Switch to atovaquone and subsequent re-challenge with trimethoprim-sulfamethoxazole for Pneumocystis prophylaxis in a kidney transplant population

Pneumocystis jirovecii Pneumonia in a Liver Transplant Recipient With an Adverse Reaction to Trimethoprim/Sulfamethoxazole Treated With a Sulfonamide Desensitization Protocol: Case Report

BACKGROUND

Pneumocystis jirovecii pneumonia (PJP) is an opportunistic fungal infection that, in immunocompromised patients, can progress to respiratory failure and death. Since trimethoprim/sulfamethoxazole (TMP/SMX) chemoprophylaxis has become a standard management, the prognosis has improved. However, there are patients with a history of TMP/SMX intolerance who cannot receive chemoprophylaxis.

BACKGROUND

We report on a 53-year-old male liver recipient treated with a standard triple immunosuppressive regimen in whom TMP/SMX was waived because of a history of allergy manifested as a generalized rash with edema more than 30 years ago. At transplantation, the immunologic risk was assessed as low, and liver graft function was normal. In the third month after engraftment, he developed dyspnea at rest required constant passive oxygen therapy. Ceftriaxone, azithromycin, and clindamycin were implemented. Mycophenolate acid was stopped, and tacrolimus was reduced. High-resolution computed tomography revealed interstitial pneumonia. Pneumocystis jirovecii pneumoniae was diagnosed from bronchoalveolar lavage. Instead of TMP/SMX, pentamidine and caspofungin were also used for PJP, with no improvement. After 3 weeks, the patient deteriorated. Because of his life-threatening condition, TMP/SMX was introduced in the sulfonamide desensitization protocol, including hydrocortisone and clemastinum. Within 4 days, the patient stabilized with no signs of TMP/SMX intolerance. Pneumonia subsided within a month, and TMP/SMX was prescribed lifelong.

CONCLUSIONS

Prophylaxis for PJP with TMP/SMX still remains an important issue in transplant recipients. Adverse reaction to TMP/SMX in the past is not always a contraindication to reintroducing prophylaxis. The decision of prophylaxis avoidance should be analyzed carefully; in uncertain cases, a sulfonamide desensitization protocol should be considered.

Mechanisms and management of drug-induced hyperkalemia in kidney transplant patients

Hyperkalemia is a common and potentially life-threatening complication following kidney transplantation that can be caused by a composite of factors such as medications, delayed graft function, and possibly potassium intake. Managing hyperkalemia after kidney transplantation is associated with increased morbidity and healthcare costs, and can be a cause of multiple hospital admissions and barriers to patient discharge. Medications used routinely after kidney transplantation are considered the most frequent culprit for post-transplant hyperkalemia in recipients with a well-functioning graft. These include calcineurin inhibitors (CNIs), pneumocystis pneumonia (PCP) prophylactic agents, and antihypertensives (angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, beta blockers). CNIs can cause hyperkalemic renal tubular acidosis. When hyperkalemia develops following transplantation, the potential offending medication may be discontinued, switched to another agent, or dose-reduced. Belatacept and mTOR inhibitors offer an alternative to calcineurin inhibitors in the event of hyperkalemia, however should be prescribed in the appropriate patient. While trimethoprim/sulfamethoxazole (TMP/SMX) remains the gold standard for prevention of PCP, alternative agents (e.g. dapsone, atovaquone) have been studied and can be recommend in place of TMP/SMX. Antihypertensives that act on the Renin-Angiotensin-Aldosterone System are generally avoided early after transplant but may be indicated later in the transplant course for patients with comorbidities. In cases of mild to moderate hyperkalemia, medical management can be used to normalize serum potassium levels and allow the transplant team additional time to evaluate the function of the graft. In the immediate post-operative setting following kidney transplantation, a rapidly rising potassium refractory to medical therapy can be an indication for dialysis. Patiromer and sodium zirconium cyclosilicate (ZS-9) may play an important role in the management of chronic hyperkalemia in kidney transplant patients, although additional long-term studies are necessary to confirm these effects.

