Strong association between capsular type and virulence for mice among human isolates of Streptococcus pneumoniae

Abstract

The relationship between capsular type and virulence for mice was examined with 69 fresh human isolates of Streptococcus pneumoniae. These isolates represented eight capsular types or groups. Serologic and molecular weight differences in PspA (pneumococcal surface protein A) indicated that the strains were clonally distinct. Mice were infected intravenously with washed bacteria of all 69 isolates in sterile salt solutions. Twenty-eight of the isolates were also injected intraperitoneally to permit comparisons between the intravenous and intraperitoneal routes. With a few exceptions, there was concordance between the ability of strains to cause fatal infections by the two routes. About 30% of the 69 isolates were virulent for mice. The abilities of the isolates to kill mice and the length of time between inoculation and death were strongly associated with capsular type. All type 4 isolates, 40% of type 3 isolates, and 60% of group 6 isolates were virulent for mice; type 1 isolates were marginally virulent; and all type or group 14, 19, and 23 isolates were avirulent. Times to death were generally longer for mice infected with group 6 or type 1 than for those infected with type 3 or 4 pneumococci. There was no relationship between clinical diagnosis or tissue source of the isolates and virulence for mice.

Clinical usefulness of pneumococcal urinary antigen test, stratified by disease severity and serotypes

“…Pneumococci are divided into serotypes based on the capsular polysaccharides they produce. Since different pneumococcal serotypes have varying tendencies toward nasopharyngeal colonization or invasiveness [10,11], the hypothesis was formed that urinary antigen detection would vary by serotype. Previous studies have suggested that capsular polysaccharide serotypes with less metabolic cost (i.e.…”

“…Pneumococci are divided into serotypes based on their capsular polysaccharide structure, which is considered to be the most important virulence factor [9], and there are serotype-specific differences in nasopharyngeal carriage prevalence and disease incidence [10,11]. These observations gave rise to the hypothesis that the utility of UAT would vary depending on the pneumococcal serotypes, and that there would be a change in the positive rate of UAT in accordance with changes in the distribution of pneumococcal serotypes that may have occurred since the introduction of the 13-valent pneumococcal conjugated vaccine (PCV13).…”

Residence ofStreptococcus pneumoniaeandMoraxella catarrhaliswithin polymicrobial biofilm promotes antibiotic resistance and bacterial persistencein vivo

“…A list of all bacterial strains, plasmids, and primers is provided in Table 1. Streptococcus pneumoniae EF3030 is a serotype 19F strain which typically establishes nasopharyngeal carriage or localized airway infection in murine models (Briles et al, 1992;Palaniappan et al, 2005). Pneumococci were grown on trypticase soy agar (BD) supplemented with 5% defibrinated sheep blood (Hemostat) and 4 lg mL À1 gentamicin.…”

Role of pneumococcal pneumolysin in the induction of an inflammatory response in human epithelial cells

“…Clinical isolates of S. pneumoniae wild-type (WT) strains D39, 6B, 19F, 23F and NTHi WT strain 12 were used in this study (Avery et al, 1979;Briles et al, 1992;Shuto et al, 2001;Jono et al, 2002). Unless specified, S. pneumoniae WT strain D39 was commonly used to treat human epithelial HeLa cells in this study.…”