In vitro activity of ceftolozane/tazobactam in combination with other classes of antibacterial agents.

•Ceftolozane/tazobactam has potent activity against many Gram-negative pathogens.•This study evaluated potential synergistic/antagonistic antibacterial interactions.•In chequerboard analyses, some treatment combinations produced synergistic effects.•No antagonistic interactions were observed.•Ceftolozane/tazobactam retained its potency in the presence of other antibacterials.