JOURNAL OF CLINICAL MICROBIOLOGY,
Copyright © 1999, American Society for Microbiology. All Rights Reserved.
Oct. 1999, p. 3353–3356 Vol. 37, No. 10
Case of Staphylococcus schleiferi Endocarditis and a Simple Scheme
To Identify Clumping Factor-Positive Staphylococci
MICHAEL J. LEUNG,1* NICHALAS NUTTALL,2MARGARET MAZUR,3TANIA L. TADDEI,1
MICHAEL MCCOMISH,3AND JOHN W. PEARMAN1
Division of Microbiology and Infectious Diseases1and Division of Internal Medicine,3Royal Perth Hospital, Perth,
Western Australia 6000, and Division of Microbiology, Queensland Health Pathology and Scientific Services,
Royal Brisbane Hospital, Herston 4029, and Gold Coast Hospital, Southport 4215, Queensland,2Australia
Received 14 December 1998/Returned for modification 27 February 1999/Accepted 17 July 1999
Staphylococcus schleiferi is a coagulase-negative staphylococcus infrequently reported as a human pathogen.
We report a case of prosthetic valve endocarditis attributed to this organism, contrast it to another Staphy-
lococcus species that gives similar clumping factor results (S. lugdunensis), and propose a simple, effective
identification scheme for identification of clumping factor-positive staphylococci.
Staphylococcus schleiferi is a recently described (6) coagu-
lase-negative staphylococcus (CoNS) that has rarely been re-
ported in human infections. We report what we believe is the
first described case of S. schleiferi endocarditis.
A 78-year-old man presented with a 2-day history of inter-
mittent rigors, night sweats, urinary and fecal incontinence on
one occasion, and urinary retention at presentation. There was
no history of dysuria, frequent urination, or abdominal pain.
He reported an influenza-like illness with rhinorrhea, cough,
myalgia, and vertigo 3 weeks prior to presentation.
His medical history included a Starr-Edwards mitral valve
replacement for myxomatous valve degeneration and coronary
artery bypass grafting to three vessels 4 years previously,
chronic atrial fibrillation, hypertension, and one transient isch-
emic attack. His regular oral medication included digoxin (250
?g per day [q.d.]), amiodarone (100 mg q.d.), warfarin (2 mg
q.d.), and captopril (50 mg/12 h). He was an ex-smoker.
On examination, he had a temperature of 38.5°C, a heart
rate of 90 to 100 in atrial fibrillation, and a blood pressure of
115/74 mm Hg. The prosthetic valve sounds were normal; no
murmurs or added sounds were heard. The rest of the clinical
examination was unremarkable; in particular, there were no
peripheral signs of endocarditis.
Investigation demonstrated a subtherapeutic international
normalized ratio of 1.2 (recommended therapeutic range, 3.0
to 4.5), and urinalysis was positive for blood. Full blood count,
creatinine, electrolyte, and liver function tests were all within
reference ranges. The chest X-ray was reported as normal. The
C-reactive protein level was 150 mg/liter (normal, ?10 mg/
liter). Despite the lack of clinical signs to support a diagnosis of
endocarditis, the occurrence of fevers in a patient with a mitral
valve prosthesis in situ necessitated antimicrobial therapy. He
was given gentamicin (180 mg, stat) and amoxicillin (1 g/6 h)
intravenously (i.v.). A transthoracic echocardiogram did not
demonstrate any vegetations. Blood cultures yielded staphylo-
cocci after 48 h, and flucloxacillin (1 g/4 h given i.v.) was
substituted for the amoxicillin. A transesophageal echocardio-
gram (TOE) showed a small (5 by 3 by 4 mm) vegetation on the
prosthetic mitral valve, with independent mobility and differ-
ent echodensity. Valve function was normal, and there was no
evidence of paravalvular regurgitation or abscess, so conserva-
tive therapy with antimicrobials was continued in lieu of urgent
All four sets of blood cultures (BacT/Alert FAN; Organon
Teknika Corporation, Durham, N.C.) yielded gram-positive
cocci in clusters that were catalase positive, consistent with
