Previous Article | Next Article 
Journal of Clinical Microbiology, September 2002, p. 3427-3431, Vol. 40, No. 9
0095-1137/02/$04.00+0 DOI: 10.1128/JCM.40.9.3427-3431.2002
Copyright © 2002, American Society for Microbiology. All Rights Reserved.
Actinomyces cardiffensis sp. nov. from Human Clinical Sources
Val Hall,1* Mattew D. Collins,2 Roger Hutson,2 Enevold Falsen,3 and Brian I. Duerden1
Anaerobe Reference Unit, PHLS, University Hospital of Wales, Cardiff,1
School of Food Biosciences, University of Reading, Reading, United Kingdom,2
Culture Collection, Department of Clinical Bacteriology, University of Göteborg, Göteborg, Sweden3
Received 15 January 2002/
Returned for modification 8 April 2002/
Accepted 11 May 2002

ABSTRACT
Eight strains of a previously undescribed catalase-negative
Actinomyces-like bacterium were recovered from human clinical
specimens. The morphological and biochemical characteristics
of the isolates were consistent with their assignment to the
genus
Actinomyces, but they did not appear to correspond to
any recognized species. 16S rRNA gene sequence analysis showed
the organisms represent a hitherto unknown species within the
genus
Actinomyces related to, albeit distinct from, a group
of species which includes
Actinomyces turicensis and close relatives.
Based on biochemical and molecular genetic evidence, it is proposed
that the unknown isolates from human clinical sources be classified
as a new species,
Actinomyces cardiffensis sp. nov. The type
strain of
Actinomyces cardiffensis is CCUG 44997
T.

INTRODUCTION
The genus
Actinomyces embraces a heterogeneous group of anaerobic
and aerotolerant, non-spore-forming, non-acid-fast, gram-positive
rods with high G+C DNA content (
14). Many
Actinomyces species
primarily belong to the facultative anaerobic indigenous microflora
of human and animal mucous membranes, particularly those of
the oral cavity. Some members of the genus are known to cause
classical actinomycosis and may also be found in polymicrobial
infections, while others are significant in periodontal disease
(
14,
15). The genus
Actinomyces has undergone considerable expansion
in recent years, with a plethora of new species defined, especially
from human sources. Recently described
Actinomyces species,
including
Actinomyces funkei (
9),
Actinomyces europaeus (
4),
Actinomyces graevenitzii (
13),
Actinomyces neuii subsp.
anitratus and
neuii (
5),
Actinomyces radingae (
17),
Actinomyces radicidentis (
1),
Actinomyces turicensis (
17), and
Actinomyces urogenitalis (
12), have been isolated from clinical specimens, where they
occur as contaminants and/or represent possible opportunistic
pathogens. Despite this increase in the number of recognized
species, it is clear that knowledge of the habitats, clinical
prevalence, and pathogenic potential of many
Actinomyces and
related organisms is inadequate, and there are indications (
6,
7) that much new diversity remains to be discovered from human
sources. During the course of study of clinical isolates of
Actinomyces, we have characterized a hitherto unknown
Actinomyces-like
species. Based on both phenotypic and phylogenetic evidence,
we propose yet another new species of the genus
Actinomyces,
namely,
Actinomyces cardiffensis.

