What signs symptoms would the nurse expect to find in a client diagnosed with acute pyelonephritis select all that apply?

Acute Uncomplicated Pyelonephritis in Women

Acute pyelonephritis is suggested by fever (temperature ≥38° C), chills, flank pain, nausea and vomiting, and costovertebral angle tenderness. Cystitis symptoms are variably present. Symptoms may vary from a mild illness to a sepsis syndrome with or without shock and renal failure. Pyuria is almost always present, but leukocyte casts, specific for UTI, are infrequently seen. Gram stain of the urine sediment may aid in differentiating gram-positive and gram-negative infections, which can influence empiric therapy. A urine culture, which should be performed in all women with acute pyelonephritis, will have 104 cfu/ml or more of uropathogens in up to 95% of patients.19

On pathologic examination, the kidney shows a focal inflammatory reaction with neutrophil and monocyte infiltrates, tubular damage, and interstitial edema (Fig. 51.3). Although imaging studies are generally not performed, the infected kidney is often enlarged, and contrast-enhanced computed tomography (CT) shows decreased opacification of the affected parenchyma, typically in patchy, wedge-shaped, or linear patterns (Fig. 51.4).

The availability of effective oral antimicrobials, especially the fluoroquinolones, allows initial oral therapy in appropriate patients or, in those requiring parenteral therapy, the timely conversion from intravenous to oral therapy and reduced need for hospitalization. Indications for hospital admission include inability to maintain oral hydration or to take medications; uncertain social situation or concern about compliance; uncertainty about the diagnosis; and severe illness with high fevers, severe pain, and marked debility. Outpatient therapy is safe and effective for select patients who can be stabilized with parenteral fluids and antibiotics in an urgent care facility and sent home with oral antibiotics under close supervision. In one population-based study of acute pyelonephritis in adult women, only 7% were hospitalized.4

The management strategy for acute uncomplicated pyelonephritis is shown inFig. 51.5. Many effective parenteral (Table 51.5) and oral (Table 51.6) regimens are available for patients with acute uncomplicated pyelonephritis. For outpatients, an oral fluoroquinolone should be used for initial empiric treatment of infection caused by gram-negative bacilli.26,33 TMP-SMX or other agents can be used if the infecting strain is known to be susceptible. If enterococci are suspected from the Gram stain, amoxicillin should be added to the treatment regimen until the causative organism is identified. Second- and third-generation cephalosporins also appear effective, although published data are sparse. Nitrofurantoin, fosfomycin, and pivmecillinam are not approved or recommended for the treatment of pyelonephritis. When antimicrobial resistance or intolerance of oral medications is a concern, one or more doses of a broad-spectrum parenteral antimicrobial is recommended until in vitro activity can be ensured.26

Imaging

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Findings of acute pyelonephritis (AP) are almost always asymmetric

Renal enlargement with loss of corticomedullary (CM) differentiation on US and CT

Geographic areas of altered echogenicity on US

Urothelial thickening on US and CT

In general, ultrasound is much more sensitive for causes (obstruction) and complications (abscess) of AP than for AP itself, which is a clinical diagnosis

Many kidneys with pyelonephritis will be sonographically normal

Foci of gas in parenchyma (rare) could indicate emphysematous pyelonephritis; treat as urologic emergency

Altered nephrogram on CT, classically striated, best seen in excretory phase

Microabscesses or areas of necrosis can emerge after 1-2 weeks of infection

Acute Pyelonephritis

The incidence of pyelonephritis in pregnancy is 1% to 2%.40 Most cases develop as a consequence of undiagnosed or inadequately treated lower urinary tract infection. Two major physiologic changes occur during pregnancy that predispose to ascending infection of the urinary tract. First, the high concentration of progesterone secreted by the placenta has an inhibitory effect on ureteral peristalsis. Second, the enlarging gravid uterus often compresses the ureters, particularly the right, at the pelvic brim, thereby creating additional stasis. Stasis, in turn, facilitates migration of bacteria from the bladder into the ureters and renal parenchyma (Fig. 58.2).

Seventy-five to 80% of cases of pyelonephritis occur on the right side, 10% to 15% are left sided, and a slightly smaller percentage are bilateral.40E. coli is again the principal pathogen.40,43K. pneumoniae and Proteus species are also important causes of infection, particularly in women with recurrent episodes of pyelonephritis. Highly virulent gram-negative bacilli, such as Pseudomonas, Enterobacter, and Serratia, are unusual isolates except in immunocompromised patients. Gram-positive cocci do not frequently cause upper tract infection. Also, anaerobes are unlikely pathogens unless the patient is chronically obstructed or instrumented.

