In 1898, Kelly and MacCullum reported the first case of kidney infection with gas accumulation . In 1962, Schultz and Klorfein described this disorder as emphysematous pyelonephritis . Since then, there have been reports of various types of kidney infection with gas accumulation.
The pathogenesis of emphysematous pyelonephritis (EPN) is still unclear. It is believed that multiple factors, including diabetes, elevated glucose levels in kidney tissue, urinary tract obstruction, impaired renal circulation, decreased host immune function, and the presence of gas-producing microbial infections could cause EPN [1, 14]. EPN most commonly affects diabetic patients [2, 15,16,17]; and it is currently believed that the increased susceptibility to developing EPN in diabetic patients is due to impaired renal tissue perfusion . Additionally, high blood glucose concentrations can also promote anaerobic growth and gas-producing metabolism .
CT scan is now considered to be the best method to diagnose EPN, and the most commonly accepted CT classification system for EPN was proposed by Huang and associates in 2000 . These authors suggested 4 classes of EPN: Class 1, where gas is confined only to the collection; Class 2, where gas is located within the renal parenchyma and does not spread to the extrarenal space; Class 3A, where gas or an abscess spreads to the perinephric space; Class 3B, where gas or the abscess spreads to the pararenal space; and Class 4, depicting a bilateral or solitary kidney with EPN .. However, in one recent study, investigators attempted to re-correlate CT classification with clinical treatment options, analyzing 34 cases from 2009 to 2018. Their results showed that most Class 1 and Class 2 patients achieved satisfactory outcomes purely by conservative treatment. Only a small number of patients with urinary tract obstruction required combined percutaneous drainage, 2 of the 6 Class 3A patients required nephrectomy, and 2 Class 3B patients also required nephrectomy .
Lu et al. retrospectively analyzed 51 patients with EPN and demonstrated that the most common bacteria were Escherichia coli, followed by Streptococcus pneumoniae, Enterococcus, and Pseudomonas aeruginosa; with a small number of patients showing mixed bacterial infections. The antibiotic-resistance rate was greater than 15% for fluoroquinolone, ampicillin, 1st- and 2nd-generation cephalosporins, and gentamicin; whereas the resistance rates for the 3rd- and 4th-generation cephalosporins were only 10.9 and 6.5%, respectively. These authors concluded that the 3rd-generation cephalosporins could be used routinely for most affected patients. However, carbapenem antibiotics such as meropenem should be selected if a patient carries high risk factors, including recent hospitalization, antibiotic use, or DIC . At the present time, most studies depict Escherichia coli as the most common pathogenic bacterium [1, 17]; although there have been recent reports of EPN caused by Candida albicans . Therefore, selection of antibiotics should be based upon the local epidemiology and antibiotic- resistance patterns. In addition, multiple blood and urine cultures should be performed. It is extremely important to then revise the antibiotics according to the disease severity and the antibiotic-susceptibility test results.
There is recent evidence that patients who received conservative management achieved satisfactory results . However, a study of 17 patients with EPN also showed that patients who received conservative treatment tend to experience acute increases in the Sequential Organ Failure Assessment (SOFA) score after the beginning of treatment, even if transient, which presents a great risk of septic mortality . Adequate surgical drainage combined with intravenous antibiotics have resulted in satisfactory results in patients with EPN and multiple organ failure who were not appropriate candidates for nephrectomy [17, 22, 23]. In another study researchers tried to evaluate the clinical prognosis and outcomes of this disorder by analyzing 74 patients with EPN . Their results showed that 1. fever was the most common clinical presentation, which was followed by lower back pain; 2. most patients had diabetes, which was followed by urolithiasis; 3. Escherichia coli was still the most common pathogen; 4. older age, high body-mass index, impaired renal function, thrombocytopenia, sensory changes, and shock were associated with a poor prognosis; and 5. treatment mainly consisted of rapid hydration, maintenance of electrolyte balance, use of systemic antibiotics, strict control of blood glucose, effective urine drainage, and nephrectomy if necessary . Sanford et al. have shown that mild EPN was treatable by conservative management that included infectious agent-susceptible antibiotics . However, patients with severe infections required percutaneous renal puncture drainage and/or double-J stenting .
Nanki et al. successfully treated a 58-year-old woman with EPN caused by Escherichia coli complicated with diabetic ketoacidosis through nephrectomy, antibiotics and recombinant human granulocyte colony-stimulating factor(rhG-CSF) . Harrabi et al. reported a 64-year-old woman with EPN complicated with diabetic ketoacidosis who died of septic shock without surgical drainage . However, another patient with EPN with diabetic ketoacidosis who underwent percutaneous renal drainage combined with antibiotics died 7 days after admission ; Unlike our patient, according to CT, this patient belongs to class 3A EPN. Recently, it has been reported that EPN with diabetic ketoacidosis in the patient with allogeneic renal transplantation improved after conservative treatment with intravenous antibiotics without percutaneous drainage or nephrectomy ; But our patient is different from this successful case in that there are urinary tract obstruction factors such as right kidney stone and right ureteral stone, and percutaneous drainage is more important in the treatment.
Our successful management of this patient lies in the following points: 1. We confirmed the diagnosis of EPN by urinary CT examination as soon as the patient was admitted to hospital; 2. Rapid correction of ketoacidosis by continuous intravenous infusion of low-dose insulin and fluid resuscitation; 3. We performed blood culture before using antibiotics and upgraded cefoperazone sulbactam to meropenem according to the results of blood culture and the antibiotic-susceptibility test results; 4. Our endocrinology department collaborated with urology, nephrology, infection and imaging departments to develop a treatment plan; 5. What is particularly important is that although the patient has sepsis, it belongs to Class 2 EPN. However, our treatment is also inadequate: the patient did not receive percutaneous drainage. Although the accumulation of gas in the kidney was less than before, the right hydronephrosis increased. In the end, the patient still underwent two percutaneous nephrolithotomy. Failed to achieve the goal that the patient wanted to have only one operation.
Our case report makes up for the gap in the clinical management of patients with EPN with diabetic ketoacidosis with urinary tract obstruction who refuse surgical drainage, but it is unclear whether our management experience can be extended to similar patients of EPN Class 3A,Class 3B and Class 4.
In conclusion, EPN with diabetic ketoacidosis should be diagnosed as soon as possible. For patients with Class 1 and Class 2 EPN with diabetic ketoacidosis and urinary tract obstruction, if surgical drainage is refused, it is particularly important to rapidly correct diabetic ketoacidosis and intravenous use of sensitive antibiotics, so as to create conditions for follow-up percutaneous nephrolithotomy.