staphylococci. Growth on solid media (chocolate agar [Oxoid
GC agar base with growth supplement; Unipath Ltd., Basing-
stoke, United Kingdom] and horse blood agar) produced col-
ony variation consisting of large and small morphotypes; pure
subcultures of both colonial morphologies also produced col-
ony variation with identical biochemical reactions. The clump-
ing factor (coagulase rabbit plasma with EDTA; BBL Becton
Dickinson, Cockeysville, Md.), STAPH-A-LEX latex aggluti-
nation (Trinity Laboratories Inc., Raleigh, N.C.), and tube
coagulase tests were all negative. The clumping factor test
using human plasma was positive. The isolate produced a heat-
stable nuclease when commercial media were used (10). The
RBH-STAPH system that utilizes Rosco diagnostic tablets, the
Murex PYR (1-pyrrolidonyl-?-naphthylamide) reagent (Murex
Biotech Ltd., Dartford, United Kingdom), and antibiotic sus-
ceptibility testing for identification of staphylococci (15)
showed the isolate to be furazolidone susceptible, to be des-
ferrioxamine resistant, to be novobiocin susceptible, to be PYR
positive, to be beta-hemolytic on horse blood agar after 18 h of
incubation at 37°C, to be polymyxin susceptible, to be resistant
to 0.04 U of bacitracin but susceptible to 10 U of bacitracin, to
exhibit a zone of inhibition greater than 30 mm in diameter
(susceptible) around a fosfomycin tablet, to be ornithine de-
carboxylase (ODC) negative, to be alkaline phosphatase
(ALP) positive, and to be urease negative. These results were
consistent with those for S. schleiferi. The ID32 STAPH iden-
tification system (bioMe ´rieux Vitek Inc., Hazelwood, Mo.)
gave an identification profile of 26112640, consistent with
99.99% certainty of identification as S. schleiferi. The Mi-
croScan WalkAway Rapid Pos Breakpoint 1 Panel (Dade-
Behring, West Sacramento, Calif.) gave an identification pro-
file of 040075762000-110, consistent with 99.9% certainty of
identification as S. schleiferi. The Staph-Zym identification
method (Rosco Diagnostica, Taastrup, Denmark) gave an
identification profile of 2171-3, consistent with unequivocal
identification as S. schleiferi, after additional tests recom-
mended by the manufacturer (acetoin production and lactose
and sucrose fermentation) were performed. The isolate was
* Corresponding author. Present address: Western Diagnostic Pa-
thology, 74 McCoy St., Myaree, WA 6154, Australia. Phone: 61-8-9317
0959. Fax: 61-8-9317 1536. E-mail: email@example.com.
not identified by Vitek GPI cards, as S. schleiferi is not in that
A nested PCR using primers specific for the S. aureus ther-
monuclease gene (nuc) and primers for the gene encoding
penicillin-binding protein 2a and conferring methicillin resis-
tance (mecA) (2) produced no amplicons. Susceptibility testing
using the Kirby-Bauer disc diffusion method (14), the Vitek
GPS-IX card (bioMe ´rieux Vitek Inc.), and the MicroScan
WalkAway Rapid Pos Breakpoint 1 Panel (Dade-Behring)
showed the isolate to be susceptible to benzylpenicillin, oxacil-
lin, ciprofloxacin, rifampin, tetracycline, erythromycin, and
vancomycin. The ?-lactamase tests in the Vitek GPS-IX card
(bioMe ´rieux Vitek Inc.) and the MicroScan panel (Dade-Be-
hring) were negative and were confirmed negative by using
growth at the margin of the zone of inhibition around a 0.5-U
penicillin disk to inoculate a nitrocefin disk (Cefinase; BBL
After confirmation of the isolate’s identity, the patient was
treated with benzylpenicillin (1.8 g/4 h) i.v. and rifampin (300
mg/8 h) orally with cessation of flucloxacillin. Gentamicin (80
mg/8 h) was given i.v. for the first 2 weeks of treatment. He
received benzylpenicillin and rifampin for a total of 6 weeks. A
follow-up TOE showed resolution of the vegetation. The pa-
tient made a complete recovery with a C-reactive protein level
of ?4 mg/liter at follow-up 6 weeks after presentation.
