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Journal of Clinical Microbiology, March 2001, p. 1202-1203, Vol. 39, No. 3
0095-1137/01/$04.00+0 DOI: 10.1128/JCM.39.3.1202-1203.2001
Copyright © 2001, American Society for Microbiology. All rights reserved.
Case of Synovitis Potentially Caused by
Dolosigranulum pigrum
G. S.
Hall,1,*
S.
Gordon,2
S.
Schroeder,1
K.
Smith,1
K.
Anthony,1 and
G.
W.
Procop1
Departments of Clinical
Pathology1 and Infectious
Diseases,2 Cleveland Clinic Foundation,
Cleveland, Ohio 44195-5140
Received 21 August 2000/Returned for modification 23 October
2000/Accepted 8 December 2000
 |
ABSTRACT |
We report a case of synovitis in a 64-year-old man who developed
the infection while on steroid therapy for rheumatoid arthritis. Dolosigranulum pigrum, a gram-positive catalase-negative
coccus, was isolated from two sets of blood cultures prior to
antibiotic therapy. The patient was treated with 4 weeks of appropriate
antibiotics, and the synovial inflammation resolved. Although synovial
aspirates were never positive for any bacteria or fungi, the timing of
positive blood cultures and absence of other pathogens suggest the
possible etiology as D. pigrum.
 |
CASE REPORT |
A 64-year-old male with rheumatoid
arthritis requiring weekly methotrexate (7.5 mg once a day) and daily
prednisone (5 mg/week) to control synovitis presented to the outpatient
clinic with a 4-day history of pain and swelling in both wrists,
metacarpal joints, and the left ankle. He also reported some nausea,
fevers, and night sweats. Examination was remarkable for an oral
temperature of 37.7°C and a warm, tender left ankle. Attempt of ankle
aspiration was unsuccessful in obtaining synovial fluid. Laboratory
studies revealed a white blood cell count of 7,180 cells/µl, a
hemoglobin level of 12.3 mg/dl, a Westergren sedimentation rate of 91 mm/h, and C-reactive protein level of 15 mg/dl. Two sets of blood
cultures drawn from two different peripheral sites were positive for
gram-positive cocci in clusters. The Streptococcus Lab at the Centers
for Disease Control and Prevention (CDC), Atlanta, Ga., eventually
identified these organisms as Dolosigranulum pigrum. The
patient was admitted to the hospital for presumed septic arthritis and
started on cefazolin (1 g every 8 h). Synovial fluid was obtained
from the left ankle and right wrist on hospital day 2. The fluid was
yellow and turbid with 86,625 white blood cells, 83% of which were
neutrophils; the fluid was negative for crystals, and cultures remained
negative for bacteria and fungi. A transthoracic echocardiogram,
performed to rule out infective endocarditis, did not reveal
vegetations or regurgitation. The patient received a total of 4 weeks
of antibiotics (2 weeks of parenteral cefazolin and 2 weeks of oral
dicloxacillin), with resolution of the synovial inflammation.
Organism.
The two blood cultures (Organon Teknika BacT/Alert
aerobic and anaerobic FAN bottles) were positive within the first
24 h of incubation. Gram staining of the fluid demonstrated
gram-positive cocci in tight clusters, resembling staphylococci.
Isolation on blood agar produced small greyish-white alpha-hemolytic
colonies. The organism was catalase negative,
L-pyrrolidonyl-
-naphthylamide (PYR) positive, leucine
aminopeptidase (LAP) positive, and hippurate weakly positive. No growth
occurred on bile esculin medium, but the organism did grow in 6.5%
NaCl. Serologic tests for Streptococcus groups A, B, C, D,
F, and G were negative. Biochemical testing gave negative results for
production of urease, esculin hydrolysis, and motility. There was no
activity in a wide variety of Andrade's sugars. There was a large zone
of inhibition around penicillin and vancomycin disks. The isolate was
submitted to the Streptococcus Lab of the CDC for further
identification. In addition to the tests performed in our lab, the CDC
obtained weakly positive results for tellurite and a positive esculin
hydrolysis, bacitracin resistance, production of neither levans nor
dextrans on 5% sucrose agar, and an arginine dihydrolase negative
reaction. They identified the organism as Dolosigranulum
pigrum.
