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Journal of Clinical Microbiology, February 2005, p. 956-958, Vol. 43, No. 2
0095-1137/05/$08.00+0 doi:10.1128/JCM.43.2.956-958.2005
Copyright © 2005, American Society for Microbiology. All Rights Reserved.
Identification and Characterization of Clinical Isolates of Members of the Staphylococcus sciuri Group
Srdjan Stepanovi
,1*
Ivana Daki
,1
Donald Morrison,2
Tomasz Hauschild,3
Petr Je
ek,4
Petr Petrá
,5
An Martel,6
Dragana Vukovi
,1
Adebayo Shittu,7 and
Luc A. Devriese6
Department of Bacteriology, Institute of Microbiology and Immunology, School of Medicine, Belgrade, Serbia,1
Scottish MRSA Reference Laboratory, Microbiology Department, Stobhill Hospital, Glasgow, United Kingdom,2
Department of Microbiology, Institute of Biology, University of Bialystok, Bialystok, Poland,3
Department of Clinical Microbiology, Regional Hospital P
íbram, P
íbram,4
Czech National Reference Laboratory for Staphylococci, National Institute of Public Health, Prague, Czech Republic,5
Department of Bacteriology, Pathology and Poultry Diseases, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium,6
School of Biochemistry and Microbiology, University of Kwa-Zulu Natal, Durban, Republic of South Africa7
Received 7 October 2004/
Returned for modification 8 October 2004/
Accepted 12 October 2004

ABSTRACT
A total of 28 staphylococcal isolates from human clinical specimens
belonging to the
Staphylococcus sciuri group were identified
and characterized. The API Staph and ID32 STAPH correctly identified
S. sciuri and
S. lentus but not
S. vitulinus strains. Identification
to the subspecies level was possible only by a PCR-based method.

TEXT
Members of the
Staphylococcus sciuri group are widespread in
nature, and they can be isolated from a variety of farm animals,
pets, and wild animals, as well as from various food products
of animal origin (
6,
9,
12,
14,
22,
26). This group is made
up of
Staphylococcus sciuri subsp.
carnaticus,
Staphylococcus sciuri subsp.
rodentium,
Staphylococcus sciuri subsp.
sciuri,
Staphylococcus lentus, and
Staphylococcus vitulinus (
12,
26).
Staphylococcus pulvereri was a member of the
S. sciuri group
until recently, when it was shown that
S. pulvereri is only
a synonym of
S. vitulinus (originally
S. vitulus) (
15,
23).
Although they are principally associated with animals, members
of the
S. sciuri group may colonize humans, and it has been
estimated that they may constitute 0.79 to 4.3% of the total
number of coagulase-negative staphylococci isolated from clinical
samples (
8,
20). However, they have been associated with serious
infections such as endocarditis (
10), peritonitis (
25), septic
shock (
11), urinary tract infection (
20), endophthalmitis (
1),
pelvic inflammatory disease (
21), and, most frequently, wound
infections (
16,
19). The aim of this study was to compare phenotypic
(conventional, API Staph, ID32 Staph) and genotypic (PCR) methods
for identification of isolates of the
S. sciuri group.
A total of 28 isolates belonging to the S. sciuri group, recovered from 1998 to 2003 from clinical samples at the Institute of Microbiology, School of Medicine, Belgrade, Serbia, and Regional Hospital P
íbram, P
íbram, Czech Republic, were analyzed (Table 1). Half of them were isolated from urine samples. Some of these strains have been reported previously (18-21) but not investigated for the characteristics presented in this study. All the isolates were previously identified by conventional methods (5, 12, 18, 26) as S. sciuri (23 strains), S. lentus (3 strains), or S. vitulinus (2 strains).
Staphylocoagulase (free coagulase) activity was determined with
rabbit plasma (Torlak, Belgrade, Serbia) by using the tube method
(
5). Oxidase activity was determined with oxidase diagnostic
tablets (Rosco, Taastrup, Denmark). Novobiocin susceptibility
was determined on Mueller-Hinton agar (Oxoid Limited, Basingstoke,
Hampshire, United Kingdom) with a disk containing 5 µg
of novobiocin (Bioanalyse, Ankara, Turkey). Strains were considered
to be resistant to novobiocin if the zone of inhibition was

