JOHNS HOPKINS
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Department of Pathology
600 N. Wolfe Street / Baltimore MD 21287-7093
(410) 955-5077 / FAX (410) 614-8087
Division of Medical Microbiology
THE JOHNS HOPKINS MICROBIOLOGY NEWSLETTER Vol. 26, No. 19
Tuesday, October 09, 2007
A. Provided by Emily Luckman, Division of Outbreak Investigation, Maryland Department
of Health and Mental Hygiene.
B. The Johns Hopkins Hospital, Department of Pathology, Information provided by,
Danielle Wehle, M.D., M.S.
Case presentation: A 64-year-old gentleman on hemodialysis status post pacemaker and
implantable cardiac defibrillator placement presented to JHH on 9/4/2007 reportedly “not feeling
well.” Due to his multiple medical problems and ongoing hemodialysis, blood cultures were
drawn and were positive for coagulase negative staphylococci on 9/4/2007. An intravenous
catheter was placed and the patient was treated with On 9/6/2007 blood cultures became positive
for a gram variable coryneform rod. This bacterium was identified by 16S rRNA gene sequencing
as a Leifsonia species (most likely L. aquatic). The organism was considered significant since it
was isolated from four blood cultures and a catheter culture.
Epidemiology & Transmission: Leifsonia species are primarily pathogens of Bermuda grass
and sugar cane and have also been isolated from distilled water and Antarctic ponds. Leifsonia
aquatica ("C. aquaticum") has rarely been described as a cause of disease in humans, e.g., as an
etiologic agent of bacteremia (including catheter-related bacteremia), endocarditis, meningitis,
peritonitis, and urinary tract infection.
In 1962 Leifson described gram-positive rods isolated from distilled water that had many
characteristics of corynebacteria and he named these rods “Corynebacterium aquaticum."
Subsequent taxonomic investigations revealing the presence of 2, 4-diaminobutyric acid (DAB)
within the cell wall suggested that "C. aquaticum" did not belong to the genus Corynebacterium.
DAB is found in the cell walls of Clavibacter species. Additional studies showed that C.
aquaticum and previously described Clavibacter species were phylogenetically related. The genus
Leifsonia was created to include C. aquaticum, previously described Clavibacter species and new
isolates discovered from grass roots.
Microbiology: Colonies of Leifsonia species are opaque with yellow pigment. The microbes are
gram positive rods which are motile at 35-37C, catalase positive and oxidase negative. These
bacteria are unusual in that they cycle through rod and coccus forms and older colonies will have
predominately coccoid cells.
Clinical features & related pathogenesis: Diagnosis: Leifsonia species are often difficult to
distinguish from other rarely encountered coryneform bacteria such as Microbacterium species
which are small gram positive diptheroid bacilli with variable motility. As a result, the application
of 16S rRNA gene sequencing is often required for final identification of these rare pathogens.
The case described here required 16S rRNA gene sequencing. This technique can be helpful in
deciphering ambiguous biochemical profiles when making identifications since 16S rRNA is
highly conserved among bacterial species.
Treatment: Experience in treating non-corynebacterial coryneforms such as Microbacterium and
Leifsonia is limited. Susceptibility tests are necessary, particularly since resistance to vancomycin
has been noted in strains of Leifsonia aquatica. In the case described here the organism was
susceptible to trimethoprim-sideally culture bottle inoculated with 10 ml of blood, optimal number
in 24h is 3 (99.9% sensitive). ulfamethoxazole and tetracycline with intermediate susceptibility to
References:
Lau S, Woo CY, Woo G, and Yuen K. Catheter-Related Microbacterium Bacteremia Identified by
16S rRNA Gene Sequencing. J Clin Microbiol. 2002 July; 40(7): 2681–2685.
A. von Graevenitz. Antimicrobial therapy of infections with aerobic Gram-positive rods. Clinical
Microbiology and Infection. 2001 August; Volume 7 (4): 43-46.
Funk G, VON Graevenitz A AND Weiss N. Primary Identification of Aureobacterium spp. Isolated from
Clinical Specimens as "Corynebacterium aquaticum." J Clin Microbiol. 1994, November; 32(11):
2686-2691.
Koneman EW. Color Atlas and Textbook of Diagnostic Microbiology, 6th edition. 2006.