Detection of NDM-1-Positive Aeromonas caviae from Bacteremia by Using Whole-Genome Sequencing

Purpose: Nosocomial infections caused by New Delhi metallo-beta-lactamase (NDM)-producing bacteria are prevalent worldwide. However, such diseases caused by NDM-producing Aeromonas caviae had never been reported. Our study aimed to elucidate the genomic characteristics of NDM-1-producing A. caviae isolated from hospital patients. Methods: Bacterial genomic features and possible origins were assessed by whole-genome sequencing (WGS) and phylogenetic analysis. Subsequent investigations include antimicrobial susceptibility testing and multilocus sequence typing (MLST). Results: We identified here two NDM-1-producing A. caviae isolates from bacteremia. Susceptibility testing showed that two isolates were multi-drug resistant and shared a similar resistance profile and were only sensitive to amikacin and trimethoprim/sulfamethoxazole. Both A. caviae isolates carry the carbapenem resistance gene bla(NDM-1) and also have antibiotic resistance genes such as beta-lactams, AmpC enzymes, macrolides, aminoglycosides, and quinolones. S1-PFGE and Southern blot analysis were negative. Whole-genome sequencing and comparative analysis revealed that these two isolates shared a close relationship. Conclusion: To the best of our knowledge, this work describes the first detection of non-plasmid encoded bla(NDM-1) in A. caviae. The A. caviae isolated in this study has a broad drug resistance spectrum. Phenotypic and molecular analysis indicated the two isolates belong to the same clone. Routine genomic surveillance of this species is now necessary to effectively curb the further dissemination of carbapenem-resistant bacteria in the region.