Characterization and multilocus sequence typing of Aeromonas strains isolated in Tianjin area

Abstract:

[Objective] To study the classification of Aeromonas genus and its pathogenicity. [Methods] Various environmental samples were collected, Aeromonas strains were isolated and characterized, and multilocus sequence typing (MLST) method was adopted to classify the isolates. [Results] Among the isolates 7 Aeromonas strains were identified, belonging to 4 different species of the genus Aeromonas based on 16S rRNA sequence analysis. Furthermore, 5 major virulence genes including Aera, Hly, Aha1, GACT and Nuc were detected in the isolates by PCR and sequencing methods. All strains contained at least one virulence gene, and 3 of them contained 4 virulence genes, respectively. Antibiotic susceptibility test showed that 6 strains exhibited multiple drug resistances to at least 3 antibiotics. Finally, 6 housekeeping genes (gyrB, groL, gltA, metG, ppsA, and recA) were chosen for the MLST analysis by PCR and sequencing. Allele sequences were aligned by searching the MLST database. All 7 Aeromonas strains were assigned a new ST number. [Conclusion] High genetic diversity existed in Aeromonas strains.