Acinetobacterin Denmark: II. Molecular studies of theAcinetobacter calcoaceticus-Acinetobacter baumanniicomplex

Abstract

The Acinetobacter calcoaceticus‐Acinetobacter baumannii complex consists of four closely related “genospecies” or DNA groups: DNA group 1 (A. calcoaceticus), DNA group 2 (A. baumannii), DNA 3, and Tjernberg & Ursing‘s DNA group 13. Strains in this complex are so similar phenotypically that it is often impossible to identify them to the DNA group level by the use of biochemical tests. Twenty‐three Danish clinical strains from 23 patients phenotypically identified to the A. calcoaceticus‐A. baumannii complex were studied by ribotyping, plasmid profiling, and DNA/DNA hybridization. Multiple isolates were recovered from four patients. These were identical in each patient as judged by phenotype, ribotype and plasmic profile. Seventeen different ribotypes were observed among the 23 strains, and by using this method 19 out of the 23 strains could be identified to the DNA group level. Five strains were allocated to DNA group 2 (A. baumannii), eight to DNA group 3, and six to DNA group 13. These findings were confirmed by DNA/DNA hybridization. Two of the four unidentified strains were genotypically most closely related to but different from DNA groups 1 and 3. The last two strains were most closely related to DNA group 13. These four strains represent two new DNA groups within the A. calcoaceticus‐A. baumannii‐complex. One to four plasmids in the size range 2.1 kb‐ > 100 kb were detected in 13 of the strains. Nine plasmid profiles were seen, indicating the usefulness of this typing method if the strains contain plasmids. The study also indicates that ribotyping is useful both for typing and for identification purposes, and that the genetic relationship in this area are more diverse than hitherto perceived. Taxonomic reconsiderations are warranted.

Validation of partial rpoB gene sequence analysis for the identification of clinically important and emerging Acinetobacter species

“…3 (30 strains) and 98.6-100 % for A. calcoaceticus (6 strains) ( Table 1). Gerner-Smidt & Tjernberg (1993) proposed that two other closely related DNA groups, A. gen. sp. 'close to 13TU' and A. gen. sp.…”

Phylogenetic structures of the genus Acinetobacter based on gyrB sequences: comparison with the grouping by DNA-DNA hybridization

“…Recent taxonomic studies have placed this genus within the y-subclass of the Proteobacteria (Rainey et al, 1994) and the genus has been resolved into seven valid species and at least 14 genomic species (DNA groups) by DNA-DNA hybridization studies (Bouvet & Jeanjean, 1989;Bouvet & Grimont, 1986;Gerner-Smidt & Tjernberg, 1993 ;Nishimura et al, 1988;Tjernberg & Ursing, 1989). Acinetobacter is a normal inhabitant of the skin in healthy people and is an opportunistic pathogen involved in outbreaks of hospital infections (Bifulco et al, 1989;Bouvet & Jeanjean, 1995;Seifert et al, 1997;Towner, 1997;Towner et al, 1991).…”

Acinetobacter indicus sp. nov., isolated from a hexachlorocyclohexane dump site

“…Species belonging to this genus have been largely reported from water, soil and even from human skin samples. At the time of writing, this genus included 32 genomic species (Bouvet & Grimont, 1986;Bouvet & Jeanjean, 1989;Tjernberg & Ursing, 1989;Gerner-Smidt & Tjernberg, 1993;Vaneechoutte et al, 1999;Nemec et al, 2001;Carr et al, 2003;Nemec et al, 2003), of which 26 have validly published names (www.bacterio.cict.fr/a/ acinetobacter.html). Members of the genus Acinetobacter are non-motile, strictly aerobic, oxidase negative, catalase positive and Gram-negative coccobacilli.…”