We believe that this case represents the first report of S.
schleiferi endocarditis. Blood samples collected by four sepa-
rate percutaneous venipunctures (eight bottles) all grew the
organism, and TOE evidence was consistent with a vegetation
on the prosthetic mitral valve. These findings fulfilled the Duke
clinical criteria for definite endocarditis (4). A recent paper (9)
suggested that endocarditis due to S. schleiferi has been previ-
ously reported. The references given were two that reported
blood culture isolates of S. schleiferi. Fleurette et al. (5) briefly
mentioned one patient with a single blood culture positive for
S. schleiferi and possible vertebral osteomyelitis; the possibility
of endocarditis was not raised. Jean-Pierre et al. (7) described
a patient with eight blood cultures positive for S. schleiferi;
echocardiography excluded endocarditis, and the probable
source of the organism was extensive venous thrombophlebitis.
At least three other papers have reported the isolation of S.
schleiferi from blood cultures, but none reported associated
endocarditis. Latorre et al. (12) described a patient with three
blood cultures positive for S. schleiferi; again, the possibility of
endocarditis was not mentioned. Ce ´lard et al. (1) described
four pacemaker infections with S. schleiferi, including one in a
patient with six positive blood cultures, without mentioning
endocarditis. Da Costa et al. (3) examined the role of preax-
illary flora in pacemaker infections and described two patients
with S. schleiferi bacteremia resulting from pacemaker infec-
tion. Endocarditis was not listed as a complication in these
A recent paper described biochemical tests that helped to
differentiate S. schleiferi subsp. schleiferi and S. schleiferi subsp.
coagulans (18). Only seven different S. schleiferi strains were
tested, making it difficult to attribute defining characteristics to
individual subspecies, and the isolates were not correlated with
human infections. We did not identify our isolate to the sub-
species level, but it was considered most likely to belong to the
subspecies schleiferi since it was tube coagulase and urease
negative (S. schleiferi subsp. coagulans is tube coagulase and
urease positive) and there is only a single report of S. schleiferi
subsp. coagulans being isolated from humans (18).
Nine S. schleiferi isolates from six distinct geographical re-
gions of Australia were tested for common phenotypic char-
acteristics. This data is presented in Table 1. In summary, all of
TABLE 1. Geographical origins, sites of isolation, and phenotypic characteristics of nine Australian S. schleiferi isolatesa
Far northern Queensland
Far northern Queensland
Sydney, New South Wales
Perth, Western Australia
Perth, Western Australia
aNeg, negative; Pos, positive.
bPYR positive by the Staph-Zym kit.
3354NOTESJ. CLIN. MICROBIOL.
the isolates were tube coagulase negative, clumping factor pos-
itive (using human plasma), heat-stable nuclease positive, ALP
positive, and urease and maltose fermentation negative. Eight
of the nine isolates were PYR positive. All of the isolates could
be definitively identified with the ID32 STAPH (bioMe ´rieux
Vitek Inc.) and RBH-STAPH systems. The Staph-Zym (Rosco
Diagnostica) system gave unequivocal identification of all iso-
lates after additional tests (acetoin production and lactose and
sucrose fermentation) recommended by the manufacturer
S. schleiferi and S. lugdunensis are the only two CoNS species
that frequently give positive clumping factor reactions. We
tested 146 staphylococcal strains with a variety of phenotypic
and biochemical tests (using Rosco diagnostic tablets and the
Murex PYR reagent). Results are presented in Table 2. From
these results, a 4-h screening scheme (Fig. 1) was derived for
the identification of staphylococci that yield positive clumping
factor results (using human plasma). None of 25 strains of S.
haemolyticus gave a weak positive ODC reaction although this
phenomenon has been reported previously (16). Three of 37
isolates of S. epidermidis did yield a weak positive ODC reac-
tion, but all S. epidermidis isolates were clumping factor and
PYR negative. We believe that this screening strategy will
accurately identify S. schleiferi and S. lugdunensis and differen-
tiate them from other tube coagulase-negative staphylococci.
