Actinomyces species: A Danish Survey on Human Infections and Microbiological Characteristics

J.M Hansen1, 2, *, H Fjeldsøe-Nielsen1, 3, S Sulim1, 4, M Kemp1, J.J Christensen1
1 Department of Bacteriology, Mycology and Parasitology, Statens Serum Institute, Copenhagen, Departments of Clinical Microbiology
2 Hvidovre Hospital, Hvidovre
3 Naestved Hospital, Naestved
4 Viborg Hospital, Viborg, Denmark

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© Hansen et al.; Licensee Bentham Open.

open-access license: This is an open access article licensed under the terms of the Creative Commons Attribution Non-Commercial License ( which permits unrestricted, non-commercial use, distribution and reproduction in any medium, provided the work is properly cited.

* Address correspondence to this author at the Department of Clinical Microbiology, Hvidovre Hospital, Kettegaard Allé 30, 2650 Hvidovre, Denmark; E-mail:


This study compared phenotypic and genotypic identification of Actinomyces strains, tested susceptibility to antibiotics and evaluated their clinical importance. Thirty-four Actinomyces strains were examined; sixteen type strains, and 18 clinical strains from different hospitals in Denmark from the period 2003-2005. Partial 16S rDNA sequencing using a stretch of 526 bases was used for genotypic identification. Susceptibility testing was done by E-test. The antibiotics examined were: benzylpenicillin, piperacillin with tazobactam, ceftriaxone, meropenem, erythromycin, clindamycin, linezolid, moxifloxacin, tetracycline and tigecycline. Clinical parameters were obtained by reviewing patient records. There was poor agreement between the phenotypic and genotypic identification. Phenotypic tests were helpful in identifying strains closely related by DNA sequences. The strains were sensitive to the examined antibiotics except for moxifloxacin to which most strains were resistant, and a few strains were resistant to meropenem and tetracycline. The clinical strains were from many different types of infections and locations. None of the patients was described as having typical actinomycetic lesions, and an apparently good outcome was obtained with different treatment regimens.

Keywords: Actinomyces species, Bacterial identification, phenotypic characterization, partial 16S rDNA sequencing.