Objective:To investigate the distribution of common pathogens of senile lower respiratory tract infection and drug resistance.to improve clinical therapeutic efficacy.Methods: The susceptibility to antimicrobial agents was tested with diffusion method on mueller-Hinton medium.The double-dish test for ESBLs Confirmed all putative ESBLs-producing strains.Results:A total of 263 strains were obtained from lower respiratory tract in senile patients.108 of 263 strains were Gram-negative bacilli(38.7%).There were 30 strains of Klebsiellae pneumonia

26 strains of Escherichia coli

21 strains of E.cloacae and 17 strains of Acinetobacter;64 strains of gram-positive bacteria(24.3%) and 91 strains of fungi(34.6%).Nineteen strains(33.9%) produced ESBLs in Escherichia coli and Klebsiella pneumoniae.Most gram-negative bacilli kept high susceptibility to the imipenem.Conclusions:Grau-negative bacilli were predominant in aged patients with lower respiratory tract infection.Attention should be paid to multi-drug resistance of pathogenic bacteria and fungus infection.