Actinobaculum Schaalii Research Articles

08 First case of spondylodiscitis caused by Actinobaculum schaalii, a rare pathogen causing urinary tract infection in the elderly

08 First case of spondylodiscitis caused by Actinobaculum schaalii, a rare pathogen causing urinary tract infection in the elderly

Actinobaculum urinale sp. nov., from human urine.

A hitherto undescribed Actinomyces-like bacterium was isolated from human urine. Based on its biochemical characteristics, the unidentified bacterium did not correspond to any currently described Actinomyces species or related taxa. Comparative 16S rRNA gene sequencing showed that the unknown bacterium exhibits a specific phylogenetic association with the genus Actinobaculum, but a sequence divergence of > 5% from the two currently recognized members of this genus, Actinobaculum schaalii and Actinobaculum suis, demonstrates that it represents a distinct species. Based on both phenotypic and 16S rRNA gene sequence considerations, it is proposed that the unknown bacterium from urine should be classified as a novel species, Actinobaculum urinale sp. nov. The type strain of Actinobaculum urinale is CCUG 46093(T) (= CIP 107424(T)).

Characterization of some Actinomyces-like isolates from human clinical specimens: reclassification of Actinomyces suis (Soltys and Spratling) as Actinobaculum suis comb. nov. and description of Actinobaculum schaalii sp. nov.

Five strains of a hitherto unknown Actinomyces-like bacterium were isolated from human clinical sources, including blood cultures. Biochemical and chemotaxonomic characterization indicated that the strains were distinct from previously described Actinomyces and Arcanobacterium species. A comparative 16S rRNA gene sequence analysis demonstrated that the undescribed strains constitute a new subline within the Actinomyces-Arcanobacterium species complex. The closest known relative of the isolates was found to be Actinomyces suis, although a 16S rRNA sequence divergence value of approximately 6% clearly demonstrated that the unknown bacterium represents a distinct species. Based on the results of the present and earlier phylogenetic investigations, it is proposed that Actinomyces suis should be reclassified in a new genus, the genus Actinobaculum, as Actinobaculum suis comb. nov. In addition, a new species, Actinobaculum schaalii, is proposed for the Actinomyces-like bacterium from human sources. The type strain of Actinobaculum schaalii is CCUG 27420.

NEWER MACROLIDES

In clinical microbiology laboratories, advancements in the methods used for routine organism identification have facilitated more accurate species level resolution. This, along with increasing knowledge regarding “new” pathogens, has provided new insights into biology and has revealed clinical associations not previously known. Aerococcus urinae, Alloscardovia omnicolens, and Actinotignum schaalii are Gram-positive bacteria associated with urinary tract infections but can also be members of the urinary tract microbiota. In addition, invasive infections have been reported for the three bacteria, usually with a urinary tract source. Importantly, the use of routine biochemical testing methods for identification of these bacteria can result in misidentification or the incorrect determination that they are not clinically significant. Of these bacteria, only A. urinae has antimicrobial susceptibility testing criteria and interpretative breakpoints. Microbiologists and clinicians need to be aware of these urinary tract pathogens and how to correctly identify them.