MATERIALS AND METHODS
Cultures and phenotypic characterization.
All eight strains were isolated in the United Kingdom and were
presumptively identified as
Actinomyces spp. and were referred
to the Public Health Laboratory Service Anaerobe Reference Unit,
Cardiff, United Kingdom, for confirmation of identity. Strain
R10394
T (CCUG 44997
T) was recovered in 1993 from an intrauterine
contraceptive device (IUCD) which was in situ for 7 years in
a 35-year-old female in Great Yarmouth, United Kingdom. Strains
R13895 (CCUG 45110) and R7770 (CCUG 46084) were also recovered
from IUCDs of 26- and 37-year-old females in Farnborough, Hampshire,
United Kingdom (2000), and Bury St. Edmunds, West Suffolk, United
Kingdom (1994), respectively. The latter patient was described
as having the IUCD in situ for a considerable period of time,
and
Actinomyces-like organisms were seen in her cervical smear.
Strain R5999 (CCUG 45108) was recovered from pus from temporal,
large parietal, small parietal, and ear abscesses of a 32-year-old
male at 4 weeks postmastoidectomy (Cardiff, United Kingdom,
1993). Concomitant organisms in each of the four abscesses were
Fusobacterium nucleatum,
Bacteroides fragilis,
Bacteroides ureolyticus,
Porphyromonas endodontalis,
Porphyromonas levii,
Prevotella oris,
Peptostreptococcus micros,
Peptostreptococcus sp.,
Arcanobacterium bernardiae,
Eggerthella lenta, and a microaerophilic
Streptococcus sp. strain R11374 (CCUG 45109) was recovered from pleural fluid
of a 74-year-old male with glaucoma, shortness of breath, and
wheezing (Burton upon Trent, East Staffordshire, United Kingdom,
1997). Strain R5571 (CCUG 44995) was recovered from pus from
an actinomycotic jaw abscess of a 78-year-old female (Hereford,
United Kingdom, 1993). Strain R2037 (CCUG 46083) was recovered
from a pericolic abscess, discovered upon resectioning of a
colon carcinoma of a 71-year-old female (Lincoln, Lincolnshire,
United Kingdom, 1985). Strain R9463 (CCUG 46085) was recovered
from a right antral washout of a 48-year-old female with sinusitis
(Carlisle, Cumbria, United Kingdom, 1996). Volatile and nonvolatile
end products of glucose metabolism were detected by gas-liquid
chromatography (
8). For biochemical testing, the strains were
cultured on Columbia agar (Difco, Detroit, Mich.) supplemented
with 5% horse blood at 37°C, incubated anaerobically. The
strains were biochemically characterized using both conventional
tests (
10) and the commercially available API rapid ID32A, API
rapid ID32Strep, and API Coryne systems according to the manufacturer's
instructions (API BioMérieux, Marcy l'Etoile, France).
Amplified 16S rDNA restriction analysis.
Amplified 16S rDNA restriction analyses were performed using HaeIII and HpaII as described previously (6, 7).
16S rRNA gene sequencing and phylogenetic analyses.
The 16S rRNA genes of the eight isolates were amplified by PCR and directly sequenced using a Taq dye-deoxy terminator cycle sequencing kit (Applied Biosystems, Foster City, Calif.) and an automatic DNA sequencer (model 373A; Applied Biosystems). The closest known relatives of the new isolates were determined by performing database searches. These sequences and those of other known related strains were retrieved from the GenBank or Ribosomal Database Project libraries and aligned with the newly determined sequences using the program PILEUP (2). The resulting multiple sequence alignment was corrected manually, and a distance matrix was calculated using the programs PRETTY and DNADIST (using Kimura 2-correction) (3). A phylogenetic tree was constructed according to the neighbor-joining method with the program NEIGHBOR (3). The stability of the groupings was estimated by bootstrap analysis (500 replications) using the programs DNABOOT, DNADIST, NEIGHBOR, and CONSENSE (3).
Protein profiling.
Polyacrylamide gel electrophoresis analysis of whole-cell proteins was performed as described by Pot et al. (11). For densitometric analysis, normalization, and interpretation of protein patterns, the GCW 3.0 software package (Applied Maths) was used. The similarity between all pairs of traces was expressed by the Pearson product moment correlation coefficient, which was converted for convenience to percent similarity.
Nucleotide sequence accession number.
The GenBank accession number for the 16S rRNA sequence of CCUG 44997 T is AJ421779.

RESULTS AND DISCUSSION
The eight isolates consisted of slender, straight or curved,
pleomorphic, gram-positive rod-shaped cells. Beaded and branched
filamentous forms occurred. Cells were non-acid-fast, non-spore-forming,
and catalase negative. Strains were facultatively anaerobic
but grew better under anaerobic conditions. After anaerobic
incubation for 48 h, colonies on Fastidious Anaerobe Agar (LabM;
Bury, Lancashire, United Kingdom) with 5% horse blood were pinpoint,
convex, smooth, entire-edged, opaque cream to pink, and nonhemolytic.
Principal end products of glucose metabolism were small amounts
of acetic acid and large amounts of lactic and succinic acids.
When subjected to conventional biochemical testing (
10), the
isolates formed acid from glucose and sucrose but not from amygdalin,
L-arabinose, cellobiose, lactose, mannitol, mannose,
D-raffinose,
salicin, trehalose, or
D-xylose. The level of acid production
from
D-ribose was variable. The isolates failed to hydrolyze
esculin and starch and were lipase and lecithinase negative.
They were indole negative. Based upon these findings, the unknown
isolates resembled
Actinomyces odontolyticus but were differentiated
from this species by the fermentation of lactose, dark red pigment,
and growth in air, which are characteristic of the latter. Using
the commercial biochemical kits, the strains were unidentified.
When the API Coryne system was used, the eight strains produced
acid from glucose and sucrose and displayed

