Antimicrobial resistance surveillance of gram-negative bacteria among solid organ transplant recipients, a 4-year retrospective study

Bacterial infections are among the major complications patients face after solid organ transplantation, resulting in substantial morbidity and mortality among them. Meanwhile, the incidence of antimicrobial resistance in gram-negative bacteria is concerning, for which establishing antibiotic stewardship programs would be essential, where an understanding of the resistance-susceptibility patterns can be detrimental. This study aims to give an understanding of this pattern in the gram-negative bacterial isolates in the past four years. In this retrospective four-year study, the resistance-susceptibility patterns of gram-negative pathogens isolated from blood, urine, sputum, wound drainage, abscess, synovial, pleural, ascitic, and cerebrospinal fluids of the adult and children patients undergoing solid organ transplantation at Shiraz Transplant Center, the biggest solid organ transplantation center of Asia, in 2020-2023. During the study follow-up period, 2075 GNB isolates were retrieved from the patients. The most frequent isolates were identified as E.coli with 765 (36.86%), Klebsiella with 684 (32.96%), Pseudomonas with 363 (17.49%), Acinetobacter with 134 (6.45%), Enterobacter with 87 (4.19%), Citrobacter with 40 (1.92%), and Stenotrophomonas maltophilia with 2 specimens (0.09%), from the highest to the lowest. Of the retrieved GNB isolates from the transplant patients, 1380 (66.50%) belonged to liver transplant recipients, 658 isolates (31.71%) belonged to kidney transplant recipients, and 23 isolates (1.10%) belonged to simultaneous kidney and pancreas transplant recipients. Carbapenem-resistant Enterobacterales, mainly carbapenem-resistant K. pneumoniae (CRKP) isolates, increased during follow-up periods. The findings of this study reveal an increasing pattern of resistance towards carbapenems in Enterobacterales, which is significant in liver transplant recipients.