Abstract: Objective:To investigate the clinical distribution,production and drug resistance of β-lactamase in nosocomial infection.Methods:The distribution and the drug resistance of 108 strains of Acinetobacter baumanii causing nosocomial infection were analyzed retrospectively.β-lactamase,cephalosporinase and extended spectrum β-lactamases (ESBLs) were detected by Nitrocefin test,3-dimension test and disc agar diffusion method,respectively.Results:The detection rates of Acinetobacter baumanii in ICU wards and neurosurgery wards were 63.89% and 11.11%,respectively.Acinetobacter baumanii was detected in 77.78% of the sputum samples and 12.96% of the secretion samples.The bacteria were resistant to most common antibiotics,and the rate of multiple-resistance was 88.89%.Eleven ESBLs bacteria and 78 cephalosporinase bacteria were detected in the 108 strains of Acinetobacter baumanii,accounting for 10.19% and 72.22%,respectively,and the positive rate of β-lactamase bacteria detected was 100.00%.Conclusions:Acinetobacter baumannii are the major opportunistic pathogenic bacteria in hospital infection.They are highly resistant to routine antimicrobial agents and even multi-drug resistant.The strains producing β-lactamase are the prominent cause of multi-drug resistance.Antimicrobial agents should be used rationally to decrease multi-drug resistance.