-glucosidase activity.
Acid was produced from ribose by five of the eight strains,
while seven of the eight strains formed acid from maltose. Nitrate
reduction was variable, with two of the eight strains testing
positive. None of the isolates produced acid from glycogen,
lactose, mannitol, or
D-xylose, and activity for alkaline phosphatase,
catalase, ß-galactosidase, ß-glucuronidase,
N-acetyl-ß-glucosaminidase, pyrazinamidase, pyrolydonyl
arylamidase, and urease was not detected. None of the strains
hydrolyzed esculin or gelatin. A code of 0/1 0 1 0 1/3 2 1 was
generated. When the API rapid 32S system was used, all eight
strains showed activity for alanine phenylalanine proline arylamidase
and three of the eight strains produced acid from sucrose. However,
none of the strains produced acid from
D-arabitol,
L-arabinose,
cyclodextrin, glycogen, maltose, mannitol, melibiose, melezitose,
methyl-ß-
D-glucopyranoside, lactose, pullulan,
D-raffinose,
D-ribose, sorbitol, tagatose, or trehalose and none displayed
activity for arginine dihydrolase, alkaline phosphatase, ß-glucosidase,

-galactosidase, ß-galactosidase, ß-glucuronidase,
glycyl tryptophan arylamidase, ß-mannosidase,
N-acetyl-ß-glucosaminidase,
pyroglutamic acid arylamidase, or urease, using the rapid ID
32S kit. When the API rapid ID32A system was used, all eight
strains displayed activity for alanine arylamidase, arginine
arylamidase,

-glucosidase, glycine arylamidase, histidine arylamidase,
leucine arylamidase, leucylglycine arylamidase, proline arylamidase,
phenylalanine arylamidase, serine arylamidase, and tyrosine
arylamidase. None of the strains displayed activity for alkaline
phosphatase,

