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Phenotypic and Molecular Characterization of AmpC β-Lactamases among Escherichia coli a Prospective Study in Southeast Iran by Roghayeh Gholizadeh Doran Mahalleh, Nadia Kazemi-Pour, Farokh Rokhbakhsh-Zamin

Background: Escherichia coli (E. coli) causes serious health problems due to the high rate of its resistance to common antibiotics. AmpC β-lactamases are important cephalosporinases, encoded by E. coli chromosome, that cause resistance to cefoxitin, cephalothin, most penicillins, cefazolin, and beta-lactamase inhibitor-beta-lactams. This study aimed to detect AmpC β-lactamases among E. coli strains at three educational hospitals in Iran.
Methods: Two hundred and thirty samples were recovered from the three educational hospitals in Zahedan City in southeast Iran. Sixty E. coli strains were identified by biochemical and differential tests. E. coli strains with extended-spectrum β-lactamases (ESBLs) were selected by disk-diffusion agar method and combined diffuse disc test. Finally, selected isolates were screened by polymerase chain reaction (PCR) for the common AmpC genotypes MOX, FOX, CIT, DHA, EBC, and ACC.
Results: Out of 60 E. coli strains, 13 isolates (21.7%) were ESBL positive and 7 strains (11.6%) were phenotypically AmpC beta-lactamase producers. Three isolates had CIT (23.1%), 5 had DHA (38.5%), 4 had EBC (30.8%), and 1 had ACC (7.7%) genotypes.
Conclusions: The high prevalence of AmpC-producing E. coli strains in hospital settings is an important challenge for health care systems. Data about beta-lactamase producers that are crucial for controlling bacterial resistance should be upgraded.

DOI: 10.7754/Clin.Lab.2020.201011