Related Experiment Video

Updated: Sep 5, 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

Population changes in Diplococcus pneumoniae

G CARTA, W FIRSHEIN

    Journal of Bacteriology
    |September 1, 1962
    PubMed

    Insights

    Avirulent Diplococcus pneumoniae strains rapidly outcompeted virulent strains in specific broth cultures. This shift was due to higher avirulent cell viability and a toxic factor, but could be prevented by deoxynucleosides.

    Area of Science:

    • Microbiology
    • Bacteriology
    • Genetics

    Background:

    • Diplococcus pneumoniae (pneumococcus) exists as virulent and avirulent strains.
    • Understanding population dynamics is crucial for studying bacterial pathogenesis and evolution.

    Purpose of the Study:

    • To investigate the population dynamics between virulent and avirulent strains of Diplococcus pneumoniae.
    • To identify factors influencing the selective establishment of avirulent strains.

    Main Methods:

    • Incubation of mixed virulent and avirulent pneumococcal strains in various broth media.
    • Monitoring population changes over 36-48 hours at 37°C.
    • Assessing the effect of aged cultures, blood-containing media, and deoxynucleosides/deoxynucleotides.

    Main Results:

    • Avirulent mutant strains rapidly established dominance over virulent strains in Brain Heart Infusion-blood broth.
    • Aged or blood-lacking cultures accelerated the establishment of avirulent cells.
    • Avirulent cells exhibited greater stationary-phase viability and produced a toxic factor inhibiting virulent cell multiplication.
    • Deoxynucleosides and deoxynucleotides stabilized virulent cultures, preventing avirulent strain establishment.

    Conclusions:

    • Selective population shifts favoring avirulent Diplococcus pneumoniae strains occur under specific culture conditions.
    • Bacterial viability, toxic factor production, and nutrient availability influence strain competition.
    • Deoxynucleoside/deoxynucleotide supplementation can maintain the dominance of virulent pneumococcal populations.
    Keywords:
    DIPLOCOCCUS PNEUMONIAEDNA

    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

    A Mouse Model for the Transition of Streptococcus pneumoniae from Colonizer to Pathogen upon Viral Co-Infection Recapitulates Age-Exacerbated Illness12:21

    A Mouse Model for the Transition of Streptococcus pneumoniae from Colonizer to Pathogen upon Viral Co-Infection Recapitulates Age-Exacerbated Illness

    Published on: September 28, 2022

    Related Concept Videos

    Atypical Pneumonia01:14

    Atypical Pneumonia

    Atypical pneumonia, often caused by Mycoplasma pneumoniae, is a form of pulmonary infection that differs from the classical presentation of bacterial pneumonia in both its cause and clinical symptoms. Mycoplasma pneumoniae is a pleomorphic bacterium notable for its lack of a rigid cell wall. This structural characteristic imparts resistance to beta-lactam antibiotics and significantly influences the bacterium’s behavior within the human host.Other pathogens responsible for the disease include...
    Pneumonia I: Introduction01:29

    Pneumonia I: Introduction

    Pneumonia is an infection of the lower respiratory tract that leads to inflammation of the lung parenchyma, often resulting in the accumulation of inflammatory exudate in the alveoli and airways. Unlike the watery, low-protein fluid exudate in pulmonary edema, the exudate in this case is a thick fluid rich in immune cells, proteins, and debris produced during infection and inflammation.This impairs gas exchange and can lead to consolidation of lung tissue. The infection may be caused by a...
    Pneumonia I: Introduction01:30

    Pneumonia I: Introduction

    Pneumonia is an acute respiratory infection that targets the lungs, specifically the alveoli. These tiny air sacs, essential for oxygen exchange, become engorged with pus and fluid, severely hindering breathing, decreasing oxygen absorption, and causing significant pain and discomfort during respiration.
    Risk Factors
    Various factors influence the likelihood of developing pneumonia. Age plays a crucial role, with infants, children under two, and individuals over 65 at increased risk due to their...
    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...
    Population Growth00:57

    Population Growth

    Population size is dynamic, increasing with birth rates and immigration, and decreasing with death rates and emigration. In ideal conditions with unlimited resources, populations can increase exponentially, which plots as a J-shaped growth rate curve of population size against time. This type of curve is characteristic of newly-introduced invasive species, or populations that have suffered catastrophic declines and are rebounding.However, realistic environmental conditions limit the number of...
    Genomic DNA in Prokaryotes00:46

    Genomic DNA in Prokaryotes

    The genome of most prokaryotic organisms consists of double-stranded DNA organized into one circular chromosome in a region of cytoplasm called the nucleoid. The chromosome is tightly wound, or supercoiled, for efficient storage. Prokaryotes also contain other circular pieces of DNA called plasmids. These plasmids are smaller than the chromosome and often carry genes that confer adaptive functions, such as antibiotic resistance.
    Genomic Diversity in Bacteria
    Although bacterial genomes are much...