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Letter
Streptomyces bikiniensis
Bacteremia
William J. Moss,* Jason A. Sager,* James D. Dick,* and Andrea Ruff*
*Johns Hopkins University, Baltimore, Maryland
Suggested citation for this article: Moss WJ,
Sager JA, Dick JD, Ruff A. Streptomyces bikeniensis Bacteremia.
Emerg Infect Dis [serial online] 2003 Feb [date cited]. Available
from: URL: http://www.cdc.gov/ncidod/EID/vol9no2/02-0275.htm
To the Editor: Carey et al. recently reported in this journal
a case of catheter-related bacteremia attributed to Streptomyces
in a patient receiving holistic infusions (1). We describe
the isolation of Streptomyces bikiniensis from multiple blood cultures
in a single patient over the course of 1 week, further illustrating that
Streptomyces is pathogenic and a cause of bacteremia even in the
absence of overt clinical symptoms and risk factors.
A 14-year-old girl with osteosarcoma of the right proximal tibia came
to our hospital 13 months after diagnosis for her final course of chemotherapy.
At the time of diagnosis, a double-lumen central venous catheter was inserted.
Her course was complicated by poor response to chemotherapy, and a limb
salvage procedure was performed 3 months after diagnosis. The proximal
tibia was replaced with a cadaveric bone graft. Several hours after the
patient received methotrexate, a fever of 39.2°C developed. No sign of
infection was observed on physical examination. Her leukocyte count was
6,300 cells/mm3 with an absolute neutrophil count of 4,914
cells/mm3. She received a single dose of acetaminophen and
was without fever for the remainder of her hospitalization. A blood culture
obtained from the central venous catheter at the time of fever grew Streptomyces.
Repeat blood cultures obtained from both ports of the central venous catheter
on day 3 and a peripheral blood culture obtained on day 4 also grew Streptomyces.
Treatment with vancomycin and cotrimoxazole was started on day 4 in the
hospital. The Streptomyces isolate was susceptible to vancomycin,
amikacin, cotrimoxazole, erythromycin, cephazolin, and tetracycline and
was resistant to ampicillin, penicillin, oxacillin, and clindamycin. A
blood culture drawn from the central venous catheter on day 3 of antibiotic
therapy (the 6th day in the hospital) grew Streptomyces after 9
days of incubation. All subsequent blood cultures were without growth.
The central venous catheter was removed, and the patient received vancomycin
intravenously for 6 weeks, without recurrence of Streptomyces bacteremia.
The bone graft was considered a potential source of infection. As most
cases of disease from Streptomyces occur in the tropics, we requested
information on whether the donor traveled or resided outside the United
States. However, the donor had no history of travel outside the United
States. All cultures taken from the donor and the graft were without growth
(although this did not exclude the graft as the source of infection),
and no reports of disease transmission were received from any other recipients
of organs from this donor. In addition, the patient had no history of
receiving infusions of holistic or alternative medicines.
The organism was initially detected in the aerobic Bact/Alert blood culture
system (bioMérieux, Inc., Durham, NC) after 72 h incubation at 35°C. Presumptive
identification of the pleomorphic gram-positive bacillus as Streptomyces
sp. was based on phenotypic characterization by using standard conventional
tests and cellular fatty acid analysis. Species identification was determined
by DNA sequencing of the 16S rRNA gene. DNA sequencing reactions were
performed with the Tag Dye Deoxy Terminator Cycle Sequencing Kit (Applied
Biosystems, Inc., Foster City, CA), and data were generated with an ABI
377 automated instrument. The sequence data were assembled, edited, and
compared with published sequences for the 16S rRNA gene of S. bikiniensis
(2).
The genus Streptomyces belongs to the order Actinomycetales,
which includes Mycobacterium, Nocardia, and Actinomyces.
Streptomyces are gram-positive, extensively branched, filamentous
bacteria that form aerial hyphae with chains of spores. Their natural
habitat is soil, and each species has a defined geographic distribution.
None are common in the United States. With the exception of specimens
from actinomycotic mycetoma, the isolation of Streptomyces from
clinical specimens frequently is considered laboratory contamination (3).
Rare cases of clinical disease attributed to Streptomyces have
been published, including bloodstream infection (1,4)
and focal invasive infections (5-9). Streptomyces
was not the only potential pathogen isolated from some of the clinical
specimens in these studies.
Scant data are available on effective treatment of Streptomyces
infection. Mycetoma caused by Streptomyces is often treated with
penicillin, sulfonamides, or tetracycline; however, the cure rate is low.
The recommended duration of therapy is lengthy (up to 10 months). Isolates
of S. griseus referred to the Centers for Disease Control and Prevention
were frequently resistant to ampicillin (80%), sulfamethoxazole (43%),
cotrimoxazole (29%), and ciprofloxacin (57%) (10). Resistance
to doxycycline (19%) and minocycline (10%) was lower. Vancomycin susceptibility
was not tested. Resistance patterns must be interpreted cautiously because
Streptomyces can synthesize antibiotics, potentially confounding
results of in-vitro susceptibility testing.
The patient described in this report had no signs or symptoms of infection.
The transient fever that prompted the first blood culture was probably
due to the methotrexate infusion and not infection with S. bikiniensis.
That the fever was of short duration despite persistently positive blood
cultures supports this conclusion. The potential for causing minimal symptoms
may contribute to assignment of Streptomyces as a contaminant.
Clinical correlation is difficult if the infection is silent. Streptomyces
isolated from blood cultures should not be dismissed as contaminants without
careful consideration of the clinical situation; the isolation of Streptomyces
from repeat blood cultures strongly suggests a pathogenic role.
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