Effects of Sub-Minimum Inhibitory Concentrations of Antibiotics on Bordetella pertussis.

Delik E., Eroğlu B., Yılmaz Çolak Ç., Tefon Öztürk B. E.

Çukurova 8th International Scientific Researches Conference, Adana, Turkey, 15 - 17 April 2022, pp.320-331

  • Publication Type: Conference Paper / Full Text
  • City: Adana
  • Country: Turkey
  • Page Numbers: pp.320-331


Pertussis is a highly contagious acute respiratory disease caused by Bordetella pertussis. Although known as a pediatric disease, which causes death primarily in unvaccinated infants, can be seen in all age groups. Despite vaccination programs against this disease, pertussis epidemics cannot be prevented. Erythromycin is a macrolide antibiotic widely used and preferred in the clinic for the treatment of pertussis. Azithromycin was developed to improve the pharmacokinetic properties and intolerance of erythromycin and is derived by adding an amino group to the erythromycin ring. There are no accepted standards for antibiotic susceptibility of B. pertussis, and reports of the effects of azithromycin and erythromycin against B. pertussis vary. In addition, there is no study on the effect of sub-minimum inhibitory concentrations (sub-MICs) of these antibiotics on B. pertussis cells growth and biofilm formation. The aim of this study is to determine the growth rate and biofilm formation ability of B. pertussis Tohama-1 strain in the presence of different sub-MIC azithromycin and erythromycin concentrations. The MICs of the antibiotics were investigated by liquid dilution method. The MIC value of azithromycin was determined as 0.08 µg/mL, and the MIC value of erythromycin was determined as 0.3 µg/mL. Then, the growth rate of Tohama-1 was investigated at antibiotic doses of 1⁄2, 1⁄4, 1⁄8, 1⁄16, 1⁄32 and 1/64 MIC. 1⁄2, 1⁄4 and 1⁄8 MIC doses of antibiotics were not tolerated by bacterial cells. Therefore, the sub-MIC doses for two antibiotics were determined as 1⁄16, 1⁄32 and 1⁄64. The growth rate of Tohama-1 grown in the presence of antibiotics at these doses was slower than that of the positive control (without antibiotics). Biofilm studies were performed using a 96-well cell culture plate. Determined sub-MIC doses decreased the ability of cells to form biofilms. In addition, sub-MIC doses of antibiotics slowed the growth rate of Tohama-1, and it can be speculated that this reduces the ability of the microorganism to form biofilms, which reduces the persistence of the bacterium in the nasopharynx, which is important for successful infection.