype 1 and 5 isolates as representatives of serotypes that are rarely carried by healthy individuals compared to that of invasive serotype 6B and 23F isolates as representatives of serotypes often carried by young children for prolonged periods. All invasive serotype 1, 5, 6B, and 23F isolates recovered from blood cultures during January 1995 to May 1999 were analyzed; these included 66 serotype 1, 30 serotype 5, 11 serotype 6B, and 15 serotype 23F isolates. One hundred thirty-three nasopharyngeal (NP) isolates of the indicated four serotypes from healthy children were also studied. The strains were characterized using serotyping, antimicrobial susceptibility testing, and pulsedfield gel electrophoresis profiling. We found that both invasive and NP serotype 1 and 5 isolates were susceptible to penicillin and that each serotype showed only one clonal type. In contrast, serotype 6B and 23F strains showed different phenotypic characteristics as well as multiple clonal types; 10 clones were identified among 6B isolates, and 11 clones were identified among 23F isolates.

Geographic Distribution and Clonal Diversity of Streptococcus pneumoniae Serotype 1 Isolates

“…The first was a study of pediatric isolates from Israel in 1995 to 1999, where serotypes 1 and 5 were the most common pediatric invasive serotypes during the 10 years prior to the study. Sixtysix invasive isolates and 13 carriage isolates (representing 0.3% of the 4,600 carried pneumococci isolated) were analyzed by pulsed-field gel electrophoresis (PFGE), and all were considered to belong to a single clonal type (21). The second molecular study was from Sweden (14) and was undertaken in response to a significant nationwide increase in invasive pneumococcal disease from 1989 to 1997.…”

“…Streptococcus pneumoniae is commonly carried in the nasopharynges of healthy children and adults; however, a characteristic epidemiological feature of serotype 1 is that it is very rarely found among healthy carriers, even in locations where serotype 1 frequently causes invasive disease (11,14,18,21,27). The fact that serotype 1 is among the most common causes of invasive disease in many parts of the world, although it is rarely carried by either adults or children, and the ability of serotype 1 to cause outbreaks suggest that this serotype has an unusually high attack rate.…”

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

“…Molecular studies of serotype 1, a usually penicillin-susceptible albeit hypervirulent serotype, have been reported less frequently (Brueggemann & Spratt, 2003;Gonzalez et al, 2004;Normark et al, 2001;Porat et al, 2001). A common factor in these reports was the low genetic diversity among the isolates, which has been associated with the short duration of carriage and/or a low density of this serotype in the nasopharynx, resulting in a reduced opportunity to exchange genes between strains (Brueggemann & Spratt, 2003;Hausdorff et al, 2005).…”

“…Molecular typing studies have greatly contributed to epidemiological investigations of pneumococci, mostly focusing on the global spread of penicillin-resistant clones (Brueggemann et al, 2003;Tomasz et al, 1998). Molecular studies of serotype 1, a usually penicillin-susceptible albeit hypervirulent serotype, have been reported less frequently (Brueggemann & Spratt, 2003;Gonzalez et al, 2004;Normark et al, 2001;Porat et al, 2001). A common factor in these reports was the low genetic diversity among the isolates, which has been associated with the short duration of carriage and/or a low density of this serotype in the nasopharynx, resulting in a reduced opportunity to exchange genes between strains (Brueggemann & Spratt, 2003;Hausdorff et al, 2005 In a pilot study conducted to obtain information on an adequate sample size for the current study, we found that the genetic diversity of type 1 pneumococci was slightly higher in the first period (1977)(1978)(1979)(1980)(1981)(1982)(1983)(1984) compared with the last period (2001)(2002)(2003)(2004)(2005) of the study.…”

“…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).…”