Renal infections: An update by ProQuest


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									Renal infections: An update

Syed A. Akbar, MD, Syed Z.H. Jafri, MD, FACR, Marco Amendola, MD, and Bridget Wiater, MD

        he kidney can be affected by           abuse, diabetes, sexual activity, preg-          contrast density, and attenuated and dis-
        numerous chronic and acute in-         nancy, and long-term urinary catheteriza-        tended pyelocalyceal structures. Rarely,
        flammatory processes that may be        tion. Acute pyelonephritis is the most           focal calyceal compression may be seen.
infectious or autoimmune. Infections           common medical complication of preg-             Dilatation of the collecting system and
include viral, bacterial, or fungal disease.   nancy. Acute pyelonephritis is almost            nodular edema of the pelvis or infundibu-
This review will specifically address           always treated as with intravenous (IV)          lum are also reported. A striated nephro-
acquired immunodeficiency syndrome              antibiotics in an inpatient setting. It occurs   gram is a relatively common presentation
(AIDS) nephropathy, acute and chronic          more often in the second and third               (Figure 1).
pyelonephritis, renal and perirenal            trimesters. However, in a recent study,
abscess, emphysematous pyelonephritis,         20% of cases occurred in the first tri-           Acute focal bacterial
emphysematous pyelitis, malacoplakia,          mester.1 Factors associated with fatality        pyelonephritis
diffuse and focal xanthogranulomatous          include an age >65 years, septic shock,             Acute focal bacterial pyelonephritis
pyelonephritis, fungal infections, tuber-      bedridden status, immunosuppression              (AFBP) is seen in uncomplicated cases
culosis (TB), and replacement lipomato-        (a risk factor in men only), and recent use      of APN. With medical therapy, most
sis. The authors will review multi-            of antibiotics (a risk factor in women           inflammatory masses resolve within in a
modality imaging findings and pitfalls of       only).2                                          few weeks without subsequent renal
renal inflammatory diseases.                        Infection usually originates from the        damage. Scarring is uncommon in un-
                                               lower urinary tract and ascends via sub-         complicated cases in the absence of
Renal infections                               epithelial lymphatic channels or directly        comorbid conditions. Severe diffuse
Acute pyelonephritis                           via the ureter. In general, Escherichia          bacterial nephritis may produce perma-
   Acute pyelonephritis (APN) refers to        coli (E coli) is the most common                 nent damage such as papillary necrosis
any inflammation affecting the renal inter-     pathogen. In elderly patients with a his-        or global atrophy. The Society of Urora-
stitium. Patients most often affected are      tory of instrumentation, however, Pro-           diology recommends that all patients
females from 15- to 40-years-old. Predis-      teus miranilis is a frequent cause.              with renal infection be referred to as
posing conditions include difficulty in         Escherichia coli has the ability to attach       having APN. Additional modifiers to
urine retention, a patient or family history   to urothelial surfaces via pili or fim-           better describe the inflammatory process
of urinary tract infections, neuropathic       briae. The kidneys become enlarged and           include unilateral or bilateral, focal or
bladder, prolonged catheter drainage,          patchy areas of inflammation can be               diffuse, and with or without focal
urine reflux, bladder malignancy, obstruc-      seen in different stages. Typically, the         swelling or renal enlargement.
tion, calculus disease, altered host resis-    pelvicalyceal system is involved first,              Dimer captosuccinic acid (DMSA)
tance, congenital anomalies, analgesic         spreading from the medullary region to           technetium-99m (99mTc) scintigraphy is
                                               the cortex. Hematogenous transmission            both a highly sensitive (92%) and spe-
 Dr. Akbar is the Medical Director of          occurs less commonly; staphylococcal             cific (93%) diagnostic study. Single-
 Radiology, Rush Copley Medical Center,        septicemia has been shown to have a              photon-emission computed tomography
 Aurora, IL; Dr. Jafri is Head of              propensity to establish renal infection.         (SPECT) imaging has an even higher
 Genitourinary Radiology, and Dr. Wiater       In hematogenous infections, the cortex           sensitivity, at 90%.4 Dimer captosuc-
 is a Staff Radiology, Department of Diag-
                                               is involved first.3                               c
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