Epsilon Archive for Student Projects

Abstract

Strains of Aeromonas spp., `non–cholera vibrios´(NCVs) and Plesiomonas shigelloides isolated from aquatic environments and fish and human diarrhoeal cases in the Philippines and Thailand were characterised for potential virulence
markers, such as the production of cytotoxin, cell-associated and cell-free haemolysin and their capacity to adhere to human intestinal (Henle 407) cells in
vitro. In addition, the occurrence of tlh and tdh haemolysin genes and urease activity among Vibrio parahaemolyticus strains were also investigated.

The antimicrobial susceptibility profile of these strains was identified with selected antibiotics used in human medicine and aquaculture. The minimum inhibitory concentration of ampicillin, ceftiofur, gentamicin, neomycin,streptomycin, enrofloxacin, florfenicol, oxytetracycline and trimethoprimsulphamethoxazole
was determined using broth microdilution method.

Susceptibility to imipenem and detection of extended-spectrum β-lactamases (ESBLs) in ampicillin resistant strains was achieved by the combination disc diffusion method.

The results showed that strains recovered from clinical sources (human and fish)produced the investigated potential virulence determinants, while these are absent in environmental strains. Such virulence factors may be involved in the pathogenesis of disease caused by these bacterial pathogens in both humans and animals.

Moreover, antimicrobial resistance among environmental strains was rare. Acquired resistance to tetracycline and fluoroquinolone was demonstrated in Aeromonas strains of clinical origin and it could be possible that acquired
resistance is associated with the use of antimicrobials in therapy.