S. lugdunensis has increasingly been reported in endocardi-
tis, characteristically an aggressive form with poor clinical out-
come similar to that of S. aureus rather than the better out-
come generally associated with other CoNS species (13, 17).
The more aggressive endocarditis associated with S. lugdunen-
sis has been attributed to the expression by the organism of
virulence factors similar to those of S. aureus (11). It is of
interest that the same group reported similar virulence factors
in strains of S. schleiferi, yet severe infections caused by S.
schleiferi seem to be underrepresented compared to infections
caused by S. lugdunensis. Moreover, S. schleiferi has not previ-
ously been reported to cause endocarditis. S. schleiferi subsp.
schleiferi is indigenous to carnivores but may be transferred
from carnivore pets to their owners or handlers (8). An earlier
article that reviewed a large number of S. schleiferi isolates
reported that almost all were considered to be part of the skin
flora of some humans (5). One report suggested that the pre-
axillary skin is a preferred site, although prospective cultures
yielded only five strains from 104 patients (1). In a more recent
study, S. schleiferi was isolated from preaxillary skin in a similar
number of patients undergoing pacemaker insertion (3 of 104)
Colony variation was noted in the strain of S. schleiferi in this
report and also in another isolate from a patient at one of our
institutions with an infected pacemaker. The feature of colony
variation has not been previously documented in S. schleiferi
isolates. We reported a similar observation in S. lugdunensis
strains and question whether colony variation is also underre-
ported in S. schleiferi, although all three of the other S. schle-
iferi strains in our previous report did not show colony varia-
S. schleiferi appears to have a propensity to cause infection
associated with implanted foreign material and should be con-
sidered when a CoNS is isolated from implants. We believe
that this is the first report of S. schleiferi endocarditis. Because
S. schleiferi has virulence factors similar to those of S. lug-
dunensis, a CoNS isolated from blood cultures from a patient
with suspected endocarditis needs to be accurately identified.
It is possible that S. schleiferi was previously incorrectly iden-
tified due to overlap of phenotypic characteristics with those of
S. aureus and other CoNS species. Application of a simple
identification method as presented in this report should en-
FIG. 1. Screening scheme for the identification of clumping factor (CF)-
positive staphylococci. Symbols: NEG *, some strains of S. lugdunensis are
clumping factor negative; #, tested by using human plasma; NEG, negative
reaction; ?, positive reaction.
TABLE 2. Key reactions for differentiation of S. schleiferi and S. lugdunensis from other staphylococci
PYR ALP ODCUrease Maltose
Other CoNS spp.
aNT, not tested.
VOL. 37, 1999NOTES 3355
hance the identification of S. schleiferi. We expect more reports
of human infections caused by S. schleiferi in the future.
1. Ce ´lard, M., F. Vandenesch, H. Darbas, J. Grando, H. Jean-Pierre, G. Kir-
korian, and J. Etienne. 1997. Pacemaker infection caused by Staphylococcus
schleiferi, a member of the human preaxillary flora: four case reports. Clin.
Infect. Dis. 24:1014–1015.
2. Coombs, G. W., I. D. Kay, J. W. Pearman, and K. J. Christiansen. 1997. The
role of multiplex mecA/nuc PCR for routine detection of methicillin resis-
tance in staphylococci, abstr. 2292, p. 38. In Programme and abstracts of the
20th International Congress of Chemotherapy. International Congress of
Chemotherapy, Sydney, Australia.
3. Da Costa, A., H. Lelie `vre, G. Kirkorian, M. Ce ´lard, P. Chevalier, F. Vanden-
esch, J. Etienne, and P. Touboul. 1998. Role of the preaxillary flora in
pacemaker infections. Circulation 97:1791–1795.
4. Durack, D. T., A. S. Lukes, D. K. Bright, and The Duke Endocarditis Service.
1994. New criteria for diagnosis of infective endocarditis: utilization of spe-
cific echocardiographic findings. Am. J. Med. 96:200–209.
