Detection of Extended-Spectrum β-Lactamases (ESBL)‎ Producing Enterobacteriaceae from Fish Trapped in the Lagoon Area of Bizerte, Tunisia

Abstract EN

Extended-spectrum β-lactamase and their molecular mechanism in Enterobacteriaceae were analyzed in 126 fish samples of 9 various wild species, living in the lagoon of Bizerte in Tunisia.

Fifty-nine (59) Gram-negative strains were isolated and identified as Escherichia coli (n=24), Klebsiella pneumonia (n=21), Citrobacter freundii (n=8), and Shigella boydii (n=6).

Forty-seven ESBL producers were identified using the synergic test.

β-Lactamase genes detected were blaCTX-M-1 (E.

coli/15; K.

pneumonia/8; C.

freundii/1; Sh.

boydii/1), blaCTX-M-1+ blaOXA-1 (E.

coli/4; K.

pneumonia/3), blaCTX-M-1+ blaTEM-1-a (K.

pneumonia/2), blaCTX-M-15+ blaTEM-1-a (K.

pneumonia/1; Sh.

boydii/1), blaCTX-M-15+ blaOXA-1 (K.

pneumonia/1), blaCTX-M-15 (E.

coli/3; K.

pneumonia/1; Sh.

boydii/3), and blaCTX-M-9 (C.

freundii/3).

Most strains (84.7%) showed a multiresistant phenotype.

qnrA and qnrB genes were identified in six E.

coli and in ten E.

coli+one K.

pneumonia isolates, respectively.

The resistance to tetracycline and sulfonamide was conferred by the tet and sul genes.

Characterization of phylogenic groups in E.

coli isolates revealed phylogroups D (n=20 strains), B2 (n=2), and A (n=2).

The studied virulence factor showed prevalence of fimA genes in 9 E.

coli isolates (37.5%).

Similarly, no strain revealed the three other virulence factors tested (eae, aer, and cnf1).

Our findings confirmed that the lagoons of Bizerte may be a reservoir of multidrug resistance/ESBL-producing Enterobacteriaceae.

This could lead to indisputable impacts on human and animal health, through the food chain.