Journal of Clinical Microbiology, January 1998, p. 248-250, Vol. 36, No. 1
0095-1137/98/$04.00+0
Copyright © 1998, American Society for Microbiology. All rights reserved.
First Report of a Human Isolate of
Erwinia persicinus
Caroline M.
O'Hara,1,*
Arnold G.
Steigerwalt,2
Bertha C.
Hill,1
J. Michael
Miller,1 and
Don J.
Brenner2
Nosocomial Pathogens Laboratory Branch,
Hospital Infections Program,1 and
Meningitis and Special Pathogens Branch, Division of
Bacterial and Mycotic Diseases,2 Center for
Disease Control and Prevention, Atlanta, Georgia 30333
Received 11 July 1997/Returned for modification 20 August
1997/Accepted 19 September 1997
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ABSTRACT |
Erwinia persicinus was first described in 1990 after
being isolated from a variety of fruits and vegetables, including
bananas, cucumbers, and tomatoes. In 1994, it was shown to be the
causative agent of necrosis of bean pods. We now report the first human isolate of E. persicinus. The strain was isolated from the
urine of an 88-year-old woman who presented with a urinary tract
infection. By the hydroxyapatite method, DNA from this strain was shown
to be 94.5% related at 60°C and 86% related at 75°C to the type
strain of E. persicinus. The biochemical profile of
E. persicinus is most similar to those of Erwinia
rhapontici, Pantoea agglomerans, and
Enterobacter species. It is negative in tests for lysine, arginine, ornithine, dulcitol, and urea. It is motile and positive in
tests for D-sorbitol and sucrose. It is susceptible to the expanded-spectrum cephalosporins, aminoglycosides, and
fluoroquinolones, but it is resistant to ampicillin, ticarcillin, and
cefazolin.
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TEXT |
Erwinia persicinus is a
plant pathogen that was described by Hao et al. (6) in 1990. These first five strains were isolated from tomatoes (n = 3), cucumber (n = 1), and banana (n = 1). In 1994, Brenner et al. (3) reported that E. persicinus was a senior subjective synonym for "Erwinia
nulandii," an organism that was pathogenic for bean pods and
seeds. There are no reports in the literature of human or animal
isolates of E. persicinus.
A computer-based program at the Centers for Disease Control and
Prevention aids in the identification of isolates that are submitted
from state public health laboratories. When the conventional biochemical reactions for a given isolate are entered into the program,
the program searches the database and returns a listing of the 50 most
closely related isolates that it contains. When the reactions from this
organism were entered, three of the first six strains on the list were
the hybridized E. persicinus strains of Hao et al.
(6); two were strains, identified in this paper, which had
previously been reported as "unidentified."
In this paper, we report the first human isolate of E. persicinus and an additional food isolate.
Bacterial strains.
The strains used in this study are listed
in Table 1. All were maintained at 
70°C in defibrinated sheep
blood. All strains were passed twice on Trypticase soy agar with 5%
sheep blood (Becton Dickinson Microbiology Systems, Sparks, Md.) before
being used.
Media and biochemicals.
The biochemical tests were performed
on conventional media by the methods of Ewing (4) and by
using some of the modifications described by Farmer et al.
(5) and by Hickman and Farmer (7). Incubations
were at 35°C, and test results were read at 24 h, 48 h, and
7 days, unless otherwise noted. Commercially available media were used
whenever possible.
Antimicrobial susceptibility.
Antimicrobial
susceptibility profiles were determined for seven strains by the
Kirby-Bauer disk diffusion method (8). MICs were determined
by using a broth microdilution method and
cation-supplemented Mueller-Hinton broth (9).
DNA methods.
The preparation, isolation, and purification of
labeled and unlabeled DNA, the method used for DNA reassociation, and
the method used to separate single-stranded and double-stranded DNAs on
hydroxyapatite have been described elsewhere (1, 2). The
DNAs were labeled enzymatically in vitro with [32P]dCTP
by using a nick-translation reagent kit (Bethesda Research Laboratories, Inc., Gaithersburg, Md.) as directed by the manufacturer.
Results and discussion.
Labeled DNA from E. persicinus 9108-82T was shown to be 81 to 100%
related (average, 87%) to unlabeled DNA from four other confirmed
E. persicinus strains tested in 60°C reactions (Table 1).
Divergence within the related sequences averaged 3%, and the degree of
relatedness in reactions at 75°C was 76 to 98% (average, 86%).
E. persicinus was 62% related to the type strain of
Erwinia rhapontici, 50% related to a second E. rhapontici strain, and 49% related to Pantoea
agglomerans. The percent divergence to these three strains was
10.0 to 10.5. The degree of relatedness of labeled DNA from E. persicinus 9108-82 to that of the human strain (strain 4073-83)
was 95% at 60°C, with 3.5% divergence, and 86% at 75°C. The type
strain showed a similar level of relatedness to the strain isolated
from tuna (strain 839-82). These relatedness values leave no doubt that
the human and tuna strains are E. persicinus.
The biochemical profiles of the two newly identified strains are
characteristic of the profiles found for E. persicinus
strains (Table 2). Reactions that differ
from those of the type strain include the methyl red, Voges-Proskauer,
Simmons citrate, rhamnose, esculin, melibiose, and galactose reactions.
Partial differentiation from other Enterobacter species,
E. rhapontici, and Pantoea species is presented
in Table 3. Accurate identification of
E. persicinus in the clinical laboratory may not be possible
without the use of the extended set of conventional biochemicals listed
in Table 2. Hao et al. (6) reported that all five strains in
their study produced a water-soluble pink pigment when grown on peptone yeast agar supplemented with 1% glucose at 20, 25, and 30°C. Of the
seven strains that we studied, strains 9108-82T and 4073-83 produced pigment at 25°C and strain 9109-82 produced pigment at both
25 and 30°C on this same medium.
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