Antagonistic, synergistic, and additive antibacterial interaction between ciprofloxacin and amoxicillin against Staphylococcus aureus

Abstract

The aim of this in vitro study was to evaluate the interaction between ciprofloxacin and amoxicillin against beta-lactamase-producing Staphylococcus aureus. Concentration-dependent curves for each individual drug were carried out to obtain the mean inhibitory concentration in the agar well diffusion assay. Then, different ratios of the ciprofloxacin-amoxicillin combination (0.

Isobolographic analysis of the ciprofloxacin–gentamicin combination against beta‐lactamase‐producing Staphylococcus aureus

“…The antibacterial effect of ciprofloxacin is produced by the inhibition of topoisomerase type II (DNA gyrase) and topoisomerase type IV [10], whereas the activity of gentamicin is induced by binding to the 30S ribosomal subunit [15, 16]. Explaining or clarifying the mechanism of action of a pharmacodynamics interaction is complicated because unknown alternative mechanisms may be involved that could complement the antimicrobial effect or be activated when such drugs are co‐administered [17].…”

“…In this study, ciprofloxacin and gentamicin could be producing synergistic antimicrobial effects due to the joint activity of both drugs within S. aureus , each on its target molecule [10, 21, 22]. On the other hand, it is important to note that the antagonistic interactions of this same combination of drugs could be due to different factors in the bacterium, such as activation of drug expulsion pumps, inactivation of the drugs by plasmids, or mutation of transportation systems [1, 21–23].…”

“…Sterile saline was used as a vehicle. The inhibition halos were assessed with a Vernier digital caliper at 24 h. The inactivation of the liquid samples was done by sterilization, and that of the bacterial cultures in Petri dishes was done by exposure to ultraviolet light [8][9][10].…”

“…However, few studies have documented the interaction between two antimicrobial drugs using the same methods and statistical analyses as this study. Previously, our research group reported different types of antimicrobial interactions when ciprofloxacin and amoxicillin were used against betalactamase-producing S. aureus [10]. Considering the lack of studies to evaluate the antimicrobial drug-drug interaction through isobolographic analysis and the interaction index, methods considered gold standards for this purpose [10][11][12][13][14], our research group is currently working on several similar projects to determine the type of interaction when different types of antibiotics are used in combination against different human pathogens.…”

Isobolographic analysis of interactions – a pre-clinical perspective

“…The IA is a universal method in interaction analysis that can be applied in both clinical and preclinical studies, especially if the tested drugs exerted some measurable effects. At present, the IA is widely used for analysis of interactions between anticancer drugs [18-21], antiseizure medications [22-25], ototoxic drugs [26, 27], antibiotics, and antmicrobial drugs [28,29], and when evaluating the antinociceptive activity of the drugs [30][31][32][33][34][35]. Quite recently, a large-scale and fully automatic IA has been incorporated into in vitro studies for assessing the interactions between anti-cancer drugs and various radiosensitizers to accelerate the discovery of anticancer drugs [36].…”