Pyelonephritis: Clinical sciences

Acute pyelonephritis is an upper urinary tract infection that typically occurs when bacteria, most commonly E. Coli, make their way from the lower urinary tract, such as the urethra and bladder, up the ureters and kidneys. Now, based on the patient’s clinical features, acute pyelonephritis can be classified as complicated or uncomplicated. Complicated pyelonephritis occurs when the patient has functional or structural abnormalities, like neurogenic bladder, or like urinary obstruction due to nephrolithiasis. Complicated pyelonephritis also occurs when the patient has specific host risk factors, such as immunosuppression, advanced age, or male sex. On the other hand, a patient has uncomplicated pyelonephritis when there are no urinary tract abnormalities and no host specific risk factors.

Now, if you suspect acute pyelonephritis, you should first perform an ABCDE assessment to determine if they are stable or unstable. Unstable individuals might present with signs of sepsis or shock, like tachycardia and hypotension, so don’t forget to stabilize their airway, breathing, and circulation. Additionally, obtain IV access, administer supplemental oxygen, and put your patient on continuous vital sign monitoring.

Ok, let’s return to the ABCDE assessment. If the patient is stable or once you stabilize them, obtain a focused history and physical examination. Your patient will likely report fever, chills, malaise, flank pain, nausea and vomiting, and sometimes dysuria. On the other hand, physical exam may reveal elevated body temperature, hypotension, tachycardia, costovertebral angle and flank tenderness, and abdominal tenderness to palpation.

At this point you should suspect pyelonephritis, so your next step is to order labs, including CBC and CMP, as well as urinalysis and urine cultures.

So, upon reviewing the labs, the CBC will reveal a leukocytosis with a left shift and the CMP might show an elevated BUN and creatinine, indicating renal insufficiency. The urinalysis will generally reveal pyuria and bacteriuria, and possibly hematuria, nitrates, leukocyte esterase, and WBC casts.

Okay, now we can make a confident diagnosis of acute pyelonephritis, so your next step is to determine whether or not your patient requires hospitalization. Outpatient management is reserved for individuals that can tolerate oral intake, adhere to the treatment plan, and have no coexisting conditions. Some important conditions to keep in mind include diabetes, renal insufficiency, a history of nephrolithiasis, or anatomical abnormalities of the urinary tract.

In a patient that meets these criteria, you should proceed with medical therapy, which consists of oral hydration and empiric antibiotics. Now, due to increasing fluoroquinolone resistance, you should give a parenteral antibiotic, like a cephalosporin, prior to starting an oral fluoroquinolone. An example would be intramuscular ceftriaxone followed by oral ciprofloxacin.

Next, review the culture results that were previously ordered. These results will hopefully identify the pathogen within a few days and allow you to tailor antibiotics based on culture results. Now, once you start tailored antibiotics, expect a response to treatment within 72 hours. If they are improving, then the response is adequate and you can be confident that they have pyelonephritis. On the other hand, if your patient is not improving, then they have failed outpatient therapy and you should suspect complicated pyelonephritis. In this case you’ll want to admit them to the hospital to proceed with inpatient management.

Okay, let’s switch gears and discuss inpatient management of pyelonephritis. This type of management is reserved for individuals who cannot tolerate oral intake, have failed outpatient treatment, might not adhere to the treatment plan, or have coexisting conditions that require inpatient treatment. In these individuals there is a greater risk for complications, such as obstruction and abscess formation.

While you are waiting for culture results, begin medical therapy with IV hydration and empiric IV antibiotics, such as ceftriaxone or piperacillin-tazobactam, and assess the patient’s response to treatment. If the patient improves and response is adequate, they can be discharged to complete treatment as an outpatient, which would require making arrangements for IV antibiotic administration or transitioning to oral antibiotics.