Three cases of presumed pneumocystis pneumonia in patients receiving bortezomib therapy for multiple myeloma

INTRODUCTION: This paper presents three probable cases of pneumocystis pneumonia in patients receiving bortezomib therapy for multiple myeloma. PRESENTATION OF CASES: Three patients receiving bortezomib therapy for multiple myeloma presented with dyspnoea, non-productive cough, and fevers. These patients deteriorated despite receiving broad-spectrum antibiotic therapy with piperacillin + tazobactam and azithromycin and an assortment of other antimicrobials but promptly responded to sulfamethoxazole + trimethoprim therapy. Only one of the patients exhibited a positive Pneumocystis jirovecii PCR test but testing was sub-optimal. DISCUSSION: Although only one of the patients exhibited a positive sputum P. jirovecii PCR test, the diagnosis of PCP in these three patients is supported by their; clinical and radiological features consistent with PCP, deterioration despite receiving broad-spectrum antibiotic therapy, and prompt responses to sulfamethoxazole + trimethoprim therapy. In the patients with negative P. jirovecii PCR bronchoalveolar lavage specimens were not obtained as these patients were deemed too high risk to undergo the procedure. Although the three patients were also receiving dexamethasone therapy, the doses and durations were at the threshold of those expected to cause PCP. CONCLUSION: 26S proteosome inhibitor therapy for multiple myeloma may be a risk factor for PCP and clinicians should adopt a high level of suspicion for PCP in patients receiving these medications until conclusive evidence is obtained.