Table 2.

The basal biofilm production of the different isolates

A540 < 0.1	A540 0.1-1	A540 > 1
ESBL 6, ESBL 7, ESBL 9, UPEC 4, UPEC 5	ESBL 1, UPEC 2, UPEC 3, MG1655	TG1

Basal biofilm production after 24 h in ESBL-producing isolates (ESBL), non-ESBL-producing UPEC isolates (UPEC) and non-pathogenic E. coli K-12 strains (MG1655 and TG1) evaluated by the crystal violet method and measured by absorbance levels (A₅₄₀). Detectable biofilm production was considered at A₅₄₀ ≥ 0.1. Mean values from three to six independent experiments