目的　同期监测老年病房住院患者的医院感染情况,及时切断医院感染的传播途径,预防医院感染的质粒暴发。方法　对老年病房住院患者进行咽拭子培养,菌体药物敏感实验,质粒提取,质粒消除实验。结果　在监测对象中发现,存有完全相同的耐药谱及质粒谱的不同铜绿假单胞菌株6 株。结论　结果表明在一定条件下有医院感染的发生及质粒暴发的可能 Objective To monitor the prevalence of nosocomial infections in hospitalized ward patients in the same period and to promptly cut off the transmission of nosocomial infections and prevent the outbreak of nosocomial infections. Methods Throat swabs, bacterial drug sensitivity test, plasmid extraction and plasmid elimination were studied in hospitalized ward patients in geriatric wards. Results Six different strains of Pseudomonas aeruginosa were found in the monitoring subjects, which had exactly the same drug resistance spectrum and plasmid spectrum. Conclusion The results show that under certain conditions, the occurrence of hospital infection and the possibility of plasmid outbreaks