Updated project metadata. Protein expression by E. coli 26561 during the late-exponential phase of cultures under anaerobic conditions was examined. E. coli 26561 is a multidrug resistant (MDR) and shows an unusual hyper-mucoviscous phenotype. Resistance includes ESBL (CTX-M-14) and proteome was determined with and without exposure to sub-MIC concentrations of the 3rd generation cephalosporin ceftazidime. Ceftazidime exposure was at two sub-MIC levels, specifically 0.25x MIC (samples 5-7), 0.5x MIC (samples 8 - 10); samples 1-4 provided the unexposed Control. Both whole and phospho-enriched fractions for each sample were analysed. Quantification of peptides was assessed using 10-plex TMT labelling in conjunction with an Orbitrap Fusion Tribrid. Raw data produced by the Orbitrap were processed using Max Quant 1.5.4.7 using the included Andromeda search engine. Peptides were searched against our own database of E. coli 26561 proteins which was produced from a hybrid assembly of our reads obtained from MiSeq and PacBio sequencing platforms.