关键词: 肺炎克雷伯氏菌; 分离; 致病性; 16S rRNA; 16-23S rRNA ITS

Abstract: To confirm a suspected Klebsiella pneumonia (K.pneumoniae) infection,and study the pathogenicity,drug sensitivity and homologies of the 16-23S rRNA ITS genes of the pathogen,one Gram-negative,rod-shaped bacteria named as KP14013 was isolated from livers and gut of the piglets with diarrhea,high-mobility and high-mortality.The isolate was preliminarily identified as K.pneumoniae by biochemical test and further identified as K.pneumoniae by 16S rRNA sequence analysis which shared 99% homology with 23 representative isolates from GenBank.Lethality tests indicated that the 50% lethal doses (LD₅₀) in mice were 3×10^1.8 colony-forming units (CFU) for the isolate and that 100% mortality in piglets by intraperitoneal inoculation with 3×10⁸ CFU.The 16-23S rRNA ITS sequence analysis indicated that KP14013 belonged to one subgroup with 15 represent isolates from GenBank and shared homologies of 98.4% to 99.2%.This study confirmed the K.pneumoniae infection with diarrhea and high mobility and high motality in piglets.One highly virulent K.pneumoniae strain was isolated from liver and gut of piglets.The KP14013 isolate was high virulent to mice and piglets, and showed multiple-drug resistance among common antibiotics.The 16-23S rRNA ITS of KP14013 proved to be a feasible and rapid way for identification of different K.pneumoniae species for its moderate conservatism and variability.

Key words: Klebsiella pneumonia (K.pneumoniae); isolation; pathogenicity; 16S rRNA; 16-23S rRNA ITS