INCREASING RESISTANCE OF PLANKTONIC AND BIOFILM CULTURES OF BURKHOLDERIA-CEPACIA TO CIPROFLOXACIN AND CEFTAZIDIME DURING EXPONENTIAL-GROWTH

The change in resistance of Burkholderia cepacia to ceftazidime and to ciprofloxacin during the exponential phase and up to the onset of sta tionary phase was assessed along the growth curve in batch culture. B. cepacia was grown in planktonic culture and in a biofilm on a membran e support. Resistance increased progressively during the exponential p hase, being increased by ten-fold about every four generations, Bacter ia grown in a biofilm were about 15 times more resistant than equivale nt planktonic-grown bacteria. The growth rate was not the key factor f or the development of resistance. The growth phase and the mode of gro wth have a fundamental impact on the susceptibility of B, cepacia towa rds antimicrobial agents. Bacteria growing at the same rate may differ greatly in their resistance to antimicrobial agents.