不同病原体引起的下呼吸道感染临床治疗常有困难，喹诺酮类抗生素通过抑制ＤＮＡ螺旋酶而杀灭细菌，具有广谱、高效、组织渗透性好等特点。我们使用乳酸环丙沙星注射液治疗下呼吸道感染４５例，总有效率８６．６％，副作用较少８．８％，提示该类药是治疗肺部感染尤其是院内感染的重要药物。探讨了环丙沙星与茶碱联用时毒副作用。 Different pathogens cause clinical lower respiratory tract infection often difficult, quinolone antibiotics kill bacteria by inhibiting DNA helicase, with broad spectrum, high efficiency, good tissue permeability and so on. We use ciprofloxacin lactate injection in 45 cases of lower respiratory tract infection, the total effective rate was 86.6%, fewer side effects 8.8%, suggesting that these drugs is an important drug for the treatment of lung infections, especially nosocomial infections. The side effects of ciprofloxacin and theophylline were discussed.