Ruxolitinib is a targeted agent that inhibits Janus 2 Kinase and is approved for use in Polycythemia Vera and Primary Myelofibrosis. Its mechanism of action involves inhibition of cellular proliferation via the Janus kinase/signal transducer and activator of transcription proteins pathway. Ruxolitinib has different immune modulating effects that result in functional immunosuppression, leading to an increased susceptibility to certain infections. Klebsiella pneumoniae infections, in particular, were common among the reported pathogens contracted by ruxolitinib users. We report a 75-year-old male patient who had recurrent K. pneumoniae urinary tract infections while on ruxolitinib for Polycythemia Vera. This case is reported to add to the literature describing an increased susceptibility of patients to this often-resistant bacteria and to raise awareness about the immune modulating effects of JAK inhibitors.
Keywords: Immunemodulation; JAK kinase (Janus Kinase); Klebsiella pneumonia; Ruxolitinib; STAT (Signal Transducer and Activator of Transcription proteins) kinase.