On Syndrome with Periodic, Episodic Manic Condition as the Primary Symptom

The tolerance of four strains of Pseudomonas aeruginosa to chlorhexidine increased 8 to 32 times during 21 passages every other day in nutrient broth containing subinhibitory concentrations of the disinfectant. The cells from the 30th subcultures died more slowly in either 0.5 or 0.02% solution of chlorhexidine than those of the parent strains. Likewase, the minimal inhibitory concentrations were greater with acrinol for the bacteria from the 30th subcultures than for those of the parent strains. On the other hand, no significant differences were observed between the parent strains and those from the 30th subcultures in minimal inhibitory concentrations of ampicillin, carbenicillin, dibekacin, amikacin, polymixin B and benzalkonium chloride. The bacteria that had acquired resistance after 30 subcultures in the presence of chlorhexidine were further subcultured for another 30 passages in a disinfectant-free nutrient broth. In three of the four strains tested, the acquired resistance to chlorhexidine was reduced to one-fourth to one-eighth, but it was unchanged in one strain.