Special aspects of studying the pharmacological modulation of activity of antibacterial agents in periodic cultures of microorganisms

Aim: The aim of the study was to identify special aspects of investigating the pharmacological modulation of the activity of antibacterial agents in periodic cultures of microorganisms. Materials and Methods. The study was conducted by using the control strain of Klebsiella pneumoniae ATCC 13883. We studied the growth dynamics of the strain in the M9 mineral medium for 24 hours in the presence of sublethal concentrations of antibacterial agents (gentamicin, ceftazidime, ciprofloxacin), constituting 50% of the minimum inhibitory concentration. Antioxidant methylethylpiridinol in concentrations of 0.25-4 mM was used as a modulator. Results. The study showed that, in the presence of sublethal concentrations of gentamicin or ciprofloxacin, the strain development complied with the classic growth curve for periodic culture. Methylethylpiridinol reduced the effects of gentamicin and ceftazidime, but enhanced the antibacterial effect of ciprofloxacin. In the mixtures containing gentamicin, a reversible change in the optical density of the bacterial suspension was observed 24 hours after beginning the incubation. The growth dynamics of bacteria in the mixtures containing ceftazidime was not described by classic growth curve and was intermittent. Conclusion. To assess the effects of pharmacological substances on the activity of antibacterial agents in periodic cultures of microorganisms, dynamic monitoring of the incubation mixtures is necessary. Acquisition of the results only at endpoint can lead to erroneous data interpretation.