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Pielonefrite Aguda I: Introdução
A pielonefrite é uma infecção bacteriana que afeta principalmente o parênquima renal e o sistema coletor, incluindo a pelve renal, os túbulos e o teci…
A pielonefrite é uma infecção bacteriana que afeta a pelve renal, os túbulos e o tecido intersticial de um ou ambos os rins.
Pode ser classificada como aguda, uma infecção grave súbita ou crônica devido a infecções repetidas ou anormalidades estruturais que danificam o rim.
A principal causa de pielonefrite aguda é uma infecção bacteriana, geralmente Escherichia coli. No entanto, outras bactérias, como Proteus, Klebsiella, Enterococcus e Pseudomonas, também causam a doença.
A pielonefrite aguda geralmente começa com a colonização bacteriana da uretra, seguida pela migração para a bexiga, causando cistite.
Da bexiga, as bactérias podem subir pelos ureteres até os rins, principalmente em casos de estase urinária ou refluxo vesicoureteral.
Uma vez que as bactérias atingem os rins, elas invadem o interstício renal, acionando o sistema imunológico para liberar citocinas e outros mediadores inflamatórios.
Essa resposta leva a edema renal, infiltração de neutrófilos e lesão do tecido renal, causando sintomas como febre alta e calafrios, leucocitose, bacteriúria, dor no flanco e na região lombar, dor ao urinar, náuseas e vômitos.
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Q1: What is acute pyelonephritis and which parts of the kidney does it affect?
Acute pyelonephritis is a sudden, severe bacterial infection affecting the renal pelvis, tubules, and interstitial tissue of one or both kidneys. It differs from chronic pyelonephritis, which develops from repeated infections or structural abnormalities that progressively damage kidney tissue. The infection typically ascends from the lower urinary tract.
Q2: How does bacteria cause acute pyelonephritis to develop?
Acute pyelonephritis typically begins with bacterial colonization of the urethra, followed by migration to the bladder, causing cystitis. From the bladder, bacteria ascend through the ureters to the kidneys, particularly when urinary stasis or vesicoureteral reflux is present. Once bacteria invade the renal interstitium, they trigger an inflammatory immune response.
Q3: Which bacteria most commonly cause acute pyelonephritis?
Escherichia coli is the primary cause of acute pyelonephritis, accounting for approximately 70-80% of cases. Other bacteria responsible for the infection include Proteus, Klebsiella, Enterococcus, and Pseudomonas. These organisms typically originate from the lower urinary tract and ascend to the kidneys.
Q4: What inflammatory changes occur in the kidney during acute pyelonephritis?
When bacteria invade the renal interstitium, the immune system releases cytokines and inflammatory mediators, triggering renal edema and neutrophil infiltration. This inflammatory response causes injury to renal tissue. If untreated, the inflammation can progress to serious complications like renal abscess formation or sepsis.
Q5: What are the typical symptoms patients experience with acute pyelonephritis?
Patients with acute pyelonephritis commonly present with high fever and chills, flank and lower back pain, painful urination, nausea, and vomiting. Laboratory findings include leukocytosis (elevated white blood cells), bacteriuria, and pyuria (pus in urine). Malaise and headache often accompany these symptoms as part of the systemic inflammatory response.
Q6: What risk factors increase susceptibility to acute pyelonephritis?
Several factors predispose individuals to acute pyelonephritis, including untreated urinary tract infections, vesicoureteral reflux, obstructive uropathy from kidney stones or tumors, immunosuppression from diabetes or HIV, pregnancy-related hormonal changes, and indwelling catheters. These conditions either promote bacterial ascension or compromise the immune system's ability to fight infection.
Q7: How does acute pyelonephritis differ from chronic pyelonephritis?
Acute pyelonephritis is a sudden, severe bacterial infection, while chronic pyelonephritis develops from repeated infections or structural abnormalities that progressively damage kidney tissue over time. Acute cases present with acute symptoms like high fever and severe flank pain, whereas chronic pyelonephritis may develop insidiously with long-term kidney damage.