title: [Biorhythms of antibiotic resistance of microorganisms].
abstract: OBJECTIVE
  To study of circadian dynamics of antibiotic susceptibility and resistance of Gram-positive and Gram-negative microorganisms.
  
  
  METHODS
  Circadian dynamics of antibiotic susceptibility was studied on clinical strains of enterobacteria, non-fermenting Gram-negative bacteria, and staphylococci which were isolated and identified by common methods. During a day, with 3-hours intervals, studied strains were tested on susceptibility to ampicillin, oxacillin, ceftriaxone, meropenem, gentamycin, and ciprofloxacin using method of serial dilutions in agar.
  
  
  RESULTS
  Circadian biorhythms of resistance to antibiotics in studied microorganisms were revealed. Along with common patterns, differences in temporal changes of microrganisms' susceptibility to antibacterial drugs were noted. Chronobiologic approach allowed to reveal significant amplitude of changes of minimal inhibitoryconcentration (MIC) of antibiotics versus resistant Gram-positive cocci reflecting presence of susceptibility periods, whereas in susceptible Gram-negative bacteria peaks of resistance were observed. Circadian dynamics of MIC of majority of antibiotics versus resistant Gram-negative bacteria and susceptible Gram-positive cocci was characterized by lower amplitude of changes without shifts from antibiotic resistance to susceptibility and vice versa.
  
  
  CONCLUSIONS
  Obtained data open perspective of using biorhythmological approach in study of susceptibility of microorganisms to antibiotics during the elucidation of mechanisms of pathogens adaptation to environmental conditions and creation of new strategies of control for antibiotic resistance strains.
authors.forename: O V
authors.initials: OV
authors.lastname: Bukharin
authors.forename: N B
authors.initials: NB
authors.lastname: Perunova
authors.forename: S B
authors.initials: SB
authors.lastname: Fadeev
authors.forename: T Kh
authors.initials: TKh
authors.lastname: Timokhina
authors.forename: S V
authors.initials: SV
authors.lastname: Iavnova
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002940:Circadian Rhythm; D024881:Drug Resistance, Bacterial / Q000502:physiology*; D006090:Gram-Negative Bacteria / Q000187:drug effects* / Q000502:physiology; D006801:Humans; D008826:Microbial Sensitivity Tests; D013210:Staphylococcus / Q000187:drug effects* / Q000502:physiology
chemical_list: D000900:Anti-Bacterial Agents