Related Experiment Video

Updated: May 7, 2026

Following in Real Time the Impact of Pneumococcal Virulence Factors in an Acute Mouse Pneumonia Model Using Bioluminescent Bacteria
11:32

Following in Real Time the Impact of Pneumococcal Virulence Factors in an Acute Mouse Pneumonia Model Using Bioluminescent Bacteria

Published on: February 23, 2014

Viability and virulence of pneumolysin, pneumococcal surface protein A, and pneumolysin/pneumococcal surface protein

Patricia A Schachern1, Vladimir Tsuprun, Sarah Goetz

  • 1Department of Otolaryngology, University of Minnesota, Minneapolis.

JAMA Otolaryngology-- Head & Neck Surgery
|September 21, 2013
PubMed
Abstract

Insights

The PspA- mutant of Streptococcus pneumoniae showed significantly reduced viability and virulence in chinchilla middle ear infections. Pneumolysin and PspA together did not further attenuate the bacteria, suggesting protein and organ specificity.

Area of Science:

  • Otolaryngology
  • Microbiology
  • Infectious Diseases

Background:

  • Otitis media, a common middle ear infection, can lead to serious complications.
  • Understanding the role of Streptococcus pneumoniae virulence factors is crucial for developing effective prevention strategies.

Purpose of the Study:

  • To investigate the impact of pneumolysin (Ply) and pneumococcal surface protein A (PspA) on the viability and virulence of Streptococcus pneumoniae in a chinchilla otitis media model.
  • To assess the combined effect of Ply and PspA deficiencies on bacterial pathogenesis.

Main Methods:

  • Chinchilla middle ears were inoculated with wild-type (Wt) Streptococcus pneumoniae and mutant strains lacking Ply, PspA, or both.
  • Bacterial loads (CFUs) were quantified in middle ear effusions at various time points.
  • Histopathological analysis of temporal bones was performed to evaluate tissue damage.

Main Results:

  • The PspA- mutant exhibited significantly reduced viability and virulence, with minimal bacterial detection in middle ear effusions.
  • The Ply- mutant showed limited viability, while the Wt and Ply-/PspA- strains maintained higher bacterial loads.
  • Histopathological examination revealed less severe pathology in PspA- and Ply- groups compared to Wt and Ply-/PspA- groups.

Conclusions:

  • Pneumococcal surface protein A (PspA) plays a critical role in the viability and virulence of Streptococcus pneumoniae in the middle ear.
  • The absence of both pneumolysin (Ply) and PspA did not result in greater attenuation than single mutations.
  • The effects of pneumococcal protein mutations on bacterial pathogenesis appear to be specific to the protein and the host organ.

More Related Videos

Constructing Mutants in Serotype 1 Streptococcus pneumoniae strain 519/4306:06

Constructing Mutants in Serotype 1 Streptococcus pneumoniae strain 519/43

Published on: September 11, 2020

Using the Overlay Assay to Qualitatively Measure Bacterial Production of and Sensitivity to Pneumococcal Bacteriocins06:05

Using the Overlay Assay to Qualitatively Measure Bacterial Production of and Sensitivity to Pneumococcal Bacteriocins

Published on: September 30, 2014

Related Concept Videos

Regulation of Bacterial Virulence01:28

Regulation of Bacterial Virulence

Pathogenic bacteria employ a range of regulatory mechanisms to modulate the expression of virulence genes in response to environmental and host-derived signals. These mechanisms ensure that virulence factors are expressed only under favorable conditions, thereby optimizing infection and survival strategies.Mechanisms of Virulence RegulationKey regulatory strategies include:Two-Component Systems: These consist of a membrane-bound sensor kinase and a cytoplasmic response regulator. Environmental...
Mechanism of Antibiotic Resistance in MRSA01:25

Mechanism of Antibiotic Resistance in MRSA

Antibiotic resistance in bacteria arises when microorganisms evolve the ability to withstand drugs designed to kill them or inhibit their growth, rendering once-effective treatments useless. This phenomenon, driven by genetic change and selection under antibiotic exposure, poses a profound threat to modern medicine. Mechanisms include drug-inactivating enzymes (e.g., β-lactamases), efflux pumps that eject antibiotics, mutations altering antibiotic targets, decreased drug uptake, and acquisition...
Gene Regulation in Microbial Communities: Quorum Sensing01:28

Gene Regulation in Microbial Communities: Quorum Sensing

Quorum sensing is a mechanism of bacterial communication that enables coordinated gene expression in response to changes in population density. This facilitates collective behaviors that enhance survival, resource acquisition, and ecological adaptation. This process relies on small signaling molecules called autoinducers that accumulate as bacterial populations grow. When a critical threshold concentration of autoinducers is reached, bacterial cells collectively modify gene expression,...
Bacterial Meningitis II: Pathophysiology01:26

Bacterial Meningitis II: Pathophysiology

Bacterial meningitis typically begins when pathogens such as Neisseria meningitidis and Streptococcus pneumoniae colonize the nasopharynx and invade the bloodstream. This process is facilitated by bacterial virulence factors, such as polysaccharide capsules, which resist phagocytosis and complement-mediated killing. Less commonly, bacteria reach the central nervous system via contiguous spread from infections like otitis media or sinusitis, through congenital or acquired dural defects, or...