| Summary: | 博士 === 高雄醫學院 === 醫學研究所 === 85 === Emphysematous pyelonephritis(EPN) is an acute,life-
threatening suppurative infection of the renal parenchyma and/or
perirenal tissues. A series of thisstudy on 30 patients with
EPN at our institution appreciation EPN and a new diagnosis and
treatment algorithm were proposed. The contents of this study
contain 2 parts and 5 topics. There are as follows:
Part I. Pathogenesis of EPN: animal studies and gas analysis
1.Animal studies Two strains
of Escherichia coli, E. coli O148 and E. coli O2,
weredirectly injected into the renal parenchyma in
streptozotocin(STZ)-diabetic rats and non-diabetic rats. E.
coli 0148 strain was isolated from abscess culture of EPN and
E. coli 02 strain was isolated from urinary culture of acute
pyelonephritis. All of the rats injected with E. coli 02
showed similar histologic changes of acute pyelonephritis
were confined to the line of inoculation. No abscesses were
identified in the rats infected with E. coli 02 strain. When
E. coli 0148 strain was injected, 6 of 10 rats were found
to have renal abscesses. Of rats having renal abscesses, 80%
were found in STZ-diabetic rats compared with 40% in non-
diabetic rats. In STZ-diabetic rats, one rat was found to have
gas-forming abscess in the kidney. In the remaining 4 rats
infected with E.coli 0148 strain, have similar changes as
acute pyelonephritis were found but the inflammatory
reactions were more extensive than rats injected with E.
coli 02 strain. The experimental data presented here in lend
support to our belief that the virulence of bacteria is an
important factor in the causation of experimental EPN and
diabetes mellitus may somewhat make renal infection more
susceptible. 2.Gas analysis The gas samples from
4 patients with EPN were aspirated under CT-guidance.
Analyses with Varian-3700 gas chromatography/thermal
conductivity detector revealed that the all gas samples had
contained CO2, H2, N2. Two of the 4 patients had sulfur
compound of gas analyzed by Varian 3400 GC/sulfur
chemiluminence detector. These gas samples have contained H2S
(1ppm and12ppm, respectively).
Part II. Clinical presenation, diagnosis and treatment of EPN 1.
EPN trends over the past 15 years (1982 to 1996) We
retrospectively reviewed30 consecutive patients with EPN at our
institution between 1982 and 1996 with particular attention to
the clinical manifestations, microbiology, the utilityof
radiologic studies and modes of therapy. The data were compared
to those presented by Michaeli et al. who reviewed the
literature of EPN between 1898 and 1982. The clinical findings
in our patients were as follows: average agewas 61.8±10.2
years; the male-to-female ratio was 1:3.3; the left kidney was
commonly as the right, one case was bilateral EPN; the most
frequentlypredisposing factor was diabetes mellitus (93%); fever
(77%) was the mostcommon presenting symptoms; abdominal or
flank tender (80%) was frequently found on physical
examination; typical laboratory data included leukocytosis(87%),
elevated creatinine level (63%), high serum glucose
concentration (93%), and pyuria (80%) etc.; the most common
causative organism was E. coli (70%). There was a remarkable
similarity between the clinical findings and infecting
organisms in our series and in that of Michaeli et al.. Average
duration of symptom before diagnosis in our series was half
the time as Michaeli et al. reported (10.4 vs 21 days).
Abscess cultures were positive in all our patients, but
only 34% of patients had the same organisms isolated from
urinary and abscess cultures. The antimicrobial susceptibility
test showed that 100% of isolated Enterobacteraceae were
susceptible to amikacin, and more than 80% strained sensitive
to cefoperazone, norfloxacin and gentamicin.EPN was diagnosed
by plain abdominal radiography (KUB) or operative findings
before 1982. In comparison, KUB, ultrasound were used in
diagnosisof our series. Michaeli et al. concluded that a
combination of medicaland surgical treatment had the greatest
chance of survival. Except of the2 cases in our series whom
underwent nephrectomy before 1984, the otherswere treated
initially by CT-guided PCD with a highly successful rate.As
the result, we noted that the clinical findings and microbiology
of EPNhave not changed during the past 15 years. However,
since the availableof CT after 1982, EPN may easily be
differentiated from the diagnosis of other suppurative disease
of the kidney. That made the identification ofEPN patients
increasing obvious and shortened the duration before
accuratediagnosis in the CT era. CT-guided aspiration offered
early selectionof proper antibiotics and PCD might replace the
traditional surgical treatment. These have become the newest
EPN treatment trends. 2.CT in the diagnosis of EPN:
comparison with other imaging modalitiesy 28
patients with EPN at our institution were
retrospectivelyanalyzed to determine the correlation of varied
categories of the CT findingsand compared with other imaging
procedures. We noted that CT demonstrated gas accumulated in
the 29 kidneys of the 28 patients (bilateral lesion,1 case). In
our studies, there were no correlation types of different gas-
forming abscesses and the extension stages (p>0.05). However,
diffuserenal damage occurred more frequently in Type I EPN than
in Type II EPN(67% vs 29%,p<0.05). We recommend the use of
modified lung window setting with more wide window width to
clearly distinguish the gas of EPN from fatty tissue, while
modified abdominal window setting with more narrowedwindow
width could easily differentiate normal renal parenchyma
fromfluid collection of abscess. Therefore, the modified
window settings replace the enhanced study of CT and prevent
side effects of contrast. Thesensitivity for detecting
abnormal gas in EPN from KUB was 65.5% in our series. However,
the extension of the abnormal gas in 5 of the 19 lesions was
underestimated, as compared with the CT study. So the accuracy
ofdiagnosing and staging EPN with KUB was about 51.9%. The
sensitivity of ultrasound diagnosing EPN was 88%, while
ultrasound combined with KUB increased sensitivity to 89.7%
and increased specificity. Other imaging procedures offer
little help in EPN diagnosis but retrograde pyelography and
renal scintigraphy may be use as follow-up study to determine
ureteral obstruction and evaluate the renal function after the
treatment of PCD. In conclusion, we recommend simple, convenient
ultrasound combined with KUB as the imaging modalities of choice
for initial screening diabetic patientspresenting with
evidence of upper urinary infection. If EPN is suspected or
urinary infection is responding poorly to medical treatment,
CT shouldbe performed to confirm the diagnosis and evaluate
different types and extension of EPN. CT also offers the
guidance of percutaneous drainage and follow-up procedures.
3.PCD in the treatment of EPN: results and techniques
A retrospective analysis was done on 28 patients with EPN who
were treatedinitially with CT guided PCD during a 11-year
period. The patients were concomitantly treated with
antibiotics, fluids, and correcting blood glucoseand/or ureteral
obstruction. We also compared our results of PCD to
CTfindings. In 22 of 28 patients (78.6%), antibiotic therapy
combined with PCDconstituted the only treatment required.
Three patients (10.7%) whose clinical status improved after
PCD subsequently underwent elective nephrectomy without
further complications. Three patients (10.7%) died ofmultiple
organ failure. There was no correlation between the gas
patterns of EPN and initial success with the antibiotics
and PCD. There were no recurrence and no complications during a
follow-up of 0.5 to 10 years (mean 5 years). Mean duration
of treatment was 34.8 days (range 6 to 92 days). Based on
our results , 14F Malecot catheter may adequately drain the
thick purulent material thick purulent materials of EPN.
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