Untersuchungen über den Diplococcus pneumoniae und verwandte Streptokokken

Kruse, Walther; Pansini, Sergio

doi:10.1007/bf02284301

Cited by 28 publications

(4 citation statements)

References 7 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…parent strain. A number of the early investigators of this organism have provided descriptions of phenotypic variation associated with the pneumococcus (8,10,18,28). These studies, however, relied principally on colonial morphology on the opaque surface of blood agar observed with reflected light.…”

Section: Discussionmentioning

confidence: 99%

Phase variation in pneumococcal opacity: relationship between colonial morphology and nasopharyngeal colonization

et al. 1994

View full text Add to dashboard Cite

When colonies of encapsulated isolates of Streptococcus pneumoniae are viewed with oblique, transmitted light on a transparent surface, they are heterogeneous in appearance because of variation in opacity. There is spontaneous phase variation among at least three discernible phenotypes at frequencies from 10-3 to 10-6. The ability to detect differences in opacity varies according to serotype, but variation is independent of capsule expression. Electron microscopy shows no difference in chain length but suggests that autolysis occurs earlier in the growth of the transparent variant. There was no identifiable difference in membrane protein profiles of opaque and transparent variants of the same strain. In an infant rat model of nasopharyngeal carriage, there was no significant colonization by opaque variants. Efficient and stable colonization by the transparent variants was observed, suggesting a selective advantage for this phenotype in the nasopharynx. In contrast, there was no difference in the incidence of bacteremia or in the 50% lethal dose among the variants following their intraperitoneal inoculation. These results suggest that phase variation which is marked by differences in colonial morphology may provide insight into the interaction of the pneumococcus with its host.

show abstract

Section: Discussionmentioning

confidence: 99%

Phase variation in pneumococcal opacity: relationship between colonial morphology and nasopharyngeal colonization

et al. 1994

View full text Add to dashboard Cite

show abstract

“…The polysaccharide capsule represents the major virulence determinant of Streptococcus pneumoniae. Classic studies demonstrated a requirement for the capsule in virulence, established its role in antiphagocytosis, and showed that mutants producing reduced amounts of capsule were correspondingly reduced in virulence and antiphagocytic ability (20,32,39). Although more than 80 distinct capsular serotypes have now been described, a small number of these account for greater than 90% of pneumococcal infections in humans.…”

mentioning

confidence: 99%

Effect of genetic switching of capsular type on virulence of Streptococcus pneumoniae

1994

View full text Add to dashboard Cite

To assess the role of capsular serotypes in the virulence of Streptococcus pneumoniae, we have constructed isogenic derivatives differing only in the type of capsule expressed. Strains of types 2, 5, and 6B were converted to type 3 by transformation and selection for an erythromycin resistance marker linked to the type 3 capsule locus. Characterization studies revealed that these type 3 derivatives were indistinguishable from the type 2, type 5, and type 6B parental strains in terms of restriction enzyme fragment pattern and expression of pneumococcal surface protein A (PspA). Expression of the type 3 capsule did not alter the mouse virulence of the similarly virulent type 2 strain. However, alteration of capsule type had a profound effect on the virulence of the type 5 and type 6B derivatives. The highly virulent type 5 strain was essentially avirulent when expressing the type 3 capsule. Conversely, the 50% lethal dose of the relatively avirulent type 6B strain was reduced > 100-fold when the type 3 capsule was expressed. Thus, the serotype of capsule expressed has a major effect on virulence, and this effect is dependent upon the genetic background of the recipient strain.

show abstract

“…Es sei auch erw/ihnt, dass ich auoh ein paar~ f~ir Versuchsthiere ziemlich virulente e chte Pneumokokkenstb;mme in derselben Traubenzuckerbouillon titrirte~ und dass ihr S/iuremaximum erheblich tiefer lag als das dot ,Parapneumokokken", n/~mlich einem Titer yon ca. 40 Die Zahlen bedeuten d~sselbe wie in den frfiheren Ti~rir~abel]en.…”

Section: S~ureproduction Und Nturetoleranzunclassified

Bakteriologische Verhältnisse in weiblichen Genitalsekreten

Natvig

1905

Arch. Gynak.

View full text Add to dashboard Cite

Untersuchungen über den Diplococcus pneumoniae und verwandte Streptokokken

Cited by 28 publications

References 7 publications

Phase variation in pneumococcal opacity: relationship between colonial morphology and nasopharyngeal colonization

Phase variation in pneumococcal opacity: relationship between colonial morphology and nasopharyngeal colonization

Effect of genetic switching of capsular type on virulence of Streptococcus pneumoniae

Bakteriologische Verhältnisse in weiblichen Genitalsekreten

Contact Info

Product

Resources

About