Antimicrobial activity on Escherichia coli strains isolated from various clinical samples

Escherichia coli is the most isolated bacterium in clinical laboratories and is implicated in infectious diseases that affect practically all human tissues and organ systems. Given the clinical importance of this bacterium, this research aimed to determine the susceptibility of seven Escherichia coli strains (LFBM Ec 01, LFBM Ec 02, LFBM Ec 05, LFBM Ec 06, LFBM Ec 07, LFBM Ec 09, LFBM Ec 10) isolated from catheterized patients and one from the American Type Culture Collection (ATCC 25922) to ampicillin, levofloxacin, cephalothin, nitrofurantoin and cefotaxime. The antibiogram was carried out in accordance with BrCast 2020 for the solid medium diffusion method. The β-lactam antibiotics (ampicillin and cefotaxime) were able to inhibit the growth of all the strains, except LFBM Ec 01, LFBM Ec 06 and LFBM Ec 10. Cephalothin proved effective on all strains except LFBM Ec 01, LFBM Ec 05, LFBM Ec 06, LFBM Ec 09 and LFBM Ec 10. LFBM Ec 01 and LFBM Ec10 were the only strains that resisted the action of levofloxacin. All the strains were sensitive to the action of nitrofurantoin, except for LFBM Ec 01, which showed intermediate sensitivity. Of the seven Escherichia coli strains, five (LFBM Ec 01, LFBM Ec 05, LFBM Ec 06, LFBM Ec 09 and LFBM Ec 10) were resistant to any of the β-lactams used. These antimicrobials are the clinical choice for treating infections caused by Escherichia coli. This study will continue with the determination of the minimum inhibitory concentration and the study of the interaction between these antimicrobials.