Acinetobacter species identification by using tRNA spacer fingerprinting

Area of Science:

• Microbiology
• Molecular Biology
• Genetics

Background:

• Phenotypic identification of Acinetobacter species to the DNA group level is challenging.
• A need exists for a reliable, routine identification method for Acinetobacter.
• DNA-DNA hybridization is the gold standard but is time-consuming.

Purpose of the Study:

• To validate tRNA spacer (tDNA) fingerprinting as a rapid identification technique for Acinetobacter species.
• To compare the discriminatory power of tDNA fingerprinting with a commercial carbon source utilization assay (Biolog MicroStation System).
• To assess the suitability of tDNA fingerprinting for routine Acinetobacter identification.

Main Methods:

• Analysis of 128 Acinetobacter strains previously identified by DNA-DNA hybridization.
• Application of tRNA spacer (tDNA) fingerprinting.
• Comparison with the Biolog MicroStation System using carbon source utilization tests.

Main Results:

• tDNA fingerprinting was highly reproducible, classifying strains into 17 distinct groups.
• The Acinetobacter calcoaceticus-A. baumannii complex strains formed two distinct clusters, indicating high genetic similarity.
• The Biolog MicroStation System showed less discriminatory power, grouping strains into 12 clusters.
• Recently described DNA groups (BJ13-BJ16) were ambiguously grouped by tDNA fingerprinting.

Conclusions:

• tDNA fingerprinting provides a quick and reliable method for routine differentiation of most Acinetobacter species at the subgenus level.
• tDNA fingerprinting demonstrates higher discriminatory power compared to commercial carbon source utilization methods.
• Further refinement may be needed for ambiguous grouping of certain Acinetobacter DNA groups.