A MIC tray containing Mueller-Hinton broth supplemented with lysed
horse blood was inoculated to determine susceptibility of the isolate,
with the following results: penicillin,
0.06 µg/ml; clindamycin,
0.03 µg/ml; ceftriaxone, 0.25 µg/ml; cefuroxime,
0.12 µg/ml;
amoxicillin,
1.0 µg/ml; trimethoprim-sulfamethoxazole,
0.5/10
µg/ml; erythromycin, 0.5 µg/ml; and tetracycline,
1.0 µg/ml.
Using the NCCLS breakpoints for these agents versus
Streptococcus spp. or S. pneumoniae specifically,
all of these results would be interpreted as susceptible except for the
result for erythromycin, which would be interpreted as nonsusceptible.
The breakpoints for erythromycin are
0.25 µg/ml (susceptible) and
1.0 µg/ml (resistant).
D. pigrum was described in 1993 (
1) as a new
genus of the lactic acid bacteria with a low G+C content. The
phenotypic characteristics
of the organism were felt originally to be
those of
Gemella spp.,
but no cross-reactivity was observed
with specific anti-
G. haemolysans or anti-
G.
morbillorum antibodies. In addition, the cell wall
peptidoglycans
proved to be different from those of
Gemella spp.
Sequencing
of the 16S rRNA verified the new phylogenetic position.
The most
consistent characteristics of
D. pigrum appear to be
PYR
positivity, LAP positivity, NaCl positivity, esculin hydrolysis
positivity, and clusters of gram-positive cocci that are catalase
negative with gamma or alpha hemolysis. Although initially our
isolate
appeared to be negative for esculin hydrolysis, it was
found to be
esculin positive by the CDC. Upon repeat testing in
our lab, the
isolate remained negative, but we only held the esculin
tube for 5 days
before reporting the results as negative. Approximately
85% of
D. pigrum isolates at CDC are esculin positive, some
requiring
as long as 2 weeks of incubation. These isolates should,
however,
be identified correctly if they fit the characteristics
mentioned
above, regardless of the esculin reaction (Richard Facklam,
personal
communication).
There are rare reports of this organism causing clinical disease in
humans. The first isolate was recovered from frozen spinal
cord tissue
removed at autopsy from a patient with multiple sclerosis;
a second
isolate was recovered from the contact lens and eye swab
cultures of a
woman with blurred vision and discomfort. LaClaire
and Facklam
(
2) have recently reported on the clinical sources
of 27 isolates of
D. pigrum sent to the CDC. In addition to the
two cases described above, there have been five cases of sepsis
and
seven additional blood culture isolates from other patients
whose
clinical conditions were unknown. There are no reports of
the organism
causing synovitis. Our report is of the association
of
Dolosigranulum with synovitis. The organism was not isolated
from the synovial fluid, but the patient was treated appropriately
24 h
before the aspiration. The isolation of a catalase-negative,
alpha-hemolytic gram-positive coccus in clusters that is positive
for
PYR, LAP, and growth in NaCl should raise suspicion of a variety
of
genera, including
Dolosigranulum, Alloiococcus, Facklamia, and
Ignavigranum (
1,
2,
3). A positive esculin
hydrolysis
test may aid in differentiating
D. pigrum from
the other three
genera. It is difficult to further identify such
organisms unless
conventional biochemical methods are employed, since
commercial
systems may not include these genera in their databases
(
4).
 |
ACKNOWLEDGMENTS |
We are thankful to the CDC for their assistance in the
identification of this isolate.
 |
FOOTNOTES |
*
Corresponding author. Mailing address: Clinical
Microbiology, L-40, Cleveland Clinic Foundation, Department of Clinical
Pathology, 9500 Euclid Ave., Cleveland, OH 44195-5140. Phone: (216)
444-5990. Fax: (216) 445-6984. E-mail: hallg{at}ccf.org.
 |
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2000.
Antimicrobial susceptibility and clinical sources of Dolosigranulum pigrum cultures.
Antimicrob. Agents Chemother.
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LaClaire, L., and R. Facklam.
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J. Clin. Microbiol.
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Atmospheric growth requirements for Alloiococcus species and related gram-positive cocci.
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34:1027-1028[Abstract].
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Journal of Clinical Microbiology, March 2001, p. 1202-1203, Vol. 39, No. 3
0095-1137/01/$04.00+0 DOI: 10.1128/JCM.39.3.1202-1203.2001
Copyright © 2001, American Society for Microbiology. All rights reserved.
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