Pseudomonas aeruginosa, especially those containing R plasmids are the major pathogenic bacteria of gerontologic pulmonary infection as well as the nosocomial infection.

• 铜绿假单胞菌是院内感染的主要致病菌1,带有耐药质粒的铜绿假单胞菌的大量存在,是造成这种情况的主要原因2。