(346) Donor Urease Producing Bacteria (DU) Detection and Serum Ammonium Screening for Hyperammonemia Syndrome (HS) Post-Lung Transplant: A Prospective Observational Study

PurposeHS is a rare but potentially fatal complication of Lung Transplantation (LT), association with DU has been hypothesized. Optimal screening methods to prevent/diagnose HS early are uncertain. Both pulmonary DU PCR and daily Serum Ammonium Screening (SAS) have been suggested. We investigated HS and the association with DU PCR and SAS.MethodsWe included all LT recipients from 07/2019-02/2020 and 10/2021-03/2022 with available donor bronchial wash samples from the LT Biobank. Briefly, DNA was extracted using Qiagen DNA kit and Mollicute PCR performed using an AMPIPROBE® Ureaplasma spp. / M. genitalium / M. hominis Assay Kit. Generation of a cycle number (Ct) value of 30 was considered positive as recommended by manufacturer. Recipients were prospectively followed for HS symptoms for 30 d post-LT. Daily ammonia serum levels were measured for the first 14 days (d) as per center-specific practice, and thereafter if clinically indicated. HS was defined by new neurological symptoms and the presence of elevated serum ammonium (>70 umol/l). We compared patients who developed HS with to those who did not.ResultsOf 139 LT recipients, 4 (2.8%) developed HS during the study period. Recipient and donor characteristics of LT recipients with and without HS are shown in Table A. All HS cases were diagnosed within the first 14 days, while daily SAS was in place, median time to HS was 7.5 days (IQR 4,11). DU PCR was found to be positive in 4.3% (6/139) at transplant. Only 1/4 cases of HS was associated with a positive DU PCR. HS was treated with Moxifloxacin/Doxycycline combination (4/4) for a median duration of 14d (IQR 12,14), 2/4 received renal replacement therapy. No patient died within 180 days post HS diagnosis.ConclusionHS was a rare complication in our LT cohort. The low prevalence of DU detection in our cohort questions the utility of donor screening. Daily SAS of the recipient might add to early HS diagnosis. HS is a rare but potentially fatal complication of Lung Transplantation (LT), association with DU has been hypothesized. Optimal screening methods to prevent/diagnose HS early are uncertain. Both pulmonary DU PCR and daily Serum Ammonium Screening (SAS) have been suggested. We investigated HS and the association with DU PCR and SAS. We included all LT recipients from 07/2019-02/2020 and 10/2021-03/2022 with available donor bronchial wash samples from the LT Biobank. Briefly, DNA was extracted using Qiagen DNA kit and Mollicute PCR performed using an AMPIPROBE® Ureaplasma spp. / M. genitalium / M. hominis Assay Kit. Generation of a cycle number (Ct) value of 30 was considered positive as recommended by manufacturer. Recipients were prospectively followed for HS symptoms for 30 d post-LT. Daily ammonia serum levels were measured for the first 14 days (d) as per center-specific practice, and thereafter if clinically indicated. HS was defined by new neurological symptoms and the presence of elevated serum ammonium (>70 umol/l). We compared patients who developed HS with to those who did not. Of 139 LT recipients, 4 (2.8%) developed HS during the study period. Recipient and donor characteristics of LT recipients with and without HS are shown in Table A. All HS cases were diagnosed within the first 14 days, while daily SAS was in place, median time to HS was 7.5 days (IQR 4,11). DU PCR was found to be positive in 4.3% (6/139) at transplant. Only 1/4 cases of HS was associated with a positive DU PCR. HS was treated with Moxifloxacin/Doxycycline combination (4/4) for a median duration of 14d (IQR 12,14), 2/4 received renal replacement therapy. No patient died within 180 days post HS diagnosis. HS was a rare complication in our LT cohort. The low prevalence of DU detection in our cohort questions the utility of donor screening. Daily SAS of the recipient might add to early HS diagnosis.