Related Experiment Video

Updated: May 17, 2026

Characterization of Inflammatory Responses During Intranasal Colonization with Streptococcus pneumoniae
09:12

Characterization of Inflammatory Responses During Intranasal Colonization with Streptococcus pneumoniae

Published on: January 17, 2014

Characterization of recombinant fluoroquinolone-resistant pneumococcus-like isolates

Luz Balsalobre1, Montserrat Ortega, Adela G de la Campa

  • 1Unidad de Genética Bacteriana, Centro Nacional de Microbiología, Instituto de Salud Carlos III and CIBER de Enfermedades Respiratorias, Majadahonda. luzbal@isciii.es

Antimicrobial Agents and Chemotherapy
|November 2, 2012
PubMed

Insights

Fluoroquinolone-resistant streptococci were identified as atypical pneumococci. Genetic analysis revealed mosaic DNA topoisomerase genes and a close relationship between these atypical pneumococci and Streptococcus pseudopneumoniae.

Area of Science:

  • Microbiology
  • Genetics
  • Molecular Biology

Background:

  • Fluoroquinolone resistance is a growing concern in streptococcal infections.
  • Streptococcus pneumoniae (pneumococci) are significant human pathogens.
  • Atypical pneumococci with recombinant DNA topoisomerase genes require further characterization.

Purpose of the Study:

  • To characterize fluoroquinolone-resistant streptococcal isolates with recombinant DNA topoisomerase genes.
  • To determine the phylogenetic relationships of these isolates.
  • To investigate the genetic basis of their resistance and atypical phenotype.

Main Methods:

  • Phenotypic and genotypic analyses were performed on fourteen resistant streptococcal isolates.
  • Phylogenetic analysis utilized sequences of seven housekeeping alleles.
  • Gene order of the atp operon and recombination evidence were assessed.

Main Results:

  • Phenotypic tests classified the isolates as atypical pneumococci.
  • Phylogenetic analysis placed isolates with Streptococcus pneumoniae, Streptococcus pseudopneumoniae, and Streptococcus mitis.
  • Recombination within housekeeping alleles of the S. pseudopneumoniae population was evident.

Conclusions:

  • Confirms the existence of pneumococci among alpha-hemolytic streptococci with mosaic DNA topoisomerase genes.
  • Reveals a close evolutionary relationship between atypical pneumococci and S. pseudopneumoniae.
  • Highlights the genetic complexity contributing to fluoroquinolone resistance in streptococci.

More Related Videos

Time-Lapse Epifluorescence Microscopy Imaging of Pseudomonas aeruginosa and Staphylococcus aureus Heterogeneous Phenotypes07:44

Time-Lapse Epifluorescence Microscopy Imaging of Pseudomonas aeruginosa and Staphylococcus aureus Heterogeneous Phenotypes

Published on: February 14, 2025

Following in Real Time the Impact of Pneumococcal Virulence Factors in an Acute Mouse Pneumonia Model Using Bioluminescent Bacteria11:32

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

Published on: February 23, 2014

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...
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,...
Inhibitors of Bacterial DNA Synthesis01:28

Inhibitors of Bacterial DNA Synthesis

Bacterial pathogens depend on precise and efficient DNA replication to sustain infection. Two type II topoisomerases—DNA gyrase and topoisomerase IV—are critical to this process, as they resolve DNA supercoiling and unlink chromosomes during replication. Fluoroquinolones, synthetic derivatives of quinolones, exploit this mechanism by stabilizing the transient DNA–enzyme cleavage complex, preventing strand religation, and causing lethal double-strand breaks. These antibiotics are selectively...