Distribution and Invasiveness of Streptococcus pneumoniae Serotypes in Switzerland, a Country with Low Antibiotic Selection Pressure, from 2001 to 2004

Abstract

To describe the serotype-specific epidemiology of colonizing and invasive Streptococcus pneumoniae isolates, which is important for vaccination strategies, we analyzed a total of 2,388 invasive and 1,540 colonizing S. pneumoniae isolates collected between January 2001 and December 2004 within two nationwide surveillance programs. We found that the relative rank orders of the most frequent serotypes (serotypes 1, 3, 4, 6B, 7F, 14, 19F, and 23F) differed among invasive and colonizing isolates. Serotypes 1, 4, 5, 7F, 8, 9V, and 14 had increased invasive potential, and serotypes/serogroups 3, 6A, 7, 10, 11, 19F, and 23F were associated with colonization. The proportion of pediatric serotypes was higher among children <5 years old (48.5%) and persons >64 years old (34.1%) than among other age groups (29.1%); it was also higher in West Switzerland (40.2%) than in other geographic regions (34.7%). Likewise, serotype-specific proportions of penicillin-resistant isolates for types 6B, 9V, 14, and 19F were significantly higher in West Switzerland. The relative frequency of pediatric serotypes corresponded with antibiotic consumption patterns. We conclude that the epidemiology of invasive and colonizing S. pneumoniae isolates is influenced by the serotype-specific potential for invasiveness, and therefore, surveillance programs should include colonizing and invasive S. pneumoniae isolates. Antibiotic selection pressure determines the serotype distribution in different age groups and geographic regions and therefore the expected direct and indirect effects of the 7-valent conjugate vaccine.

In vitro expression of the first capsule gene of Streptococcus pneumoniae, cpsA, is associated with serotype-specific colonization prevalence and invasiveness

“…Pneumococcal serotypes have been shown to differ in their propensity to be carried in the nasopharynx or to be associated with invasive disease. Expression of cpsA was plotted against serotype-specific carriage prevalence values from an international study (Brueggemann et al, 2004) and a local (Swiss) study (Kronenberg et al, 2006). The serotype-specific carriage prevalence correlated inversely with cpsA expression using values from Brueggemann et al (2004) (P50.005, Fig.…”

“…This serotype and any with a higher odds ratio (OR) were considered invasive and all others as colonizing. ORs for the invasive potential of individual serotypes were kindly provided by Dr A. Brueggemann, University of Oxford (Brueggemann et al, 2004), or obtained from our local analysis (Kronenberg et al, 2006).…”

“…Clinical isolates of S. pneumoniae were randomly selected from two nationwide surveillance programmes that collected nasopharyngeal and invasive isolates (Mühlemann et al, 2003;Hathaway et al, 2004;Kronenberg et al, 2006). Both surveillance programmes started in 1998 and are ongoing, with short interruptions between January 2000 and March 2002.…”

“…The antigenic and biochemical properties of the polysaccharide capsule are used to characterize Streptococcus pneumoniae strains into over 90 distinct serotypes. Some serotypes such as 1, 4, 5, 7F and 14 have been associated with invasive disease, whilst others such as 6A, 6B, 15, 18C, 19F and 23F are more efficient at colonizing the nasopharynx (Brueggemann et al, 2004;Hanage et al, 2005;Kronenberg et al, 2006;Sandgren et al, 2004). However, when the latter do invade they cause more severe disease than serotypes which are commonly associated with invasive disease (Sjostrom et al, 2006).…”

Streptococcus pneumoniae worsens cerebral ischemia via interleukin 1 and platelet glycoprotein Ibα

“…Because major virulence factors such as pneumolysin are conserved across all S. pneumoniae strains, we used mock infection in control mice to account for any unexpected effects caused by the inoculum in the lungs. In general, serotype 19F isolates are associated with colonization of mucosa, 33 and are less commonly associated with invasive disease (serotype 19F is included in the 7-valent conjugated pneumococcal polysaccharide vaccine PCV-7). Lack of invasiveness of ATCC 49619 was also confirmed in our experimental model.…”