Rapid discrimination methods for clinical and environmental strains of Aeromonas hydrophila and a. veronii biovar sobria using the N-terminal sequence of the flaA gene and investigation of antimicrobial resistance.

Although the genus Aeromonas inhabits the natural environment, it has also been isolated from hospital patient specimens as a causative agent of Aeromonas infections. However, it is not known whether clinical strains live in the natural environment, and if these strains have acquired antimicrobial resistance. In this study, we performed the typing of flagellin A gene (flaA) of clinical and environmental strains of A. hydrophila and A. veronii biovar sobria using PCR assay with newly designed primers. Detection rates of the clinical and environmental flaA types of A. hydrophila were 66.7% and 88.2%, and the corresponding rates for A. veronii bv. sobria were 66.7% and 90.9%. The PCR assays could significantly discriminate between clinical and environmental strains of both species in approximately four hours. Also, among the 63 clinical Aeromonas strains used, only one extended-spectrum β-lactamase (ESBL)-producing bacteria, no plasmid-mediated quinolone resistance (PMQR) bacteria, and only four multidrug-resistant (MDR) bacteria were detected. Therefore, the PCR assays could be useful for the rapid diagnosis of these Aeromonas infections and the monitoring of clinical strain invasion into water-related facilities and environments. Also, the frequency of drug-resistant Aeromonas in clinical isolates from Okinawa Prefecture, Japan appeared to be low.