Distribution of genes encoding 16S rRNA methyltransferase in plazomicin-nonsusceptible carbapenemase-producing Enterobacterales in Brazil.

Background: The presence of 16S rRNA methyltranferases (16S-RMTases) in carbapenemase-producing Enterobacterales (CPE) is a major concern because it inactivates all clinical use of aminoglycosides, including plazomicin. The aim of this study is to investigate the prevalence of 16S-RMTases in CPE nonsusceptible to plazomicin collected in different Brazilian hospitals.

Methods: All isolates with plazomicin MIC ≥ 4 µg/mL (n = 67) were screened for the presence of 16S-RMTases by sequencing.

Results: 54 (80.6%) isolates encoded 16S-RMTase genes (41 rmtB1, 7 armA, 3 rmtD2, 1 rmtD1 and 2 rmtC). Among 41 samples rmtB1 positive, 40 co-harbored bla and 1 bla gene. Of the seven isolates harboring armA gene, 6 were New Delhi Metallo-beta-lactamase (NDM)-producer. rmtD was only found in isolates Klebsiella pneumoniae Carbapenemase (KPC)-producers, one in Serratia marcescens with rmtD2, not reported in Brazil.

Conclusion: The co-existence of 16S-RMTase and CPE is worrisome because of limited treatment options and the endemic characteristic of (KPC) and NDM in Brazil.