-arabinosidase, arginine dihydrolase,

-fucosidase,

-galactosidase, ß-galactosidase, ß-galactosidase
6-phosphate, ß-glucosidase, ß-glucuronidase,
glutamic acid decarboxylase, glutamylglutamic acid arylamidase,
N-acetyl-ß-glucosaminidase, pyroglutamic acid, arylamidase,
or urease. Some strains produced acid from mannose (one of eight)
and raffinose (two of eight), and three of eight reduced nitrate.
None of the isolates produced indole. In this test system, a
code of 0 4 0 0/2/4 0/1 7 3 7 0 5 was generated. The cellular
morphology and biochemical reactions of the isolates were consistent
with their tentative assignment to the genus
Actinomyces, but
the strains did not appear to correspond to any recognized species
of this genus. To investigate the genetic relatedness of the
isolates, amplified 16S rDNA restriction analyses was performed.
All eight strains produced identical 16S rDNA restriction profiles
with
HaeIII and
HpaII (profile, 001/016), indicating that the
strains were highly related to each other. To ascertain the
phylogenetic relationships of the unknown organisms, their almost
complete 16S rRNA gene sequences (>1,400 nucleotides) were
determined. Pairwise analysis showed that the organisms were
genetically highly related to each other, displaying >99.5%
sequence relatedness. These data, in conjunction with the high
phenotypic resemblance of the clinical isolates, strongly support
their assignment to a single species. Sequence database searches
confirmed that the unknown isolates were most closely related
to species of the genus
Actinomyces. The highest sequence similarity
values were seen with
Actinomyces species and phylogenetically
related organisms. Other
Actinomyces species showed substantially
lower levels of relatedness (data not shown). Tree analysis
further demonstrated the placement of the unidentified bacterium
(as exemplified by strain R10394
T = CCUG 44997
T) within the
genus
Actinomyces, with the novel bacterium displaying a specific
association to a small subcluster of species which included
Actinomyces funkei,
Actinomyces radingae,
Actinomyces turicensis,
and their close phylogenetic relatives (Fig.
1). The results
of comparative analysis of whole-cell protein profiles of the
unidentified strains and reference species of the genus
Actinomyces and related genera are shown in Fig.
2. The eight clinical isolates
formed a distinct group (greater than 70% intragroup similarity)
that was distinct from all other recognized species.
Actinomyces funkei displayed the closest similarity to the unidentified
clinical group, joining the latter at about 55% similarity (Fig.
2). Other species displayed much lower levels of similarity.
In recent years, numerous new
Actinomyces species have been
isolated from human and animal sources. Most of these new species
have come to light as a result of increased interest by clinical
microbiologists in the possible role of such organisms as opportunistic
pathogens and due to the implementation of improved molecular
identification methodologies that permit their differentiation
from recognized species. It is evident from the results of the
present investigation that the unidentified gram-positive, catalase-negative,
rod-shaped organisms represent another hitherto undescribed
Actinomyces species from clinical sources. The novel bacterium
forms a distinct subline within a subcluster of species within
the
Actinomyces genus, which includes
Actinomyces turicensis,
Actinomyces funkei,
Actinomyces radingae,
Actinomyces canis,
Actinomyces georgiae,
Actinomyces hyovaginalis,
Actinomyces meyeri,
Actinomyces odontolyticus, and
Actinomyces suimastitidis.
Bootstrap resampling, however, showed that the novel bacterium
did not possess a particularly significant affinity with any
member of this subcluster. Sequence divergence values of 3 to
6% with the aforementioned species further reinforced the distinctiveness
of the clinical isolates. Although there is no precise correlation
between percent 16S rRNA sequence divergence values and species
delineation, it is now universally recognized that organisms
displaying values close to 3% or more do not belong to the same
species (
16). The observed >3% sequence divergence between
the unidentified clinical isolates and all presently defined
Actinomyces species is therefore consistent with separate species
status. The separateness of the unknown bacterium is also supported
by phenotypic evidence. Protein profiling showed that the clinical
isolates were phenotypically closely related to each other and
were quite distinct from other species within the
A. turicensis-A. radingae rRNA subcluster. The biochemical profile of the novel
bacterium also readily distinguishes it from all presently described
Actinomyces species. Therefore, on the basis of the distinct
phenotypic characteristics of the unidentified rod-shaped bacterium
and molecular chemical and molecular genetic evidence, we think
the clinical isolates warrant classification as a new species
of the
Actinomyces genus, for which the name
Actinomyces cardiffensis sp. nov. is proposed. Tests that are useful in distinguishing
Actinomyces cardiffensis from its closest relatives are shown
in Table
1. We believe that the formal description of this new
species, together with biochemical tests for its identification,
will facilitate its recognition in the clinical laboratory,
thereby permitting a future evaluation of its distribution,
clinical prevalence, and significance.
View this table:
[in this window]
[in a new window]
|
TABLE 1. Results of tests used to distinguish Actinomyces cardiffensis sp. nov. from its nearest phylogenetic relativesa
|
Description of Actinomyces cardiffensis sp. nov.
Actinomyces cardiffensis (car.dif.fen'sis, L. adj.
cardiffensis,
pertaining to Cardiff, a city in Wales) cells are pleomorphic,
slender, straight-to-curved rods; beaded branching filaments
occur. Cells stain gram positive, are non-acid-fast and nonmotile.
On Fastidious Anaerobic Agar with 5% horse blood after 48 h
of incubation, colonies are pinpoint, convex, smooth surfaced,
entire-edged, and opaque cream to pinkish. Nonhemolytic. Facultatively
anaerobic and catalase negative. Using conventional testing,
acid is formed from glucose and sucrose but not from amygdalin,
L-arabinose, cellobiose, lactose, mannitol, mannose,
D-raffinose,
salicin, trehalose, or
D-xylose. Acid production from
D-ribose
variable. Principal end products of glucose metabolism are lactic
and succinic acids, together with small amounts of acetic acid.
Hydrolysis of esculin and starch is negative. Lipase and lecithinase
are not produced. Using API systems, acid is produced from
D-glucose
but not from
L-arabinose,
D-arabitol, cyclodextrin, glycogen,
lactose, mannitol, melibiose, melezitose, methyl-ß-
D-glucopyranoside,
N-acetyl-ß-glucosamine, pullulan, sorbitol, tagatose,
trehalose, or
D-xylose. Acid may or may not be formed from maltose,
mannose,
D-raffinose,
D-ribose, and sucrose. Gelatin, esculin,
and hippurate are not hydrolyzed. Alanine phenylalanine proline
arylamidase, alanine arylamidase, arginine arylamidase,

