PCR-AMPLIFIED 16S AND 23S RDNA RESTRICTION ANALYSIS FOR THE IDENTIFICATION OF ACINETOBACTER STRAINS AT THE DNA GROUP LEVEL

The genus Acinetobacter is phenotypically rather homogeneous, but geno typically heterogeneous. In this study, a simple method based on restr iction analysis of a PCR-amplified large fragment (4.5 kb) of most of the ribosomal operon (16S and 23S ribosomal genes and the spacer in-be tween) was investigated. Sixty-seven collection strains belonging to t he 20 DNA groups proposed until 1993 were studied. Using the enzyme Sa u3AI, 25 DNA profiles were obtained. Strains belonging to DNA groups 1 , 3, 6, TU13 and TU15 showed two profiles each, and DNA groups 4, 5 an d 7 showed profiles with variants showing less intensive additional ba nds. The remaining 12 groups showed 12 different profiles. The profile s obtained were DNA-group-specific except for one profile which was sh ared between the unnamed DNA group 3 and a rarely encountered genotypi cally related DNA group. These two DNA groups could be separated by us ing the enzyme Hinf1. Twenty-five additional clinical isolates previou sly characterized by standard DNA-DNA hybridization were selected in a double-blind fashion for identification at the DNA group level to che ck the reliability of the assay. All strains were correctly identified at the DNA group level, PCR-amplified 16S and 23S rDNA restriction an alysis is both an accurate and rapid method for the identification of Acinetobacter at the DNA group level.