**Abstract**

*Escherichia coli* has become a major significant pathogen behind infections, many researches have been conducted on possible drugs that can successfully eradicate the pathogenic isolates. To ensure survival*, E. coli* strains improvised resistant mechanisms to allow them to maneuver through with life among bactericidal agents. The chapter gives an overview of the antimicrobial resistance mechanisms found in major groups of antimicrobial drugs. *E. coli* uses enzymes in defying drug susceptibility for example aminoglycoside modifying enzymes in modifying drug recognition sites, in cephalosporin, penicillin the pathogen indulged in the use of β-lactamases to break down the β-lactam ring on the structure of the drugs. In fluoroquinolones, the pathogen uses efflux pumps, DNA gyrase mutation as a mechanism of resistance. The continuous use of drugs induces resistance mechanisms to increase, there is a need for continuous researches on drugs effectivity and the discovery of new and better medication to fight against *E. coli* pathogens.

**Keywords:** mutation, ESBL, efflux-pumps, genes, enzyme

## **1. Introduction**

*Escherichia coli* is one of the most primitive microorganisms that are affecting the normal body functionality, bringing sickness, attributed by infections that are becoming difficult to cure since the microorganisms are evolving with time they tend to mutate and produce different species which are resistant to drugs that were previously effective in fighting and eradicating the bacterial species. The aspect of antimicrobial resistance has become a non-healing wound in as much as health is concerned, with time the wound continues to deepen and expand bringing in more confusion, sickness as well as problems in medicinal drug references [1].

*E. coli* Resistant germs are emerging at an alarming rate, posing a growing threat to human society. Antibiotic misuse and overuse, as well as antibiotic buildup in the environment, have been blamed for the growth of antimicrobial resistance (AMR). With the pharmaceutical industry's lack of new medication development, it is becoming very difficult to tackle diseases behind the infection [2].

It is believed the long-term use of drugs on *E. coli* has brought problems in curing the infections it causes because of many adaptive mechanisms the pathogen has developed to discard drug susceptibility over time thereby allowing its survival and perpetuation [3]. According to the World Health Organization (WHO) [4], the long-term use of drugs, misuse and abuse of drugs are the foundation of creating resistant mechanisms that may lead to difficulties in prevention as well as treatment.
