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[Virulence of Streptococcus pneumoniae strains belonging to different serovars]
Abstract:
The study of the virulence of 352 S. pneumoniae strains isolated from patients with inflammatory lung diseases revealed that their virulence depended, to a certain extent, on the state of the polysaccharide capsule of streptococci, as among 299 typed cultures 38.1% were virulent, while out of 53 nontypable strains of these bacteria only 8 strains (15.1%) proved to be highly pathogenic for white mice and all S. pneumoniae R-forms proved to be avirulent. All 11 S. pneumoniae strains under study belonging to serovars 1 and 2 and 87% of the cultures belonging to serovar 3, isolated from patients with inflammatory lung diseases in Leningrad, were highly virulent. The characteristic feature of S. pneumoniae cultures of other serotypes was their wide spectrum of pathogenicity. S. pneumoniae cultures isolated from the spinal fluid of patients with pneumococcal meningitis also differed in their pathogenicity levels but strains highly pathogenic for mice prevailed.
Insights
The polysaccharide capsule state influences Streptococcus pneumoniae virulence. Typed strains showed higher virulence than nontypable strains, with specific serovars exhibiting pronounced pathogenicity in lung disease patients.
Area of Science:
- Microbiology
- Pathogen Research
Background:
- Streptococcus pneumoniae is a leading cause of bacterial pneumonia and meningitis.
- Understanding pneumococcal virulence factors is crucial for developing effective treatments and vaccines.
Purpose of the Study:
- To investigate the relationship between the polysaccharide capsule state and the virulence of Streptococcus pneumoniae strains.
- To assess the pathogenicity of different pneumococcal serovars isolated from patients with inflammatory lung diseases and meningitis.
Main Methods:
- Isolation and characterization of 352 Streptococcus pneumoniae strains from patients.
- Virulence assessment in white mice.
- Serotyping of pneumococcal isolates.
- Pathogenicity evaluation of different serovars and R-forms.
Main Results:
- Virulence was significantly associated with the polysaccharide capsule state; 38.1% of typed strains were virulent versus 15.1% of nontypable strains.
- Streptococcus pneumoniae serovars 1, 2, and 3 demonstrated high virulence, particularly in strains from Leningrad patients.
- Pneumococcal meningitis isolates showed varied pathogenicity, with a prevalence of highly virulent strains.
Conclusions:
- The polysaccharide capsule is a key determinant of Streptococcus pneumoniae virulence.
- Specific serovars (1, 2, 3) are associated with high pathogenicity in inflammatory lung diseases.
- Further research into pneumococcal serovar-specific virulence is warranted for targeted therapeutic strategies.