-glucosidase,
glycine arylamidase, histidine arylamidase, leucine arylamidase,
leucylglycine arylamidase, proline arylamidase, phenylalanine
arylamidase, serine arylamidase, and tyrosine arylamidase are
detected. No activity is detected for

-arabinosidase, arginine
dihydrolase, alkaline phosphatase,

-fucosidase,

-galactosidase,
ß-galactosidase, ß-galactosidase 6-phosphate,
ß-glucosidase, ß-glucuronidase, glycyl tryptophan
arylamidase, glutamic acid decarboxylase, glutamylglutamic acid
arylamidase,
N-acetyl-ß-glucosaminidase, pyrazinamidase,
pyroglutamic acid arylamidase, ß-mannosidase, pyrolydonyl
arylamidase, or urease. Acetoin is not produced. Nitrate may
or may not be reduced. Indole negative. The type strain is CCUG
44997
T = CIP 107323
T. Isolated from human clinical sources,
including pleural fluid, brain, jaw, pericolic and ear abscesses,
antrum, and IUCDs. Habitat is not known.

ACKNOWLEDGMENTS
We are grateful to Hans Trüper for help in coining the
species name and to Lena Dahl for technical assistance.

FOOTNOTES
* Corresponding author. Mailing address: Anaerobe Reference Unit, PHLS, University Hospital of Wales, Cardiff CF14 4XW, United Kingdom. Phone: 44 2920742171. Fax: 44 2920744123. E-mail:
hallv{at}cardiff.ac.uk.


