Predisposing conditions include difficulty in urine retention, a patient or family history of urinary tract infections, neuropathic bladder, prolonged catheter drainage, urine reflux, bladder malignancy, obstruction, calculus disease, altered host resistance, congenital anomalies, analgesic abuse, diabetes, sexual activity, pregnancy, and long-term urinary catheterization. [...] in a recent study, 20% of cases occurred in the first trimester. 1 Factors associated with fatality include an age 65 years, septic shock, bedridden status, immunosuppression (a risk factor in men only), and recent use of antibiotics (a risk factor in women only).2 Infection usually originates from the lower urinary tract and ascends via subepithelial lymphatic channels or directly via the ureter. Atypical infectious causes include TB, Mycobacterium avium-intercellulare, Pneumocystis carinii, Cytomegalovirus, Candida, and toxoplasmosis.21 Extrapulmonary Pneumocystis carinii pneumonia in AIDS Pneumocystis carinii pneumonia (PCP) is the most common opportunistic infection in AIDS patients.
Renal infections: An update Syed A. Akbar, MD, Syed Z.H. Jafri, MD, FACR, Marco Amendola, MD, and Bridget Wiater, MD T 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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