Abstract： Objective To analyze the drug-resistant genotypes and phylogenetics of resistance genes in AmpC and extended-spectrum β-lactamases (ESBLs) producing Klebsiella pneumoniae isolated from airway secretion or sputum of patients with lower respiratory tract infections (LRTI). Methods Between January 2009 and August 2010, 53 strains of Klebsiella pneumoniae were isolated from airway secretion or sputum specimens of LRTI patients in respiratory wards of our hospital. Of the Klebsiella pneumoniae strains,Kirby-Bauer method was used to assess the sensitivity to common antibacterial drugs, three-dimensional extract test to determine AmpC, and PCR to detect the genes encoding ESBLs (CTX-M, TEM and SHV) and plasmid-mediated AmpC, quinolones resistance (qnrA, qnrB and qnrS) , antiseptics and sulfanilamide resistance (qacE△1-sul1) and class 1 integrase (Int Ⅰ 1). Cluster analysis of bacteria was performed.Results Of the 53 strains of Klebsiella pneumoniae, none showed resistance to imipenem, meropenem and ertapenem, but over 80％ was resistant to ciprofloxacin and levofloxacin. Moreover, a varying range of resistance to other antibacterial agents was also shown. Of 53 strains of Klebsiella pneumoniae, 60.4％(32/53) was positive for Int Ⅰ 1, 54.7％(29/53) for qnrA, 13.2％(7/53) for qnrS, 5.7％(3/53) for qnrB,71.7％(38/53) for qacE△1-sul1, 92.5％(49/53) for TEM, 100％(53/53) for CTX-M, 9.4％(5/53) for SHV and 92.5％ (49/53) for AmpC. Notably, 4 strains were found to simultaneously carry qnrA, qnrS, int Ⅰ 1,qacE△1 -sul1, AmpC and CTX-M genes. Cluster analysis demonstrated the phylogenetic relationship among number 40, 41, 10 and 18 strains, between number 25 and 42 strains, and between number 8 and 35strains. ConclusionsESBLs- producing Klebsiella pneumoniae may have integron- related multi- drug resistance, and carry multiple drug- resistant genes. Cluster analysis reveals evidences of clonal transmission and hospital-acquired infections.