Alternative pneumocystis prophylaxis in solid organ transplant recipients at two large transplant centers

BACKGROUND

Trimethoprim-sulfamethoxazole (TMP-SMX) is the drug of choice for Pneumocystis jirovecii pneumonia (PJP) prophylaxis and has activity against other opportunistic infections (OIs) after solid organ transplant (SOT). We aimed to describe the incidence, reasons for and outcomes of use of alternative prophylactic agents (APAs) across SOT programs in our high volume centers.

METHODS

Solid organ transplant recipients (SOTRs) at our centers from 1/2015-12/2016 were identified. Pharmacy records identified APA (pentamidine, atovaquone, or dapsone) use within 1 year. Records were reviewed for allergies, laboratory values at APA initiation, diagnostic tests for TMP-SMX-preventable OIs, and APA side effects.

RESULTS

An APA was initiated in 105/1173 (8.9%) SOTRs. Of these, 51 (48.6%) were because of sulfonamide allergy recorded pre-SOT, mostly rash/hives (58.8%). The remaining 54 (51.4%) had TMP-SMX discontinued post-SOT, mostly for neutropenia (48%) and renal effects (34%). Differences occurred across programs, with kidney transplant never stopping TMP-SMX for renal issues. Of those changed to APAs post-transplant, 19 (35%) were later successfully re-challenged with TMP-SMX. With thresholds in mind, 67 (64%) received an APA unnecessarily, accounting for up to $100 000/y excess cost. Potential TMP-SMX-preventable OIs occurred in 7 (5 Nocardia; 2 PJP). APA side effects occurred in 14/105 (13.3%).

CONCLUSIONS

Use of APAs for PJP prophylaxis after SOT is less than previously reported but often unwarranted. Such decisions require scrutiny to avoid TMP-SMX-preventable OIs, cost and important APA side effects. Use of reasonable thresholds for cessation of TMP-SMX and data-driven approaches to re-challenge would substantially reduce APA use.

Opportunistic Infections in Transplant Patients

Transplants have become common with excellent patient and graft outcomes owing to advances in surgical technique, immunosuppression, and antimicrobial prophylaxis. In 2017, 34,770 solid organ transplants were performed in the United States. For solid organ transplant recipients, infection remains a common complication owing to the regimens required to prevent rejection. Opportunistic infections, which are infections that are generally of lower virulence within a healthy host but cause more severe and frequent disease in immunosuppressed individuals, typically occur in the period 1 month to 1 year after transplantation. This article focuses on opportunistic infections in the solid organ transplant recipient.

Sulfonamide desensitization in solid organ transplant recipients: A protocol-driven approach during the index transplant hospitalization

Trimethoprim-sulfamethoxazole (TMP-SMX) is the first-line agent for Pneumocystis jiroveci pneumonia (PJP) prophylaxis for solid organ transplant (SOT) recipients because of its efficacy for this indication, extended antimicrobial coverage, and favorable cost. Reported sulfonamide allergy is not uncommon and often results in TMP-SMX avoidance. Desensitization offers an efficacious and cost-effective alternative to TMP-SMX avoidance. Herein, we reviewed our experience with desensitization during the index transplant hospitalization among 52 SOT recipients with history of a non-anaphylactic sulfonamide allergy. Of those enrolled in the desensitization protocol, 92% (48/52) completed the protocol, with nearly 80% (41/52) still on TMP-SMX at 3 months without adverse reaction. Eleven patients discontinued TMP-SMX (7 for allergic reactions and 4 for non-allergic reasons) and switched to pentamidine. A cost savings of $575 per desensitization was calculated based on annual wholesale drug prices, for a total savings of $23 575. Additionally, the protocol did not delay discharge in any patient nor was it associated with any severe allergic reactions. These findings suggest TMP-SMX desensitization is safe and effective in SOT recipients with a history of non-anaphylactic, non-life-threatening sulfonamide hypersensitivity.