The replication kinetics of nonpathogenic anelloviruses belonging to the Alphatorquevirus genus (such as torque teno virus) might reflect the overall state of posttransplant immunosuppression. We analyzed 221 kidney transplant (KT) recipients in whom plasma alphatorquevirus DNA load was quantified by real-time polymerase chain reaction at baseline and regularly through the first 12 posttransplant months. Study outcomes included posttransplant infection and a composite of opportunistic infection and/or de novo malignancy (immunosuppression-related adverse event [iRAE]). Alphatorquevirus DNA loads at month 1 were higher among patients who subsequently developed posttransplant infection (P = .023) or iRAE (P = .009). Likewise, those with iRAE beyond months 3 and 6 also exhibited higher peak viral loads over the preceding periods. Areas under the curve for log 10 alphatorquevirus DNAemia estimated by months 1 or 6 were significantly higher in patients experiencing study outcomes. Alphatorquevirus DNA loads above 3.15 and 4.56 log 10 copies/mL at month 1 predicted the occurrence of posttransplant infection (adjusted hazard ratio [aHR]: 2.88; 95% confidence interval [CI]: 1.13-7.36; P = .027) and iRAE (aHR: 5.17; 95% CI: 2.01-13.33; P = .001). In conclusion, posttransplant monitoring of plasma alphatorquevirus DNA kinetics may be useful to identify KT recipients at increased risk of immunosuppression-related complications. K E Y W O R D S biomarker, clinical research/practice, complication: infectious, complication: malignant, infection and infectious agents, infection and infectious agents -viral, infectious disease, kidney transplantation/nephrology

Monitoring for CMV-specific CMI in intermediate-risk KT recipients must be regular to reflect dynamic changes in overall immunosuppression and individual susceptibility. The early assessment at post-transplant day 15 remains particularly informative.

Objectives: To evaluate the potential role of PCR-based assays in the over-diagnosis of Clostridium difficile infection (CDI) by using a validated diagnostic algorithm in daily clinical practice. Methods: We performed a retrospective cohort study evaluating all C. difficile-positive stool samples identified at our institution during a 12-month period, to compare outcomes and recurrence rates between patients with a positive enzyme immunoassay (EIA) for both glutamate dehydrogenase (GDH) and toxin A/B ('toxin-positive group'), with those with GDH-positive, toxin-negative samples in whom the diagnosis was made by a positive PCR-based assay ('toxin e /PCR þ group'). Medical records were reviewed by two independent investigators blinded to the mode of diagnosis. Results: We analysed 231 first CDI episodes (106 (45.8 %) in the 'toxin-positive group' and 125 (54.1%) in the 'toxin e /PCR þ group'). Both groups had similar baseline characteristics. Patients in the 'toxin-positive group' presented more frequently with a severe/severe complicated form than those in the 'toxin e /PCR þ group' (36 (33.9%) versus 24 (19.2%); p 0.011) and had more recurrences (27 (25.5%) versus 9 (7.2%); p 0.001). Diagnosis of CDI based on a GDH/toxin-positive EIA independently predicted severe/severecomplicated course (adjusted OR 2.11; 95% CI 1.06e4.22; p 0.033) and recurrence (adjusted OR 3.79; 95% CI 1.65e8.69; p 0.002). There were no differences in all-cause mortality (12.3% versus 12.0%; p 0.95) or CDI-attributable mortality (4.7% versus 4.8%; p 0.93). Conclusions: Toxin-positive patients were more likely to have severe-complicated forms of CDI and recurrences. Nevertheless, CDI-related complications may still occasionally occur among toxin-negative patients diagnosed by PCR, which stresses the need for individualized clinical evaluation.