Search for new antimicrobials against extended spectrum β-lactamase-positive Escherichia coli: Potential of fungi from the phylum Ascomycota

Pathogenic strains of Escherichia coli can cause gastrointestinal infections, urinary tract infections (UTIs), bacteremia, and other severe infections. Some isolates of this species are capable of producing extendedspectrum (3-lactamase (ESBL) enzymes, which mediate resistance against penicillin derivates and cephalosporins. Fungi of the Ascomycota phylum are known to produce antibiotics from different classes with activity against various bacterial agents. Among them, the genera Penicillium, Cephalosporium, Acremonium and Fusidium are known for the production of antimicrobial substances such as penicillin derivates, cephalosporins and fusidic acid. Currently, the search for new antimicrobials produced by species of the Ascomycota phylum includes the assessment of less explored habitats including aquatic environments, extreme environments, and the interior of plants/animals. The genus Penicillium remains promising for the discovery of new antimicrobial substances against resistant bacteria. In addition, those fungi have also been investigated regarding their usefulness for the biosynthesis of nanoparticles with antimicrobial activity. This narrative review introduces clinically relevant Escherichia coli pathovars, the historical contributions of the phylum Ascomycota to the production of antimicrobials, aspects of bioprocesses in the production of antimicrobial metabolites and different approaches of research targeting new antimicrobials such as screenings for fungi in environments not yet studied and the green synthesis mediated by fungi with antimicrobial activity.