Pneumocystis jirovecii colonization in patients treated with infliximab.

BACKGROUND: Infliximab, a chimeric antitumour necrosis factor (TNF) monoclonal antibody, has become an established effective therapy for inflammatory rheumatic disease. However, TNF is a critical factor in host defence, and the suppression of its biological activity may be associated with the increased risk of opportunistic infections. The frequent use of infliximab in clinical practice has identified Pneumocystis jirovecii pneumonia (PcP) as a serious complication. Individuals colonized with Pneumocystis may be at high risk of development of PcP when they have undergone immunosuppression. Hence, we addressed the question of the frequency of Pneumocystis colonization among patients treated with infliximab. DESIGN: We examined 125 oropharyngeal washes collected from 78 individuals with rheumatoid arthritis, 30 with ankylosing spondylitis and 17 with psoriatic arthritis, half of them underwent infliximab therapy, using a real-time polymerase chain reaction assay that employs specific primers from a portion of the mitochondrial large-subunit rRNA gene of P. jirovecii. RESULTS: Pneumocystis jirovecii colonization was detected in 32 (25·6%) patients. In a multivariate regression model, only duration of infliximab treatment for more than 3 years and use of corticosteroid were significantly and independently associated with risk of Pneumocystis colonization. However, the effect of corticosteroid on P. jirovecii colonization rate was not linearly dose dependent as showed other logistic regression analysis. CONCLUSIONS: There is a high rate of P. jirovecii colonization among patients with rheumatologic diseases treated with infliximab. The identification of patients colonized by P. jirovecii before starting the treatment with infliximab could be a strategy for PcP prevention.

Pneumocystis jiroveci dihydropteroate synthase gene mutations among colonized individuals and Pneumocystis pneumonia patients from Spain.

Cotrimoxazole, an association of trimethoprim and sulfamethoxazole, and dapsone, are mainstays for the prophylaxis and treatment of Pneumocystis pneumonia (PcP). The inability to culture Pneumocystis prevents routine susceptibility testing and detection of drug resistance. Instead, molecular techniques have been used to detect Pneumocystis jiroveci dihydropteroate synthase (DHPS) mutations that cause sulfa resistance in other microorganisms. The most frequent DHPS mutations occur at nucleotide positions 165 and 171, which lead to an amino acid change at positions 55 and 57. Several studies suggest that these mutations are associated with the failure of chemoprophylaxis for PcP. The aim was to establish the frequency and characteristics of P jiroveci DHPS mutations among colonized individuals and PcP patients from Spain. A total of 50 colonized individuals and 25 PcP patients were studied. DHPS polymorphisms were identified by restriction fragment length polymorphism assay. The analysis provided a rate of 28% of DHPS gene mutations in our population, with the presence of all possible polymorphisms described. The presence of mutations was higher in PcP patients than in colonized subjects (40% vs 22%), probably because of the chemoprophylaxis used in PcP patients. The comparison between patients with and without DHPS mutations did not show statistical differences due to age, sex, steroid use, sulfa drug exposure, or smoking. A high rate of DHPS mutations in our area of Spain, not only confined to patients previously exposed to sulfa drugs, is shown in this study. As well as PcP patients, colonized individuals who harbor P jiroveci strains with DHPS mutations could play a major role in the transmission cycle of these mutations, representing a reservoir and source of infection for susceptible individuals. Further research is thus warranted to assess the true scope of the problem and to design rational preventive strategies.

Comparison of two ELISA assays for anti-Sp100 determination.

Antibodies to Sp100 have been described not only in primary biliary cirrhosis (PBC), but also in other diseases. Two assays for detection of Sp100 levels by enzyme-linked immunosorbent assay (ELISA) have been compared in a cohort of patients from our area: (a) Sp100 kit produced by IMTEC, Immunodiagnostica GmbH, and (b) Quanta Lite Sp100 kit produced by INOVA Diagnostics. We analyze here the correlation between the two assays and compare their efficiency in diagnosing PBC. We also comment on the exceptions derived from reactivity with other diseases. We studied 78 sera by IIF with the typical multiple nuclear dots (MND) pattern from patients who suffered from PBC, hepatopathies different from PBC, systemic lupus erythematosus (SLE), other connective tissue diseases (CTD), skeletal diseases, lung diseases, hematological disorders, a miscellaneous group, and a healthy IIF negative control group. The tests work equally well despite their different quantification system: (a) it is based on a standard curve; and (b) it is based on a single-point antigen-specific calibration. Some discrepancies could be explained by differences in the immunodominant epitope used in the ELISA. The main finding of this study is that the presence of MND/Sp100-positive antibodies were detected not only in hepatic diseases, mainly PBC, but also in other clinical conditions, confirmed by both tests. Diagnosis of PBC must be established in the right clinical context, because other diseases recognizing the same epitope, mainly SLE, may also show high Sp100 levels. Sera from PBC patients with antimitochondrial antibodies (AMA) showed higher anti-Sp100 than the AMA-negative group.