Resistance profiling, evolution of biofilm formation and genetic diversity of Vibrio alginolyticus isolated from aquaculture systems

Rim LAJNEF; Miguel Angel  MORIÑIGO; Abdennaceur HASSEN; Lotfi BEN ABDALLAH

doi:10.80367/instmbulletin.v49.1674

Authors

Rim LAJNEF Institut National des Sciences et Technologies de la Mer https://orcid.org/0000-0002-2482-1052
Miguel Angel MORIÑIGO Facultad de Ciencia de Malaga. Departamento de Microbiologia https://orcid.org/0000-0003-1452-4844
Abdennaceur HASSEN Université de Carthage. Technopôle de Borj-Cédria. Centre des Recherches et des Technologies des eaux, Laboratoire de Traitement des Eaux Usées, Hammam-Lif, Tunisia https://orcid.org/0000-0003-0555-2974
Lotfi BEN ABDALLAH Université de Carthage. Institut National des Sciences et Technologies de la Mer, Salammbô, Tunisia https://orcid.org/0000-0002-5084-0329

DOI:

https://doi.org/10.80367/instmbulletin.v49.1674

Keywords:

Vibrio alginolyticus, Aquaculture systems, PCR-RFLP, Antibiotic resistance, MAR, Biofilm formation, Tunisia

Abstract

This study analyzes 26 presumptive Vibrio alginolyticus strains extracted from two fish farms (Khenis and Hergla, East Tunisia) that raised sea bream (Sparus aurata) and sea bass (Dicentrarchus labrax). In addition, from a shellfish farm located in Menzel Jmil, North Tunisia that raises mussels (Mytilus edulis) and oysters (Crassostrea gigas).

We have evaluated (i) the discriminatory power of PCR-RFLP for identification of closely related strains, (ii) the antibiotic resistance of the V. alginolyticus strains and (iii) their ability to form a biofilm in aquaculture farm.

Results showed that there is great heterogeneity in the diversity observed via the PCR-RFLP method related to the number of 20 genotypes generated by the two enzymes SduI and FaqI tested. The heterogeneity was observed in both fish (aquaculture farm) and bivalve (shellfish farm) origins, as well as in the same sample.

For antibiotic resistance, all isolates present a high resistance to ampicillin, erythromycin, cefotaxime, kanamycin and doxycycline. The resistance is displayed by 15 distinct profiles.

The Multiple Antibiotic resistance (MAR) index was ranged from 0.55 to 0.80 for the isolates from the aquaculture farm of Hergla followed by the index aquaculture farm of Khenis (0.55 to 0.75). While for the shellfish farm of Menzel Jmil the index ranges from 0.50 to 0.65. This finding indicated high-risk sources of antibiotic contamination in the three locations. Isolates from aquaculture systems with strong biofilm formation have been found to be resistant to antibiotics, which may allow them to survive longer in these environments.

Present findings could be relevant in aquaculture systems and underscore the importance of the linkage between adhesion, antibiotic susceptibility, and genetic diversity of these pathogenic bacteria to avoid fish and shellfish diseases. The results will provide helpful guidance on how to use antibiotics to control Vibrio alginolyticus diseases in aquaculture to be healthy.