5. Fleurette, J., M. Be `s, Y. Brun, J. Freney, F. Forey, M. Coulet, M. E. Reverdy,
and J. Etienne. 1989. Clinical isolates of Staphylococcus lugdunensis and S.
schleiferi: bacteriological characteristics and susceptibility to antimicrobial
agents. Res. Microbiol. 140:107–118.
6. Freney, J., Y. Brun, M. Bes, H. Meugnier, F. Grimont, P. A. Grimont, C.
Nervi, and J. Fleurette. 1988. Staphylococcus lugdunensis sp. nov. and Staph-
ylococcus schleiferi sp. nov., two species from human clinical specimens. Int.
J. Syst. Bacteriol. 38:168–172.
7. Jean-Pierre, H., H. Darbas, A. Jean-Roussenq, and G. Boyer. 1989. Patho-
genicity in two cases of Staphylococcus schleiferi, a recently described species.
J. Clin. Microbiol. 27:2110–2111.
8. Kloos, W. 1997. Taxonomy and systematics of staphylococci indigenous to
humans, p. 113–137. In K. B. Crossley and G. L. Archer (ed.), The staphy-
lococci in human disease. Churchill Livingstone, New York, N.Y.
9. Kluytmans, J., H. Berg, P. Steegh, F. Vandenesch, J. Etienne, and A. Van
Belkum. 1998. Outbreak of Staphylococcus schleiferi wound infections: strain
characterization by randomly amplified polymorphic DNA analysis, PCR
ribotyping, conventional ribotyping, and pulsed-field gel electrophoresis.
J. Clin. Microbiol. 36:2214–2219.
10. Lachica, R. V., P. D. Hoeprich, and C. Genigeorgis. 1972. Metachromatic
agar-diffusion microslide technique for detecting staphylococcal nuclease in
foods. Appl. Microbiol. 23:168–169.
11. Lambe, D. W., K. P. Ferguson, J. L. Keplinger, C. G. Gemmell, and J. H.
Kalbfleisch. 1991. Pathogenicity of Staphylococcus lugdunensis, Staphylococ-
cus schleiferi and three other coagulase-negative staphylococci in a mouse
model and possible virulence factors. Can. J. Microbiol. 36:455–463.
12. Latorre, M., P. M. Rojo, M. J. Unzaga, and R. Cisterna. 1993. Staphylococcus
schleiferi: a new opportunistic pathogen. Clin. Infect. Dis. 16:589–590.
13. Leung, M. J., N. Nuttall, T. M. Pryce, G. W. Coombs, and J. W. Pearman.
1998. Colony variation in Staphylococcus lugdunensis. J. Clin. Microbiol.
14. National Committee for Clinical Laboratory Standards. 1998. Performance
standards for antimicrobial susceptibility testing. Sixth informational supple-
ment. NCCLS document M100-S8. National Committee for Clinical Labo-
ratory Standards, Villanova, Pa.
15. Nuttall, N. 1996. RBH-STAPH: a simple, effective method to identify coag-
ulase negative staphylococci of clinical significance, abstr. O-18, p. 67. In
Programme and abstracts of the 8th International Symposium on Staphylo-
cocci and Staphylococcal Infections.
16. Schnitzler, N., R. Meilicke, G. Conrads, D. Frank, and G. Haase. 1998.
Staphylococcus lugdunensis: report of a case of peritonitis and an easy-to-
perform screening strategy. J. Clin. Microbiol. 36:812–813.
17. Vandenesch, F., J. Etienne, M. E. Reverdy, and S. J. Eykyn. 1993. Endocar-
ditis due to Staphylococcus lugdunensis: report of 11 cases and review. Clin.
Infect. Dis. 17:871–876.
18. Vandenesch, F., C. Lebeau, M. Bes, G. Lina, B. Lina, T. Greenland, Y.
Benito, Y. Brun, J. Fleurette, and J. Etienne. 1994. Clotting activity in
Staphylococcus schleiferi subspecies from human patients. J. Clin. Microbiol.
3356NOTES J. CLIN. MICROBIOL.