Association of extended-spectrum beta-lactamase genes and biofilm formation in Escherichia coli isolated from poultry in western Algeria

Background. Antibiotic resistance is a well-known problem worldwide and of particular concern is extended spectrum β-lactamase (ESBL)-producing Escherichia coli strains. Biofilm producers increase the spread and persistence of antibiotic resistance. The aim of this study was the evaluation of biofilm formation by extended spectrum beta‐lactamase (ESBL)‐producing E. coli strains isolated from healthy broiler chicken samples in Western Algeria. Materials/Methods. A total of 10 ESBL‐producing E. coli strains and one ESBL negative strain, isolated from poultry were evaluated for their ability to form biofilm by crystal violet staining assay. E. coli ATCC 25922 was used as positive control. The extent of biofilm formation was determined by applying the following formula: BFS = (AB-CW)/G, where BFS is the specific biofilm formation, AB is the OD 492 nm of stained attached bacteria, CW is the OD 492 nm stained control wells containing bacteria-free medium only and G is the OD 492 nm of cells growth in suspended culture. Results. Among ESBL producing E. coli strains only one, carrying SHV gene, was classified as moderate biofilm producers. Contrariwise, E. coli ATCC 25922 (non beta-lactamase producer) and the ESBL negative E. coli strain were classified moderate biofilm producers (p<0,05). Relationships between biofilm formation and ESBL genes expression were evaluated. As shown in our previous study, 8 (80%) of these ESBL producing E. coli strains possessed TEM gene, one (10%) had SHV gene and another one possessed both TEM and CTX-M-1 genes. Taken together our results highlighted a relationship between the expression of the TEM gene and a defect in biofilm formation. The presence of SHV gene does not affect the production of biofilm instead. Moreover, the co-expression of the TEM and CTX-M-1 genes does not increase the biofilm production. Conclusion. The ability of biofilm formation was found to be significantly higher in non ESBL producing strains of E. coli than in ESBL producing strains which had TEM gene, suggesting that the expression of TEM gene, belonging to class A beta-lactamases, can negatively impact biofilm formation in E. coli.