A followup study of asymptomatic carriers of Pneumocystis jiroveci during immunosuppressive therapy for rheumatoid arthritis.

OBJECTIVE: To examine the preventive effects of prophylaxis against Pneumocystis jiroveci-induced pneumonia (PCP) in patients receiving immunosuppressive therapy for rheumatoid arthritis (RA) who are colonized by this organism.
METHODS: We performed molecular testing by polymerase chain reaction (PCR) for P. jiroveci on induced sputum or bronchoalveolar lavage fluids of 82 patients with RA. During primary prophylaxis, asymptomatic carriers of this organism were examined by high-resolution computed tomography and PCR every 2 weeks. RA patients who had developed PCP received PCR tests every week. Once negative results were obtained, PCR testing was scheduled at Months 1, 3, and 6, followed by reexaminations every 6 months.
RESULTS: We found 9 cases of asymptomatic carriage of P. jiroveci. All the carriers had received low doses of methotrexate. Upon introduction of PCP prophylaxis, 5 cases tested negative for PCR within 1 month. Three carriers developed PCP before starting prophylaxis, but these tested negative for PCR after short periods (1-2 weeks) of PCP treatment. Once P. jiroveci was eradicated, all cases maintained negative PCR results during followup without prophylactic intervention, even after resuming immunosuppressive therapy. One patient refused PCP prophylaxis, but no PCP developed.
CONCLUSION: RA patients with asymptomatic carriage of P. jiroveci benefited from short-term prophylaxis against PCP. Positive PCR results appeared to be predictive of future development of PCP in RA patients. Identification of P. jiroveci carriers will encourage prompt introduction of PCP prophylaxis when rheumatologists consider immunosuppressive therapy for RA.