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Implementation of In Vitro Drug Resistance Assays: Maximizing the Potential for Uncovering Clinically Relevant Resistance Mechanisms
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Implementation of In Vitro Drug Resistance Assays: Maximizing the Potential for Uncovering Clinically Relevant Resistance Mechanisms

Published on: December 9, 2015

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Effects of in vitro-induced drug resistance on the virulence of Streptococcus

Yue-Xia Ding1,2,3, Qun Wu4, Yan Guo1

  • 1College of Coastal Agricultural Sciences, Guangdong Ocean University, Zhanjiang, PR China.

Veterinary Medicine and Science
|December 14, 2020
PubMed

Insights

Inducing drug resistance in Streptococcus dysgalactiae in vitro reduced its virulence. However, resistant strains still pose a public health risk in animal production, necessitating vigilance against emerging antibiotic resistance.

Area of Science:

  • Microbiology
  • Veterinary Science
  • Antimicrobial Resistance

Background:

  • Antibiotic resistance in Streptococcus species is a growing concern in animal production.
  • Understanding the impact of induced drug resistance on bacterial virulence is crucial for public health.
  • Streptococcus agalactiae and Streptococcus dysgalactiae are significant pathogens in livestock.

Purpose of the Study:

  • To evaluate the effects of in vitro-induced drug resistance on the virulence of Streptococcus.
  • To investigate changes in resistance and virulence genes following antimicrobial exposure.
  • To assess the impact of induced resistance on bacterial pathogenicity in a mouse model.

Main Methods:

  • Minimal inhibitory concentration (MIC) determination using micro-dilution.
  • In vitro induction of antibiotic resistance in S. agalactiae and S. dysgalactiae.
  • Polymerase Chain Reaction (PCR) for gene analysis.
  • Colony morphology observation.
  • Median Lethal Dose (LD50) testing in Kunming mice.

Main Results:

  • Both S. agalactiae and S. dysgalactiae developed resistance to seven antibiotics.
  • Penicillin induction altered resistance and virulence genes in S. dysgalactiae (CVCC3701-PEN).
  • CVCC3701-PEN exhibited reduced growth and significantly decreased virulence (1.1 × 10^2 times lower LD50) compared to the original strain.
  • Despite reduced virulence, the resistant strain remained capable of causing mortality in mice.

Conclusions:

  • In vitro-induced drug resistance in S. dysgalactiae (CVCC3701) led to a reduction in virulence.
  • The emergence of drug-resistant Streptococcus strains in animal production warrants public health attention due to their potential pathogenicity.
  • Continuous monitoring and strategies to combat antibiotic resistance in veterinary settings are essential.
Keywords:
Streptococcusdrug resistancevirulence

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