DISCRIMINATION OF ACINETOBACTER GENOMIC SPECIES BY AFLP FINGERPRINTING

AFLP is a novel genomic fingerprinting method based on the selective P CR amplification of restriction fragments. The usability of this metho d for the differentiation of genomic species in the genus Acinetobacte r was investigated. A total of 151 classified strains (representing 18 genomic species, including type, reference, and field strains) and 8 unclassified strains were analyzed. By using a single set of restricti on enzymes (HindIII and TaqI) and one particular set of selective PCR primers, all strains could be allocated to the correct genomic species and all groups were properly separated, with minimal intraspecific si milarity levels ranging from 29 to 74%. Strains belonging to genomic s pecies 8 (Acinetobacter lwoffii sensu stricto) and 9 grouped together in one cluster. The closely related DNA groups 1 (Acinetobacter calcoa ceticus), 2 (Acinetobacter baumannii), 3, and 13TU (sensu Tjernberg & Ursing 1989) were clearly distinguishable, with intraspecific linkage levels above 50%. Strains of the independently described genomic speci es 13BJ (sensu Bouvet & Jeanjean 1989) and 14TU linked together at a r elatively low level (33%). Although a previous DNA-DNA hybridization s tudy seemed to justify the unification of these genomic species, AFLP analysis actually divides the 13BJ-14TU group into three well-separate d subgroups. Finally, four unclassified strains obtained from diverse sources and origins grouped convincingly together, with a similarity l inkage level of approximately 50%. These strains showed no similaritie s in their AFLP patterns with any of the other 155 strains studied and may represent a thus-far-undescribed Acinetobacter species. Based on these results, AFLP should be regarded as an important auxiliary metho d for the delineation of genomic species. Furthermore. because AFLP pr ovides a detailed insight into the infraspecific structure of Acinetob acter taxa, the method also represents a highly effective means for th e confirmation of strain identity in the epidemiology of acinetobacter s.