The usual clinical manifestations of acute pyelonephritis in pregnancy are fever, chills, flank pain and tenderness, urinary frequency or urgency, hematuria, and dysuria. Patients also may have signs of preterm labor, septic shock, and acute respiratory distress syndrome (ARDS). Urinalysis is usually positive for white blood cell casts, red blood cells, and bacteria. Urine colony counts greater than 102 colonies/mL in samples collected by catheterization confirm the diagnosis of infection.

Pregnant patients with pyelonephritis may be considered for outpatient therapy if their disease manifestations are mild, they are hemodynamically stable, and they have no evidence of preterm labor.46,47 Caution should be applied in treating diabetic women as outpatients as these women may be at risk for diabetic ketoacidosis. If an outpatient approach is adopted, the patient should be treated with agents that have a high level of activity against the common uropathogens. Acceptable oral agents include amoxicillin-clavulanic acid 875 mg twice daily or double-strength trimethoprim-sulfamethoxazole twice daily for 7 to 10 days. Alternatively, a visiting home nurse may be contracted to administer a parenteral agent, such as intravenous (IV) or IM ceftriaxone 2 g once daily. Although an excellent drug for lower tract infections, nitrofurantoin monohydrate does not consistently achieve the serum and renal parenchymal concentrations necessary for successful treatment of more serious infections.

DIAGNOSTIC CHECKLIST

Acute pyelonephritis

Acute pyelonephritis is acute suppurative bacterial infection of the kidney. The route of infection is either haematogenous spread secondary to septicaemia or ascending urinary tract infection.

Clinical features: infection of the kidney is associated with signs of systemic sepsis such as fever and malaise, together with local signs of loin pain and tenderness. There may be symptoms of lower urinary tract infection, such as frequency and dysuria. Urine microscopy demonstrates large numbers of neutrophils (pyuria), with neutrophil casts. The diagnosis is confirmed with urine culture, significant bacteriuria being regarded as greater than 105 culture-forming units/mL.

Pathogenesis: lower urinary tract infections of the urethra and bladder are common but most are not associated with pyelonephritis; bacteria can only gain access to the upper urinary tract if there is reflux of urine from the bladder into the ureters (vesicoureteric reflux; VUR). VUR may be congenital with an abnormal insertion of the ureter into the bladder, causing recurrent upper urinary tract infections in childhood. It may also result from bladder outflow obstruction, for example, due to congenital urethral valves in infancy, tumours, and benign prostatic hyperplasia. In adults, urinary tract infections are most common in women due to the short urethra and urethral trauma associated with sexual intercourse. The highest incidence of pyelonephritis is in pregnancy. Other predisposing factors are instrumentation of the urinary tract and DM. Ascending infection is usually with enteric Gram-negative bacilli, such asE. coli,Proteus spp. andEnterobacter.

Pyelonephritis due to haematogenous spread is less common than ascending infection and follows bacteraemia associated with various infections, such as endocarditis, osteomyelitis and soft tissue abscesses. The spectrum of organisms is wide, staphylococci being the most common.

Morphology: in ascending infection, there is purulent urine in the renal pelvis with radiating lines of erythema and suppuration extending up the medulla into the cortex. These show a segmental distribution; infection of the renal parenchyma is via the collecting ducts and requires reflux of urine into the renal papillae. Reflux depends in part on the morphology of the papillae and tends to involve the upper and lower poles of the kidney. The inflammation is associated with a reduction in medullary blood flow that, if exacerbated by obstruction, may result in papillary necrosis (Fig. 21.19). DM also predisposes to this complication. Microscopy shows intratubular neutrophils (seeFig. 21.19) with microabscesses. In haematogenous infection, there are randomly distributed cortical abscesses.

Acute Pyelonephritis

Acute pyelonephritis usually results from reflux of infected urine. The clinical diagnosis of acute pyelonephritis based on fever, flank pain, and positive urine cultures is unreliable and especially difficult in infants. Therefore, recurrent infections often occur and lead to significant damage and scarring. This process is a significant cause of long-term morbidity, causing hypertension and chronic renal failure. The need for a noninvasive test to diagnose acute pyelonephritis is clear.