16 mm. Commercial identification kits, namely, API Staph and
ID32 STAPH (bioMérieux, Marcy-l'Etoile, France), were
used according to the manufacturer's instructions. All the strains
were coagulase negative and oxidase positive. In addition, the
disk diffusion method with the 5-µg novobiocin disk confirmed
that all strains were resistant to novobiocin. However, only
three
S. sciuri strains showed resistance to novobiocin by use
of the ID32 STAPH kit. The problem with determination of resistance
to novobiocin by ID32 STAPH was also noted by Chesneau et al.
(
2). Moreover, the identification system in the instruction
manual (identification table, version 2.0) indicated that only
26% of
S. lentus isolates and 43% of
S. sciuri isolates could
exhibit resistance to novobiocin by use of the ID32 STAPH kit.
Identification of isolates based on the conventional and commercial
methods (API Staph and ID32 Staph) agreed in the identification
of 26 out of 28 strains. The commercial methods agreed in the
identification of all the
S. sciuri and
S. lentus strains, although
some discrepancies between results obtained by API Staph versus
ID32 STAPH were noted (Table
2). However, two isolates identified
as
S. vitulinus by the conventional method were identified as
Staphylococcus capitis and
S. sciuri by API Staph and as
S. capitis by ID32 Staph. This discrepancy could be attributed
to the fact that
S. vitulinus is not included in the database
of these tests. Misidentification of the members of the
S. sciuri group by commercial identification systems has been reported
previously (
13,
17). Differentiation of
S. sciuri from
S. vitulinus is possible on the basis of utilization of mannose,
L-arabinose,
maltose, and 2-naphthyl phosphate (alkaline phosphatase) as
substrates:
S. sciuri utilizes some or all of these while
S. vitulinus is unable to utilize any of them (
5,
12,
26). However,
we noted that production of acid from mannose by
S. vitulinus could vary depending on the identification system (Table
2).
Identification of the
S. sciuri strains to the subspecies level
was not possible on the basis of phenotypic characteristics,
since
S. sciuri isolates of different subspecies showed similar
biochemical profiles.
Generally, molecular approaches proposed for the identification
of staphylococci can be divided into those based on the detection
of species-specific sequences and those based on the detection
of sequence variations in ubiquitous elements such as rRNA and
tRNA operons or chaperonin-encoding genes (
3). To the best of
our knowledge, species-specific primers have been published
only for
S. sciuri (of all the staphylococci in the
S. sciuri group) (
7). All the strains were tested by PCR using species-specific
primers for
S. sciuri based on previously published primers
and methods (
7). Bright bands indicating a positive reaction
were obtained for all 23
S. sciuri strains (Table
1) and agreed
with the identification by API Staph and ID32 STAPH. However,
the fact that strong or weak hybridization signals were obtained
for all
S. lentus and
S. vitulinus strains suggests that this
set of primers may not be reliable in the identification of
S. sciuri. PCR amplification of the 16S-23S rRNA intergenic
spacer region was performed in accordance with the protocols
previously described by Couto et al. (
4) and Shittu et al. (
16).
This PCR method enabled identification of all isolates to the
species or subspecies level. Out of the 28 isolates, 8 strains
were identified as
S. sciuri subsp.
sciuri, 15 were identified
as
S. sciuri subsp.
rodentium, 3 were identified as
S. lentus,
and 2 were identified as
S. vitulinus by the 16S-23S rRNA PCR
method.
In conclusion, our study showed that the members of the S. sciuri group can be identified and differentiated from other staphylococci from human clinical samples on the basis of the oxidase test. Only the recently described Staphylococcus fleurettii is also novobiocin resistant, coagulase negative, and oxidase positive as well (24). It should be noted that this bacterium has not been isolated from clinical samples of humans. However, certain problems could arise in the identification of these bacteria to the species level by use of API Staph and ID32 STAPH, since S. vitulinus is not included in the database for these tests.

FOOTNOTES
* Corresponding author. Mailing address: Institute of Microbiology and Immunology, School of Medicine, Dr Suboti

a 1, 11000 Belgrade, Serbia. Phone: 381-11-685961. Fax: 381-11-656950. E-mail:
stepan{at}afrodita.rcub.bg.ac.yu.


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Journal of Clinical Microbiology, February 2005, p. 956-958, Vol. 43, No. 2
0095-1137/05/$08.00+0 doi:10.1128/JCM.43.2.956-958.2005
Copyright © 2005, American Society for Microbiology. All Rights Reserved.
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