肾皮质化脓性感染

　　1、发病原因

　　最常见的致病菌为金黄色葡萄球菌，细菌可由体内其他部位的化脓性病灶，经血液循环进入肾脏。如疖、痈、脓肿、感染的伤口、上呼吸道感染或者肾邻近组织感染，偶可继发于尿路梗阻如尿路结石或先天性畸形如儿童的膀胱输尿管反流。

　　2、发病机制

　　早期病变局限于肾皮质，形成多发性微小脓肿，这些微小脓肿可集合成多房性脓肿。如未及时治疗，可形成肾痈；少数可穿破肾包膜、侵入肾周脂肪，形成肾周肿块。

　　本病治疗不及时，可发展为败血症，肾皮质脓肿可穿透肾包膜进入肾周围引起肾周围脓肿。由细菌血源性播散可产生化脓性关节炎、心内膜炎、脑膜炎或脑脓肿、骨髓炎和肝脓肿等。目前此类并发症在有效抗菌药物治疗以来已罕见。急性肾小球肾炎多在链球菌感染后第3周起病，A组链球菌的某些型别感染与肾炎发病有关，如呼吸系感染菌12型以及致脓疱疮的49型均为引起肾炎的常见菌株，其他尚有1、4、25、55、57、60和61型等。在可引起肾小球肾炎的链球菌感染中，并发该病者可达10％～15％。

　　It is often preceded by a history of bacterial infection in other parts, sudden chills, high fever, back pain, accompanied by fatigue and loss of appetite. Initially, there are no symptoms of frequent urination or urgency. In the later stage, due to the invasion of the infection into the renal pelvis, bladder irritation symptoms appear, the muscle in the affected side of the waist is tense, and there is obvious percussion pain in the renal area and costovertebral angle.

　　Due to the close relationship between group A Streptococcus infection and rheumatic fever, patients with rheumatic heart disease or rheumatic fever should prophylactically use antibacterial drugs to prevent the occurrence of streptococcal respiratory tract infection. Penicillin is the first choice for prophylactic medication, which can be

　　Benzathine penicillin is used, with an intramuscular injection of 1.2 million units per month for adults, and 600,000 to 1.2 million units for children. The course should last for several years until the condition is stable. For those allergic to penicillin, erythromycin 250 mg can be taken twice a day for a long time. If the patient cannot persist with a long course, regular throat swab cultures can be performed. When group A Streptococcus is detected, a course of penicillin or erythromycin for acute streptococcal pharyngitis should be administered with the same dose as mentioned earlier.

　　Benzathine penicillin should also be administered to carriers until the culture turns negative to control the source of infection, which is particularly important for staff in nurseries and kindergartens.

　　During the epidemic of streptococcal respiratory tract infection, it is advisable to avoid crowded public places to reduce the chance of infection by droplet transmission. Improving the environment and paying attention to personal hygiene can prevent wound contamination and reduce the incidence of skin and wound infections.

　　The total white blood cell count and neutrophils in the blood increase, blood culture may be positive. In the early stage, there are no leukocytes in the urine. When the infection spreads to the renal pelvis, leukocytes may be found in the urine. The results of urine culture should be the same as those of blood culture. B-ultrasound-guided puncture and pus culture can detect the pathogenic bacteria.

　　Imaging examination shows different manifestations according to the degree of the lesion.

　　1. Acute focal bacterial nephritis:The abdominal X-ray usually shows no significant abnormalities, intravenous urography is helpful for diagnosis, and in a few patients, compression of the renal pelvis and calyces may occur. Ultrasound examination shows focal hyperechoic areas in the renal parenchyma, with unclear boundaries. CT examination shows a low-density solid mass, with inhomogeneous enhancement after contrast administration, which is still lower than normal renal tissue. The mass boundary is unclear, unlike the clear boundary of the wall formed by new blood vessels in renal cortex abscess. There are reports that CT shows localized swelling of the renal parenchyma and thickening of multiple layers of renal fascia as the diagnostic criteria for this disease.

　　2. Pyogenic abscess of renal cortex:Abdominal X-ray shows enlargement of the affected kidney, perinephric edema makes the renal shadow blurred, the lumbar plexus shadow unclear or disappeared, when the abscess breaks into the perinephric space, lumbar scoliosis, intravenous urography can show compression and deformation of renal pelvis and calyces, B-ultrasound: shows irregular abscess outline, abscess is hyperechoic area, or mixed echo area, renal sinus echo shift, slightly convex to the renal edge, CT renal scan shows irregular hypodense focus in renal cortex, CT value between cyst and tumor, enhanced CT scan shows obvious enhancement at the edge, no enhancement in the center, renal capsule, perirenal fascia thickening, interface with adjacent tissues disappeared, radionuclide renal scan: shows renal space-occupying lesions, renal defect area similar to renal cyst, 67Ga can suggest infected tissue.

　　1. Adjust daily life and work load, engage in regular activities and exercise, and avoid overexertion.

　　2. Maintain emotional stability and avoid emotional excitement and tension.

　　3. Keep the bowels smooth and avoid strenuous defecation, eat more fruits and high-fiber foods.

　　4. Avoid cold stimulation and pay attention to keeping warm.

　　I. Treatment

　　1. Antibiotic Treatment:Before the results of bacterial culture are reported, antibiotics can be selected based on experience; when the results of urine culture or blood culture are obtained, sensitive antibiotics can be administered intravenously.

　　2. Active treatment of the primary disease:If there are stones, they should be removed.

　　3. Surgical Treatment:If drug treatment is ineffective, it is possible to perform abscess incision and drainage; if the abscess drainage is not smooth, and the renal function is poor, but the contralateral renal function is good, renal resection can be considered.

　　II. Prognosis

　　If early diagnosis is obtained for pyogenic infection of renal cortex, and effective antibiotics against Staphylococcus aureus are selected, the prognosis is good, the general course of the disease is 1-2 weeks, and the acute inflammatory symptoms gradually disappear. In some cases, death may occur due to severe sepsis, but due to the widespread use of broad-spectrum antibiotics, it is extremely rare. If diagnosis is delayed and medical treatment is ineffective, and perinephric abscess develops, early surgical incision and drainage can also lead to cure.