Originally, contrast IVP was used. However, IVP was found to be insensitive, in addition to the risk associated with intravenous contrast. CT can often identify the inflammatory change in the kidney, as can radiolabeled white blood cells and gallium-67 citrate. However, these tests are not suitable for frequent use, especially in children. Ultrasound is widely used to assess the kidney and is generally considered an essential part of the pyelonephritis workup. However, sonography is relatively insensitive to the inflammatory changes of acute pyelonephritis, as well as the residual cortical defects and scars. Reported ultrasound sensitivities range from 24–40% for pyelonephritis and are approximately 65% for the detection of scars.

Cortical scintigraphy with Tc-99m DMSA is significantly more sensitive then sonography. Sensitivities for acute pyelonephritis are difficult to determine as Tc-99m DMSA itself is considered the gold standard. Most frequently, cortical scanning is done in children with acute pyelonephritis. It may also be performed as part of the workup of patients with vesicoureteral reflux who have no evidence of active pyelonephritis.

Acute Pyelonephritis

Acute pyelonephritis usually results from reflux of infected urine. The clinical diagnosis of acute pyelonephritis based on fever, flank pain, and positive urine cultures is unreliable and especially difficult in infants. Therefore recurrent infections often occur and lead to significant damage and scarring. This process is a significant cause of long-term morbidity, causing hypertension and chronic renal failure.

CT can often identify the inflammatory change in the kidney, as can radiolabeled white blood cells and gallium-67 citrate. However, these tests are not suitable for frequent use, especially in children. Ultrasound is widely used to assess the kidney and is generally considered an essential part of the pyelonephritis workup. However, sonography is relatively insensitive to the inflammatory changes of acute pyelonephritis and the residual cortical defects and scars. Reported ultrasound sensitivities range from 24% to 40% for pyelonephritis and are approximately 65% for the detection of scars.

Cortical scintigraphy with Tc-99m DMSA is significantly more sensitive than sonography. Sensitivities for acute pyelonephritis are difficult to determine because Tc-99m DMSA is considered the gold standard. Most frequently, cortical scanning is done in children with acute pyelonephritis, but it also may be performed as part of the workup in patients with vesicoureteral reflux who have no evidence of active pyelonephritis.

MICROSCOPIC FINDINGS

There is an intense neutrophilic response within the tubules and interstitium (Fig. 5-59). In sites of early involvement, neutrophils and, rarely, bacteria can be seen within tubules and collecting ducts of the cortex and medulla. Soon the suppurative inflammation spills into the interstitium. Glomeruli may be spared initially, but with increasing severity generalized parenchymal destruction occurs, resulting in abscess formation that may extend into the perinephric tissues. In emphysematous pyelonephritis, empty spaces lacking epithelial cell linings form, distorting the parenchyma. Adjacent areas show vascular thrombosis, ischemic necrosis, suppurative inflammation, and abscesses (Figs. 5-60 and 5-61).

ACUTE PYELONEPHRITIS—FACT SHEET

ACUTE PYELONEPHRITIS—PATHOLOGIC FEATURES

Acute Pyelonephritis

Acute pyelonephritis is an ascending infection that occurs in both the presence and the absence of VUR, although it is more severe in the presence of VUR. The acute infection is caused most often by Escherichia coli, Proteus, or Staphylococcus aureus and manifests as flank pain in 80% of cases. It is blood borne in neonates and in patients with endocarditis. The kidney may be edematous and/or contain an inflammatory cellular infiltrate.

There is a paucity of imaging findings in acute pyelonephritis (Fig. 6-41). Nuclear medicine studies are most useful. Scintigraphic evaluation with 99mTc MAG3 (99mTc DMSA involves a higher radiation dose to the kidneys) is the most reliable modality to demonstrate acute bacterial infection of the kidneys. It is more accurate than US, but it is less accurate than CT with regard to suspected perirenal infection. Ultrasonographic clues to acute pyelonephritis are (1) an indistinct corticomedullary junction in part or all of an enlarged kidney that may show either increased or decreased echogenicity; (2) impaired renal movement with respiration; and (3) a size discrepancy of more than 1 cm in comparison with the contralateral, normal kidney. In a child with pyelonephritis, complications such as perinephric abscess, pyonephrosis, and a renal carbuncle (most commonly caused by S. aureus) may occur. A focal area of pyelonephritis, also called lobar nephronia, may progress to a carbuncle (a spherical mass of increased echotexture) that then rarely progresses to the findings of an abscess with central necrosis.