Got BK?

Posted by Jody at Sunday, August 29, 2010

“What is BK?” I asked the same question when I found out my patient had “BK”.

As I am rounding with the team one day I hear the attending mention my patient has BK. I immediately start racking my brain, what in the world is “BK”? I have no idea. I turn to my classmates and ask them. They respond, “BK? I thought he said PK.” Well then, “What does PK mean?” (This is the reason you ALWAYS stand as close to the attending as possible – they’re quiet talkers.) Whatever my patient has I know one of the symptoms they are experiencing is hematuria and they are going to be treated either cidofovir or leflunomide. My classmates and I are completely lost and ask our preceptor. He informs us that the attending was talking about “BK”. But our preceptor would not give us any further information. He told us we should research it tonight and gave us one clue, to start with renal transplant patients.

Returning to answer the question: “Do you have BK?” The answer: Yes, you most likely do have BK.

What is BK?

BK refers to the BK virus (BKV), and up to 90% of healthy adults are infected with the virus. The virus was first reported in 1971 in a renal transplant patient, and thus the virus was named after the patient’s initials. BK is a polyomavirus that is transmitted via the respiratory tract, especially during early childhood. The initial infection is usually asymptomatic, but it can result in a mild fever or upper respiratory symptoms. After the initial infection the virus remains latent for years in the kidneys and does not reactivate until a state of immunosuppression. In renal transplant patients BK virus manifests as nephritis (i.e. BKV nephritis), however in bone marrow transplant the clinical manifestation is hemorrhagic cystitis (HC). The presentation of HC is hematuria, bladder spasms, frequent urination, and dysuria due to inflammation of the bladder mucosa.

Diagnosis and Treatment of BK

Once symptoms of HC occur a qPCR of the plasma and urine is ordered. If results are positive the patient is then treated. However, there is no approved treatment for BKV. Clinical trials have been investing various drugs to combat the virus. Currently, trials with cidofovir and leflunomide have shown positive outcomes yet further research is warranted in both the virus itself and treatment options.

After my basic search of BKV it was time to tackle articles on clinical trials. In rotation, when a preceptor asks you to “look-up” or research something it doesn’t just mean hit Wikipedia and get the general information. We are pharmacy students, soon to be pharmacists, once we understand the condition/disease state we need to understand the treatment options and know what works (or doesn’t) and why. (A helpful hint my preceptor gave me, read the literature and know it because no one else will)

Bottom line: The learning never stops.