Identification of Acinetobacter Genospecies by Analysis of rRNA Spacer Regions

Lee, Seung Ho; Lee, Mi Kyung; Park, Ae Ja; Choi, Eung Sang

Abstract

BACKGROUND: Recently, the genus Acinetobacter have become increasingly important as nosocomial pathogens. Colonization and infection caused by multiresistant epidemic strains are common manifestations in intensive care units. Up to now 21 genomic species have been described, of which 7 have been named. However, there is no approach about distribution of Acinetobacter species in Korea. The objective of this study was to evaluate the performance of PCR analysis for the accurate identification and distribution of Acinetobacter species.
METHODS
tRNA intergenic spacer length polymorphism(tRNA-ILP), 16S-23S rRNA spacer length polymorphism(16S-23S ILP) and restriction analysis of the 16S-23S rRNA intergenic spacer sequences(RA 16S-23S) were performed to identify the 7 type strains and 83 clinical isolates of Acinetobacter.
RESULTS
1. In the 7 Acinetobacter type strains, tRNA-ILP data could be easily analyzed by visual comparision. Eighty one of 83(97.6%) clinical isolates of Acinetobacter were identified as A. baumannii and the others were identified as A. haemolyticus and A. calcoaceticus. 2. The 16S-23S ILP patterns were not distinguished among the species, except A. haemolyticus, A, johnonii and A. lwoffii. The three species could be discriminated by a number of specific DNA fragments. 3. In RA 16S-23S, restriction endonuclease Alu I was able to not only digest the amplification products but also gave characteristic restriction patterns for the 7 type strains.
CONCLUSION
The tRNA-ILP analysis and RA 16S-23S can be used as a tool for the rapid identification of Acinetobacter species with a high degree of specificity.