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Journal of Clinical Microbiology, October 1998, p. 3055-3056, Vol. 36, No. 10
0095-1137/98/$04.00+0
Copyright © 1998, American Society for Microbiology. All rights reserved.
Isolation of Enterobacter intermedium
from the Gallbladder of a Patient with Cholecystitis
Caroline Mohr
O'Hara,1,*
Christine D.
Steward,1
Joan L.
Wright,2
Fred C.
Tenover,1 and
J.
Michael
Miller1
Centers for Disease Control and Prevention,
Atlanta, Georgia,1 and
Jefferson
Hospital, Pittsburgh, Pennsylvania2
Received 23 December 1997/Returned for modification 11 May
1998/Accepted 9 July 1998
 |
ABSTRACT |
We describe the isolation and identification of
Enterobacter intermedium from the gallbladder of a
patient with cholecystitis. There have been only four documented
isolations of this organism from humans; it normally occurs in surface
water and unpolluted soils. The identification was initially made by a
MicroScan Walk/Away system with a Neg Combo 18 conventional
identification-susceptibility panel. The organism is susceptible to the
aminoglycosides and imipenem but resistant to the cephalosporins and
ciprofloxacin.
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TEXT |
Enterobacter intermedium
is a member of the family Enterobacteriaceae and is
usually isolated from surface water and unpolluted soil. It was
originally characterized by Izard et al. (4) in 1980 and had
previously been referred to as "Group H1" (5), a group
phenotypically related to E. cloacae. It had not been known
to occur in humans until 1987, when Prats et al. (8) reported four strains of E. intermedium that had been
isolated from a foot wound, blood, stool, and bile, respectively. No
clinical history was available for any of the patients from whom these specimens were taken. We report here the isolation and identification of E. intermedium from the gallbladder of a patient with
cholecystitis.
Case report.
The patient was a 94-year-old white male who was
a resident of a personal care home. He had mild senile dementia and
hypertension. His medical history included cerebrovascular disease,
cardiomegaly secondary to hypertensive cardiomyopathy, vitamin
B12 deficiency, prostatism, chronic vertigo, and
transient ischemic attacks. He presented to Jefferson Hospital,
Pittsburgh, Pa., with a 1-day history of nausea, vomiting, high-grade
fever (101.1°F), and epigastric pain. His blood pressure was 124/80,
his pulse was 110 beats/min, and his respiratory rate was 20 breaths/min. On examination, the patient had tenderness in the right
upper and lower quadrants of his abdomen and a computerized axial
tomography scan revealed inflammation in the pancreas. An ultrasound of
the gallbladder revealed numerous gallstones in the lumen. His
leukocyte count was 20,200, with a left shift in the differential.
Chemistry tests revealed an immensely elevated lipase level of 1,218, an amylase level of 421, and a creatinine level of 1.4, all of which
are consistent with pancreatitis. With an empirical diagnosis of
pancreatitis but needing to rule out gallbladder disease, the patient
was given ampicillin-sulbactam (Unasyn) and taken to surgery, where a
cholecystectomy was performed. The patient recovered with no
complications.
Cultures of the blood and gallbladder were sent to the microbiology
laboratory at Jefferson Hospital. The blood culture was negative, but
the gallbladder culture yielded a polymicrobic mixture containing
group D Streptococcus, coagulase-negative
Staphylococcus, and a gram-negative bacillus identified as
E. intermedium. The enteric organism was
identified by using a MicroScan Walk/Away system (Dade
Behring, Inc., Dade MicroScan, Inc., West Sacramento, Calif.) with a
Neg Combo 18 conventional identification-susceptibility panel. The
profile number was 77101372. Because of the unusual identification, the
identification test was repeated by using an API20E strip
(bioMérieux Vitek, Inc., Hazelwood, Mo.). This yielded
the profile number 1105573 for an identification of
Enterobacter species at the very good probability level,
requiring additional tests of dulcitol fermentation and methyl red
production for a definitive identification of E. intermedium. The laboratory, however, reported the organism as
Enterobacter sp.
Confirmatory identification was performed at the Centers for Disease
Control and Prevention (CDC) by methods previously cited
(
1-3). A computer-based program at CDC aids in the
identification
of isolates that are submitted from hospital
laboratories. When
the conventional biochemical reactions of 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 of this organism were
entered,
10 of the first 12 strains on the listing were
E. intermedium,
including the type strain and 9 of Izard's original
isolates (
4).
Our single strain from Prats' collection
(528-V) did not appear
on the listing.
When we inoculated this isolate into other commercially available
identification systems, we obtained the following answers.
The
Vitek GNI+ card (bioMérieux Vitek, Inc.) gave a profile
number
of 6664771632 with an identification of
E. cloacae (88%) and
E. intermedius (sic) (5%). The
BBL Crystal E/NF system (Becton Dickinson
Microbiology
Systems, Sparks, Md.) gave a profile number of 5764457156,
which was
"Unacceptable."
E. intermedium is in the
Vitek GNI+
database, but it is not in the Crystal database.
Broth microdilution susceptibility testing of the isolate was performed
(
6) by using in-house microdilution plates prepared
with cation-adjusted Mueller-Hinton broth (Difco
Laboratories,
Detroit, Mich.). The organism was susceptible to
amikacin, gentamicin,
imipenem, meropenem, tobramycin,
and trimethoprim-sulfamethoxazole.
It was intermediate to
piperacillin and tetracycline. It demonstrated
resistance to
amoxicillin-clavulanic acid, ampicillin, aztreonam,
cefazolin, cefotaxime, cefotetan, cefoxitin, ceftazidime,
ceftriaxone,
cefuroxime, chloramphenicol, ciprofloxacin, ofloxacin, and
ticarcillin.
Susceptibility results obtained with the MicroScan
panel were
identical to the CDC reference results for the
antibiotics listed
above except for one minor error. The organism was
determined
to be aztreonam intermediate by the MicroScan system
(MIC = 16
µg/ml) and aztreonam resistant by broth microdilution
(MIC = 64
µg/ml). The MicroScan system also reported resistance
to ampicillin-sulbactam
and piperacillin-tazobactam.
This organism remains a rare isolate from human specimens. A
differential table which may assist in separating the species
of
Enterobacter has been published previously (
7).
Table
1 lists biochemical tests that are useful in differentiating
E. intermedium from
E. cloacae.
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ACKNOWLEDGMENTS |
We acknowledge the staff of the Microbiology Laboratory at
Jefferson Hospital for their contributions to this study.
| |
FOOTNOTES |
*
Corresponding author. Mailing address: Mailstop
C16, Centers for Disease Control, Atlanta, GA 30333. Phone: (404)
639-2316. Fax: (404) 639-3241. E-mail: cmol{at}cdc.gov.
| |
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Journal of Clinical Microbiology, October 1998, p. 3055-3056, Vol. 36, No. 10
0095-1137/98/$04.00+0
Copyright © 1998, American Society for Microbiology. All rights reserved.
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