Isolation, identification and 16S rDNA phylogenetic analysis of Klebsiella pneumonia from diarrhea specimens / 中华流行病学杂志

ABSTRACT

Objective To understand the biochemical characteristics and 16S rDNA genetic sequence evolution of strains isolated from diarrhea specimens so as to provide basis for classification and identification of Klebsiella pneumoniae. Methods Specimens were cultured using MacConkey and SS medium. All isolates were identified as K. pneumoniae by automated biochemical tests. DNA was extracted, 1500 bp fragments of the 16S rDNA gene were by amplified PCR and sequenced with K. pneumoniae 16S rDNA primer, after being cut. Fragments of 1000 bp overlapping sequences were analyzed by Blastn to confirm the identity of the isolates. A phylogenetic tree was constructed by PHYLIP process to analyze the 16S rDNA sequence of the isolated strain with other relative bacteria species in the GenBank databases. Results Among 113 specimens of infectious diarrhea, 25 K. pneumoniae strains were identified by biochemical tests, of which 21 subsp, pneumoniae and 4 subsp, ozaenae, no subsp, of rhinoseleroma were isolated. Strains of subsp, pneumoniae were found having nature of resistance. All isolates were resistant to penicillin G and susceptible to polymyxin with some strains were resistant to Nitrofurantoin, Cephalothin, Kanamycin, Tobramycin. After searching in GenBank of 16S rDNA, strains biochemical identified as subsp, ozaenae shared high similarity with Salmonella strains and other intestinal bacteria. 16S rDNA phylogenetie analysis could be used to confirm subsp, pneumoniae, but could not separate other subspecies of K. pneumoniae completely. Conclusion 16S rDNA phylogenetic analysis useful in identifying and classifying K. pneumoniae.