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Quinoline Antimalarials Increase the Antibacterial Activity of Ampicillin

Olajumoke A Olateju1, Chinedum P Babalola1,2, Olujide O Olubiyi3

  • 1Department of Pharmaceutical Chemistry, Faculty of Pharmacy, University of Ibadan, Ibadan, Nigeria.

Frontiers in Microbiology
|June 21, 2021
PubMed

Insights

Quinine and chloroquine enhance ampicillin’s antibacterial effectiveness against common co-infections. This study investigated drug interactions, finding additive effects that may improve treatment outcomes for bacterial and malaria co-infections.

Area of Science:

  • Microbiology
  • Pharmacology
  • Infectious Diseases

Background:

  • Bacterial and malaria co-infections are prevalent in malaria-endemic regions.
  • Co-administration of antibiotics and antimalarials is clinically necessary.
  • Anecdotal reports suggest interactions between penicillins and antimalarials, but mechanisms are unclear.

Purpose of the Study:

  • To investigate the in vitro interaction between ampicillin and two quinoline antimalarials (chloroquine, quinine).
  • To determine the effect of these antimalarials on ampicillin's antibacterial activity.
  • To assess the impact of drug combinations on bacterial cell integrity.

Main Methods:

  • Antimicrobial interaction testing: paper strip diffusion, modified disc diffusion, and checkerboard assays.
  • Evaluation of ampicillin-antimalarial combinations against Gram-positive and Gram-negative bacteria.
  • Measurement of potassium ion release to assess bacterial cell integrity.

Main Results:

  • Antimalarials showed minimal intrinsic antibacterial activity, except quinine at high concentrations (bactericidal).
  • Chloroquine and quinine significantly enhanced ampicillin's inhibitory effect, increasing inhibition zones.
  • Interactions were predominantly additive, with Fractional Inhibitory Concentration Indices between 0.5 and 1.

Conclusions:

  • Quinine and chloroquine potentiate the antibacterial activity of ampicillin.
  • These findings have significant implications for the combined clinical use of ampicillin and antimalarials.
  • Further research into ampicillin-antimalarial interactions may optimize treatment strategies for co-infections.
Keywords:
ampicillinchloroquinedrug combinationmodified disc diffusion checkerboardpaper strip diffusionpenicillinsquinine

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