**3. Classification of** *E. coli* **according to their antimicrobial resistance pattern**

The continuous emergence of resistance to antimicrobial agents among the prevalent pathogens is the most dangerous obstacle facing the treatment of infectious diseases. Many different definitions for multidrug-resistant (MDR), extensively drug-resistant (XDR), and pandrug-resistant (PDR) bacteria are being used in the medical literature to characterize the different patterns of resistance found in healthcare-associated, antimicrobial-resistant bacteria [36]**.**

Lists of antimicrobial categories proposed for antimicrobial susceptibility testing were created using documents and breakpoints from the Clinical Laboratory Standards Institute (CLSI), the European Committee on Antimicrobial Susceptibility Testing (EUCAST) and the United States Food and Drug Administration (FDA) [37]**.**

I.MDR E. coli:

MDR was defined as acquired non-susceptibility to at least one agent in three or more antimicrobial categories.

II.XDR E. coli:

XDR was defined as non-susceptibility to at least one agent in all but two or fewer antimicrobial categories (i.e., bacterial isolates remain susceptible to only one or two categories).

III.PDR E. coli:

PDR was defined as non-susceptibility to all agents in all antimicrobial categories. To ensure the correct application of these definitions, bacterial isolates should be tested against nearly all of the antimicrobial agents within the antimicrobial categories and selective reporting and suppression of results should be avoided [37].
