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Pielonefritis Aguda I: introducción
La pielonefritis es una infección bacteriana que afecta principalmente al parénquima renal y al sistema colector, incluyendo la pelvis renal, los túbu…
La pielonefritis es una infección bacteriana que afecta la pelvis renal, los túbulos y el tejido intersticial de uno o ambos riñones.
Se puede clasificar como aguda, una infección grave repentina o crónica debido a infecciones repetidas o anomalías estructurales que dañan el riñón.
La causa principal de la pielonefritis aguda es una infección bacteriana, típicamente Escherichia coli. Sin embargo, otras bacterias, como Proteus, Klebsiella, Enterococcus y Pseudomonas, también causan la enfermedad.
La pielonefritis aguda suele comenzar con la colonización bacteriana de la uretra, seguida de una migración a la vejiga, que causa cistitis.
Desde la vejiga, las bacterias pueden ascender a través de los uréteres hasta los riñones, particularmente en casos de estasis urinaria o reflujo vesicoureteral.
Una vez que las bacterias llegan a los riñones, invaden el intersticio renal, lo que hace que el sistema inmunitario libere citocinas y otros mediadores inflamatorios.
Esta respuesta conduce a edema renal, infiltración de neutrófilos y lesión del tejido renal, causando síntomas como fiebre alta y escalofríos, leucocitosis, bacteriuria, dolor en el flanco y en la parte baja de la espalda, dolor al orinar, náuseas y vómitos.
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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.