Escherichia coli is a famous Gram-negative bacillary bacterium that belongs to Enterobacteriaceae. It is either micro-biota innocent for human or pathogenic with arrays of diseases. The pathogenic E. coli can be assigned to intestinal (InPEC) or extraintestinal (ExPEC) with disease ranging from watery diarrhea to pulmonary distress. The most prevalent form of InPEC is enteropathogenic E. coli (EPEC), while the most prevalent ExPEC is uropathogenic E. coli (UPEC). The other InPEC includes Shiga toxin–producing (STEC), enteroaggregative (EAEC), enterotoxigenic (ETEC), enteroinvasive (EIEC), diffusely adherent (DAEC) and adherent invasive E. coli (AIEC). ExPEC was implicated in cystitis, pyelonephritis, sepsis, respiratory tract infection, cervicovaginal infection (CVEC), meningitis (NMEC), otitis media, cholecystitis and wound infection. Antibiotic resistance is the challenging in world nowadays. Multidrug-resistant (MDR) Escherichia coli has become challenging with existing antibiotic options. E. coli pathogens have various virulence factors that determine their pathogenesis and antimicrobial resistance mechanisms. The rapid and ongoing spread of antimicrobial-resistant organisms threatens our ability to successfully treat a growing number of infectious diseases. It is well established that antibiotic use is a significant, and modifiable, driver of antibiotic resistance. The most commonly used antibiotic classes for InPEC and ExPEC were third-generation cephalosporin, carbapenem, fluoroquinolone and aminoglycosides. Actually, the most effective prescribed medication is one of the following: cefotaxime, ceftriaxone, ciprofloxacin, amikacin, gentamycin, levofloxacin and imipenem. Generally, according to our review for more than 100 local Iraqi studies among Iraqi provinces, the results revealed the resistance rate from highest to lowest as follows: cefotaxime (76.5%), ceftriaxone (75.9%), gentamycin (41.65%), ciprofloxacin (32.13%), amikacin (17.3%), levofloxacin (15%) and imipenem (5.14%). The resistance mechanisms may include genes encoding antibiotic-modifying enzymes like those of extended-spectrum beta-lactamases gene comprising: blaCTX-M, blaTEM, blaSHV, blaOXA, blaPER, blaVIM, blaIMP, blaNDM and blaAMPc. Efflux pumping includes AcrAB, while resistance to quinolone may be mediated by mutation among qnrA, qnrB, qnrD and qnrS. Resistance to aminoglycosides includes encoding to aminoglycoside-modifying enzymes like aac(6)-Ib, aph(3)-I, aph(3)-IIa, aph(3)-Ib, ant(3)-I, aac(3)-II and aac(3)-IV.
Part of the book: E. Coli Infections