Effect of temperature on the activity of efflux pumps in selected species of human opportunistic bacterial pathogens

BACKGROUND Efflux pumps represents one of the most important mechanisms of antibiotic resistance. They allow bacteria to expel antibiotics from their cells before they reach the target site. OBJECTIVES The main objective of this work was to examine how cultivation temperature and its variations affect the activity of efflux pumps in Acinetobacter junii, Bacillus cereus, and Enterobacter cloacae isolated from a skin swab. METHODS The isolation and purification of bacterial colonies were done through the streak plate method. For the identification of bacterial species, MALDI-TOF was utilised. To detect the activity of efflux pumps, agar-ethidium bromide cartwheel method was implemented. FINDINGS The accumulation of ethidium bromide (EtBr) in bacterial cells was higher at 43ºC than at 30ºC, so the activity of efflux pumps was reduced at 43ºC in all isolates. A temperature of 7ºC also caused increased cumulation of EtBr in the cells, hence decreasing the activity of efflux pumps in isolated bacteria. Moreover, B. cereus was more sensitive to meropenem at 43ºC than at 36ºC. MAIN CONCLUSIONS The activity of efflux pumps and antibiotic resistance can be strongly affected by changes in incubation temperature in vitro in tested human opportunistic bacterial pathogens.