REFERENCES
1 - Collins, M. D., L. Hoyles, S. Kalfas, G. Sundquist, T. Monsen, N. Nikolaitchouk, and E. Falsen. 2000. Characterization of Actinomyces isolates from infected root canals of teeth: description of Actinomyces radicidentis sp. nov. J. Clin. Microbiol. 38:3399-3403.[Abstract/Free Full Text]
2 - Devereux, J., P. Haeberli, and O. Smithies. 1984. A comprehensive set of sequence analysis programs for the VAX. Nucleic Acids Res. 12:387-395.[Abstract/Free Full Text]
3 - Felsenstein, J. 1989. PHYLIP-phylogeny inference package (version 3.2). Cladistics 5:164-166.
4 - Funke, G., N. Alvarez, C. Pascual, E. Falsen, E. Akervall, L. Sabbe, L. Schouls, N. Weiss, and M. D. Collins. 1997. Actinomyces europaeus sp. nov., isolated from human clinical specimens. Int. J. Syst. Bacteriol. 47:687-692.[Abstract/Free Full Text]
5 - Funke, G., S. Stubbs, A. von Graevenitz, and M. D. Collins. 1994. Assignment of human-derived CDC group 1 coryneform bacteria and CDC group 1-like coryneform bacteria to the genus Actinomyces as Actinomyces neuii subsp. neuii sp. nov., subsp. nov., and Actinomyces neuii subsp. anitratus subsp. nov. Int. J. Syst. Bacteriol. 44:167-171.[Abstract/Free Full Text]
6 - Hall, V., G. L. O' Neill, J. T. Magee, and B. I. Duerden. 1999. Development of amplified 16S ribosomal DNA restriction analysis for identification of Actinomyces species and comparison with pyrolysis-mass spectrometry and conventional biochemical tests. J. Clin. Microbiol. 37:2255-2261.[Abstract/Free Full Text]
7 - Hall, V., P. R. Talbot, S. L. Stubbs, and B. I. Duerden. 2001. Identification of clinical isolates of Actinomyces species by amplified 16S ribosomal DNA restriction analysis. J. Clin. Microbiol. 39:3555-3562.[Abstract/Free Full Text]
8 - Holdeman, L. V., E. P. Cato, and W. E. C. Moore. 1977. Anaerobe laboratory manual, 4th ed. Virginia Polytechnic Institute and State University, Blacksburg, Va.
9 - Lawson, P. A., N. Nikolaitchouk, E. Falsen, K. Westling, and M. D. Collins. 2001. Actinomyces funkei sp. nov., isolated from human clinical specimens. Int. J. Syst. Bacteriol. 51:853-855.[Abstract]
10 - Phillips, K. D. 1976. A simple and sensitive technique for determining the fermentation reactions of non-sporing anaerobes. J. Appl. Bacteriol. 41:325-328.[Medline]
11 - Pot, B., P. Vandamme, and K. Kersters. 1994. Analysis of electrophoretic whole-organism protein fingerprints, pp. 493-521. In M. Goodfellow and A. G. O'Donnell (ed.), Modern microbial methods. Chemical methods in prokaryotic systematics. Wiley, Chichester, England.
12 - Nikolaitchouk, N., L. Hoyles, E. Falsen, J. M. Grainger, and M. D. Collins. 2000. Characterisation of Actinomyces isolates from samples from human urogenital tract: description of Actinomyces urogenitalis sp. nov. Int. J. Syst. Evol. Microbiol. 50:1649-1654.[Abstract]
13 - Pascual, C., E. Falsen, E. Akervall, B. Sjoden, and M. D. Collins. 1997. Actinomyces graevenitzii sp. nov., isolated from human clinical specimens. Int. J. Syst. Bacteriol. 47:885-888.[Abstract/Free Full Text]
14 - Schaal, K. P. 1986. Genus Actinomyces, pp. 1383-1418. In P. H. A. Sneath, N. S. Mair, M. E. Sharpe, and J. G. Holt (ed.), Bergey's manual of systematic bacteriology, vol. 2. Williams and Wilkins Co., Baltimore, Md.
15 - Schaal, K. P. 1997. Actinomycoses, actinobacillosis and related diseases, p 777-798. In W. J. Hausler and M. Sussman (ed.), Topley and Wilson's microbiology and microbial infections, 9th ed., vol. 3. Edward Arnold, London, England.
16 - Stackebrandt, E., and B. M. Goebel. 1994. Taxonomic note: a place for DNA-DNA reassociation and 16S rRNA sequence analysis in the present species definition in bacteriology. Int. J. Syst. Bacteriol. 44:846-849.[Abstract/Free Full Text]
17 - Wüst, J., S. Stubbs, N. Weiss, G. Funke, and M. D. Collins. 1995. Assignment of Actinomyces pyogenes-like (CDC coryneform group E) bacteria to the genus Actinomyces as Actinomyces radingae sp. nov. and Actinomyces turicensis sp. nov. Lett. Appl. Microbiol. 20:76-81.[Medline]
Journal of Clinical Microbiology, September 2002, p. 3427-3431, Vol. 40, No. 9
0095-1137/02/$04.00+0 DOI: 10.1128/JCM.40.9.3427-3431.2002
Copyright © 2002, American Society for Microbiology. All Rights Reserved.
This article has been cited by other articles:
-
Hall, V., Collins, M. D., Lawson, P. A., Falsen, E., Duerden, B. I.
(2005). Actinomyces dentalis sp. nov., from a human dental abscess. Int. J. Syst. Evol. Microbiol.
55: 427-431
[Abstract]
[Full Text]
-
Hall, V., Collins, M. D., Lawson, P. A., Falsen, E., Duerden, B. I.
(2003). Actinomyces nasicola sp. nov., isolated from a human nose. Int. J. Syst. Evol. Microbiol.
53: 1445-1448
[Abstract]
[Full Text]
-
(2003). Validation of publication of new names and new combinations previously effectively published outside the IJSEM. Int. J. Syst. Evol. Microbiol.
53: 1-2
[Abstract]
[Full Text]